Honestly, most of these people are just reading the forecasts from the National Weather Service. Then, they spice them up a little.
The
http://www.ametsoc.org/">American Meteorological Society is quite clear on the topic:
http://www.ametsoc.org/policy/2007climatechange.html Climate Change
An Information Statement of the American Meteorological Society
(Adopted by AMS Council on 1 February 2007)
Bull. Amer. Met. Soc.,
88http://www.ametsoc.org/policy/2007climatechange.pdf">pdf versionThe following is an Information Statement intended to provide a trustworthy, objective, and scientifically up-to-date explanation of scientific issues of concern to the public at large.
…
Despite the uncertainties noted above, there is adequate evidence from observations and interpretations of climate simulations to conclude that the atmosphere, ocean, and land surface are warming; that humans have significantly contributed to this change; and that further climate change will continue to have important impacts on human societies, on economies, on ecosystems, and on wildlife through the 21st century and beyond. Focusing on the next 30 years, convergence among emission scenarios and model results suggest strongly that increasing air temperatures will reduce snowpack, shift snowmelt timing, reduce crop production and rangeland fertility, and cause continued melting of the ice caps and sea level rise. Important goals for future work include the need to understand the relation of climate at the state and regional level to the patterns of global climate and to reverse the decline in observational networks that are so critical to accurate climate monitoring and prediction.
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