"Global warming has neither stopped nor slowed in the past decade, according to a draft analysis of temperature data by the NASA Goddard Institute for Space Studies

Scientific American


STILL WARMING: Global temperatures over the past decade have "continued to rise rapidly," despite large year-to-year fluctuations.
NASA


Global warming has neither stopped nor slowed in the past decade, according to a draft analysis of temperature data by NASA's Goddard Institute for Space Studies.

The analysis, led by Goddard director Jim Hansen, attempts to debunk popular belief that the planet is cooling. It finds that global temperatures over the past decade have "continued to rise rapidly," despite large year-to-year fluctuations associated with the tropical El Niño–La Niña cycles.

The analysis also predicts, assuming current El Niño conditions hold, that 2010 will go down in history as the hottest year on record despite an unusually snowy winter in the Northern Hemisphere.

"Communicating the reality of climate change to the public is hampered by the large natural variability of weather and climate," the Goddard scientists wrote in the draft, which was circulated by Hansen Friday evening and posted on the ClimateProgress.org blog shortly after.

"We conclude there has been no reduction in the global warming trend of 0.15 (to) 0.20ºC (per) decade that began in the late 1970s."

The new analysis combines sea-surface temperature records with meteorological station measurements and tests alternative choices for ocean records, urban warming and tropical and Arctic oscillations. It concludes the urban "heat island" impacts are small compared to the warming attributed to greenhouse gas emissions.

And it finds that, while this winter's unusually strong Arctic Oscillation - which funnels cold northern air to the East Coast and pulls warm mid-latitude air up to the Arctic - is predicted as atmospheric carbon dioxide levels rise, seasonal temperature anomalies associated with it aren't enough to blunt long-term warming trends.

"In the United States only one of the past 10 winters and two of the past 10 summers were cooler than the 1951-1980 climatology, a frequency consistent with the expected 'loading of the climate dice,' " the scientists wrote.

Hansen and other co-authors could not be reached for comment. The analysis has not been subjected to a peer review, though Hansen, in an email sent discussing the paper, said he intended to revise it for submission to a journal "within a month or so."

Michael Mann, director of the Earth System Science Center at Pennsylvania State University, called the analysis solid.

"Essentially he's just pointing out that we've come out of this short-term, relatively cool period," Mann said. "The globe clearly continues to warm."

Joe Romm, editor of ClimateProgress.org and a senior fellow at the liberal Center for American Progress, added that the study is "important for those who care about the science."

Whether it would quell the debate over global cooling - fueled in part by the East Coast's hard winter and the revelation of errors in the United Nation's Intergovernmental Panel on Climate Change synthesis report - is less certain.

Mann said many claims of global cooling are spurious and "intellectually dishonest."

"The question becomes can you confront those who are choosing to be intellectually dishonest with more facts and hope they become more honest? Unfortunately, that's not the case," he said.

"But hopefully, as evidence continues to come in, those who have genuinely, honestly skeptical views about climate change will be swayed by the fact that evidence continues to ... to be stronger and stronger."..."