Warming has led to changes in climate extremes such as heat waves, record high temperatures and, in many regions, heavy precipitation since 1950, the U.N. climate panel warned in a report Wednesday.
"It is very likely that there has been an overall decrease in the number of cold days and nights, and an overall increase in the number of warm days and nights, at the global scale," the scientists wrote.
Some populations are already living on the edge of disaster, given the projected increases in the magnitude or frequency of some extreme events in many regions, the report stated.
"Small increases in climate extremes above thresholds or regional infrastructure 'tipping points' have the potential to result in large increases in damages to all forms of existing infrastructure," the experts said.
In the past, the Intergovernmental Panel on Climate Change has focused on the gradual rise of temperatures and oceans. This report is the first to look at less common but far more noticeable extreme weather changes, which lately have been costing on average about $80 billion a year in damage.
The study forecasts that some tropical cyclones -- which include hurricanes in the United States -- will be stronger, while the frequency might diminish.
"Average tropical cyclone maximum wind speed is likely to increase, although increases may not occur in all ocean basins," the experts stated. "It is likely that the global frequency of tropical cyclones will either decrease or remain essentially unchanged."
Some other specific changes in severe weather that the scientists said they had the most confidence in predicting include more heat waves and record hot temperatures worldwide and increased downpours in Alaska, Canada, northern and central Europe, East Africa and north Asia.
"We mostly experience weather and climate through the extreme," said one of the report's top editors, Chris Field, an ecologist with the Carnegie Institution of Washington. "That's where we have the losses. That's where we have the insurance payments. That's where things have the potential to fall apart.
"There are lots of places that are already marginal for one reason or another," Field said. But it's not just poor areas: "There is disaster risk almost everywhere."
At 592 pages long, the report elaborates on a summary of findings released last November.
The report specifically points to New Orleans during 2005's Hurricane Katrina, noting that "developed countries also suffer severe disasters because of social vulnerability and inadequate disaster protection."
In coastal areas of the United States, property damage from hurricanes and rising seas could increase by 20 percent by 2030, the report said. And in parts of Texas, the area vulnerable to storm surge could more than double by 2080.
Already, U.S. insured losses from weather disasters have soared from an average of about $3 billion a year in the 1980s to about $20 billion a year in the last decade, even after adjusting for inflation, said Mark Way, director of sustainability at insurance giant Swiss Re. Last year that total rose to $35 billion, but much of that was from tornadoes, which scientists are unable to connect with global warming. U.S. insured losses are just a fraction of the overall damage from weather disasters each year.
The scientists say that some places, particularly parts of Mumbai in India, could become uninhabitable from floods, storms and rising seas. In 2005, over 24 hours nearly 3 feet of rain fell on the city, killing more than 1,000 people and causing massive damage. Roughly 2.7 million people live in areas at risk of flooding.
The IPCC and former Vice President Al Gore won the 2007 Nobel Peace Prize for their efforts around climate change.
Since then, the IPCC has also come under fire from those questioning whether warming can be attributed to mankind's burning of fossil fuels. Critics found a flawed analysis of Himalayan glacier melt, and a few other questionable data, but overall the thousands of pages of IPCC documents have stood the test of scientific review.
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