Global Environmental Change Impacts on the Caribbean Food System

Ulric O’D Trotz, Ph.D

Project Manager

RPIU/ACCC Project

Working Group I of the IPCC TAR Concluded

• Global average surface temperature increased by 0.6±0.2°C over 20th Century

• For range of scenarios considered global average surface temp. projected to warm 1.4-5.8 °C by 2100 relative to 1990

• Global average sea level projected to rise 0.09-0.88m by 2100

• Changes in climatic variability, and frequency and intensity of some extreme climate events

Projected Adverse Impacts

• General reduction in crop yields in most tropical and subtropical regions for most projected increase in temperature

• General reduction, with some variation, in potential crop yields in most regions in mid-latitudes for increase in annual average temperature

• Reduced water availability in most water scarce regions

• Widespread increase in risk of flooding from increased heavy precipitation events and sea level rise

• populations in some water scarce regions

Agriculture and Food Security

• Crop yield responses to climate change varies, and depends on:– Species and cultivar– Soil properties– Pests and pathogens

– Interactions between C02, air temperature, water stress, mineral nutrition, air quality and adaptive responses

Temperature

• In tropics, some crops near their max. temperature tolerance yields expected to decrease with even minimal changes in temperature. If coupled with large reductions in rainfall, crop precipitation yields even more adversely affected.

• Few degrees projected warming will lead to general increase in temperate crop yields. larger amounts of warming will lead to a reduction.

• Higher minimal temperatures – beneficial to some crops, especially in temperate regions – detrimental to numerous crops

Temperature

• In the absence of climate change most studies predict declining real prices for agricultural commodities

• Impacts of climate change on agriculture estimated to result in small percentage changes in global income – positive in developed regions, and smaller or negative in developing world

Temperature

• Mean annual temperature increase of 2.5°C or greater, prompt food prices to increase as a result of slowing expansion of global food capacity relative to growth in global food demand.

• At lesser amounts of warming, global impact assessment models cannot distinguish climate signal from other sources of change

• Recent aggregated studies estimated economic impacts on small holder producers and poor urban consumers, indicate that climate change will lower incomes of vulnerable populations and increase number of people at risk to hunger.

• Subsistence agricultural production vital to the economies, nutritional status and social well-being of SIDS

• Climate change could precipitate heat stress, changes in soil moisture and temperature, evapotranspiration, rainfall

• Such changes may affect growth of some subsistence root crops and vegetables. Consequences likely to be more severe in areas already under stress, for example, water scarce islands. Agriculture can also be affected by tropical cyclones and other extreme events such as floods and droughts.

• Likely that crop production will be impacted by alterations in patterns of these events, as a consequence of climate change

• Established that these processes likely to be intensified by adverse change in temperature and precipitation

• Land use and management has greater impact on soil conditions than indirect effect of climate change

• Opportunity to mitigate the latter

Degradation of Soil and Water Resources – one of the major challenges for global agriculture

Carbon dioxide

• Research on direct effects of CO2 on crops suggest that beneficial effects may be greater under certain stressful conditions including warmer temperature and drought

• Effects established for a few crops under experimental conditions – yet to be validated in ‘on-farm’ conditions

• Numerical estimates of climate change impacts on production, income, prices obtained from aggregated integrated assessment models

Carbon Dioxide

• Confidence in outputs low due to uncertainties in:– Magnitude and persistence of rising CO2 on

crop yield under realistic farming conditions– Potential changes in crop and animal pest losses– Spatial variability in crop responses to climate

change– Effects of changes in climate variability and

extreme events on crops and livestock

Carbon Dioxide

• GCM (CCCII) outputs and high, medium and low CO2 emission scenarios coupled with FAO crop model to simulate crop yields:– Sugar cane yields may << from between 20-40% under 2 x CO2 climate change

scenario in Trinidad and Tobago

– Attributed to >>moisture stress caused by warmer climate. Results supported by

findings in Mauritius

– Derived from Agricultural Production Systems Simulator Model (APSIM –

Sugarcane)

– Projects decline in sucrose yield by more than 50% for doubling CO2

– Work on maize (C4 crop) in Venezuela also predicts declining yields

Sea Level Rise, Sea Surface Temperature

• Salt water intrusion into estuaries

• Salinization of aquifers and agricultural soil

• Inundation

• Impacts on marine ecosystems – reefs (sea water temp), sea grass beds, mangroves

Fisheries

• Habitat degradation – mangroves, reefs, sea grass beds

• Profound impact on biological production of oceans including fish production changes in upwelling rates would have major impact on coastal fish production

• Increase in frequency of El Niño events will lead to decline of plankton biomass and fish larvae abundance – adverse effect on fish and ocean biodiversity

Fisheries

• Fluctuations in fish abundance are increasingly regarded as– Biological responses to medium term climate

fluctuations in addition to• Overfishing• Other anthropogenic factors

Fisheries• Growing recognition of the role of the climate-ocean

system in management of fish stocks leading to new adaptive strategies based on determination of acceptable removable percentages of fish stock resilience.

• Adaptation by expansion of marine aquaculture – in 1997 accounted for about 30% total commercial fish and shell production.

• Conservation, restoration and enhancement of vital habitats

• Establishment of marine reserves and protected areas for identified critical species