November 19, 2011
Climate Change Has Already Boosted Heat Waves And Rainfall
According to a report by U.N. scientists, man-made climate change has already boosted heat waves and flood-provoking rainfall and is likely to contribute to future natural disasters.
It said that the toll from these extreme weather events will depend as much on the measures taken to protect populations and property as the violence of nature's outbursts.
The report is the U.N.'s first comprehensive review of global warming's impact on weather extremes and how best to manage them.
"We can actually attribute the increase of hot days in the past few years to an increase in greenhouse gases," Thomas Stocker, co-chair of the Intergovernmental Panel on Climate Change (IPCC), said at a press conference.
"And it is virtually certain that increases in the frequency and magnitude of warm daily temperature extremes, and decreases in cold extremes, will occur in the 21st century," he said.
"Heavy precipitation will become more frequent in many regions of the world," he added.
Heat and rain extremes under three projections, including a sharp reduction in carbon emissions, a modest reduction, and current "business-as-usual" levels, were both reviewed in the report.
The scenarios are a rough trajectory of increased extremes up to the mid-century.
Towards the end of the century, the pathways of the scenarios diverge, with far higher and more frequent heat waves and rainfall peaks in the worse-case scenario.
The report showed that for the high-emission scenario, one-in-20-year heat peaks would occur every five years by about 2050, and every year or two by the end of the century.
Qin Dahe, also an IPCC co-chair, said the panel was "more confident" that climate change is boosting glacier retreat, which is a concern for nations in Asia and South America.
Stocker said that scientists are still unable to determine the impact of climate change because of lack of data and the "inherent variability and variations in the climate system."
"Uncertainty cuts both ways. Events could be more severe and more frequent than projections suggest, or vice versa," he said at the press conference.
Some studies have suggested that warmer air and sea surface temperatures combined with greater moisture in the air will intensify tropical storms.
The report was written by about 200 scientists and was approved this week by the 194-nation IPCC, which gathers government representatives as well as experts.
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