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2005 Edges out 1998 as Warmest Year on Record NEW YORK, New York, January 25, 2006 (ENS) - The highest global surface temperature in more than a century of instrumental data was recorded in the 2005 calendar year, according to a new NASA analysis. The scientific team says 2005 is practically in a dead heat with 1998, the warmest previous year. The analysis was conducted by Dr. James Hansen, director of NASA's Goddard Institute for Space Studies (GISS) at Columbia University in New York, and collaborators Dr. Reto Ruedy and Dr. Ken Lo, also with the Goddard Institute, and Dr. Makiko Sato of the Columbia University Center for Climate Systems Research. "We believe that the remarkable Arctic warmth of 2005 is real, and the inclusion of estimated Arctic temperatures is the primary reason for our rank of 2005 as the warmest year," the team wrote in its analysis.
Dr. James Hansen, director of NASA's Goddard Institute for Space Studies at Columbia University. (Photo courtesy GISS)Record warmth in 2005 is important, the scientists said, because global temperature has not received any boost from a tropical El Niño weather event this year. The previous record year, 1998, was lifted 0.2 degrees Celsius above the trend line by the strongest El Niño of the past century.El Niño is a disruption of the ocean-atmosphere system in the tropical Pacific that has consequences for weather around the globe. El Niño events happen roughly every two to seven years when tropical Pacific trade winds diminish and ocean temperatures become unusually warm. The ranking of 2005 as warmer than 1998 is a result mainly of the large positive Arctic anomaly, or variation from the norm. Excluding the region north of 75N, 1998 is warmer than 2005. The team says that if the entire Arctic Ocean were excluded, the ranking of 2005 might be even lower. The quasi-regularity of recent El Niños at intervals of about four years suggests the likelihood of an El Niño in 2006 or at latest 2007. In such a case the 2005 global temperature record will almost surely be broken. Global warming is now 0.6 degrees Celsius (°C) in the past three decades and 0.8°C in the past century. The scientists say there was slow global warming, with large fluctuations, over the century up to 1975 and subsequent rapid warming of almost 0.2°C per decade. Recent warming coincides with rapid growth of "human-made greenhouse gases," the scientific team says. Climate models show that the rate of warming is consistent with expectations of the Intergovernmental Panel on Climate Change as stated in its 2001 report.
A polar bear sits atop a glacier in the Arctic. (Photo by Marcus Rex courtesy NASA)"The observed rapid warming thus gives urgency to discussions about how to slow greenhouse gas emissions," the GISS team said in its analysis. Current warmth is pervasive around the globe and largest at high latitudes in the Northern Hemisphere, they said.The NASA GISS Surface Temperature Analysis provides a measure of the changing global surface temperature with monthly resolution for the period since 1880, when, the team says, "a reasonably global distribution" of meteorological stations was established. Over the past 50 years, the Goddard team said, the largest warmings have occurred in Alaska, Siberia and the Antarctic Peninsula, and most ocean areas have warmed. The remote location of most warming makes it clear that the warming is not a product of local urban influence, they said. Another group of climatologists at the UK Met Office and the University of East Anglia says 1998 was slightly warmer than 2005, but their results do not include much Arctic data. "The data also show that the sea surface temperature in the northern hemisphere Atlantic is the highest since 1880," said Dr. David Viner, from the Climatic Research Unit at the University of East Anglia. No measurements of average temperature can be completely accurate. The Goddard Institute's analysis is made with 95 percent confidence. Dr. Viner believes his team's calculations are subject to an error of about plus or minus 0.1 degree Celsius. He confirms that the long-term climate trend is rising, demonstrating the reality of global warming due to human activities. The Met Office is predicting that this winter will be colder than average in the British Isles, a prediction they say is linked to year to year variability not long-term climate change. Their prediction is based on differences in sea level pressure between a weather station in the Azores and another in Iceland, during the period December to February, known as the North Atlantic Oscillation. A negative pressure difference indicates a weather pattern dominated by colder continental airstreams, such as the pattern predicted for this winter. |
