Themes of major importance

for SOLAS research over the next decadeEarly white paper draft versions- October 2013

This preliminary draft is intended as a consultation document.

Comments/edits welcome. Please do not use or cite.

Table of Contents

1 Theme 1: Greenhouse gases and the oceans..................................................................................................2

2 Theme 2: The air-sea interface and fluxes of mass, energy.............................................................................7

3 Theme 3: Atmospheric nutrient and particles supply to the surface ocean.....................................................11

4 Theme 4: Interconnections between aerosols, clouds, and ecosystems........................................................17

5 Theme 5: Ocean emissions and tropospheric oxidizing capacity...................................................................22

6 Theme 6: Interconnections between ocean biogeochemistry and stratospheric chemistry............................25

7 Theme 7: Multiple stressors and ocean ecosystems......................................................................................27

8 Theme 8: High Sensitivity Systems- HS2........................................................................................................31

1

2

1 Theme 1: Greenhouse gases and the oceansAuthor: Christoph Heinze

1. Brief statement defining the theme:The major driving forces for on-going climatic change are large additions of greenhouse gas to the Earth system resulting from human activities. The natural cycles of these greenhouse gases in the oceans and troposphere interact with these unprecedented direct inputs and lead to climatic feedbacks as well as environmental impacts, which need to be identified, quantified, and predicted on local to global scale and on a variety of different time scales.

2. The scientific and societal basis justifying research on this issue. Why is it critical and why does it need to be done now? What is the end goal? Why is international coordination required?Scientific basis: For the present increase in greenhouse gases - notably CO2, N2O, and CH4 - no adequate paleo-analogue exists. While for the inorganic carbon cycling a well-developed fundamental research framework has been established, still oceanic and atmospheric measurements are lacking in specific key regions - and especially the Southern Ocean. For the modulation of the carbon cycle through biologically induced changes our process-based knowledge is very poor. This applies as well for the increasing ocean acidification and associated impacts/feedbacks. The N2O and CH4 cycles are still less well understood than the carbon cycle, especially in view of changing physical as well as chemical boundary conditions. Global databases for N2O and CH4 are only slowly emerging. The potential vulnerabilities of ocean carbon uptake as well as potentially further strongly increasing ocean based greenhouse gas sources must be identified and taken into account in estimating future greenhouse gas budgets for the Earth system. Societal basis: A firm understanding and quantification (past, present, future) of greenhouse gas sources and sinks is key to predict climatic change and environmental change appropriately within the on-going Anthropocene. Energy production, food production, redistribution of goods, access to natural resources and local societal infrastructures are dependent on a best possible understanding and governance of related biogeochemical cycles. Why is it critical and why does it need to be done now? We are currently at the beginning of an accelerating climatic and environmental change due to increasing population and emergent greenhouse gas emissions on the pessimistic/high side of potential alternatives. There are two major reasons why research on ocean-atmosphere interaction of greenhouse gases is essential: 1. We need to provide a description of the present state of greenhouse gas budgets and related Earth system variables now, in order to have a reference point for calibrating predictive models better once climatic/environmental change will have progressed more strongly in the coming decades. 2. We need to set up a complete as possible spectrum of processes and greenhouse gas interactions to determine whether postulated and emergent feedbacks, impacts, as well as vulnerabilities are occurring as predicted or whether new surprises become evident. What is the end goal? The end goal of the theme is to provide integrated predictive capabilities of the distribution of key greenhouse gases - primarily CO2, N2O, and CH4 – in the ocean-atmosphere system including impacts, feedbacks, and vulnerabilities for optimal design of mitigation/adaptation measures concerning management of the carbon and nutrient cycles worldwide. Why is international coordination required? Observations on greenhouse gases - data collection (ships, aircraft, satellites, automated devices) as well as in-situ, laboratory, and mesocosm experiments - and Earth system modelling including dynamical interactive greenhouse gas cycles are expensive undertakings and cannot be carried out in national isolation. Data sets on measurements and modelling have to be merged from different originators in a sound way in order to achieve calibrated, homogeneous, and quality checked data synthesis products. Earth system models need to be developed within the context of international discussion, as hardly at every modelling centre key expertise on all critical aspects is present.

3. Background – major scientific concepts, key prior work defining the issues:Coupled cycles: CO2 is still the major anthropogenic greenhouse gas directly emitted into the atmosphere and then partially taken up by the ocean and land. In recent years, increasing focus has emerged also on other important greenhouse gases whose cycle is influenced by human behaviour and climate/environmental change. After all, the cycles of CO2, CH4, and N2O are interlinked, e.g. after release of CH4 from gas hydrates it becomes relatively quickly oxidised to CO2, N2O production is highest near production of biogenic organic matter (N2

3

fixation) or its degradation at low oxygen levels (denitrification). Though considerable knowledge gaps concerning the CO2 related carbon cycle still exist, uncertainties with respect to CH4 and N2O are presumably even higher. The cycling of CH4 is critically linked to warming (destabilisation threshold) and tectonics, the N2O cycle is linked to a multitude of other factors influenced by human beings (de-oxygenation, nutrient inputs from continents and artificial fertiliser production/use, increased water column stratification and slowing ocean circulation as consequence of warming). Vulnerable greenhouse gas sources/sinks: Oceanic cycling of greenhouse gases may undergo potential critical changes for the different long-lived gases CO2, N2O, and CH4. For CO2 buffering it is critical that water saturated already with respect to CO2 is mixed downward in the water column and replaced by water masses carrying still lower CO2 loads. In the recent past, transient decreases in CO2 sink strengths have occurred in regions, which so far are hot spots of anthropogenic carbon storage (northern North Atlantic, Southern Ocean; Watson et al., 2009; Le Quéré et al., 2007). On the other hand until the end of this century, the Southern Ocean is projected to become one of the strongest sink regions for anthropogenic carbon. Do these predictions hold? Will evidence from observations support this? For modulation of anthropogenic CO2 uptake rates through the biological pump, a change in size spectra of marine particle flux under warming/increased stratification and less CaCO3 ballasting could lead to shallowing of the organic carbon remineralisation depth interval with a corresponding increase in outgassing (e.g., Laws et al., 2000; Klaas and Archer, 2002). On the other hand, carbon overconsumption in response to ocean acidification has been suggested as a potential negative feedback (Riebesell et al., 2007). O2/N2 measurements in the atmosphere so far do not directly indicate such changes but do not exclude them for the future as yet. For N2O, decreased upwelling and de-oxygenation in conjunction with eutrophication and slowing overturning increase production, especially close to continents (Naqvi et al., 2010). Further increases in marine levels N2O could occur through a potential stimulation of N2 fixation if dust deposition and additional iron supply would happen, though the change of atmospheric dust mobilisation, transport, and deposition is not yet conclusively quantified (Mahowald and Luo, 2003). For the open ocean, N2 fixation has been proposed to be the key source of N2O (Freing et al, 2012). Potential marine CH4 sources could occur due to accelerating deoxygenation and respective methanogenesis in very low oxygen regimes (water column, sediment) especially in shallow seas and at the continental margins, but also especially due to large scale destabilisation of methane gas hydrates once the stabilisation point (temperature, pressure) has been reached under global warming. Arctic Ocean shallow shelves (sub-sea permafrost areas) and continental margin areas may be susceptible (Biastoch et al., 2011), as they are areas of higher tectonic activity. Critical oceanic GHG domains are marked in Figure 1. Observational systems and related data sets: A suite of recent data syntheses and data collections concerning the marine carbon and nitrogen cycles has emerged (GLODAP, CARINA, PACIFICA, SOCAT, MEMENTO). Still some oceanic areas are highly under sampled in space and time. Modelling efforts, MIPs and related data sets: For climate projections on timescales of several centuries, coupled Earth system models (ESMs) have been developed which include detailed chemical and biogeochemical interactions as far as relevant process knowledge is available. Output data sets are available through large international model intercomparison projects (MIPs) such as CMIP5. Combining observations and models: Data assimilation of biogeochemical ocean models is still in its infancy but progress has been made in implementing sequential as well as variational methods for ocean biogeochemical models. The emergent constraint approach (e.g. Cox et al., 2013) can provide a short cut for identifying the potentially most reliable models for future projections.

4

Figure 1: Overview on critical areas for modifications of atmospheric greenhouse gases through the ocean.

4. Approaches – what will it take to make substantive progress on the issue? What will be achieved in the 10 years of Future SOLAS? APPROACHES: Dynamical process formulations and firmer knowledge about impacts: The various drivers for modifications of greenhouse gas fluxes such as changes in ice cover, reactive nitrogen input into the ocean, warming, ocean acidification, and increasing stratification need to be linked in a dynamical way to the respective impacts and feedbacks. This can be achieved to some degree by laboratory and mesocosm experiments. In addition, a biogeographical approach is needed, where case studies in selected key regions along physical and biogeochemical gradients are carried out in order to ground truth findings from artificially forced experiments. Bridging the spatial scales: In order to quantify and predict oceanic greenhouse gas budgets and related air-sea fluxes correctly, the highly heterogeneous continental margins have to be included in global budgets (as well as for national greenhouse gas budgets to close budgets across national borders). This is a particular challenge as outlined by Regnier et al. (2013). Respective higher resolution coupled ocean-atmosphere models including biogeochemical cycles need to be developed, which allow for a proper representation of continental margins and shallow seas in greenhouse gas budgets. This is of particular importance to upwelling systems and areas of large N2O production. Better observational coverage in space and time through automated systems: In order to assess variations in greenhouse gas fluxes within the ocean and across the air-sea interface still a far denser observing system is needed. Automated systems need not only be installed on ships, but also on floats. Some progress has been made to install O2 sensors on ARGO floats. Calibration problems still need resolving. With high priority also pH sensors and highest-accuracy alkalinity sensors are needed in order to monitor changes in ocean acidification and their impacts. Remotely sensed atmospheric greenhouse gas concentrations need to be linked to oceanic measurements. Combining models and observations: The combination of observations and models through systematic performance assessment and data assimilation will improve the models through optimisation of free parameters in process descriptions and also elucidate the reason for regional variations in marine greenhouse gas sources and sinks. Both sequential and variational methods are being implemented currently and may come to full operational state within the next pentad.ACHIEVEMENTS:● Combined Observing-modelling capabilities will be created in order to monitor expected and potentially un-expected changes in GHG budgets and allow a better check on emission reductions.● Transformations of biogeochemical cycles and ecosystems under multiple stressor forcing will be assessed and predicted including the effects of ocean acidification, de-oxygenation, and reactive nitrogen deposition to the ocean.

5

● Internationally coordinated data syntheses actions will provide legacy data sets as reference for future generations when climate as well as environmental change will have progressed more severely than now. This includes also high accuracy CaCO3 and BSi (biogenic silica hard parts) production maps for the world ocean.● An improved estimate of the varying land carbon sink through better ocean/atmosphere assessment including O2 budgets will be achieved. This is important especially in view of the current discussion about nutrient limitation of the terrestrial carbon fertilisation effect. ● Standardised procedures, formats, models, observations will be made open access to a wide user community working on climate mitigation/adaptation.

5. Community readiness – is there an existing community engaged on this issue? Are there institutional or other barriers to progress? Is infrastructure or human capacity building required in order to achieve the goals?Community readiness – is there an existing community engaged on this issue? Worldwide projects such as SOLAS, IMBER, IOCCP, and GCP have essentially contributed to recent achievements in quantifying marine greenhouse gas fluxes. The recently established international ocean acidification coordination centre (OA-ICC) is underpinning this collaboration. Continent-/basin-wide projects have provided actual resources to carry out respective research work such as OCB (US), the EU framework programmes 6 and 7 (with CARBOOCEAN, CARBOCHANGE, EPOCA, and more), PICES and others. Linking the South American and in particular African communities needs still a lot of improvement though progress could be made (e.g. cooperation with CSIR South Africa, and Morocco). Ocean carbon cycle research is also supported through CLIVAR (repeat hydrography programme). The community is linked to GEO and GOOS/FOO through a number of projects. Are there institutional or other barriers to progress? An increasing number of joint projects between the terrestrial, atmospheric, and oceanic greenhouse gas communities have emerged over the past decade, but still the disciplinary groups work quite separately. Specifically targeted projects and collaboration networks may help to enhance the communication and joint research work between these communities further. A better link to LOICZ for incorporating the coastal oceans in worldwide greenhouse gas budgets would be welcomed. With respect to oceanic greenhouse gas cycling, the spatial discrimination between SOLAS (upper ocean) and IMBER (deep ocean) is somewhat artificial from an oceanographic point of view. Therefore, the SOLAS-IMBER carbon groups (SIC, WG1-3) have been implemented. Concerning the coordination of international research, IOCCP and OA-ICC are encouraged to collaborate closely with each other in order to avoid fragmentation of the research coordination worldwide. Is infrastructure or human capacity building required in order to achieve the goals? Ocean observations as well as Earth system modelling are both expensive undertakings. Optimal international coordination and use of research vessels as well as supercomputers is essential for greenhouse gas research. Tracer measurements should be done as multi-tracer data sets in order to correlate as many as possible different variables from the same casts. A particular problem is the storage of large model data sets as computer power progresses faster than storage technology. Transdisciplinary collaboration is needed to take into account for and implement dynamics of human behaviour (economics, energy, matter flow/waste handling, etc.) also in the Earth system models through interactive modules. Personnel for professional data management have to be trained and sustained, in particular also to facilitate data extraction from the substantial data archives.

6. External connections – what partnerships are required in order to achieve the goals? What mechanisms will be used to accomplish the interactions?As outlined in section 5, the ocean greenhouse gas communities are already based on established projects, which are linked through coordination mechanisms (IOCCP, OA-ICC). Therefore, a firm framework for collaboration and communication is already in place. Concerning the collaboration between modellers and observing scientists, one may envisage a task team – possibly as part of the already well functioning SIC groups – on greenhouse gas data assimilation and Earth system modelling (with links to their respective programmes and networks such as WCRP and ENES). Further the SIC groups may open up to also include research on nitrogen cycling and N2O.

6

7. Sustainability – articulate relationship (if any) between this project and the FE goals of Global Development and Transformation Towards Sustainability.Optimal information and knowledge concerning greenhouse gas fluxes are the foundation for informed policy decisions on measures for climate mitigation and adaptation. Integration of ocean-atmosphere greenhouse gas cycling is therefore a condition sine qua non for any development towards sustainability (impacts of greenhouse gases – also through ocean acidification, sources/sinks of greenhouse gases, optimal pathways for emission reductions etc.). Because greenhouse gas emissions and greenhouse gas levels in the atmosphere and ocean are tightly coupled to energy production, food supply, land use (including fertiliser applications), traffic, and also health, the research topic is at the heart of FE.

References:Biastoch, A., T. Treude, L. H. Rüpke, U. Riebesell, C. Roth, E. B. Burwicz, W. Park, M. Latif, C. W. Böning, G. Madec, and K. Wallmann, 2011, Rising Arctic Ocean temperatures cause gas hydrate destabilization and ocean acidification, Geophysical Research Letters, 38, L08602, doi:10.1029/2011GL047222.

Cox, P. M., D. Pearson, B. B. Booth, P. Friedlingstein, C. Huntingford, C. D. Jones, and C. M. Luke, 2013, Sensitivity of tropical carbon to climate change constrained by carbon dioxide variability, Nature, 494, 341-344, doi:10.1038/nature11882.

Freing, A., D. W. R. Wallace, and H. W. Bange, 2012, Global oceanic production of nitrous oxide, Phil. Trans. R. Soc. B, 367, 1245–1255, doi:10.1098/rstb.2011.0360.

Klaas, C., and D. E. Archer, 2002, Association of sinking organic matter with various types of mineral ballast in the deep sea: Implications for the rain ratio, Global Biogeochemical Cycles, 16(4), 1116, doi:10.1029/2001GB001765.

Laws, E.A., P. G. Falkowski, W. O. Smith Jr., H. Ducklow, J. J. McCarthy, 2000, Temperature effects on export production in the open ocean, Global Biogeochemical Cycles, 14(4), 1231-1246.

Le Quéré, C. Rödenbeck, E.T. Buitenhuis, T.J. Conway, R. Langenfelds, A. Gomez, C. Labuschagne, M. Ramonet, T. Nakazawa, N. Metzl, N. Gillett, and M. Heimann, 2007, Saturation of the Southern Ocean CO2 sink due to recent climate change, Science, 316(5832), 1735-1738.

Mahowald, N., and C. Luo, 2003, A less dusty future? Geophysical Research Letters, 30(17), 1903, doi:10.1029/2003GL017880.

Naqvi, S. W A., H. W. Bange, L. Farías, P. M. S. Monteiro, M. I. Scranton, and J. Zhang, 2010, Marine hypoxia/anoxia as a source of CH4 and N2O, Biogeosciences, 7, 2159–2190, www.biogeosciences.net/7/2159/2010/, doi:10.5194/bg-7-2159-2010.

Regnier, P., P. Friedlingstein, P. Ciais, F. T. Mackenzie, N. Gruber, I. A. Janssens, G. G. Laruelle, R. Lauerwald, S. Luyssaert, A. J. Andersson, S. Arndt, C. Arnosti, A. V. Borges, A. W. Dale, A. Gallego-Sala, Y. Goddéris, N. Goossens, J. Hartmann, C. Heinze, T. Ilyina, F. Joos, D. E. LaRowe, J. Leifeld, F. J. R. Meysman, G. Munhoven, P. A. Raymond, R. Spahni, P. Suntharalingam, and M. Thullner, 2013, Anthropogenic perturbation of the carbon fluxes from land to ocean, Nature Geoscience, published online: 9 June 2013, 11 p., doi: 10.1038/NGEO1830.

Riebesell, U., K.G. Schulz, R.G.J. Bellerby, M. Botros, P. Fritsche, M.Meyerhöfer, C. Neill, G. Nondal, A. Oschlies, J.Wohlers, and E. Zöllner, 2007, Enhanced biological carbon consumption in a high CO2 ocean, Nature, 450(7169), 545-548, doi:10.1038/nature06267.

Watson, A.J., U. Schuster, D.C.E. Bakker, N.R. Bates, A. Corbière, M. González-Dávila, T. Friedrich, J. Hauck, C. Heinze, T. Johannessen, A. Körtzinger, N. Metzl, J. Olafsson, A. Olsen, A. Oschlies, X.A. Padin, B. Pfeil, J. M. Santana-Casiano, T. Steinhoff, M. Telszewski, A.F. Rios, D.W.R. Wallace und R. Wanninkhof, 2009, Tracking the variable North Atlantic sink for atmospheric CO2, Science, 326, 1391-1393.

7

2 Theme 2: The air-sea interface and fluxes of mass, energyCo-authors: Brian Ward and Christoph Garbe

1. Brief statement defining the theme:The transfer of material across the air-sea interface is controlled by several processes including wind, waves, turbulence, bubbles, sea spray, rain, and surface films. Air-sea transfer is mostly modelled by various functional dependencies of the wind speed, but more sophisticated measurement techniques and physically based parameterisations are required to adequately describe air-sea fluxes.

2. The scientific and societal basis justifying research on this issue. Why is it critical and why does it need to be done now? What is the end goal? Why is international coordination required?The scientific and societal basis justifying research on this issue: Atmospheric greenhouse gas (GHG) concentrations (CO2 and non-CO2) are about 40% higher today than they were in 1850 and surpass all levels in the past 2M years. It is estimated that a business-as-usual scenario could cost at least 5% of annual global gross domestic product (GDP). Reduction in GHG emissions to 80-95% of 1990 levels could limit this economic cost to 1% of annual GDP.Ocean-atmosphere fluxes are some of the most critical factors affecting climate. However, these fluxes remain poorly quantified. For this reason, there is an urgent requirement to generate more scientific expertise for the quantification of air-sea fluxes.On regional scales, air-sea fluxes are a driving factor of air-quality and ecological communities. On these scales, fluxes are even less well constrained than on global ones. This is mainly due to the inhomogeneous nature of processes and their complex interactions on a wide range of scales.There is also a strong policy requirement: nothing in the current international agreements on climate specifically addresses the effects of GHG absorption in the oceans. But it is likely that future treaties will require accurate quantification of the transport of GHGs across the air-sea interface. The scientific community therefore needs to act now to develop skills required to address this.Why is it critical and why does it need to be done now? Recent evidence from observations of air-sea fluxes has shown that the North Atlantic efficiency in CO2 uptake is declining (Watson et al., 2009). The question as to whether this is a trend or whether it will fluctuate remains to be answered. At the same time, regional and meso-scale numerical models have been making significant progress in these areas, but are currently limited by our current inability to produce an accurate parameterization of fluxes.What is the end goal? The end goal is to parameterise air-sea exchange with processes that more completely describe the transport, and to accurately predict the transfer over the full range of conditions. This prediction will not be limited to global scales, but also include meso- and regional scales.Why is international coordination required? This challenge can only be addressed at the international level, as individual countries have neither the means nor the expertise to address all the scientific issues. In order to make progress, a strong interlink between measurement facilities and techniques as well as modelling capabilities are required. Particularly for regional studies, expertise in the uniqueness of the region at hand is also required.The challenge of Future SOLAS is a global one, and meeting these challenges cannot be at the national level.

3. Background – major scientific concepts, key prior work defining the issues:The oceans are the biggest reservoirs for heat, freshwater, and CO2, and distribute these constituents globally. Ocean-atmosphere fluxes are the exchanges of these quantities at the air-sea interface. Uncertainty in the quantification of these fluxes inhibits our ability to model a changing climate. Accurate knowledge of air-sea fluxes is essential for assessing the ocean’s role in climate variability, understanding climate dynamics, for forcing ocean models for predictions from weather to climate timescales.It is well recognised that the ocean and atmosphere are a coupled system which affects and is affected by climate and environmental change. Understanding the air-sea interconnection requires that the processes that control the transport across the interface be accurately quantified. The primary forcing factor for air-sea exchange is wind speed, which induces near-surface turbulence, causing the molecular boundary layer to be eroded thereby enhancing transport across the interface. Traditionally the air-sea exchange of the physical

8

parameters (momentum, sensible & latent heat) are the best understood as they have been the most widely measured, and advances in understanding the fluxes of gas and aerosols are largely based on heat fluxes. Of the GHGs, we are primarily concerned with CO2 as this contributes to radiative forcing more than the others. The air-sea exchange of aerosols is largely driven by wave breaking at the ocean surface. Turbulence in the ocean surface controls the air-sea exchange of heat, GHGs, and momentum. These exchanges heavily control the ability of the oceans to regulate climate. The ocean surface boundary layer (OSBL) also controls the subduction of atmospheric material into the ocean interior through the boundary conditions to deep-ocean stratification and dynamics. The surface ocean is therefore critical in determining the role of global ocean circulation on climate. Quantitative understanding of the turbulent processes in the OSBL is likely to be the key to understanding air-sea exchange and the role in affecting climate.

Figure 1: Processes controlling air-sea fluxes of heat, gas, momentum, and aerosols.

Figure 2: Simplified schematic of factors influencing air-sea CO2 fluxes.

4. Approaches – what will it take to make substantive progress on the issue? What will be achieved in

9

the 10 years of Future SOLAS? Approaches what will it take to make substantive progress on the issue?• Technology development for new observations: improved sensitivity and accuracy for sensors for direct gas and particle fluxes; longer battery life; deployment of microstructure sensors on platforms such as autonomous gliders and floats. • More realistic, multidisciplinary experiments, e.g. wind/wave channel experiments with full saline water, including biology, surface films • Linking measurements and models through advances in coupled models, simulating gas transfer over a wide range of Schmidt numbers.

What will be achieved in the 10 years of Future SOLAS?Ability to accurately quantify air-sea fluxes of GHG’s and particles through new observations and to better parameterize these fluxes for inclusion into Earth-System models. Significant progress will be made particularly on regional and meso-scales.

5. Community readiness – is there an existing community engaged on this issue? Are there institutional or other barriers to progress? Is infrastructure or human capacity building required in order to achieve the goals?The need for progress in understanding air-sea fluxes has been widely recognized. The community is strongly pushing forward. The questions of air-sea fluxes are major themes in national and international programs, such as the German SOPRAN or the international CARBOOCEAN initiative. Recently, there has also been a push from the earth observation community through ESA’s Oceanflux projects. Currently available satellite products have been merged to refine a more physically based parameterization and improving the accuracy of flux estimates.Is infrastructure or human capacity building required in order to achieve the goals?Capacity building is strongly needed, in order to gain expertise in the complex processes involved and their influence ranging from small-scale processes all the way to ecological impact and regional effects. Even though a strong infrastructure is in place for global assessments, this is still lacking for a wide range of very important regional studies.One of the fundamental goals for FE is to bring capacity building to developing countries. Future SOLAS should consider establishing capacity building programmes in developing countries whereby SOLAS scientists and PhD students would spend short periods training students in SOLAS science.

6. External connections – what partnerships are required in order to achieve the goals? What mechanisms will be used to accomplish the interactions?What partnerships are required in order to achieve the goals?Strong international partnerships between observationalists (linked studies in the laboratory and in the field), theoreticians, modellers and earth observationalists are required in order to achieve the set goals. Through the multifaceted and highly complex processes, strong links between disciplines such as physicists, chemists, biologist and ecologists are required. Particularly on regional scales, on which air-sea fluxes have a significant impact on ecosystems and human activities, research of this theme needs to be put in a wider context.

7. Sustainability – articulate relationship (if any) between this project and the FE goals of Global Development and Transformation Towards Sustainability.Transport of heat and mass across the air-water interface directly impacts ecosystems and is central to a number of different services important to achieve FE's goals of global development and transformation towards sustainability. Regulating services such as air quality, waste treatment, climate regulation and nutrient cycles are becoming increasingly more important, also for policy makers. Only through a better understanding of fluxes and relevant processes at the interface can predictions be made and future impacts be assessed. This theme is central to FE and might also be cross cutting to other projects such as IGAC, IMBER, iLEAPS, PAGES and CLIVAR.

References:

10

Watson, A. J., et al. (2009), Tracking the variable north Atlantic sink for atmospheric CO2,Science, 326, doi:10.1126/science.1177394.

11

3 Theme 3: Atmospheric nutrient and particles supply to the surface oceanCo-authors: Cécile Guieu, Diego Gaiero and Huiwang Gao

1. Brief statement defining the theme:The ocean receives a broad variety of particles, a range of key macro- and micronutrients, and toxic elements from the atmosphere. These materials are delivered in chemical forms and amounts that are very different from the upward supply of internally recycled nutrients from within the ocean. This atmospheric deposition affects vast regions of the ocean, including sensitive regions far from land. It is a result of both natural processes (e.g. dust deposition, volcanic eruptions) and, increasingly, by human activities (e.g. increased nitrogen deposition from pollution). Indirectly, human activity is also likely altering dust emissions/deposition with unknown feedbacks on climate and biogeochemistry. Despite significant laboratory, field and modelling work over the past decade, the links between atmospheric deposition, nutrient availability, ocean productivity (up to high trophic levels), carbon cycling and feedbacks to climate are still poorly understood and modelled.

2. The scientific and societal basis justifying research on this issue. Why is it critical and why does it need to be done now? What is the end goal? Why is international coordination required?This theme focuses on the relation between atmospheric input, the carbon cycle and feedbacks to climate. The consideration of the impacts of atmospheric input on the biogeochemistry of the ocean is quite recent (only few decades). There is a need to better understand and parameterize the numerous processes involved at a fundamental level. Work in this area is progressing thanks to recently developed tools (such as measurements of nutrients and micronutrients at very low levels both in the atmosphere and in seawater and new experimental enclosures to perform artificial seeding, etc.). Ongoing and future anthropogenic and global changes, both increasing emissions (e.g., N) and in situ conditions (stratification, pH) may induce changes in atmospheric deposition fluxes/turn over time in the surface mixed layer and in stoichiometry of the ‘new nutrients’ coming from the atmosphere. In turn, these changes may result in changes in both biodiversity and microorganism adaptive strategies for competing for nutrients. Fundamental differences in the response of the microbial community structure to the input of new nutrients (e.g. stimulation of heterotrophy v. autotrophy) will result in opposite effect regarding carbon budget depending on the balance between CO2 fixation and respiration. This is critical because it has direct implications for the way we think about productivity in the ocean and therefore atmospheric CO2 uptake and fisheries.This theme has relevance for society as it concerns global and transnational pollution issues, health of the ocean, and, via potential impacts on fish and higher trophic levels, it touches on issues closely related to deliberate (as opposed to inadvertent) fertilization of the ocean.The end goal is to assimilate all information gained from field measurements and laboratory experiments into more realistic models of deposition and associated mechanisms, taking into account the variable stoichiometry of atmospheric nutrients and surface ocean biota, with better representation of competitive interactions between plankton groups. Modeling should also include prediction considering on going and future anthropogenic and global changes, including both increasing emissions (e.g.., N) and changes in situ conditions (stratification, pH). International coordination is required considering the vast multi-disciplinary fields involved (atmosphere/ocean both for biology, chemistry, physic, modeling) and the large spatial variability observed in response to atmospheric deposition. For example, international coordination is necessary to create a network of existing time-series data to couple aerosol composition and biogeochemistry of the ocean (e.g. HOT, BATS, CVOO and DYFAMED). Such coordination could also allow for the integration/implementation into the network of new coupled atmosphere/ocean time-series in a number of key areas (Patagonia, Falkland/Malvinas) and also in HNLC area under the influence of volcano plumes (NE Pacific). The end result will be a large database integrating all the observations acquired. International coordination could also allow for conducting similar experiments in different locations, possibly employing Lagrangian studies using tracers or drifting buoys. Trace element clean mesocosms and tracer-labeled in situ manipulations could also be used to address whole-ecosystem effects of atmospheric nutrient input, including particulate organic carbon export.

12

3. Background – major scientific concepts, key prior work defining the issues:- Material transported in the atmosphere originates from a variety of natural and anthropogenic sources and contains both macro- and micronutrients (N, P, C, Si, trace metals including Fe and Cu), and potentially toxic elements (e.g. Cu, Pb) (GESAMP 1989, Duce et al. 1991, Paytan et al. 2009). Atmospheric transport and deposition are an important source of new nutrients and particles for large regions of the open ocean (GESAMP, 1989, Duce et al., 1991) and the significance of air-sea exchange to marine nutrient budgets has been established for nitrogen (Duce et al., 2008), iron (Mahowald et al., 2005; Jickells et al., 2005) and phosphorus (Mahowald et al., 2008).- Atmospheric supply of dissolved constituents to the surface ocean depends on particle concentration and size spectrum, and the solubility of the element-bearing phases in aerosols (Trapp et al., 2010; Baker and Jickells, 2006), which is influenced by atmospheric processing during transport (Krishnamurthy et al., 2009).- The main natural source of land-derived particles to the open ocean is wind-blown desert dust, which constitutes the primary atmospheric source of iron (Jickells et al., 2005) and Figure 1.- Atmospheric nitrogen is mainly derived from anthropogenic combustion or agricultural sources from densely populated regions throughout the world (Duce et al., 2008)- Phosphorus originates from both desert dust and anthropogenic sources (Mahowald et al., 2008)- The extent to which dust interacts with anthropogenic acids (H2SO4 and HNO3) during transport increases the solubility of various elements (Desboeufs et al., 2001) resulting in enrichment of nitrogen (Geng et al., 2009), and enhanced supply of potentially bioavailable compounds to the surface ocean.- Post-depositional processes associated with the quantity and quality of dissolved organic matter in seawater are very important in the bioavailability of atmospheric new (micro)nutrients (Wagener et al., 2010, Bressac and Guieu, 2013); for example it could result in a strong scavenging of iron on dust instead of dissolution from dust (Bressac and Guieu, 2013; Wagener et al., 2010; Wuttig et al., 2013).- The supply of new nutrients to the ocean from external sources such as atmospheric deposition has been extensively addressed in iron-limited High Nutrient-Low Chlorophyll regions (i.e. Boyd et al., 2007), most of which receive low atmospheric inputs at the present time (Figure 1). However, much less attention has been paid to the importance of atmospheric deposition to LNLC regions where it likely represent an important source of new nutrients for the surface mixed layer (Guieu et al., 2013). - Impact from volcanoes has been recently emphasized (see for ex. Olgun et al., 2013) with consequences up to high trophic levels.- Impact on biota from field and laboratory experiments in LNLC areas indicate positive responses to aerosol addition, with bacterial production and N2 fixation showing the strongest responses (see review Guieu et al., 2013). Increases in chlorophyll-a are seen to a lesser extent, however, differential responses among phytoplankton groups are also apparent (i.e. Paytan et al., 2009; Giovagnetti et al., 2013). Changes in standing stocks tend to be smaller than changes in metabolic rates (Guieu et al., 2013) (Figure 2). - The effect of atmospheric deposition on the surface ocean may vary with the degree of oligotrophy of the receiving waters (Marañon et al., 2010)- The effect of atmospheric deposition on the surface ocean cannot be seen as a simple fertilization effect (Guieu et al., 2013) as it results in fundamental differences in the response of the microbial community structure (e.g. stimulation of heterotrophy v. autotrophy), and hence, in the vertical carbon export and nutrient cycling (Marañon et al., 2010).- Aggregation between atmospheric particles and dissolved organic matter can induce a strong and rapid POC export independently of a fertilization effect (Ternon et al., 2010; Bressac and Guieu, 2013). This ‘lithogenic carbon pump’ (Bressac and Guieu, 2013) may significantly augment the export flux resulting from increased nutrient supply by atmospheric deposition.- Atmospheric impacts in LNLC regions have been underestimated by models as they typically overlook large synoptic variations in atmospheric deposition and the associated nutrient and particle inputs (Guieu et al., 2013)

13

Figure 1. Average estimation of dust deposition (g.m-2. yr-1) over the world oceans (Jickells et al., 2005)

Figure 2. Box-Whisker plots (mean ± standard error and 95% confidence limits) showing the responses of different biological variables to aerosol additions in LNLC waters (60% of the ocean): synthesized from available data from a total of 26 field and laboratory aerosol addition bioassay experiments, and mesocosms experiments. The responses are % changes in the aerosol treatment relative to the control after 2-8 days, with zero indicating no difference between the aerosol treatment and the control, and a positive response indicating an increase in the parameter measured for the aerosol treatment relative to the control. Parameters: (BA) Bacteria Abundance, (BR) Bacteria Respiration, (BP) Bacteria Production, (Syn.) Synechococcus abundance, (Proc.) Prochlorococcus abundance, (pico & nano-euks) Nano- and Picoeukaryotes abundance, (nano & microphyto) nano- and micro-phytoplankton abundance, (Chla) Chlorophyll-a, (PP) primary production, (N2Fix) nitrogen fixation. (Guieu et al., 2013)

14

4. Approaches – what will it take to make substantive progress on the issue? What will be achieved in the 10 years of Future SOLAS? Systematic measurements are required of atmospheric deposition and nutrients in the surface mixed layer in regions where atmospheric (natural and/or anthropogenic) supply plays an important role as in Low Nutrient Low Chlorophyll regions (Guieu et al., 2013) and also in HNLC area such as the NE Pacific. Anthropogenic nitrogen forcing is primarily a Northern hemisphere phenomenon but, as climate and ocean acidification are global drivers, there is a requirement for coupled atmosphere marine time-series sampling sites in both hemispheres. Although reliable measurements of dry deposition remain technically challenging, it will be beneficial to extend wet and dry deposition measurements and particle characterization to repeat sampling lines across regional deposition gradients and surface water biogeochemical gradients, using research vessels and voluntary observing ships. These transects should ideally accommodate rate measurements and nutrient manipulation experiments to gain insight into the proximal controls of plankton composition and process rates. Linking time-series studies of aerosol composition with oceanic time-series data (Schultz et al., 2012) is valuable for constraining the response of the marine ecosystem to deposition events. Existing time series stations that monitor both atmosphere and ocean properties (e.g. HOT, BATS, CVOO, DYFAMED) could become focal points for more detailed experiments and process studies, possibly employing Lagrangian studies using tracers and/or drifting buoys. Trace-element clean mesocosms and tracer-labeled in situ manipulations could also be used to address whole-ecosystem impacts of atmospheric nutrient input, including particulate organic carbon export. If such international effort is deployed (allowing comparative studies and data collection from time-series and data sharing, the SOLAS community should be able, within 10 years, to provide the necessary information for their assimilation into realistic models of deposition and associated mechanisms, taking into account the variable stoichiometry of atmospheric nutrients and surface ocean biota, with better representation of competitive interactions between plankton groups and aerosols/organic matter aggregation processes. Transport, deposition and biogeochemical models require thorough testing and validation against in-situ time series datasets and remote-sensing observations. In addition, methodological intercalibration, sample sharing, common reference materials and standardization of techniques are all required to ensure global coherence and quality control.

5. Community readiness – is there an existing community engaged on this issue? Are there institutional or other barriers to progress? Is infrastructure or human capacity building required in order to achieve the goals?An existing research community is addressing these issues but it is not well coordinated due to the multi-disciplinary nature of the research. In addition, in general, each group works in a dedicated area with no geographical connection with other groups (e.g.,. Sargasso Sea, East tropical Atlantic, off Patagonia, Western Pacific, Mediterranean Sea). International coordination is a difficult task because it has to be maintained over time. Recently the existing marine time-series started to coordinate their effort (Karl et al., 2003) for the marine biogeochemistry. Recently Schultz et al. 2012 proposed to set up a ‘Marine Atmospheric network’ for the long-term observation of the link between dust/iron and marine biogeochemistry. They recommended focusing on an HNLC area because of the impacts of dust in such regions. The Schultz et al. (2012) work results from GESAMP Working Group 38 ‘The Atmospheric Input of Chemicals to the ocean’. Coordinated aerosol – marine biogeochemistry measurements could also be implemented for other atmospheric nutrients that impact LNLC areas. In addition to encouraging international coordination in a “Marine Atmosphere time-series network”, SOLAS could help reach the presented goals for this theme by encouraging a large group of experts to setup a common processes studies project in a dedicated area that would be chosen by all the experts to fulfill a large number of remaining questions. Finally, research related to this theme is evolving with time; for example the potential fertilizing effect of volcanic ash is the subject of many new projects that produce important literature. Multi-disciplinary meetings where people with different interests (ex. dust, volcanic ashes, pollution) can share their experience and point of view should be encouraged.Considering all those different tasks, a dedicated person to organize a successful international effort will be necessary.

15

6. External connections – what partnerships are required in order to achieve the goals? What mechanisms will be used to accomplish the interactions?To setup a network and/or initiate a joint process studies project, SOLAS could organize a joint workshop with coordinators of GESAMP working group 38, BioGEOTRACES, ISAR (International Society for Aeolian Research*), and IMBER. Another important community is the one dedicated to understanding atmospheric deposition fluxes to the ocean. Still models yield a wide range of estimates of the ratios of wet-to-dry deposition. The knowledge of deposition over the ocean is based upon a few limited experimental data sets that are today mostly discontinued (e.g., SEAREX, AEROCE). Fostered by the World Meteorological Organization (WMO), a few monitoring stations exist that are equipped with sophisticated instrumentation (e.g., Malta and Izaña), and some programmes in Africa and Asia (e.g. AMMA, SAMUM, ACE-ASIA) and ship measurements have provided shorter-term information.

* (ISAR) scientists undertaking research in aeolian processes, landforms, and modeling, to stimulate scientific research in aeolian topics and related fields and contribute largely to understand the emission process of dust/aerosols. This community is very active in trying to improve our knowledge in subjects like the amount of dust/aerosol emitted and its embedded nutrients and largely contribute on having reasonable information on the geographic distribution of dust sources.

7. Sustainability – articulate relationship (if any) between this project and the FE goals of Global Development and Transformation Towards Sustainability.As detailed in section 3, the project will first tackle fundamental scientific questions on the impact of atmospheric deposition in biogeochemistry and (end to end) ecosystem functioning. Because we consider (via experimental approach and modelling) how ongoing anthropogenic and natural changes will modify the present functioning and how this will impact on carbon storage- one of the most important ecosystem service that ocean is providing to Man- this project can indeed be articulated with the objectives of FE.

References:Baker A.R. and T.D. Jickells (2006), Mineral particle size as a control on aerosol iron solubility, Geophysical Res. Let., VOL. 33, L17608, doi: 10.1029/2006GL026557.

Boyd, P. W., Jickells, T., Law, C. S., Blain, S., Boyle, E. A., Buesseler, K. O., Coale, K. H., Cullen, J. J., de Baar, H. J. W., Follows, M., Harvey, M., Lancelot, C., Levasseur, M., Owens, N. P. J., Pollard, R., Rivkin, R. B., Sarmiento, J., Schoemann, V., Smetacek, V., Takeda, S., Tsuda, A., Turner, S., and A.J Watson (2007), A synthesis of mesoscale iron enrichment experiments 1993–2005: key findings and implications for ocean biogeochemistry, Science, 315, 612–617.

Bressac M., C. Guieu. Post-depositional processes: What really happens to new atmospheric iron in the ocean surface? Global Biogeochemical Cycles, doi:10.1002/gbc.20076, in press.

Desboeufs, K. V., Losno, R. and J.L. Colin (2001), Factors influencing aerosol solubility during cloud processes. Atmos. Environ. 35, 3529-3537.

Duce R.A, J. LaRoche, K. Altieri, K.R. Arrigo, A.R. Baker, D.G. Capone, et.al., Impacts of atmospheric anthropogenic nitrogen on the open ocean,Science, 2008, 320(5878): doi:10.1126/science.1150369, 893-897

Duce R.A, P.S. Liss, J.T. Merill, E.L. Atlas, P. Buat-Menard, B.B. Hicks, et al., The atmospheric input of trace species to the world ocean, Global Biogeochem. Cycles, 1991, 5, 193–259

Geng, H., Park, Y., Hwang, H., Kang, S. and Ro, C.U., 2009. Elevated nitrogen-containing particles observed in Asian dust aerosol samples collected at the marine boundary layer of the Bohai Sea and the Yellow Sea. Atmospheric Chemistry and Physics, 9: 6933-6947

GESAMP, The atmospheric input of trace species to the world ocean, Rep. Stud., GESAMP, 1989, 38, 111 PP

Giovagnetti V. , C. Brunet, F. Conversano, F. Tramontano, I. Obernosterer, C. Ridame, and C. Guieu , 2013, Assessing the role of dust deposition on phytoplankton ecophysiology and succession in a low-nutrient low-chlorophyll ecosystem: a mesocosm experiment in the Mediterranean, Sea , Biogeosciences 10, 2973–2991 (SI

16

DUNE)

Guieu C., O. Aumont, A. Paytan, L. Bopp, C.S. Law, N. Mahowald, E. P. Achterberg, E. Marañón, B. Salihoglu, A. Crise, T. Wagener, B. Herut, K. Desboeufs, M. Kanakidou, N. Olgun, F. Peters, E. Pulido-Villena, A. Tovar-Sanchez, C. Völker, 2013, The significance of episodicity in atmospheric deposition to Low Nutrient Low Chlorophyll regions, Global Biogeochemical Cycles, submitted.

Jickells T.D., Z.S. An, K.K. Andersen, A.R. Baker, G. Bergametti, N. Brooks, et al., Global iron connections between dust, ocean biogeochemistry and climate, Science , 2005, 308 5718 DOI: 10.1126/science.1105959, 67–71

Karl D.M et al., Temporal Studies of Biogeochemical Processes Determined from Ocean Time-Series Observations During the JGOFS Era, Global Change — The IGBP Series (closed) 2003, pp 239-267

Krishnamurthy, A. J. K Moore, N Mahowald, C Luo, S C. Doney, K Lindsay and C S. Zender (2009), Impacts of increasing anthropogenic soluble iron and nitrogen deposition on ocean biogeochemistry. Global Biogeochem. Cycles 23, GB3016, 10.1029/2008gb003440.

Mahowald N.M, A.R Baker, G. Bergametti, N. Brooks, T.D.Jickells, R.A. Duce, et. al, The atmospheric global dust cycle and iron inputs to the ocean, Global Biogeochemical Cycles, 2005, 19: GB4025 doi:10.1029/2004GB002402

Mahowald N.M, T.D. Jickells, A.R. Baker, P.Artaxo, C.R. Benitez-Neslon, G. Bergametti, et al., Global distribution of atmospheric phosphorous sources, concentrations and deposition rates, and anthropogenic impacts., Global Biogeochemical Cycles, 2008, 22 4: GB4026 DOI: 10.1029/2008GB003240

Marañón, E., Fernández, A., Mourino-Carballido, B., Martínez-García, S., Teira, E., Cermeno, P., et al. (2010), Degree of oligotrophy controls the response of microbial plankton to Saharan dust. Limnology and Oceanography, 55(6), 2339-2352

Olgun N, Duggen S, Langmann B, Hort M, Waythomas CF, Hoffmann L, Croot P (2013) Geochemical evidence of oceanic iron fertilization by the Kasatochi volcanic eruption in 2008 and the potential impacts on Pacific sockeye salmon. Mar Ecol Prog Ser 488:81-88

Paytan A., Mackey, Y. Chen, I.D. Lima, S.C. Doney, N.M. Mahowald, et al., Toxicity of Atmospheric Aerosols on Marine Phytoplankton, PNAS, 2009, 106 doi:10.1073/pnas.08114868106, 4601-4605

Schulz, M., J. M. Prospero, A. R. Baker, F. Dentener, et al., The atmospheric transport and deposition of mineral dust to the ocean - Implications for research needs, Environmental Science and Technology, 2012, 46, 10, 390-10.

Ternon E. , C. Guieu , M-D. Loÿe-Pilot, N. Leblond, E. Bosc, B. Gasser, J. Martin, J-C. Miquel, 2010, The impact of Saharan dust on the particulate export in the water column of the North Western Mediterranean Sea, Biogeosciences, 7, 809–826, 2010.

Trapp, J. M., Millero, F.J. and Prospero, J.M. (2010), Temporal variability of the elemental composition of African dust measured in trade wind aerosols at Barbados and Miami. Mar. Chem. 120, 71-82Wagener T., Pulido-Villena E., Guieu C., 2008, Dust iron dissolution in seawater: Results from a one-year time-series in the Mediterranean Sea, Geophys. Res. Lett., 35, L16601, doi:10.1029/2008GL034581.

Wagener, T., Guieu C., Leblond N., 2010, Effects of dust deposition on iron cycle in the surface Mediterranean Sea: results from a mesocosm seeding experiment., Biogeosciences, 7, 3769-3781.

Wuttig K., T. Wagener, M. Bressac, A. Dammshäuser, P. Streu, C. Guieu, and P. L. Croot, 2013, Impacts of dust deposition on dissolved trace metal concentrations (Mn, Al and Fe) during a mesocosm experiment Biogeosciences 10, 2583-2600 (SI DUNE)

17

4 Theme 4: Interconnections between aerosols, clouds, and ecosystemsCo-authors: Trish Quinn, Ilan Koren and Rafel Simo

1. Brief statement defining the theme:Interconnections between ocean-derived aerosols, clouds, and marine ecosystems are not well understood. Assessing the system as a whole is required for an accurate understanding of how a change in one component is manifested in another as well as the potentially complex web of associated feedbacks. In addition, accurate projections of the evolution of climate and the ocean biosphere can only be achieved through a better understanding of these potential interactions and feedbacks. The intent of this theme is to assess interactions between key components of marine aerosols, clouds, and ecosystems and associated feedbacks.

2. The scientific and societal basis justifying research on this issue. Why is it critical and why does it need to be done now? What is the end goal? Why is international coordination required?Although clouds play a major role in climate and account for approximately two thirds of Earth’s albedo, they are the least understood component of the climate system and carry the largest uncertainty in global warming projections (Forster et al., 2007). Interactions between aerosol and clouds and impacts of the biosphere on both aerosols and clouds contribute to this uncertainty. Links between oceanic ecosystems and clouds may act as either amplifiers or buffers of climate variability.Changes in cloud properties may impact ecosystems, including plankton physiology and dynamics, by altering incident radiation, precipitation, surface winds, the ocean mixed layer energy budget, and sea surface temperature. At the same time, aerosols alter the microphysical (e.g., cloud droplet number concentration and size distribution) and macrophysical (e.g., extent and lifetime) properties of clouds by acting as seeds for cloud droplet and ice crystal formation, i.e., by serving as cloud condensation nuclei (CCN) and ice nuclei (IN). A large fraction of the emission and production of ocean-derived CCN occurs in remote regions where concentrations of continentally derived CCN are low. In these regions, clouds are particularly susceptible to small changes in aerosol concentration. Due to the scarcity of measurements and limited modelling capabilities, the emission, formation, transformation, and climate effects of ocean-derived aerosols are poorly understood. Hence, this theme will focus on first order problems including the biological, physical and chemical processes that determine the emission, production, and composition of ocean-derived aerosols and their effects on clouds. A first step is to obtain the data necessary to develop empirically constrained parameterizations of the emission flux and production rates of ocean-derived sea spray aerosol (SSA) and gaseous precursors of secondary aerosol (SA) and their impacts on cloud properties. The goal is to develop parameterizations for use in chemical transport models (CTMs), cloud resolving models (CRMs) and global climate models (GCMs) to accurately estimate impacts of ocean-derived aerosols on cloud properties and associated feedbacks on marine ecosystems. A concerted effort involving shipboard measurements, remote sensing, and modelling studies is required to achieve these goals. The research will be interdisciplinary in nature involving oceanographers and atmospheric scientists. Current limitations in funding and ship time require that resources be pooled and that the effort be internationally coordinated.

3. Background – major scientific concepts, key prior work defining the issues:Primary ocean-derived SSA is produced from the entrainment of air bubbles as waves break on the ocean surface. When injected to the atmosphere, the bubbles burst and yield SSA composed of both inorganic sea salt and organic matter. SSA is highly enriched in organic matter relative to seawater, especially for particles less than 500 nm in diameter (Keene et al., 2007; Facchini et al., 2008; Bates et al., 2012). The composition of the organic fraction is not fully known but has been reported to be composed of viruses, bacteria, microalgal debris, biogenic polymeric and gel-forming organic material (Facchini et al., 2008; Hawkings and Russell, 2010; Orellana et al., 2011). The processes controlling the source of the organics are not well understood and the impact of organics on the ability of SSA to act as CCN or IN and nucleate cloud droplets is very uncertain. This uncertainty is due, in large part, to a scarcity of measurements of freshly emitted SSA. Current model estimates of the flux and climate impact of SSA either do not take into account the organic component or parameterize the

18

organic component based on surface seawater chlorophyll concentrations (e.g., Rinaldi et al., 2013). Chlorophyll is a measure of phytoplankton biomass but does not account for species composition, physiological status, productivity and non-phytoplankton planktonic activity, all of which may play a role in the production of organic matter available for incorporation into SSA. Secondary aerosols (SA) form by nucleation of low volatility, oxidized products of trace gases and subsequent growth by condensation of semi volatile species on the seed particles. The most studied SA production process in the marine atmosphere is the oxidation of biogenic dimethylsulfide (DMS) into sulfuric and sulfonic acids. This process is the basis for the CLAW hypothesis whereby emissions of DMS, a by product of phytoplankton processes, lead to enhanced CCN concentrations and cloud albedo resulting in a biological regulation of climate (Charlson et al., 1987). The impact of a change in cloud albedo on DMS emission relies on particle nucleation in the boundary layer. The lack of observations of MBL nucleation over the open ocean along with evidence for primary (wind-driven) and free tropospheric sources of MBL CCN (including DMS) has led to the realization that sources of CCN to the MBL are much more complex than originally thought (Carslaw et al., 2010; Quinn and Bates, 2011; Clarke et al., 2013).Nucleation events have been observed at coastal sites (Modini et al., 2009; O’Dowd et al., 2010; Chang et al., 2011) and sulfuric and sulfonic acids have been shown to nucleate new particles in the presence of organic condensable species in smog chamber studies (Metzger et al. 2010; Dawson et al. 2012). How these results apply to open ocean conditions is yet to be determined. Recent improvements in observational tools (Kulmala et al., 2013) should reveal the actual contribution of nucleation to total CCN numbers.The growth of primary organic aerosols by condensation of surface active and hygroscopic compounds is also suggested as a CCN source (Andreae and Rosenfeld, 2008; Clarke et al., 2013). A very recent work suggests that bursts of nanoparticles can occur by in-cloud downsizing of primary organic aerosols (Karl et al., 2013). All in all, the contribution of primary and secondary sources to CCN numbers is yet to be fully assessed. The task stands as a formidable challenge due to the reaction of freshly emitted SSA with existing atmospheric gases and particles soon after emission resulting in a blurring of the distinction between SSA and SA.Further complication comes from the transport of gases and aerosols that are derived in continental atmospheres and advected into the marine atmosphere resulting in complex internal and external particle mixtures (Andreae and Rosenfeld, 2008). Attempts to evaluate the impact of the ocean on cloud formation and properties and the radiative budget on a global scale must be able to distinguish between ocean and continental sources of aerosols that exist in the marine atmosphere.The effects of marine ecosystem changes associated with global change (such as water warming and stratification, regional oligotrophication or eutrophication, and ocean acidification) on the formation and properties of ocean-derived aerosol and clouds remains uncertain. Equally uncertain are the feedbacks of naturally driven or global change associated changes in clouds and aerosols on marine ecosystems.

4. Approaches – what will it take to make substantive progress on the issue? What will be achieved in the 10 years of Future SOLAS? Simultaneous observations of surface seawater and freshly emitted SSA properties are required to determine

the processes controlling the organic enrichment of freshly emitted SSA.

New approaches for determining the emission flux of SSA and SA precursors, especially at high wind speeds, are required to reduce associated uncertainties.

Development of techniques for the identification of the most important players among marine SA precursors (beyond DMS, isoprene and iodine) and to determine their sources, volatility, and aerosol yields. Amines and semi volatile hydrocarbons are suggested as target candidates.

New techniques that allow for counting and characterizing nascent ultra-small aerosols to better assess the frequency and mechanisms of particle nucleation in the marine boundary layer.

Measurements able to elucidate processes that modify aerosol in the MBL including growth, aging, photo-chemistry and internal mixing. Implementation of these processes in models.

Simultaneous studies of surface ocean plankton taxonomy/ecophysiology/bloom dynamics, surface concen-

19

trations of aerosol precursors and aerosol characteristics to constrain and model the biological and environ-mental drivers of biogenic aerosol emission. Time-series studies (both short term –through bloom phases- and long term –through seasons and years) and across-provinces studies will be fundamental tools.

Development of methods to discriminate between ocean- and continentally-derived aerosols found in the mar-ine atmosphere to allow for the assessment of the impact of the marine biosphere on tropospheric aerosols and clouds.

High quality and high-resolution measurements of the physical properties of the surface ocean mixed layer and the atmospheric MBL to decouple ocean-derived aerosol affects on marine clouds from physical effects.

In situ and high-resolution satellite observations of aerosols, winds and cloud properties to improve process understanding and develop parameterizations of marine – cloud interactions. Participation by the marine aerosol community in the development of new remote sensing platforms and sensors, ensuring their rele-vance to ocean-aerosol-clouds feedbacks.

Development of high-resolution numerical models to integrate cloud microphysics into small-scale process dy-namics.

5. Community readiness – is there an existing community engaged on this issue? Are there institutional or other barriers to progress? Is infrastructure or human capacity building required in order to achieve the goals?There is a growing effort among existing oceanographic and atmospheric science communities to address this issue, largely triggered by SOLAS during the last decade. Yet field studies with balanced contributions from both sides of the ocean-atmosphere interface are rare and should be emphasized in the future. Development of a common language (both concepts and terminology) to be shared by the two communities is in its infant stages but is needed for progress in address interconnections between aerosols, clouds, and ecosystems. In addition, the education of a new generation of scientists capable of looking across the interface will eventually be reflected in the building of truly coupled ocean-atmosphere modules in Earth System models.

There is a clear need to maintain and reinforce a dedicated international, interdisciplinary program like SOLAS to build frameworks that will bring the two disciplines together to facilitate the exchange of ideas and enhance the results of future experiments.

6. External connections – what partnerships are required in order to achieve the goals? What mechanisms will be used to accomplish the interactions?Desired partnerships:

IGAC Atmospheric Chemical Transport and Climate Modeling Communities Ocean Ecosystem Community ICCP (The International Commission on Clouds and Precipitation) http://www.iccp-iamas.org

7. Sustainability – articulate relationship (if any) between this project and the FE goals of Global Development and Transformation Towards Sustainability. The production of climate-active aerosols and clouds by the oceans must be considered when accounting for

ecosystem services. The pelagic ocean provides aerosols that scatter sunlight as well as water vapor and seeds for cloud condensation, in addition to food provision, CO2 sequestration, O2 production, waste dumping and recycling, transportation and recreation, and cultural reference.

Aerosols stand as one of the largest paradoxes in global change mitigation efforts. Since the Industrial Revo-lution, global dimming by anthropogenic aerosols has acted as the most powerful counterforce to greenhouse gas derived warming (IPCC 2007). Since the decade of 1980s when the harmful effects that aerosols have on health, visibility and cultural heritage were fully recognized, the development of cleaner and more efficient combustion technologies has led to reductions in anthropogenic aerosol emissions, at least in the most indus-

20

trialized countries. The benefits of this reduction have (and will) come along with an acceleration of warming by reduction of the atmospheric dimming. An accurate assessment of the effects of aerosol emission policies on climate requires a solid knowledge of the current and projected roles of natural (including marine) aerosols on the energy balance at the regional and global scales.

References:Andreae, M.O., D. Rosenfeld, Aerosol–cloud–precipitation interactions. Part 1. The nature and sources of cloud-active aerosols, Earth-Science Rev., 89, 13–41, 2008.

Bates, T.S., P.K. Quinn, A.A. Frossard, L.M. Russell, J. Hakala, T. Petäjä, M. Kulmala, D.S. Covert, C.D. Cappa, S.-M. Li, K.L. Hayden, I. Nuaaman, R. McLaren, P. Massoli, M.R. Canagaratna, T.B. Onasch, D. Sueper, D.R. Worsnop, and W.C. Keene, Measurements of ocean derived aerosol off the coast of California, J. Geophys. Res., 117(D00V15), doi:10.1029/2012JD017588, 2012.

Carslaw et al., A review of natural aerosol interactions and feedbacks within the Earth system, Atmos. Chem. Phys., 10, 1701 – 1737, 2010.

Charlson, R.J., Lovelock, J.E., Andreae, M.O., & Warren, S.G. Oceanic phytoplankton, atmospheric sulphur, cloud albedo, and climate, Nature, 326, 655 – 661, 1987.

Chang, R. Y.-W., S. J. Sjostedt, J. R. Pierce, T. N. Papakyriakou, M. G. Scarratt, S. Michaud, M. Levasseur, W. R. Leaitch, and J. P. D. Abbatt, Relating atmospheric and oceanic DMS levels to particle nucleation events in the Canadian Arctic, J. Geophys. Res., 116, D00S03, doi:10.1029/2011JD015926, 2011.

Clarke, A.D. et al., Free troposphere as a major source of CCN for the equatorial pacific boundary layer: long-range transport and teleconnections, Atm. Chem. Phys., 13, 7511-7529, 2013.

Dawson, M.L., M.E. Varner, V. Perraud, M.J. Ezell, R.B. Gerber, and B.J. Finlayson-Pitts, Simplified mechanism for new particle formation from methanesulfonic acid, amines, and wáter via experiments and ab initio calculations, Proc. Nat. Acad. Sci. USA, 109, 18719–18724, 2012.

Facchini, M.C., M. Rinaldi, S. Decesari, C. Carbone, E. Finessi, M. Mircea, S. Fuzzi, D. Ceburnis, R. Flanagan, E.D. Nilsson, G. de Leeuw, M. Martino, J. Woeltjen, C.D. and O’Dowd, C.D, Primary submicron marine aerosol dominated by insoluble organic colloids and aggregates, Geophys. Res. Lett., 35, L17814, doi:10.1029/GL034210, 2008.

Forster, P. et al., Changes in atmospheric constituents and in radiative forcing, In Climate Change 2007: The physical science basis, Cambridge University Press, Cambridge, UK, 129 – 234, 2007.

Hawkins, L.N. and L.M. Russell, Polysaccharides, Proteins, and Phytoplankton Fragments: Four Chemically Distinct Types of Marine Primary Organic Aerosol Classified by Single Particle Spectromicroscopy, Advances in Meteorology, 612132, doi10.1155/2010/612132, 2010.

Karl, M., C. Leck, E. Coz, and J. Heintzenberg, Marine nanogels as a source of atmospheric nanoparticles in the high Arctic, Geophys. Res. Lett., 40, doi:10.1002/grl.50661, 2013.

Keene, W.C., H. Maring, J.R. Maben, D.J. Kieber, A.A.P. Pszenny, E.E. Dahl, M.A. Izaguirre, A.J. Davis, M.S. Long, X. Zhou, L. Smoydin, and R. Sander, Chemical and physical characteristics of nascent aerosols produced by bursting bubbles at a model air-sea interface, J. Geophys. Res., 112, D21202, doi:10.1029/2007JD008464, 2007.

Kulmala, M. et al., Direct observations of atmospheric aerosol nucleation, Science, 339, 943-946, 2013.

Metzger, A. et al., Evidence for the role of organics in aerosol particle formation under atmospheric conditions, Proc. Natl. Acad. Sci., 107, 6646 – 6651, 2010.

Modini, R.L., Z.D. Ristovski, G.R. Johnson, C. He, N. Surawski, L. Morawska, T. Suni, and M. Kulmala, New

21

particle formation and growth at a remote, sub-tropical location, Atm. Chem. Phys., 9, 7607 – 7621, 2009.

O’Dowd, C., C. Monahan, and M. Dall’Osto, On the occurrence of open ocean particle production and growth rates, Geophys. Res. Lett., 37, L19805, doi:10.1029/2010GL044679, 2010.

Orellana, M.V., P.A. Matrai, C. Leck, C.D. Rauschenberg, A.M. Lee, and E. Coz, Marine microgels as a source of cloud condensation nuclei in the high Arctic, Proc. Nat. Acad. Sci, doi/10.1073/pnas.1102457108, 2011.

Quinn, P.K. and T.S. Bates, The case against climate regulation via oceanic phytoplankton sulfur emissions, Nature, 480, 51-56, doi:10.1038/nature10580, 2011.

Rinaldi, M., S. Fuzzi, S. Decesari, S. Marullo, R. Santoleri, A. Provenzale, J. von Hardenberg, D. Ceburnia, A. Vaishya, C.D. O’Dowd, and M. C. Facchini, Is chlorophyll-a the best surrogate for organic matter enrichment in submicron primary marine aerosol? J. Geophys. Res., doi:10.1002/jgrd.50417, 2013.

22

5 Theme 5: Ocean emissions and tropospheric oxidizing capacityCo-authors: Roland von Glasow and Eric Saltzman

1. Brief statement defining the theme:Compounds that can affect the tropospheric oxidation power are being exchanged across the air-sea interface. This includes reactive (inorganic) halogens, sulphur-containing compounds, halocarbons with lifetimes of minutes to weeks, halogen-containing aerosol particles, certain organic gases, nitrogen-containing gases as well as organic aerosol.

2. The scientific and societal basis justifying research on this issue. Why is it critical and why does it need to be done now? What is the end goal? Why is international coordination required?The oxidation capacity of the troposphere is key for the self-cleansing capability of the troposphere and is to a large degree determined by ozone, which also acts as a greenhouse in the troposphere. Methane is a very strong greenhouse gas, which is predominantly broken down in the marine troposphere, especially in the tropics. These two gases are the only greenhouse gases that have relevant chemical sinks in the troposphere.Air quality and climate change are some of the most important challenges that our societies face but despite decades of research large uncertainties remain to quantify the response of the Earth’s climate system to natural and anthropogenic emissions. Pollution and issues relating to the oxidation capacity of the atmosphere are global issues due to atmospheric transport patterns and lifetimes of these compounds in the atmosphere. In brief, these challenges are global challenges and can efficiently only be addressed in the international framework

3. Background – major scientific concepts, key prior work defining the issues:In the last decades the importance of natural emissions from the oceans on the composition and reactivity of the troposphere has been established and major progress has been made. The quantification of the bidirectional fluxes is however still very uncertain and recent discoveries of new interactions show that our knowledge about ocean-atmosphere interactions is still limited. The compounds exchanged at the ocean-atmosphere interface can be divided into the following groups:

Inorganic halogens (e.g., I2, HOI) Organic halogens (e.g., CH3I, CH2I2, CHBr3...) Sulphur-containing compounds (e.g., dimethylsulphide, DMS) Volatile organic compounds (VOCs) and oxidized volatile organic compounds (OVOCs) (e.g., isoprene,

methanol, acetone) Nitrogen-containing gases (e.g., ammonia, amines, alkyl nitrates) Primary marine aerosol (organic and inorganic)

The marine troposphere is furthermore exposed to long-range transport from the continents, especially coastal cities and emissions from ships.Inorganic halogens can be directly released from the ocean surface (e.g., I2, HOI, Carpenter et al., 2013), originate from the breakdown of organic halogens or be released by acid displacement or photochemical reactions from sea salt aerosol. Inorganic halogens destroy ozone very efficiently but also oxidise DMS, the greenhouse gas CH4 (only Cl atoms) and iodine oxides can lead to particle formation and growth (e.g., Saiz-Lopez et al., 2012). Recent studies showed that reactive halogens can account for about a third of photochemical ozone destruction in the North Atlantic (e.g., Read et al., 2008, Sommariva and von Glasow, 2012) and likely also in other ocean regions. Global model studies suggest an important role of halogens, mainly of marine origin, for the ozone budget in the free troposphere as well (see e.g. Saiz-Lopez and von Glasow, 2012, for a recent review on tropospheric halogen chemistry).Most of the photochemical loss of the greenhouse gas methane occurs in the marine troposphere by reaction with the OH radical. Measurements in the North Atlantic further suggested that up to 15% of the breakdown of methane could be due to chlorine chemistry (Lawler et al., 2011).

23

Figure: Simplified schematic depiction of the most important halogen-related processes in the troposphere. (From Saiz-Lopez and von Glasow, 2012)

Ozone concentrations are further affected by long-range transport and ship emissions but potentially also by NOx

released from marine alkyl nitrates.Dimethylsulphide is produced biologically in the ocean and together with volcanic emissions amounts for the bulk of natural sulphur emissions. The resulting SO2 and is a precursor for sulphate aerosol and plays a role in the formation and growth of aerosol particles and can lead to the formation/growth of so-called cloud condensation nuclei (CCN). Aerosol particles (sea salt, sulphate, organic) play an important role as CCN and can affect climate directly by scattering sunlight.The detection of the very shortlived glyoxal (Sinreich et al., 2010) over the eastern Pacific Ocean might indicate that large, currently unquantified sources exist. A large number of Volatile organic compounds (VOCs) and oxidized volatile organic compounds (OVOCs) are monitored on the Cape Verde site (Carpenter et al., 2010) and their importance for regional and global ozone production needs to be established.

4. Approaches – what will it take to make substantive progress on the issue? What will be achieved in the 10 years of Future SOLAS? In order to make substantive progress in this field a combination of smaller “pilot” field studies combined with larger campaigns that are ship and / or aircraft based are required. These should be supported by model studies to support the field campaigns but also to improve our process understanding and to upscale from the study region to ocean basins and globally.Many fundamental questions regarding reaction pathways especially related to multiphase reactions are still unknown hence laboratory studies that address these issues are essential.Measurements over the oceans always require coordination between various groups in terms of logistics but also regarding the scientific equipment as a full characterisation of the composition of the atmosphere (gas phase and aerosol) is usually beyond individual laboratories and often requires scientists from different countries.

5. Community readiness – is there an existing community engaged on this issue? Are there institutional or other barriers to progress? Is infrastructure or human capacity building required in order to achieve the goals?SOLAS has made a major contribution to the establishment of an international community and the training of the next generation of scientists through its open science meetings, focussed workshops and summer schools. This is a great achievement but an ongoing effort is required to maintain the links in this “new” community.

24

6. External connections – what partnerships are required in order to achieve the goals? What mechanisms will be used to accomplish the interactions?The issues related to atmospheric composition have a strong connection with the International Global Atmospheric Chemistry (IGAC) project as well as the international Commission on Air Chemistry and Global Pollution (iCACGP).Focussed workshops have been held for specific topics partly together with IGAC. The SOLAS/IGAC sponsored task Halogens in the Troposphere has also played a role in this.Coordination of these collaborations is essential to enable progress in this important field. Funding through the Belmont Forum would facilitate international collaboration and lobbying to this end would be very helpful.

7. Sustainability – articulate relationship (if any) between this project and the FE goals of Global Development and Transformation Towards Sustainability.The oceans provide a vast amount of ecosystem services to humanity. Pollution of the atmosphere has a detrimental effect on this. Furthermore it is likely that the processes listed above are affected by Global Change but given the link with greenhouse gases Global Change is also affected by oxidative processes or marine gases and particles in the troposphere.

References:Carpenter et al., Seasonal characteristics of tropical marine boundary layer air measured at the Cape Verde Atmospheric Observatory, J. Atmos. Chem, 2010, 67, 87 - 140

Carpenter , L. J. and S. M. MacDonald and M. D. Shaw and R. Kumar and R. W. Saunders and R. Parthipan and J. Wilson and J. M. C. Plane, Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine, Nature Geosc., 2013, 6, 108 - 111

Lawler, M. J., R. Sander, L. J. Carpenter, J. D. Lee, R. von Glasow, R. Sommariva, and E. S. SaltzmanHOCl and Cl2 observations in marine air, Atmos. Chem. Phys., 11, 7617-7628, 2011

Read et al., Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean, Nature, 2008, 453, 1232 - 1235

Saiz-Lopez A. and R. von Glasow, 2012, Reactive halogen chemistry in the troposphere. Chem. Soc. Rev., 2012, 41, 6448-6472, DOI:10.1039/C2CS35208G

Saiz-Lopez, A., J. M. C. Plane, A. R. Baker, L. J. Carpenter, R. von Glasow, J. C. Gomez Martin, G. McFiggans and R. W. Saunders, Atmospheric Chemistry of Iodine, Chem. Rev., 112, 1773-1804, 2012

Sinreich, R., S. Coburn, B. Dix and R. Volkamer, Ship-based detection of glyoxal over the remote tropical Pacific Ocean, Atmos. Chem. Phys., 2010, 10, 11359 – 11371

Sommariva, R. and R. von Glasow, Multi-phase halogen chemistry in the tropical Atlantic Ocean, Env. Sci. Tech., 46, 10429-10437, 2012

25

6 Theme 6: Interconnections between ocean biogeochemistry and stratospheric chemistryCo-authors: Eric Saltzman and Roland von Glasow

1. Brief statement defining the theme:Reactive gases emitted from the sea surface are transported to the stratosphere in the tropics, where they can influence photochemistry and chemistry and catalytically destroy ozone. The chemical composition and spatial/temporal distributions of these emissions, and the biogeochemical factors controlling them are not well understood. The goal of this theme is to provide a basis for understanding how the oceans impact stratospheric chemistry and how future changes in oceanic ecosystems will influence stratospheric ozone.

2. The scientific and societal basis justifying research on this issue. Why is it critical and why does it need to be done now? What is the end goal? Why is international coordination required?Stratospheric chemistry is of great importance to the Earth system because of its role as a protective shield against harmful ultraviolet solar radiation and its influence on Earth’s energy budget. Over the past century, industrial and agricultural emissions have altered stratospheric chemistry by the emission of chlorofluorocarbons and other halogenated chemicals, methane, nitrous oxide, and sulfur dioxide. There has been progress controlling the emissions of some of these compounds through international agreements under the international Montreal Protocol and others are discussed under the Kyoto Protocol and other frameworks. However, the task of returning stratospheric ozone to a natural or preindustrial state is complicated by other ongoing environmental changes, which have the potential to alter biogeochemical emissions of stratospheric ozone-depleting chemicals. For example, large-scale changes in oceanic ecosystems are anticipated over the coming century, driven by the multiple stressors of climate change, ocean acidification, and anthropogenically-driven changes to nutrient cycles. These changes may affect the emissions of ozone depleting substances from the ocean surface. As a consequence, predicting the future evolution of stratospheric ozone during the coming century involves understanding the oceanic emissions of ozone-depleting substances and how they will evolve.

Understanding the oceanic impact on stratospheric chemistry is a multidimensional problem, involving ocean ecosystem dynamics, surface ocean biogeochemistry, and atmospheric chemistry and dynamics. The research requires interaction across a wide range of disciplines – from phytoplankton physiology to photochemistry, meteorology, oceanography, and climate. The observational requirements include coordinated observations in the oceans and atmosphere, remote sensing, and coupled ocean/atmosphere modeling. The need for international coordination is compelling in order to plan, and execute major field programs, involving both oceanographic and atmospheric research platforms, and to facilitate communication between the various communities engaged in the work. In terms of societal need, we require not only a scientific understanding of the problem, but policies capable of responding to the factors coupling the two issues of stratospheric ozone and climate change.

3. Background – major scientific concepts, key prior work defining the issues:It is well established that halogen atoms (Cl, Br) released from halocarbons lead to the catalytic destruction of stratospheric ozone. The majority of the chlorine and bromine in the stratosphere is derived from anthropogenic emissions of long-lived compounds which are long-lived in the atmosphere, and which are controlled under the Montreal Protocol. However, a portion of stratospheric ozone depletion can be attributed to the emissions and transport of so-called “very short-lived substances” or VSLS. These are defined as trace gases whose chemical lifetimes are comparable to transport times in the troposphere (<0.5 years). Hence, they are non-uniformly distributed in the lower atmosphere and their effects on the upper atmosphere are highly sensitive to their chemistry and transport, and the location of their emissions. VSLS include both anthropogenic and natural compounds.

It has been shown that the tropical oceans play a role in the delivery of VSLS: 1) a wide range of volatile halogenated and sulfur-containing compounds are produced biologically and photochemically in seawater and are released to the marine atmosphere, and 2) some biologically productive waters occur in tropical regions with

26

strong vertical uplift, where air is entrained into the upper troposphere/lower stratosphere.

4. Approaches – what will it take to make substantive progress on the issue? What will be achieved in the 10 years of Future SOLAS? Field observations of emissions, and atmospheric distributions of stratospherically active compounds and pre-

cursors over oceanic, most importantly the Indonesian “maritime continent” and tropical western Pacific where strong uplift occurs.

Laboratory, mesocosm, and field studies of the mechanism of production of such gases and the processes that control their emissions from the sea surface, and investigation of how future changes in ocean nutrients, pH, etc. will impact these processes at the organism or ecosystem level.

Atmospheric chemistry field, laboratory, and modeling studies of the transformations of VSL compounds after emission.

Modeling studies examining the impact of oceanic emissions on stratospheric chemistry and the linkages be-tween climate and the biogeochemistry of these compounds.

5. Community readiness – is there an existing community engaged on this issue? Are there institutional or other barriers to progress? Is infrastructure or human capacity building required in order to achieve the goals?This research requires collaborative interaction among communities which historically are trained in different institutions, attend different scientific conferences, and utilize very different vocabularies. These include microbiologists, biomolecular chemists, chemical oceanographers, tropospheric/stratospheric chemists and dynamicists, and climate scientists. Progress in this area will require scientists who share a common understanding of the complex interconnections between the ocean, stratosphere, and climate. The atmospheric chemistry and dynamics communities are fairly well linked via joint consortia (e.g., the recent EU-funded SHIVA consortium) and assessments, most prominently the WMO Scientific Assessment of Ozone depletion. New efforts are needed to extend these linkages to the other communities listed above.

6. External connections – what partnerships are required in order to achieve the goals? What mechanisms will be used to accomplish the interactions?Important partnerships include the IGAC/SPARC Chemistry-Climate Model Initiative (CCMI), the SPARC Stratospheric Sulfur and its Role in Climate (SSiRC).

7. Sustainability – articulate relationship (if any) between this project and the FE goals of Global Development and Transformation Towards Sustainability.Maintaining a healthy stratosphere is one of the most fundamental requirements of a sustainable society. The costs of stratospheric degradation include human health risks, damage to oceanic ecosystems and food web, potential changes in genetic mutation rates, damage to agricultural crops and livestock. In addition, there are many interactions between stratospheric ozone and other elements of the climate system. There is a direct societal interest in understanding the risks associated with various forms of human activity. The Montreal Protocol was an outstanding example of how dramatic environmental change (i.e. the Antarctic ozone hole) galvanized nations society to successfully cope with an urgent global environmental issue. The longer-term climate/ozone interactions discussed here have the potential to change the “baseline” of ozone depleting gases which the Montreal Protocol seeks to regulate. Furthermore, some proposed geoengineering schemes involve changing surface oceanic biogeochemistry. It is important to have a multidisciplinary community capable of assessing such scheme for the full range of possible environmental consequences.

27

7 Theme 7: Multiple stressors and ocean ecosystemsCo-authors: Minhan Dai and Anja Engel

1. Brief statement defining the theme:Over the last century, the ocean ecosystems have been experiencing unprecedented changes driven by both natural and anthropogenic stressors such as temperature rising, eutrophication, deoxygenation/hypoxia, plastic litter and ocean acidification. Several of these stressors occur simultaneously and interact with each other, which presents an immense challenge to identify key stressors and combined effects on ocean biogeochemistry, air-sea interactions, as well as ecosystem functioning and services.

2. The scientific and societal basis justifying research on this issue. Why is it critical and why does it need to be done now? What is the end goal? Why is international coordination required?The ocean and its ecosystems provide a variety of valuable economic services to human society. Examples include supporting services of nutrient balance, hydrological balance, regulating services of pollutant attenuation and climate regulation and cultural services of science and education, recreational opportunities as well as food production. Theme 7 has thus a clear and direct relevance to the human society.

Understanding how marine ecosystems respond to individual stressors and their combinations in the past, present and future is however scientifically challenging but essential in order to identify the associated ecological and economic implications of environmental changes, as well as to seek effective management strategies towards sustainability. Moreover, multiple changes in ecosystem structure, functioning and dynamics can be expected to differ from single stressor effects, and vary by region, and over time. International coordination is thus crucial in order to identify research priorities, evaluate and guide experimental and methodological approaches, and intercomparison of individual research results, and to translate scientific knowledge to support socioeconomic risk assessment and political decision making

The primary goal of theme 7 is to identify anthropogenic key stressors and to understand consequences of the simultaneous interaction of stressors resulting in multiple transitional ecosystem states and to significantly improve our predictive ability of the future marine ecosystem changes. In focus are the most vulnerable/hot, ecologically and economically important regions that currently experience unprecedented change (link to theme 8) such as human impacted coastal and marginal seas, large river delta systems, upwelling systems, and the pristine Polar Seas. The scientific challenge is to establish an ecosystem baseline, i.e. identify natural variability, to capture changes driven by anthropogenic stressors, and ultimately to provide a holistic view of multiple stressors interactions with respect to global and regional ecosystems. An FE related goal would be to estimate socioeconomic consequences of multiple stressors with respect to regional and global climate change, ocean productivity, ocean health and ecosystem services, and to transfer this knowledge to support policy and decision making.

3. Background – major scientific concepts, key prior work defining the issues:Human footprints have imbedded in and impacted on the ocean’s ecosystems on various ways and at different spatial-temporal scales (Fig. 1, Doney et al., 2010). Several key stressors can be identified: The progressive increase in atmospheric CO2 directly and indirectly affects the marine biosphere. Indirect effects are expected through global warming related rising of sea surface temperatures, which may cause increased surface ocean stratification and mixed layer insulation, thereby changing the dissolved oxygen content in seawater. Due to the rapid air-sea exchange of CO2, direct, and already determined, effects of increased atmospheric CO2 concentration are the rise of CO2 concentration in the surface ocean and a related shift in its chemical equilibrium (Chen and Millero 1979), including an unprecedented rapid decline in surface seawater pH, referred to as ocean acidification. Multiple effects of changes in pH, O2 and CO2 concentration are expected for plankton

28

organisms, their physiological rates, species diversity, and population dynamics, in turn affecting the productivity and biogeochemical cycling of marine ecosystems (Gattuso and Hansson, 2011). Yet, mechanisms and magnitude of biological and biogeochemical responses to environmental change in a “hot”, “sour” and “breathless” ocean are largely unknown. Another suites of stressors are primarily related to the nutrient influxes into the ocean through land-ocean (Cai et al., 2011) or air-sea interfaces (Kim et al., 2011). Accumulative and even excessive nutrients input into the ocean have clearly affected the coastal ecosystems, the similar signals of which have emerged in open waters. Since the middle of the last century, increasing global production of plastic material resulted in the accumulation of plastic litter in the ocean. Thereby, larger plastic litter mostly fragments over time to form a pool of microplastics (< 5 mm) together with primary plastic litter of micro-size. Microplastics can enter the food chain and affect the nutritional quality of marine products, particularly as they contain and adsorb toxins such as persistent organic polutants (POPs) (Hidalgo-Ruz et al. 2012).

We currently fail to understand how multiple stressors impact marine ecosystems and related biogeochemical processes, being themselves variable in time and space, primarily because we do not understand how marine ecosystems function. The number of studies addressing the ocean’s responses to environmental change has been vastly increasing over the past decades, yet the insight gained is relatively small. This is due to the complexity of the problem on the one hand, but also owing to a lack of coherent scientific approaches, resulting in the danger of global change research becoming ‘a Gordian Knot of disparate strands of data’ (Boyd, 2013) (Fig. 2). Moreover, there is a striking disparity between sound scientific knowledge and attempts/ needs to economically value the impact of multiple stressors on marine ecosystems.

(from Doney et al., 2010)

29

Fig. 2 from Boyd, 2013, Nature Climate Change, 3, 530-533.

4. Approaches – what will it take to make substantive progress on the issue? What will be achieved in the 10 years of Future SOLAS? Theme 7 will expand the SOLAS theme of atmosphere-ocean interactions by emphasizing the effect of the human perturbation. SOLAS can improve and maximize the output of multiple stressor research by a series of actions. The primary aims would be to:

Gain coherence by i) stimulating the dialog between disciplines to identify the quality and quantity of observa-tional data needed for regional and global physical-ecosystem coupled models and ii) set-up a frame for future scenarios being tested (i.e. IPCC), iii) identify key regions

Improve quality by i) enforcing experimental and methodological standardization, ii) fostering intercomparison ex-ercises on disparate studies, iii) supporting capacity building

Enhance outreach of scientific results by i) promoting the assimilation of empirical and observational-based knowledge in Earth System Models, economic models, impact assessments, and policy frameworks, ii) foster in-formation exchange with FE, policy makers, stakeholders etc…

5. Community readiness – is there an existing community engaged on this issue? Are there institutional or other barriers to progress? Is infrastructure or human capacity building required in order to achieve the goals? 6. External connections – what partnerships are required in order to achieve the goals? What mechanisms will be used to accomplish the interactions?

There is quite consensus in the scientific community that the ocean ecosystem is changing under multiple stressors. Such a consensus is at least partially attributable to the fast growing community in ocean acidification research. As a result, the Ocean Acidification Working Group jointly sponsored by SOLAS and IMBER has fostered a new initiative, the Ocean Acidification International Coordination Centre (OA-ICC) presently operated by the IAEA Environment Laboratories in Monaco. Given the magnitude of the problems and the complexity of the largely unknown future changes that the ocean ecosystem is facing requires international coordination more

30

than the researches of ocean acidification. Partner coordination with OA-ICC would however be very beneficial in progressing the present multiple stressor theme.

7. Sustainability – articulate relationship (if any) between this project and the FE goals of Global Development and Transformation Towards Sustainability.

The ocean ecosystem and multiple stressors is clearly a direct and complex issue of sustainability, which shall be an obvious goal of the FE.

References:Boyd, Philip W. "Framing biological responses to a changing ocean." Nature Climate Change 3.6 (2013): 530-533.

Cai, W.-J., X. Hu, W.-J. Huang, M.C. Murrell, J.C. Lehrter, S.E. Lohrenz, W.-C. Chou, W. Zhai, J.T. Hollibaugh, Y. Wang, P. Zhao, X. Guo, K. Gundersen, M. H. Dai, and G.-C. Gong (2011), Acidification of subsurface coastal waters enhanced by eutrophication, Nature Geoscience, 4 (11), 766-770.

Chen, G.-T. and Millero, F.J. (1979). Gradual increase of oceanic CO2. Nature 277, 205-206.

Doney, Scott C. "The growing human footprint on coastal and open-ocean biogeochemistry." Science 328.5985 (2010): 1512-1516.

Gattuso J.-P. & Hansson L. (Eds.), 2011. Ocean acidification, 326 p. Oxford: Oxford University Press.

Hidalgo-Ruz, Valeria, et al. "Microplastics in the marine environment: a review of the methods used for identification and quantification." Environmental science & technology 46.6 (2012): 3060-3075

Kim, Tae-Wook, et al. "Increasing N abundance in the northwestern Pacific Ocean due to atmospheric nitrogen deposition." Science 334.6055 (2011): 505-509.

31

8 Theme 8: High Sensitivity Systems- HS2

Co-authors: Michelle Graco, Anja Engel, Lisa Miller, Véronique Garçon and Jacqueline Stefels

1. Brief statement defining the theme:In the global context Eastern Boundary Upwelling Systems (EBUSs) and Polar systems have been identified as hot spots for air-sea exchange research, because of their significant role in the ocean ecosystems and global biogeochemical cycles. They are also identified as High Sensitivity Systems (HS2) to the global change impacts. Hence, research on the potential consequences and feedbacks of global change needs to include focused studies of such specific HS2.

2. The scientific and societal basis justifying research on this issue. Why is it critical and why does it need to be done now? What is the end goal? Why is international coordination required?The Equatorial Boundary Upwelling Ecosystems (EBUSs) and Sea-Ice ecosystems are particularly relevant to the SOLAS goal ”To achieve quantitative understanding of the key biogeochemical-physical interactions and feedbacks between the ocean and the atmosphere”. These environments are included in the SOLAS Mid-term Strategies (Law et al., 2013). However the existing knowledge is still insufficient and because of their implications and complexity it is necessary to reinforce multidisciplinary studies in the coming years in these systems and also other HS2.

The EBUSs are among the most productive areas in the world ocean and support important fisheries. Their high productivity feeds one of the world’s largest and most intense Oxygen Minimum Zones (OMZs), which are associated with new paradigms in the nutrient cycling and significant releases of greenhouse gases. We know that these areas influence the cloud properties and the climate and any change in the upwelling and OMZ conditions, such as change in circulation patterns, deoxygenation, is expected to result in changes in productivity, biogeochemical processes and trace gases production. In turn, the dynamics and consequence of the changes in Sea-Ice characteristics and distribution in the polar oceans are critical to understand and model feedback effects and future scenarios of climate change. We understand that sea ice is an active player in the climate, through air-sea gas exchange and aerosol production, as well as carbon dioxide export.

However, in EBUSs and Sea-Ice systems existing knowledge is yet insufficient to a) assess the direction and extent of future changes in biogeochemical cycles resulting from warming, deoxygenation and changing sea-ice distributions, b) determine critical thresholds and resilience capacity of these systems, and c) improve management strategies for human interactions with high sensitive systems (HS2) and apply an ecosystemic ap-proach based management including other aspects as resource extraction, tourism, transportation and pollutant cycling.

The challenge of this “hot-spot” research of complex systems in unique environments is to develop multi-disciplinary collaborations with highly qualified scientists, and to combine research and capacity building, with new techniques and innovative technologies for observational and modeling approaches. In such contexts na-tional efforts are insufficient and international coordination is required.

3. Background – major scientific concepts, key prior work defining the issues:EBUSs, as the California, Humboldt, Benguela and Canary Currents, are characterized by high

productivity and support the largest fisheries of the world (e.g. Chavez et al., 2009). The high productivity is associated with shallow and intense Oxygen Minimum Zones (OMZs) with high CO2 contents, low pH values and a shallow aragonite saturation horizons that can impinge on the euphotic zone, impacting the surface ecosystem and releasing CO2 and N2O, strong greenhouse gases, to the atmosphere (e.g. Bange et al., 2006, Farías et al., 2007, Friederich et al., 2008, Paulmier et al., 2008; Paulmier and Ruiz-Pino, 2009). EBUSs and OMZs are characterized also by an intense microbial recycling associated with the nitrogen and sulphur cycling that deeply impact in the environmental conditions, the communities and the greenhouse sink-source of the coastal waters (e.g. Lam et al, 2010, Schunk et al., 2013, Ulloa et al., 2012). Ultimately, these biogeochemical processes

32

determine the productivity of these systems and their role as sinks or sources of climate-active gases needs to be adequately addressed in order to understand the interactions with the climate system (Law et al., 2013).

Until now, sea ice was assumed to block air-sea gas and material exchange, momentum and heat were thought to be the only parameters that effectively passed through the ice. However, over the last 10 years and thanks to a massive research effort, much of which has been conducted by SOLAS scientists, we now understand that sea ice is not a passive barrier to air-sea exchange, but is an active participant in the biogeochemical cycles of many elements, producing climatically-active atmospheric aerosols (Leck and Bigg, 2010), modulating the surface ocean ecosystem (e.g., Arrigo et al., 2010), contributing to substantial seasonal CO2 fluxes, and possibly facilitating long-term export and CO2 sequestration in deep waters (e.g., Loose et al., 2011). Dramatic changes in air-sea gas exchange rates co-vary with the open-water fraction (Loose et al., 2009; Else et al., 2011). Therefore, the polar oceans are a true, year-round hot spot for air-sea interactions. The researches over the last decade conclude that sea ice is a very rich and complex system in which biotic and abiotic processes interact in changing ways throughout the lifetime. The freeze melt of sea ice strongly impacts on the physical characteristics of surrounding surface waters (Thomas and Dieckmann, 2010). This newly identified complexity in the sea-ice system is confounding efforts to predict how changes in ice cover will propagate throughout polar ecosystems and feed back onto the global climate system.

Sea ice and the EBUSs are only two examples of complex regional systems undergoing dramatic changes that are not only intimately linked with climate, but that also impact human communities. Nonetheless, the interdisciplinary and international framework SOLAS provides to tackle these problems will also serve research in other high sensitivity systems, as their importance becomes evident.

Sea- ice Ecosystems Coastal Upwelling Ecosystems /OMZsHabitat, source, sink and barrier for gas exchange:

Habitat, source, sink for gas exchange:

-Trace Gas emissions/ Photochemistry -Trace gas Emissions/ Photochemistry-DMS and Climate -Atmospheric Nitrogen Cycling, N2O and

Climate-CO2 Cycling and climate -CO2 Cycling, acidification, deoxygenation and

ClimateFrom Law et al., 2013

4. Approaches – what will it take to make substantive progress on the issue? What will be achieved in the 10 years of Future SOLAS? “Holistic” multidisciplinary approaches are required to address ocean-atmosphere exchange, processes and feedbacks in high sensitivity systems if we are to improve our capacity to predict climate change impacts and identified effective mitigation and/or adaption strategies.

The Future SOLAS has a key role in coordinating national efforts and to implement the multidisciplinary research projects required to address climate-change impacts by the High Sensitivity Systems- HS2 .

33

For the next 10 years, Future SOLAS will support research in High Sensitive Systems (HS2) through:-GAS EXCHANGE MONITORING AND PROCESS STUDIES. Continue and reinforce the biological, chemical and physical controls of greenhouse and reactive trace gas cycling in EBUSs and at the sea-ice interfaces.-HS2 AND MULTIPLE STRESSORS. To explore the regional dynamics of relevant stressors and their synergistically effect in EBUSs and Sea Ice systems.-REGIONAL MODELS. Improve representations of biogeochemistry in regional models of sea ice and EBUSS, with better descriptions of biogeochemical processes coupled with higher temporal and spatial resolution of observational data. Develop high-resolution coupled atmosphere-physical and biogeochemical models nested in larger resolution models.-EARTH SYSTEM MODELS. Identify the elements of HS2 systems that are key parameters to global change and incorporate them into Earth System Models to address impacts and feedbacks in future global change scenarios. -OBSERVATIONAL PLATFORMS. Articulate and reinforce observation platforms (local and regional ship-based cruises, moorings, floats, autonomous vehicles, satellites) in order to obtain time series with good resolution on spatial and temporal scales of different climatic variables (e.g. temperature, salinity, trace and greenhouses gases, nutrients, oxygen, carbonate system). - HS2 DATABASES AND INTERCOMPARISONS. Organize linked databases at LOCAL AND GLOBAL LEVEL, facilitating decision making for local countries, while also feeding global climate models to determine vulnerability and risk and to predict future social-economics impacts of climate change. Evaluation and standardization of methodology and protocols for comparable measurements. -OTHER HS2 REGIONS. Develop flexible and innovative strategies for initiating air-sea exchange research in other climatically important hot spots.

5. Community readiness – is there an existing community engaged on this issue? Are there institutional or other barriers to progress? Is infrastructure or human capacity building required in order to achieve the goals?

In 2008, five research topics and issues that require international coordination to make progress have been identified. Air-sea gas fluxes at Eastern boundary upwelling and Oxygen Minimum Zone (OMZ) systems (PI: V. Garcon) and Sea-ice biogeochemistry and interactions with the atmosphere (PI: J. Stefels) compose the so-called SOLAS Mid-Term Strategy. Following initiatives within SOLAS’ Mid-Term Strategy other programs as CLIVAR-IMBER and SCOR Working Group (WG 140) examining these systems but in complementary aspects, e.g. to develop strategies and initiate a number of important activities, including methodological intercomparison and standardizations, database development, and regional and earth system model advancements. These working groups will directly benefit from continuing SOLAS support.

6. External connections – what partnerships are required in order to achieve the goals? What mechanisms will be used to accomplish the interactions?

The Global Ocean Observing System (GOOS) Through their focus on autonomous observation platforms and remote sensing, GOOS is facilitating the high temporal and spatial resolution monitoring necessary to resolve many of the complex processes in HS2 and to improve the success rate and usefulness of in situ biogeochemical sensor deployments. The GOOS subsidiaries AOOS and SOOS (in the Arctic and Southern Oceans, respectively) are also enhancing our capacity to understand sea-ice and ocean dynamics in these regions where ship-based work is difficult and sparse.

The SFB 754 at GEOMAR "Climate-Biogeochemistry Interactions in the Tropical Ocean. Collaborative Research Center addresses the relatively newly recognized threat of ocean deoxygenation, its possible impact on tropical oxygen minimum zones and implications for the global climate-biogeochemistry system. The overall goal of the SFB 754 is to improve understanding of the coupling of tropical climate variability and circulation with the ocean's oxygen and nutrient balance, to quantitatively evaluate the nature of oxygen-sensitive tipping points, as well as to assess consequences for the Ocean's future. (https://www.sfb754.de/de).

The French AMOP project (Activités de recherche dédiées au Minimum d’Oxygène du Pacifique-est: http://www.legos.obs-mip.fr/recherches/projets-en-cours/amop/scientific-objective), with collaborations with

34

Germany, Denmark, Mexico and Peru, to cite a few, is focused on the Eastern South Pacific and its overarching goal is to understand the oxygen dvnamics in this OMZ by providing a comprehensive budget for oxygen based on oceanographic cruise efforts, time series acquisition from a mooring deployed off Peru, and a high resolution coupled atmosphere-physical and biogeochemical modeling platform.

International collaboration and cooperation will also be sought within the networks of SCOR, SCAR, PICES, and AOSB in order to involve key scientific groups, to interact with stakeholders and communicate the progress of our knowledge.

7. Sustainability – articulate relationship (if any) between this project and the FE goals of Global Development and Transformation Towards Sustainability.

At present, many key ecosystems are threatened by climate change and other stressors associated with human exploitation, and those threats are feeding back into strains on the communities that depend on those ecosystems. Every country must rise to the challenge of protecting Biodiversity and Ecosystem Services, but it must also be done through international collaboration. Present and future changes are particularly critical at HS2, and impacts need to be addressed at different levels, local, national, regional, and global. In this context it is important to sensibly mobilize all the stakeholders to focus on national and international research efforts and capacity building for sustainable development.

References:Arrigo K.R., Mock T. & Lizotte M.P. 2010: Primary producers in sea ice. In: Thomas D.N. and Dieckmann G.S.

(eds.): Sea Ice. Pp. 283-325. Chichester: Wiley-Blackwell.

Bange, H. W.: New Directions: The importance of the oceanic nitrous oxide emissions, Atmos. Environ., 40, 198–199, 2006.

Chávez, F.P., Messié, M. (2009). A comparison of Eastern Boundary Upwelling Ecosystems.” Prog. Oceanogr.,doi:10.1016/j.pocean.2009.07.032

Else B.G.T., Papakyriakou T.N., Galley R.J., Drennan W.M., Miller L.A. & Thomas H. 2011. Wintertime CO2

fluxes in an Arctic polynya using eddy covariance: Evidence for enhanced air-sea gas transfer during ice formation. Journal of Geophysical Research 116, C00G03, doi:10.1029/2010JC006760.

Farías, L., Paulmier, A., and Gallegos, M.: Nitrous oxide and Nutrient cycling in the oxygen minimum zone off northern Chile, Deep-Sea Res. I, 54, 164–180, 2007.

Friederich, G.E., Ledesma, J., Ulloa, O., Chavez, F.P., 2008. Air-Sea Carbon Dioxide Fluxes in the Coastal Southeastern Tropical Pacific. Progress in Oceanography 79, 156-166.

Lam P. and M. Kuypers., 2010. Microbial Nitrogen Cycling Processes in Oxygen Minimum Zones. Annu. Rev. Mar. Sci. 2011. 3:317–45.

Leck C and E. K. Bigg (2010) New Particle Formation of Marine Biological Origin. Aerosol Science and Technology, 44:570–577, DOI: 10.1080/02786826.2010.481222

Loose B., McGillis W.R., Schlosser P., Perovich D. & Takahashi T. 2009. Effects of freezing, growth, and ice cover on gas transport processes in laboratory seawater experiments. Geophysical Research Letters 36, L05603, doi:10.1029/2008GL036318.

Loose B., Miller L.A., Elliott S. & Papakyriakou T. 2011. Sea ice biogeochemistry and material transport across the frozen interface.Oceanography 24(3), 202-218, doi:http://dx.doi.org/10.5670/oceanog.2011.72.

Schunck H, Lavik G, Desai DK, Großkopf T, Kalvelage T, et al. (2013) Giant Hydrogen Sulfide Plume in the Oxygen Minimum Zone off Peru Supports. Chemolithoautotrophy. PLoS ONE 8(8): e68661. doi:10.1371/journal.pone.0068661.

35

Paulmier, A., Ruiz-Pino, D., and V. Garçon, V. (2008). The Oxygen Minimum Zone (OMZ) off Chile as intense sources of CO2 and N2O. Continental Shelf Research, 10.1016/j.csr.2008.09.012.

Paulmier and Ruiz-Pino, 2009 PiO

Thomas D.N. & Dieckmann G.S. 2010. Sea Ice. Wiley-Blackwell, 621 pp.

Ulloa et LA PNAS 2012

36