Studies: Global warming to worsen

LONDON, England (CNN) -- Two new climate studies predict that global warming by the end of the century will be even more dramatic than a United Nations group has predicted.

But more important than that long-range outlook, said one climate expert, is the data that both teams of scientists show for the years 2020-2030.

"These very different approaches both tell us that two to three decades from now, it will be warmer than it is now," said Francis Zwiers, a statistics and climate expert with the Meteorological Service of Canada.

A British study says that in those years the Earth will be 0.5 to 2.3 degrees Fahrenheit warmer than the period between 1990-2000. A Swiss study predicts a temperature increase ranging from 0.9 to 1.9 degrees Fahrenheit.

"In that time scale, we can do planning for changing fuel sources, so there are less greenhouse gases," Zwiers said.

The two studies are detailed in the latest issue of the journal Nature.

The studies are consistent with findings from the U.N. Intergovernmental Panel on Climate Change. That group has predicted world temperatures could rise as much as 10.5 degrees or as little as 3 degrees Fahrenheit by the end of the century.

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In the Swiss study, climate modelers at the University of Bern, Switzerland, projected temperatures would rise 7.7 degrees by 2100. The British study, done at the Hadley Center for Climate Prediction and the Rutherford Appleton Laboratory, predicted a rise of as much as 12.4 degrees Fahrenheit in a worst-case scenario.

By comparison, scientists estimate that the temperature difference between the last Ice Age and today is only 9 degrees Fahrenheit.

The U.N. study, published last year, concluded that "most of the warming observed over the past 50 years is attributable to human activities," including gases from industry and automobiles.

Continuing over short term

But even if greenhouse gases were curbed immediately, warming would continue over the short term, Zwiers said.

"The climate still hasn't come into complete adjustment to the gases emitted during the last century," he said.

Climate prediction analysis involves complex computer modeling recipes, taking into account the buildup of greenhouse gases, the role of oceans, uncertainty about technological change, and incomplete knowledge of how the Earth's climate has changed over thousands of years.

While there is general agreement among most climate scientists that global warming is real, and that it is at least partially attributable to human activity, some climate scientists sharply disagree.

The dissenters argue that the Earth has been in a long-term, natural cycle of rising temperatures since the so-called "Little Ice Age" 500 years ago. Further, they point out that many temperature monitoring stations are located in cities, where heat-absorbing buildings and pavement can give misleadingly high temperature readings.

Zwiers, an author of the U.N. study, said a warmer world could have a number of affects on health. Even a couple of degrees could make some areas more hospitable to pests and insects that carry diseases, he said.