|March 16, 2007|
World's Warmest Winter Ever, Report Says
The report comes just over a month after the Intergovernmental Panel on Climate Change said global warming is very likely caused by human actions and is so severe it will continue for centuries.
The National Oceanic and Atmospheric Administration said the combined land and ocean temperatures for December through February were 1.3 degrees Fahrenheit above average for the period since record keeping began in 1880.
The report said that during the past century, global temperatures have increased at about 0.11 degrees per decade. But that increase has been three times larger since 1976, NOAA's National Climatic Data Center reported.
Most scientists attribute the rising temperatures to so-called greenhouse gases which are produced by industrial activities, automobiles and other processes. These gases build up in the atmosphere and trap heat from the sun somewhat like a greenhouse.
Also contributing to this winter's record warmth was an El Nino, a periodic warming of the tropical Pacific Ocean. It was particularly strong in January --- the warmest January ever --- but the ocean surface has since begun to cool.
The report noted that in the Northern Hemisphere the combined land and water temperature was the warmest ever at 1.64 degrees above average. In the Southern Hemisphere, where it was summer, the temperature was 0.88 degree above average and the fourth warmest.
The late March date of the vernal equinox noted on most calendars notwithstanding, for weather and climate purposes northern winter is December, January and February.
For the United States, meanwhile, the winter temperature was near average. The season got off to a late start and spring-like temperatures covered most of the eastern half of the country in January, but cold conditions set in in February, which was the third-coldest on record.
For winter, statewide temperatures were warmer than average from Florida to Maine and from Michigan to Montana, while cooler-than-average temperatures occurred in the southern Plains and areas of the Southwest.
For Alaska, both February and winter were warmer than average but far from the record warmth of 2003 and 2001, respectively.
This has been the world's warmest winter since record-keeping began more than a century ago, the U.S. government agency that tracks weather reported Thursday.The National Oceanic and Atmospheric Administration (NOAA) said the combined global land and ocean surface temperature from December through February was at its highest since records began in 1880.
A record-warm January was responsible for pushing up the combined winter temperature, according to the agency's Web site; Contributing factors were the long-term trend toward warmer temperatures, as well as a moderate El Nino in the Pacific," Jay Lawrimore of NOAA's National Climatic Data Center said in a telephone interview from Asheville, North Carolina.
The next-warmest winter on record was in 2004, and the third warmest winter was in 1998, Lawrimore said. The 10 warmest years on record have occurred since 1995.
"We don't say this winter is evidence of the influence of greenhouse gases," Lawrimore said. However, he noted that his center's work is part of the Intergovernmental Panel on Climate Change process, which released a report on global warming last month that found climate change is occurring and that human activities quite likely play a role in the change.
"So we know as a part of that, the conclusions have been reached and the warming trend is due in part to rises in greenhouse gas emissions," Lawrimore said. "By looking at long-term trends and long-term changes, we are able to better understand natural and anthropogenic [human-caused] climate change."
The combined temperature for the December-February period was 1.3 degrees F (0.72 degree C) above the 20th century mean, the agency said.
Lawrimore did not give an absolute temperature for the three-month period, and said the deviation from the mean was what was important. He did not provide the 20th century mean temperature.
Temperatures were above average for these months in Europe, Asia, western Africa, southeastern Brazil and the northeast half of the United States, with cooler-than-average conditions in parts of Saudi Arabia and the central United States.
Global temperature on land surface during the Northern Hemisphere winter was also the warmest on record, while the ocean-surface temperature tied for second warmest after the winter of 1997-98.
Over the past century, global surface temperatures have increased by about 0.11 degree F per decade, but the rate of increase has been three times larger since 1976 -- around 0.32 degree F per decade, with some of the biggest temperature rises in the high latitudes of the Northern Hemisphere.