Ž .Marine Chemistry 72 2000 79–81www.elsevier.nlrlocatermarchem

Preface

Second international symposium on carbon dioxide in the oceans,ž /Tsukuba, Japan January 1999

More than 200 scientists from 16 countries werepresent to hear Dr. Taro Takahashi while he wasgiving the first talk at the Second International Sym-posium on Carbon Dioxide in the Oceans held from18–22 January 1999 at the Tsukuba Center for Insti-tutes, Tsukuba, Japan. The title was ANet sea-airCO flux over the global oceans: An improved2

estimate based on sea-air pCO differencesB. During2

the 5 days, 73 papers were given orally, 27 paperswere presented at the poster sessions and a furtherfive papers joined Asubmitting onlyB papers. Thenumber of papers presented a substantial increase

Ž .compared to that at the first meeting 66 on thistopic held in January 1996 in Mayaguez, PuertoRico. The number of participants also increased from65 to 256. This seems to be due to the rapid develop-ment of activities in this young research field.

When we compare the two meetings in moredetail, we may be able to understand the recent trendin this field. The presentations can be classified intoexperimental methods and sampling, field observa-tions reporting new data, laboratory experiments,synthesis and modeling, and CO sequestration or2

countermeasures. In regard to the number of presen-tations, the mainstream was still field observations,which was 55 in 1999 compared to 34 in 1996. Thefield observations performed in the Pacific and itsadjacent seas largely increased from 19 in 1996 to 29in 1999, while those in the Atlantic region decreasedfrom 12 to 9. This seems partly due to the locations

Ž .of meetings held, and to a large proportion 40% ofJapanese contributors in 1999, but it may also be dueto the fact that we were late in studying the Pacific,which comprises 53% of the world ocean waters,

with recent sophisticated research means. Researchconducted in the Indian Ocean also increased.

There was a pronounced increase in the numberof papers on synthesis and modeling, which grewfrom 12 in 1996 to 27 in 1999. This trend willcontinue in the next meeting because many data setshave been accumulating and we need to understandoceanic CO on a global scale. A new session on the2

CO sequestration was added and the biological2

aspect was somewhat strengthened at this sympo-sium. The marine CO issue will be broadened and2

more complicated in the future.The results of the symposium have been docu-

Ž .mented in a proceeding book Nojiri, 1999 and inŽthe US JGOFS Newsletter Murphy and Nojiri,

.1999 .One of the highlights of the symposium was the

wealth of contributions on oceanic CO distribution,2

presented in three lengthy observation sessions cov-ering the research areas of air–sea CO fluxes,2

partial pressure of CO , dissolved inorganic carbon2Ž .DIC and anthropogenic CO from the Pacific, At-2

lantic, Indian, and Southern Oceans, including theAntarctic waters. These outstanding data sets frommany contributing nations were the result of well-organized and methodically executed field programsunder the global CO survey of IOC-JGOFS on2

WOCE global cruise tracks. To ensure high qualitydata compatibility, vigorous interlaboratory compari-son of methods and availability of reference stan-dards are indispensable. As an example, Feely et al.made 41 cross-over comparisons of certified refer-ence material-corrected DIC for the global CO sur-2

vey stations in the Pacific Ocean to bring data sets

0304-4203r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved.Ž .PII: S0304-4203 00 00098-0

Preface80

from different cruises and time periods to a coherentsynthesis. These sessions covered basin-scale resultsas well as efforts to ensure the quality of global datasets. JGOFS is in the final phase of synthesis andmodeling.

Two modeling sessions and a related one onisotopes were devoted to advances in ocean CO2

modeling using the global CO data set, and tracers2

such as CFCs, to gain insights into the penetration offossil-fuel CO into the oceans. Stable isotopes2

demonstrate their usefulness in constraining the air–sea CO flux, as shown in the approach by Francey2

et al., using an inverse model and by Gruber andKeeling using a re-evaluation of isotopic air–seadisequlibrium of CO , based on high-quality global2

data sets of surface 13Cr12 C in DIC. While thesepresentations illustrated the usefulness of isotopictracers and O rN in studying the partitioning of2 2

atmospheric fluxes into ocean and terrestrial reser-voirs, the ocean geochemical community needs anintensive intercalibration and reference standardsprogram for these tracers. Modeling and data man-agement are logical developments after a decade ofJGOFS observational efforts. These were well repre-sented in the two sessions on modeling. The globalCO survey and a decade of the WOCE hydro-2

graphic program have produced full water columnprofiles of DIC, total alkalinity and pCO in 1–282

intervals, and 14,000 d14C samples in the world

oceans. These anthropogenic carbon tracers enabledSabine et al. to evaluate global carbon models. Thecarbon data sets also enable modelers to examine

Ž .biogeochemical variability Follows et al. and inter-annual variations, e.g. CO uptake in the Southern2

Ž .Ocean Louanchi et al. . The CSIRO climate modelwas used by Matear and Hirst to investigate theeffect of climate change on oceanic CO uptake:2

warming of the upper ocean, reduction of meridionaloverturn and convective mixing, increased stratifica-tion and decrease in nutrient and carbon suppliesfrom deep waters to the upper ocean. By 2100, theseclimate feedbacks will make the oceans 15% lesseffective in taking up atmospheric CO , whereas the2

cumulative ocean uptake could be about 400 GtCwithout climate change feedbox.

Another highlight of the conference was the newtechnology or platform for CO measurements. These2

included the increasing use of platforms other than

conventional research vessels, e.g. the use of cargocarriers, the improved capability of the pCO CARI-2

OCA buoy, and the acceptance of pH as a reliableocean CO parameter. The use of ships-of-opportun-2

ity, e.g. the Skaugran by the National Institute forŽ .Environmental Studies NIES in Japan in coopera-

tion with the Institute of Ocean Sciences in Canada,has greatly improved our understanding of the CO2

distribution both in the temporal and spatial scales inthe North Pacific, between Japan and North Amer-ica. This very intensive observation program has led

Ž .to the use of directly measured fCO fugacity2

without extrapolation based on SSTs, a commonlyused approach to overcome the lack of data, espe-cially seasonal coverage, to produce reliable air–seaCO flux and interannual variability on a basin-scale.2

This approach has an advantage over time-seriesstations requiring expensive shiptime, although inspecial cases, e.g. Bermuda and Hawaii, with theirlocations in the open ocean, permits time-series ob-servations at low cost. New technology, such as the

Ž .CARIOCA pCO system Merlivat , is now in wider2

use for both deep-sea mooring or free-drifting datacollection. The pH parameter has gained acceptabil-ity for reliable continuous shipboard measurements,as illustrated by the range of presentations on itsdistribution, calibration and methodology develop-ment.

Biogeochemistry is the new paradigm in CO2

research. The two sessions on biological processescentered on the biological pump, but in fact, biogeo-chemistry was evident in other sessions of modeling,observations and coral reefs. It is now so intertwinedwith other fields that it is difficult to separate it. Ironis now the new emphasis in marine ecosystems in

Ž .HNLC high nitrate, low chlorophyll waters, wherethe iron limitation affects production. Watson et al.pointed out that an increased aeolean supply of ironin the Southern Ocean was needed for the drawdownof atmospheric CO during the last glacial period.2

This supply to the Southern Ocean could come fromthe Northern Hemisphere, such as the Sahel andSahara, because of an increase in global aridityduring glaciation. Emerson and Karl examined thebiological pump in the subtropical Pacific Ocean bylooking at the nutrient limitations on the CO flux.2

They suggested that the rapid change in atmosphericpCO during the last glaciation could be related to2

Preface 81

the thickness of the upper ocean thermocline reser-voir. However, the question of whether carbon ex-port is limited by nutrients supplied by ocean circula-tion has to be answered. A continental shelf pumpwas postulated by Tsunogai and Watanabe as amechanism for absorbing atmospheric CO through2

active biology and water density distributions. Thesubsequent carbonate export to subsurface open-oc-ean could have an impact on carbon cycle modeling,based on open ocean processes only.

The ocean CO community is also facing new2

challenges on socio-economic issues, such as avoid-ing harm to the climate by limiting CO emissions2

into the atmosphere. A doubling of the atmosphericCO level from the pre-industrial period will be2

reached early in the new millenium. Ocean CO2

sequestration is one of the mitigating options consid-ered by energy policy makers to combat the expo-nential rise in atmospheric CO level due to fossil-2

fuel burning. The session on carbon sequestrationand a number of the posters presented research inresponse to this new challenge. Peter Brewer de-scribed novel experiments from an unmanned deep-sea vehicle to study the behavior of liquid CO in2

the deep ocean and the reaction of deep-sea animalsto CO hydrates. Carbonate dissolution was another2

idea for CO disposal that was put forward by2

Caldeira and Rau. Hirose et al. described a new typeof water-soluble glass that releases iron to seawaterto enhance phytoplankton growth and Takeda et al.described the use of an open-ocean plastic enclosureto study the effects of iron fertilization. Presentationsof ocean CO sequestration in this conference is the2

beginning of a new direction in research. It is per-haps not yet too familiar to most researchers in themarine CO community but it definitely will have2

phenomenal growth in the next decade.In his closing address, Andrew Watson, as chair-

man of the IOCrJGOFS CO advisory panel, ex-2

plained the task of the panel in guiding the interna-

tional global CO survey of JGOFS and the2

WOCErJGOFS one-time hydrographic survey, in aninternational effort to measure CO parameters. He2

pointed out that the next task would be the datasubmission phase to create a global data set forsynthesis and modeling so that the full marine car-bon cycle can be understood. He mentioned hisobservations of the symposium: the new theme ofocean sequestration and the growth and usefulness ofa new international cooperative program, such as theSkaugran ship-of-opportunity between Japan andCanada. In closing, he thanked Yukihiro Nojiri andNIES for their efforts in hosting this very successfulconference.

References

Murphy, P.P., Nojiri, Y., 1999. Japan is host to Second Interna-tional Symposium on CO in the Oceans. U.S. JGOFS Newsl.2

Ž .10 2 , 12–13, Oct.Ž .Nojiri, Y. Ed. , Proceedings of the 2nd International Symposium

on CO in the Oceans. Center for Global Environmental2

Research, National Institute for Environmental Studies, Envi-ronmental Agency of Japan. 688 pp.

Shizuo Tsunogai)

Marine and Atmospheric GeochemistryLaboratory, MAG, DiÕision of Ocean andAtmospheric Science, Graduate School of

EnÕironmental Earth Science, HokkaidoUniÕersity, Sapporo 060-0810, Japan

E-mail address: mag-hu@ees.hokudai.ac.jp

C.S. WongInstitute of Ocean Sciences,

Sidney, British Columbia, Canada

) Corresponding author. Tel.: q81-11-706-2368; fax: q81-11-706-2247.http:rrwwwoa.ees.hokudai.ac.jpredurmagrtsunogai.htm.