FOOD PRODUCTION Hotter temperatures, changes in the hydrologic cycle (evaporations, precipitation, etc.), and an increase in severe weather events will impact human agriculture systems. Analyzing the global agriculture system is complex as the number of factors that contribute to a productive agriculture system varies widely. Soil quality, type of crop, elevation, population density, rainfall patterns, market incentives, land ownership rights, government policy, farmers’ knowledge, and more contribute to the success or decline of crop yields and food security. The impacts of climate change on plant growth will vary, as warmer weather in some climates will result in a longer or even an additional growing season, warmer weather in other areas will result in heat stress and drought. Even within countries, the impacts will vary as the growing conditions vary and are impacted in different ways by climate change.

For example, examining one of the primary crops of the US, soybeans, research found that yields increased in some areas and decreased in others. On the map below, green areas are counties where yields increased, red and orange areas are counties where soybean yields have declined.

A similarly varied picture emerges when researchers examined corn/maize yields at the global level. While the yields increase in parts of the US, Asia, and South America, they decline dramatically in other areas, Europe in particular.

Not every impact of climate change is negative. Some studies show that higher concentrations of CO2 are beneficial for some types of crops. But it is essential to remember that higher concentrations of CO2 are not the only effect of climate change and cannot be considered in isolation. When the cumulative impacts of climate change are taken into account, on balance, the global impact on agriculture is expected to be negative.

The impacts on agricultural productivity will depend in part on the degree and speed of temperature and precipitation changes. If the rate of change is slow enough, some farmers will be able to adapt if their social context gives them access to technological resources. Wealthy nations with more advanced science and technology readily accessible will be better able to adapt to changes. Using irrigation, genetic engineered crops, soil amendments (like fertilizers), and more accurate and timely weather forecasts, many farmers in the US and Europe will be able to buffer themselves from the negative effects, at least for a little while. Others, living in poorer nations as subsistence farmers (largely growing the food they need to survive) do not have access to the same tools. The lack of technology, crop insurance, or assets, combined with the predictions that many of these areas (the tropics) will increase in temperature more than the average, makes their livelihoods (and lives) highly susceptible to climate change. Many developing nations rely on agriculture for a significant portion of their national economy and as much as 60-70% of the population works in the agriculture sector — up to 80% in some rural areas.

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