Transcript Temperature - Global Environmental Change and Food Systems

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 0.090.88m 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 midlatitudes 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
Degradation of Soil and Water Resources – one of
the major challenges for global agriculture
• 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
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:
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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