A map depicts temperature changes over the past 20 years, compared to the average between 1901 and 1960. “The period from 2001 to 2011 was warmer than any previous decade in every region,” according to the National Climate Assessment.
Temperatures will continue to rise in America, “with the next few decades projected to see another 2 degrees [Fahrenheit] to 4 degrees [Fahrenheit] of warming in most areas,” according to the latest National Climate Assessment, which came out Friday afternoon.
That means we can expect to see more “extreme weather events,” according to the report, such as heavy precipitation — particularly in the Northeast and Midwest — and intense Atlantic hurricanes. Other parts of the U.S. will experience heat waves and droughts, especially in the West.
By 2100, U.S. temperatures are projected to rise 3 to 5 degrees, under the most optimistic estimates — and 5 to 10 degrees if global greenhouse gas emissions continue to increase.
While it doesn’t seem to bring any startling new facts to the table, the assessment’s authors say that “evidence for a changing climate has strengthened considerably” since the last report, issued in 2009.
Some of that evidence has been on display recently. Earlier this week, we were told that 2012 was the hottest year on record for most of the U.S. The year’s weather, marked by droughts and powerful storms, led NPR’s Adam Frank to call 2012 “the year that climate change got real for Americans.”
Seeking to highlight the everyday effects of those changes, the report’s advisory committee included a “Letter to the American People,” in which they laid out some of the ways the changing weather has begun to affect livelihoods and futures:
“Many more impacts of human-caused climate change have now been observed. Corn producers in Iowa, oyster growers in Washington State, and maple syrup producers in Vermont have observed changes in their local climate that are outside of their experience. So, too, have coastal planners from Florida to Maine, water managers in the arid Southwest and parts of the Southeast, and Native Americans on tribal lands across the nation.”
The 1,193-page report, the work of more than 240 scientists, is in “draft” form; it has been released for three months of review and comment by other scientists and the public. That review period will begin Monday.
“This could help restart a national conversation about climate change,” writes Todd Sanford, of the Union of Concerned Scientists. “It gives us a road map for climate change. And the road is much bumpier if we continue along a higher emissions pathway.”
By BILL CHAPPELL of npr.org