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    BEIJING, April 2 (Xinhuanet) -- One of the lead authors in a 20-chapter draft report from the Intergovernmental Panel on Climate Change -- global warming -- says a chart that projects degree-by-degree rises in worldwide temperatures is a "highway to extinction."

    The chart forecasts more and more animal species will go extinct as the heat rises, and hundreds of millions (perhaps billions) of people may starve, face water shortages or floods, according to the draft report obtained by The Associated Press.

    The chart is likely to be the source of sharp closed-door debate, some scientists say, along with a multitude of other issues in the draft report. While the wording in the draft is almost guaranteed to change at this week's meeting in Brussels, several scientists say the focus won't.

    University of Victoria climate scientist Andrew Weaver said the chart of results from various temperature levels is "a highway to extinction, but on this highway there are many turnoffs. This is showing you where the road is heading. The road is heading toward extinction."

    The final document will be the product of a United Nations network of 2,000 scientists as authors and reviewers, along with representatives of more than 120 governments as last-minute editors. It will be the second of a four-volume authoritative assessment of Earth's climate released this year. The last such effort was in 2001.

    While humanity will survive, hundreds of millions, maybe billions of people may not, according to the chart -- if the worst scenarios happens. The report says global warming has already degraded conditions for many species, coastal areas and poor people.

    The scientists, who feel a 90 percent level of confidence in the draft report, say man-made global warming "over the last three decades has had a discernible influence on many physical and biological systems."

    As the world's average temperature warms from 1990 levels, the projections get worse. Add 1.8 degrees Fahrenheit (1 degree Celsius) and between 400 million and 1.7 billion extra people won't have enough water, some infectious diseases and allergenic pollens rise, and some amphibians go extinct.

    But the world's food supply, especially in northern areas, could increase. That's the likely outcome around 2020, according to the draft.

    Add another 1.8 degrees and as many as 2 billion people could be without water and about 20 percent to 30 percent of the world's species near extinction. Also, more people start dying because of malnutrition, disease, heat waves, floods and droughts -- all caused by global warming. That would happen around 2050, depending on the level of greenhouse gases from the burning of fossil fuels.

    At the extreme end of the projections, a 7- to 9-degree average temperature increase, the chart predicts: "Up to one-fifth of the world population affected by increased flood events ... "1.1 to 3.2 billion people with increased water scarcity¡± ..." major extinctions around the globe."

    Despite that dire outlook, several scientists involved in the process say they are optimistic that such a drastic temperature rise won't happen because people will reduce carbon dioxide emissions that cause global warming.

    "The worst stuff is not going to happen because we can't be that stupid," said Harvard University oceanographer James McCarthy, who was a top author of the 2001 version of this report. "Not that I think the projections aren't that good, but because we can't be that stupid."

    (Agencies)