Latest global warming report urges world to begin adapting

The poor may be hit the hardest by climate changes, IPCC report says; calls for stronger action

from the April 6, 2007 edition

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Scientists have outlined a range of effects that have already taken place; they vary depending on how regional climates respond to rising global average temperatures. But as scientists look ahead, broad patterns emerge. Among them:

Fresh-water resources. By the middle of the century, average river runoff is expected to increase by 10 to 40 percent in areas nearest the two poles and in some wet tropical areas. But it's expected to shrink by 10 to 30 percent in dry, mid-latitude regions as well as in dry tropical parts of the globe. Drought-prone regions are likely to expand their boundaries, while heavy snowfall and rainfall elsewhere raises the likelihood of more frequent and severe flooding.

Ecosystems. The report notes that if temperatures increase between 1.5 and 2.5 degrees C (2.7 to 4.5 degrees F.), 20 to 30 percent of the plant and animal species researchers have examined so far could become extinct.

Farming. Globally, food production overall improves if temperature increases locally remain with a 1 degree to 3 degree C range. Productivity is projected to fall if temperatures rise above that range.

Coastal areas. By 2080, millions of people are expected to be affected by floods because of sea-level rise, especially in regions with high land subsidence, such as the Louisiana coast, or regions in Asia and Africa with large, low-lying, heavily populated river deltas. Small islands, the report notes, are particularly vulnerable.

Human habitation. Cities and industries that sit along coastal areas or river flood plains are expected to face the largest challenges – especially in already poor countries. Even in wealthy nations the poorest people are likely to suffer most.

Public Health. The report sets out a mixed picture, with the heaviest effects falling on poor areas where health care services, sanitation, and sources of clean water already are scarce.

Researchers acknowledge that pegging the changes they see in specific physical and biological systems to global warming is difficult. Changes are being measured at a relatively small number of sites around the world. And they cover a relatively small number of ecological and physical systems.

Still, the report notes that out of 29,000 data sets contained in 75 studies regarding changes under way, 89 percent are consistent with what models project should happen as the world warms. And the warming patterns people are seeing regionally are consistent with broad distribution of temperature changes global-scale models.

Moreover, research over the past six year has allowed scientists to project the possible effects of warming more accurately based on each degree of temperature increase.

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