Extreme weather risks

Paradoxically, as global warming raises the risk of floods, it also increases the probability of long-term droughts. Past rain and snowfall patterns are likely to change - with potentially severe impacts upon agriculture production (United Nations Foundation and Sigma XI, 2007). In fact, we may have seen the first signs of this problem during the 1970s, when the rainfall patterns that sustained sub-Saharan African agriculture in the arid Sahel changed for the worse. The ensuing decade-long drought caused cyclical crop failures, livestock deaths and famine across the Sahel - and contributed to the Ethiopian famine in the 1980s. New research suggests that this rainfall shift was most likely caused by atmospheric pollution and global warming, which shifted the rainfall north of its normal zone (NOVA, 2006). Current IPCC modelling suggests some areas in the Sahel will have more rainfall; but a larger area will have less - impacting negatively upon agriculture production - in regions that are barely achieving subsistence (United Nations Foundation and Sigma XI, 2007).

Future rainfall shifts expected in the temperate zone are likely to occur in highly productive regions like the US 'corn belt'. US agriculture, which is concentrated in the central plains and California, accounts for 20 per cent of global production. While some of this production is irrigated, much of the cereal crops depend upon rainfall. Persistent drought conditions will reduce production and, likely, the global food balance. Globally, lower production and rising food prices could occur over an extended period as other cereal-producing regions also experience climate change. Over time, production would move to less affected zones (e.g. possibly Canada); but farmers in the US central plains may go out of business. A draft study by the US Climate Science Program forecasts a number of the consequences from climate change - lower yields, less production and higher crop loss due to pests (USCCSP, 2007).

Changes in snowfall patterns could threaten major irrigation schemes in California's Imperial Valley and other areas of the US south-west if the spring melt water flow declines. During the last century, politicians and planners saw the harnessing of rivers - the Platte, the Rio Grande and the Colorado - as opportunities to develop agriculture in relatively arid regions. These popular public investments made settlement possible and supplied hydroelectric power to the western US. In Europe, the Rhine Valley industry has been powered by similar snow-fed hydroelectric systems for decades. The Alpine snow pack is also under pressure. The prospect of reduced water availability and power suggests that the economic activity and energy demand in these regions are likely to change. If we are to sustain productivity and individual livelihoods under new climate conditions, planning must begin now.

Several climate models forecast that the agriculture situation may improve in parts of Russia and China; but some regions within both countries may suffer from production declines (United Nations Foundation and Sigma XI, 2007). The consequence of lower food production globally, combined with the disruption of climate-related natural disasters, has serious implications for national and regional security, which is dependent upon society's ability to maintain economic growth and social development. If these changes occur over long periods of time and vary from region to region, the world may have the ability to adapt to new economic development patterns. Sustained disruptions in major producing areas, however, will have global and local effects - and many of these could occur simultaneously (United Nations Foundation and Sigma XI, 2007). As the global economy's resilience to meet such challenges is predicated on maintenance of political and economic stability in the developed world, anticipating and developing a response to these challenges is a clear responsibility of policy-makers.

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