CLIMATE CHANGE AND FOOD PRODUCTION Glenn Stone Part 1 1
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CLIMATE CHANGE AND FOOD PRODUCTION Glenn Stone Part 1 1
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Agriculture affects the greenhouse 2
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Source: U.S. Environmental Protection Agency (2006) Global
Anthropogenic Non-CO2 Greenhouse Gas Emissions, 19902020. EPA
Report 430-R-06-003; Burney et al 2010. crop weeds, insects, and
diseases are projected to expand to higher latitudes 3
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Agriculture affects the greenhouse and the greenhouse affects
agriculture Source: U.S. Environmental Protection Agency (2006)
Global Anthropogenic Non-CO2 Greenhouse Gas Emissions, 19902020.
EPA Report 430-R-06-003; Burney et al 2010. crop weeds, insects,
and diseases are projected to expand to higher latitudes CO 2 level
affects yields -photosynthesis and transpiration, mainly positive
effects on crop growth and water use may also affect nutrients in
crops Climate and weather affect yields -temperature -water -soil
-weeds, insects, and diseases And the people who farm (e.g.,
population displacement) Other poorly understood effects (e.g.,
phytomicrobiome) Parry, Martin, Cynthia Rosenzweig, and Matthew
Livermore. 2005. Climate change, global food supply and risk of
hunger. Philosophical Transactions of the Royal Society B:
Biological Sciences 360 (1463):2125-2138. 4
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Global Warming and Agriculture 1.Will GW lead to reduced global
food production? Possibly. Most models predict production rising in
temperate areas and dropping in tropical areas (unfortunately,
poorer developing countries). But the projections make unrealistic
simplifying assumptions. 2.Will GW lead to less nutritious food?
Almost certainly. But industrial agriculture has been making our
food less nutritious for many years anyway. 3.Will GW lead to
isolated food crises? With absolute certainty; in fact it already
is. The worst problems will come not from agriculture being
backward, but the lack of safety nets. 4.Will agricultural
technology meet the challenges of GW? Probably not. Industrial
agriculture will continue to contribute to GHG emissions and
promote input- intensive agriculture. 5
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Rosenzweig, C. and M. L. Parry. 1994. Potential impact of
climate change on world food supply. Nature 367 (6459):133-138.
World Bank. 2010. World development report 2010: Development and
change. Washington DC: World Bank. POINTS OF AGREEMENT on CROP
PRODUCTION: -severity on impacts increase with degree of warming
-worst impacts in tropical areas currently with greatest hunger
-(but hunger does not equate with unproductive crops; more later) 6
Parry, Martin, Cynthia Rosenzweig, and Matthew Livermore. 2005.
Climate change, global food supply and risk of hunger.
Philosophical Transactions of the Royal Society B: Biological
Sciences 360 (1463):2125-2138. Theoretical projections
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Depending on the circulation model, developed countries are
either going to have lots more food or somewhat less. Different
models predict decreased production in developing countries but
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Unrealistic Assumptions (especially about developing countries)
The crop growth models embody a number of simplifications. For
example, weeds, diseases and insect pests are assumed to be
controlled, there are no problem soil conditions (e.g. high
salinity or acidity) and there are no extreme weather events such
as heavy storms. The crop models simulate the current range of
agricultural technologies available around the world. They do not
include induced improvements in such technology Parry et al. 2005
Agricultural practices and technologies are always changing,
including in developing countries. 8
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Retrospective studies Corn: down 3.8% from where it would have
been with constant climate Wheat: down a bit Rice and soybean: up
Developed countries fare worse in this study. (Jones, Nicola 2011
Climate change curbs crops. Nature 5 May) 9
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Unrealistic Assumptions (especially about developing countries)
The authors admit that their results are packed full of
assumptions. They could be overestimating climate's effects,
because the model doesn't account for the fact that farmers might
switch to different crop varieties or change their planting dates
as conditions change. Conversely, the results could be an
underestimate, given that the model doesn't look specifically at
extreme weather events such as droughts, floods and heatwaves.
"It's the best we can do with the data available," says Lobell.
Jones, Nicola. 2011. Climate change curbs crops. Nature (5 May).
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Seeds and other technologies are developed all the time 11 Seed
varieties developed by the thousands by international, national,
and local breeding centers; universities; governments; seed
companies; even farmers themselves.
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Farmers in developing countries adjust agricultural practices
all the time 12 Sustainable intensive farming in Nigeria
Intercropping with crop mixes adjusted to ecology and economic
changes Low reliance on external inputs American Anthropologist
1990
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Indian farmers adapt to delayed monsoon Main responses: Changed
irrigation Switch to more drought-tolerant crops Delayed planting
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Global Warming and Agriculture 1.Will GW lead to reduced global
food production? Possibly. Predictions tend to agree on higher
production in temperate areas and lower in tropical areas (where
most poorer developing countries are, esp. subSaharan Africa).
These are plausible, but projections make unrealistic simplifying
assumptions. We know that farmers will adjust practices, although
we dont know how successful they will be. And a big question is
whether it will be in the interests of agricultural technology
developers to develop technologies that help farmers in developing
countries adapt. 14