The 1,600-page report incorporates the work of hundreds of scientists working for the UN-chartered Intergovernmental Panel on Climate Change.
It is widely considered to be one of the most authoritative studies on climate change and its conclusions are expected to be dire.
"Most of the glaciers in low-latitude mountain areas [could] disappear within the coming decades." Wilfried Haeberli, Zurich University
According to recent drafts, scientists say they are now 90-percent certain that man-made greenhouse gas emissions are the major cause of global warming.
They estimate that if current trends continue, we will see dramatic effects from climate change within the next few decades.
Melting Glaciers Spell Trouble
Among those changes: some temperate areas, such as the Mediterranean basin, will become drought-ridden, barely habitable regions in the summer.
Alpine ski resorts, devoid of snow in winter, will instead become cool summer refuges for those fleeing the heat.
Rivers will dry up and sea levels will rise, flooding coastal areas. Violent storms will become frequent, as will other types of natural disasters.
A global consensus that climate change is happening appears to have been reached.
One group of scientists, working at the World Glacier Monitoring Service in Switzerland, is not surprised. These scientists been warning about global warming, and its acceleration, for many years.
For decades, the research institute at Zurich University has monitored 30 mountain glaciers around the world.
Because they are so visible, and measurable, institute director Wilfried Haeberli says glaciers are the best natural indicator of climate change.
They are like the proverbial canary in the mine shaft, and what they indicate is pretty dramatic, Haeberli says.
"Most of these medium-sized glaciers have an average thickness of about 30-40 meters," Haeberli says. "And if glaciers lose about half-a-meter per year, or even up to a meter per year, it is quite easy to estimate that with the continuation of the warming trend, most of these glaciers and most of the similar glaciers in low-latitude mountain areas would disappear within the coming decades."
Calls For Urgent Action
On average, the world’s glaciers are now melting three times faster than they were in the 1980s.
And that spells trouble not just for ski resorts, says Haeberli:
"In the summertime, in the dry season, many, many rivers are really nourished by glacier meltwater," Haeberli says. "If the glaciers go away, the Rhine and Rhone rivers in Europe, for instance, will have very little water during hot and dry summers, as we experienced in 2003, and as may become much more frequent in the future. And then we may really have very serious drought problems."
Calls for UN Secretary-General Ban Ki-moon to convene an urgent meeting on global warming have redoubled this week.
Meanwhile, some U.S. legislators, who have been holding their own hearings on the issue, are urging faster government action to curb emissions.
The United States produces about a quarter of the planet’s greenhouse gases, but the administration of President George W. Bush has resisted the idea of mandating industrial emissions cuts, calling that harmful to the economy.
Bush, however, did recently call for new laws to make cars more fuel-efficient, with the aim of curbing U.S. gasoline consumption by 20 percent over the next decade.