Farmers Feel Effects of Climate Change

Crystal Davis

Earth Trends - 2008-02-28

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The warmest winter ever recorded in Finland may boost the country's agricultural production by lengthening the growing season, demonstrating some of the early impacts of global climate change. Finland's southern regions experienced average temperatures above freezing point this year and had snow cover for only 20 days, far below the typical 70. Although global warming appears to favor agriculture in this Nordic country, world agriculture as a whole is predicted to suffer as global temperatures rise. The greatest production losses are expected in developing countries due to natural vulnerability and limited capacity to adapt, threatening already food-insecure regions.

Change in Agriculture Output Potential Due to Climate Change, 2000-2080

Source: EarthTrends, 2008 using data from Cline, 2007

Climate Change and Agriculture

The relationship between climate change and agriculture is complex. While climate is the single most important factor affecting agriculture production around the world, agricultural activities are also a significant source of greenhouse gas (GHG) emissions. The latest report from the Intergovernmental Panel on Climate Change (IPCC) estimates that agriculture contributes 13.5% of global GHG emissions, largely a result of methane emissions from livestock and flooded rice cultivation and nitrous oxide emissions from fertilizer application. If you include GHG emissions from deforestation, of which agriculture is a leading driver, the share grows even larger. The forestry sector accounts for another 17.4% of human-induced emissions.

Contributions of Greenhouse Gas Emissions by Sector, 2004

Source: EarthTrends, 2008 using data from IPCC, 2007

Projecting Impacts

Estimating potential impacts of climate change on agriculture is challenging, especially considering scientific uncertainties surrounding the magnitude of future warming. Several potentially positive effects of global warming on agriculture have been identified, including the "CO2 fertilization" theory, which posits that increased atmospheric concentrations of carbon dioxide will actually favor plant growth. The extent to which such benefits will cancel out the expected negative impacts (such as increased drought) is uncertain and accounts for the wide range of predictions surrounding the future of agriculture productivity.

There is certainty, however, that the worst impacts will not be experienced equally around the world. At high latitudes and elevations, including countries like Finland, higher temperatures will likely generate net benefits for agriculture, and could even create new agricultural land in areas previously too cold for farming. In the lower latitudes, where most of the world's poor countries reside, impacts will be overwhelmingly negative, including increased frequency of heat waves, heavy precipitation events and insect outbreaks and an expansion of the area affected by drought. When combined with the poor adaptive capacity in the developing world, and particularly in Africa, these impacts on agriculture could have devastating consequences for food security, poverty, and social welfare.

Possible Impacts on Agriculture, Forestry and Ecosystems by Region in the Developing World

Region
Potential Impacts

Africa
By 2020, in some countries, yields form rain-fed agriculture could be reduced by up to 50%. Agricultural production, including access to food, in many African countries is projected to be severly compromised. This would further adversely affect food security and exacerbate malnutrition.

Asia
By the 2050s, freshwater avaiability in Central, South, East, and Southeast Asia, particularly in large river basins, is projected to decrease.

Latin America
By mid century, increases in temperature and associated decreases in soil water are porjected to lead to gradual replacement of tropical forest by savanna in eastern Amazonia. Semi-arid vegetation will tend to be replaced by arid-land vegetation. Productivity of some important crops is projected to decrease and lviestock productivity to decline, with adverse consequences for food security. In temperate zones, soybean yields are porjected to increase. Overal, the number of people at risk of hunger is projected to increase.

Source: FAO, 2008 based on information from IPCC, 2007

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