2015 Was Hottest Year in Historical Record, Scientists Say

Scientists reported Wednesday that 2015 was the hottest year in the historical record by far, breaking a mark set only the year before — a burst of heat that has continued into the new year and is roiling weather patterns all over the world.

In the contiguous United States, the year was the second-warmest on record, punctuated by a December that was both the hottest and the wettest since record-keeping began. One result has been a wave ofunusual winter floods coursing down the Mississippi River watershed.

Scientists started predicting a global temperature record months ago, in part because an El Niño weather pattern, one of the largest in a century, is releasing an immense amount of heat from the Pacific Ocean into the atmosphere. But the bulk of the record-setting heat, they say, is a consequence of the long-term planetary warming caused by human emissions of greenhouse gases.

“The whole system is warming up, relentlessly,” said Gerald A. Meehl, a scientist at the National Center for Atmospheric Research in Boulder, Colo.

It will take a few more years to know for certain, but the back-to-back records of 2014 and 2015 may have put the world back onto a trajectory of rapid global warming, after a period of relatively slow warming dating to the last powerful El Niño, in 1998.

Politicians attempting to claim that greenhouse gases are not a problem seized on that slow period to argue that “global warmingstopped in 1998,” with these claims and similar statements reappearing recently on the Republican presidential campaign trail.

Statistical analysis suggested all along that the claims were false, and that the slowdown was, at most, a minor blip in an inexorable trend, perhaps caused by a temporary increase in the absorption of heat by the Pacific Ocean.

“Is there any evidence for a pause in the long-term global warming rate?” said Gavin A. Schmidt, head of NASA’s climate-science unit, the Goddard Institute for Space Studies, in Manhattan. “The answer is no. That was true before last year, but it’s much more obvious now.”

Michael E. Mann, a climate scientist at Pennsylvania State University, calculated that if the global climate were not warming, the odds of setting two back-to-back record years would be remote, about one chance in every 1,500 pairs of years. Given the reality that the planet is warming, the odds become far higher, about one chance in 10, according to Dr. Mann’s calculations.

Two American government agencies — NASA, the National Aeronautics and Space Administration, and NOAA, the National Oceanic and Atmospheric Administration — compile separate analyses of the global temperature, based upon thousands of measurements from weather stations, ships and ocean buoys scattered around the world. Meteorological agencies in Britain and Japan do so, as well. The agencies follow slightly different methods to cope with problems in the data, but obtain similar results.

The American agencies released figures on Wednesday showing that 2015 was the warmest year in a global record that began, in their data, in 1880. British scientists released figures showing 2015 as the warmest in a record dating to 1850. The Japan Meteorological Agency had already released preliminary results showing 2015 as the warmest year in a record beginning in 1891.

Posted by admin on Jan 21 2016. Filed under News Worldwide. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry