Record-breaking temperatures in the continental United States last year were caused in large part by human activities and greenhouse gases, according to a new analysis.
Last year’s average temperature was the second highest on record, a mere 0.08 degrees Fahrenheit cooler than the hottest year, 1998, according to the National Oceanic and Atmospheric Administration.
Both 1998 and 2006 were El Niño years, but Marty Hoerling, a scientist with NOAA in Boulder, used computer models and analysis of past weather patterns to determine El Niño unlikely played any role in the 2006 warmth.
Other natural weather patterns may have affected the heat, but global warming, caused primarily by fossil fuel burning, was responsible for at least half of the excess temperature in 2006, Hoerling and his colleagues report in the current issue of Geophysical Research Letters. The researchers also report a 16 percent chance that this year’s temperatures will break the 1998 record.
