Washington
When a UN-backed panel releases section two of a global climate report next week, one thing will be certain: scientists have grown increasingly confident of global warming's dire impact on human life.

The latest installment - the second of three by the Intergovernmental Panel on Climate Change (IPCC,) to be released April 6 in Brussels - examines the expected impact of climate change on human society. It follows the first installment released February in Paris, which focused on the scientific evidence of global warming itself.

Some of the April report's expected predictions: coastal and low-lying regions will be flooded by rising sea levels, driving millions inland; higher global temperatures will lead to changing crop yields, increasing famine and disease; more heat-waves and stronger storms will lead to more deaths; and changing ecosystems mean countless animal and plant species will become extinct.

"Many of us believe we are on the threshold of a massive extinction event," says Jeff Price of California State University at Chico and a lead author of the IPCC report's chapter on ecosystems.

All of those findings are already known, through the reams of scientific research published in the six years since the IPCC's last series of reports. The job of the more than 2,000 scientists aiding the panel is to sift through those findings rather than conduct any new research.

What singles out this report, scientists say, is the consensus found within the worldwide literature. That consensus is not only stronger since the last round of IPCC reports in 2001, but it has spread to new areas.

Virginia Burkett, of the US Geological Survey's National Wetlands Research Centre, said there was a "plethora of new information" and literature to sift through, yet she doesn't remember any "major debates" her group had about its findings.

"The recent advances ... in the literature have allowed the consensus to include a much broader range of drivers and impacts," said Burkett, who co-authored a chapter dealing with global warming's effect on coastal regions, in both the April report and in 2001.

The 2007 IPCC report series has also allowed scientists to use the huge range of models that have come out since 2001 and set specific timeframes for events.

"We have for the first time started putting bounds, temperature limits on when things will start happening," Price said. 

Though Price would not discuss specific findings ahead of the April release, he said it was generally agreed that just a 2-degree Celsius hike in global temperature would lead to a "serious conversion of habitats," while anything above 2 degrees Celsius could result in "major ecosystems' collapses."

The IPCC report's first section already set an ominous tone. The panel found an "unequivocal" trend of rising global temperatures and sea levels and placed the blame squarely on man-made emissions. 

It predicted the Earth would heat up between 1.8 and 4 degrees Celsius by the end of this century, and up to 6.4 degrees Celsius at the poles, which heat up twice as fast as around the equator. Melting ice has led sea levels to climb 17 cm in the 20th century, and at a rate of 3.1 mm per year since 1993.

Another ominous finding of the upcoming April report is that it may already be too late to prevent some of global warming's impacts - humans can only adapt to so much, especially when it comes to rising sea levels flooding islands.

"There are some cases that may be beyond the limits of adaptability," according to Roger Pulwarty of the National Oceanic and Atmospheric Administration (NOAA), a co-author of a chapter on how humans have, and can, deal with the effects of climate change.

On a positive note, Pulwarty said his group also found that many effects of global warming could still be accommodated, but only if preparations for "long-term" environmental changes start immediately.

That kind of warning, scientists hope, will push governments and people into action.

The February IPCC installment's findings were welcomed by governments around the world and led the European Union to announce stiff new curbs on greenhouse-gas emissions and fresh efforts to find renewable energy alternatives. In the US, the world's largest polluter, businesses and states are piling pressure on the federal government to place mandatory, nationwide caps on emissions.

"I hope it will finally wake people up to the sheer magnitude if the problem," Price said.

But while the April report will offer recommendations on how already-occurring effects of climate change can be dealt with, many governments are likely to wait until the IPCC's third section is released in Bangkok in May, offering specific advice on how policy makers can reduce global warming.

A final draft of the second installment will be discussed and voted on by government officials and scientists at a summit meeting starting April 2 in Brussels. The final work will be presented at a news conference April 6.