The report looks at regional and state-level effects of global warming, compared with recent reports from the United Nations that lumped all of North America together. A draft of the report was released in January 2013, but this version has been reviewed by more scientists, the National Academy of Science and 13 government agencies and had public comment. It is written in a bit more simple language so people could realize "that there's a new source of risk in their lives," said study lead author Gary Yohe of Wesleyan University in Connecticut.
Even though the nation's average temperature has risen by as much as 1.9 degrees since record keeping began in 1895, it's in the big, wild weather where the average person feels climate change the most, said co-author Katharine Hayhoe, a Texas Tech University climate scientist. Extreme weather like droughts, storms and heat waves hit us in the pocketbooks and can be seen by our own eyes, she said.
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And it's happening a lot more often lately.
The report says the intensity, frequency and duration of the strongest Atlantic hurricanes have increased since the early 1980s, but it is still uncertain how much of that is from man-made warming. Winter storms have increased in frequency and intensity and shifted northward since the 1950s, it says. Also, heavy downpours are increasing—by 71 percent in the Northeast. Heat waves, such as those in Texas in 2011 and the Midwest in 2012, are projected to intensify nationwide. Droughts in the Southwest are expected to get stronger. Sea level has risen 8 inches since 1880 and is projected to rise between 1 foot and 4 feet by 2100.
Since January 2010, 43 of the lower 48 states have set at least one monthly record for heat, such as California having its warmest January on record this year. In the past 51 months, states have set 80 monthly records for heat, 33 records for being too wet, 12 for lack of rain and just three for cold, according to an Associated Press analysis of federal weather records.
"We're being hit hard," Hayhoe said, comparing America to a boxer. "We're holding steady, and we're getting hit in the jaw. We're starting to recover from one punch, and another punch comes."
The report also says "climate change threatens human health and well-being in many ways." Those include smoke-filled air from more wildfires, smoggy air from pollution, more diseases from tainted food, water, mosquitoes and ticks. And then there's more pollen because of warming weather and the effects of carbon dioxide on plants. Ragweed pollen season has lengthened by 24 days in the Minnesota-North Dakota region between 1995 and 2011, the report says. In other parts of the Midwest, the pollen season has gotten longer by anywhere from 11 days to 20 days.
And all this will come with a hefty cost, the report says.
Flooding alone may cost $325 billion by the year 2100 in one of the worst-case scenarios, with $130 billion of that in Florida, the report says. Already the droughts and heat waves of 2011 and 2012 added about $10 billion to farm costs, the report says. Billion-dollar weather disasters have hit everywhere across the nation, but have hit Texas, Oklahoma and the Southeast most often, the report says.