CLIMATE CHANGE AND FOOD PRODUCTION Glenn Stone Part 1 1

Agriculture affects the greenhouse 2

Source: U.S. Environmental Protection Agency (2006) Global Anthropogenic Non-CO2 Greenhouse Gas Emissions, 1990–2020. EPA Report 430-R ; Burney et al crop weeds, insects, and diseases are projected to expand to higher latitudes 3

Agriculture affects the greenhouse and the greenhouse affects agriculture Source: U.S. Environmental Protection Agency (2006) Global Anthropogenic Non-CO2 Greenhouse Gas Emissions, 1990–2020. EPA Report 430-R ; Burney et al 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 Climate change, global food supply and risk of hunger. Philosophical Transactions of the Royal Society B: Biological Sciences 360 (1463):

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

Rosenzweig, C. and M. L. Parry Potential impact of climate change on world food supply. Nature 367 (6459): World Bank 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 Climate change, global food supply and risk of hunger. Philosophical Transactions of the Royal Society B: Biological Sciences 360 (1463): Theoretical projections

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… 7

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 Agricultural practices and technologies are always changing, including in developing countries. 8

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

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 Climate change curbs crops. Nature (5 May). 10

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.

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

Indian farmers adapt to delayed monsoon Main responses: Changed irrigation Switch to more drought-tolerant crops Delayed planting 13

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 don’t 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