Global warming called a human creation

BY MARTIN MERZER

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The world's scientific community will issue an emphatic call to action today, saying that global warming will spike temperatures by two to 11 degrees and elevate oceans by seven inches to two feet by the end of the century -- and will intensify hurricanes.

The long-anticipated report, to be issued in Paris by scientists, government officials and others from 113 countries, will seek to erase any lingering doubt about the reality of global warming or its primary cause.

Human activities ''very likely'' play a major role in producing the phenomenon, the 20-page study concludes, according to a copy obtained Thursday night by The Associated Press.

That means the world's scientists are 90 to 99 percent certain that the burning of fossil fuels is responsible.

Worse, the study reportedly describes global warming as a runaway climatological train that already is racing down the track and will ``continue for centuries . . . even if greenhouse gas concentrations were to be stabilized.''

The study was to be officially issued early this morning by the Intergovernmental Panel on Climate Change, which is sponsored by the United Nations and the World Meteorological Organization.

The report, the IPCC's fourth since 1990, appears to be the most blunt of the series, represents the consensus of the world's scientific community and is certain to influence governments and corporations.

''I think the take-home message of the 2007 report for the general public is that global warming is real, it's happening now and its impacts will become more pronounced during our lifetime,'' said Brian Soden, a global climate specialist at the University of Miami's Rosenstiel School of Marine and Atmospheric Science on Virginia Key.

Soden served as one of numerous lead authors of the report.

''We know that the planet has warmed by a little over a degree Fahrenheit during the last century, that the rate of warming is accelerating and that human activities are a primary contributor to that warming,'' he said. ``There is no serious scientific debate on that.''

Likely of primary interest to Floridians: the panel's conclusions about rising sea levels and more powerful hurricanes.

The study predicts average worldwide sea level increases of seven to 23 inches by 2100, the AP reported. Another four to eight inches could be added if the little-understood melting of polar ice sheets continues.

''That would obviously be a concern for low-lying areas,'' Soden said.

''Ecosystems like the Everglades are also very vulnerable to such a change,'' he said. ``Coral bleaching from the warmer temperatures and increasing acidity of the ocean would be another concern.''

As for hurricanes, the group reportedly said recent increases in the power of the storms ''more likely than not'' are attributed to human-induced global warming.

If one accepts that contention, Soden said, hurricane intensity is likely to continue growing for years to come.

Still, the contention further fuels debate over the impact of global warming on hurricane development and intensity.

Some experts recently reported strong links between human activities and rising sea temperatures -- an important component of hurricane production.

But others say the increase in sea temperatures is still too small to significantly enhance hurricane development or intensity and that the upswing in storm activity since 1995 has been caused by long-term natural cycles unrelated to global warming.

''There is intense scientific debate on this topic,'' Soden said.

Though considered authoritative and state-of-the-art, the IPCC's work is not viewed by all experts as the final word on the subject of global climate.

For one thing, climatology is a bewilderingly complex field that is affected by the interplay of countless natural processes, unfolds slowly over vast periods of time and involves the entire planet, its seas and its atmosphere.

Scientists know that natural cycles of global warming and cooling -- generally stretching over thousands of years -- occurred long before humans began burning fossil fuels.

So, they avidly debate the meaning of each new measurement or other discovery, seeking to determine:

How significant is it? Does it indicate long-term, human-induced, unnatural change? Or, when considered over the long run, is it just a brief burst of meaningless static?

And they are constantly surprised.

Just this week, for instance, a less publicized but scholarly report issued by scientists at Baylor University found that the Great Plains cooled 7,000 to 12,000 years ago when current knowledge suggests it should have warmed and that, about 6,000 years ago, the region was two degrees warmer than it is now.

In addition, the issue of global warming has become thoroughly politicized.

Al Gore's movie, An Inconvenient Truth, has emerged as a surprise hit, Sens. John McCain, R-Ariz., and Barack Obama, D-Ill., have sponsored a bill to reduce greenhouse gas emissions by two-thirds by 2050, other presidential hopefuls have adopted the issue, the White House and Congress have clashed over climate policy, and many scientists and private advocacy groups have accused the Bush administration of attempting to suppress scientific debate on the matter.

Even the IPCC, the group that will issue the first section of its report today and at least two other sections later this year, found itself embroiled in debate over nearly every element of its work.

It repeatedly wrestled over nuances in terminology, with some members fearing that the need to reach consensus would dilute the study's wording and impact.

Still, the final study reportedly produces some of the most powerful language ever employed by reputable scientists.

''I believe that the IPCC reports are the most comprehensive and thoroughly vetted climate assessments produced,'' Soden said. ``And I also believe that a vast majority of experts would view it as the most authoritative assessment of climate change.''