The Grand Island Independent (Nebraska): Researchers say that extreme summer temperatures are occurring more frequently in the United States, and will become normal by mid-century if the world continues on a business-as-usual schedule of emitting greenhouse gases.By analyzing observations and results obtained from climate models, a study led by Phil Duffy of the Lawrence Livermore National Laboratory in California showed that previously rare high summertime (June, July and August) temperatures are already occurring more frequently in some regions of the 48 contiguous United States.
"The observed increase in the frequency of previously rare summertime-average temperatures is more consistent with the consequences of increasing greenhouse gas concentrations than with the effects of natural climate variability," said Duffy, who is the lead author of a report in a recent edition of the journal Climatic Change. "It is extremely unlikely that the observed increase has happened through chance alone."
The geographical patterns of increases in extreme summer temperatures that appear in observations are consistent with those that are seen in climate model simulations of the 20th century, Duffy said. Duffy and colleague Claudia Tebaldi, a senior scientist at the nonprofit news and research group Climate Central, showed that the models project that previously rare summer temperatures will occur in well more than 50 percent of summers by mid-century throughout the lower 48 states.
....A second statistical analysis showed that this increase also is very unlikely to be due to chance weather variations alone, such as El Niños or La Niñas.
..."What was historically a one-in-20-year occurrence will occur with at least a 70 percent chance every year. This work shows an example of how climate change can affect weather extremes, as well as averages."...
A dried up lake in Oklahoma from Al Jazeera English, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license
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