Key Findings of UN Scientific Report

Saturday, Nov. 17, 2007 | 9:23 a.m.

The following are some key findings in a report issued Saturday by the United Nations Intergovernmental Panel on Climate Change:

- Global warming is "unequivocal." Temperatures have risen 1.3 degrees Fahrenheit in the last 100 years. Eleven of the last 12 years are among the warmest since 1850. Sea levels have gone up by an average seven-hundredths of an inch per year since 1961.

- About 20 percent to 30 percent of all plant and animal species face the risk of extinction if temperatures increase by 2.7 degrees Fahrenheit. If the thermometer rises by 6.3 degrees Fahrenheit, between 40 to 70 percent of species could disappear.

- Human activity is largely responsible for warming. Global emissions of greenhouse gases grew 70 percent from 1970 to 2004. The concentration of carbon dioxide in the atmosphere is far higher than the natural range over the last 650,000 years.

- Climate change will affect poor countries most, but will be felt everywhere. By 2020, 75 million to 250 million people in Africa will suffer water shortages, residents of Asia's large cities will be at great risk of river and coastal flooding, Europeans can expect extensive species loss, and North Americans will experience longer and hotter heat waves and greater competition for water.

- Extreme weather conditions will be more common. Tropical storms will be more frequent and intense. Heat waves and heavy rains will affect some areas, raising the risk of wildfires and the spread of diseases. Elsewhere, drought will degrade cropland and spoil the quality of water sources. Rising sea levels will increase flooding and salination of fresh water and threaten coastal cities.

- Even if greenhouse gases are stabilized, the Earth will keep warming and sea levels rising. More pollution could bring "abrupt and irreversible" changes, such as the loss of ice sheets in the poles, and a corresponding rise in sea levels by several yards.

-A wide array of tools exist, or will soon be available, to adapt to climate change and reduce its potential effects. One is to put a price on carbon emissions.

- By 2050, stabilizing emissions would slow the average annual global economic growth by less than 0.12 percent. The longer action is delayed, the more it will cost.

(This version CORRECTS seven-tenths to seven-hundredths of an inch.))

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