From Huffington Post: http://www.huffingtonpost.com/2014/05/06/national-climate-assessment_n_5270541.html
WASHINGTON -– Climate change is no longer a distant threat, but a real and present danger in the United States, according to a government report issued Tuesday.
The report is the latest update from the U.S. Global Change Research Program, and details ways that climate change — caused predominantly by the emission of heat-trapping greenhouse gases — is already being felt across the country.
“Climate change, once considered an issue for a distant future, has moved firmly into the present,” the report says in its introduction. The full report, at more than 800 pages, is the most comprehensive look at the effects of climate change in the U.S. to date, according to its authors. (Even the “highlights” document provided to reporters the day before the release weighed in at 137 pages). The report includes regional and sectoral breakdowns of current and anticipated impacts, which have implications for infrastructure, agriculture, human health, and access to water.
Those impacts include increased severity of heat waves and heavier downpours. On the coasts, sea level rise is already contributing to increased flooding during high tides and storms, the report notes. And in the West, conditions are getting hotter and drier, and the snowpack is melting earlier in the year, extending wildfire season.
Average U.S. temperatures have increased 1.3 degrees to 1.9 degrees Fahrenheit (depending on the part of the country) since people began keeping records in 1895, and much of that warming has come in recent decades. The report notes that the period from 2001 to 2012 was warmer than any previous decade on record, across all regions of the country.
The length of time between the last spring frost and the first fall frost also has increased across the U.S. The average time between frosts in the Southwest increased by 19 days in the years 1991 to 2012, compared with the average from 1901 to 1960.
Heat waves are already the top cause of weather-related deaths in the U.S., and that will only get worse. Extreme heat can cause more heart, lung and kidney problems, especially among the poor, sick and elderly. The number of days where temperatures top 100 degrees is predicted to increase in the future. If emissions continue to rise, temperatures on the very hottest days during the last 20 years of this century may be 10 degrees to 15 degrees hotter across most of the country, the report finds. Under a lower-emission scenario, those hottest days of the years 2081 to 2100 would still be 3 degrees to 4 degrees warmer than now.
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