A U.S. research team says global temperatures are reaching a million-year highpoint, and could surpass that peak in coming decades if current global warming trends continue. The scientists say there is still time to combat the swift rise in temperatures, and to delay or even prevent the potentially devastating consequences of global warming, but that time is running out.

Global Warming map

The researchers say global temperatures have been rising by 0.2 degrees Celsius per decade over the last 30 years. They say the rate of increase could accelerate in coming decades if global energy consumption continues to rise, resulting in ever-larger amounts of so-called "greenhouse gasses" being released into the atmosphere.

David Lea is a professor of earth science at the University of California at Santa Barbara and co-author of Global Temperature Change, a report published by the National Academy of Sciences.

Lea, who teamed with researchers from NASA's Goddard Institute for Space Studies, helped derive temperature estimates going back hundreds of thousands of years by studying the chemical content of fossilized microbes. The results, compared with today's temperature readings from land, sea and air, are startling.

"There is only, essentially, one time period about 400,000 years ago when temperatures appear to have been significantly - in this case about one degree Celsius - warmer than they are today. So, it becomes a very interesting baseline, or metric, for comparison of just where we are in terms of our global temperatures today compared to where we have been over the last million years," he said.

If current warming trends continue, the earth would surpass the million-year temperature highpoint at some point near the middle of this century.

Lea acknowledges that a 0.2 degree temperature rise over a decade may sound trivial to some.

"Point two degree Celsius per decade does not sound that dramatic in the human context of what we experience every day or every season [in temperature variation]. But when we look globally, that is actually quite significant," he said.

The researcher says even minute temperature changes can have drastic consequences. "The melting of the icecaps in, specifically, Greenland and West Antarctica, and the potential to raise sea levels on the order of several meters maybe up to even tens of meters is the thing that we are most concerned about," he said.

Lea also warns of the potential for plant and animal extinctions on a massive scale, as well as more severe weather phenomena, such as hurricanes. The report concludes that, unless greenhouse gas emissions are scaled back over the next 10 years, some of the negative consequences of global warming could become unavoidable.

After years of debate, the scientific community appears to have reached a consensus that global warming is a reality, not just a theory. What remains a point of contention for some is the extent to which climate change is occurring and the degree to which human activity is affecting it. President Bush has urged further study of global warming before implementing any costly measures.