May 20, 2013
Global Climate Change May Be Overstated, Says New Research
Brett Smith for redOrbit.com - Your Universe Online
Based on current trends, the Earth is expected to warm considerably over the coming centuries. However, a new study in Nature Geoscience suggests that the more acute predictions of climate change may be overstated.
In the study, the international team of researchers looked to see how doubling the concentrations of carbon dioxide in the atmosphere and the Earth's subsequent response would impact climate over several thousand years, a method known as climate sensitivity.
The analysis used temperatures from the last decade and found that the projected increase would be 1.6 to 3.6 degrees Fahrenheit. By comparison, The Intergovernmental Panel on Climate Change said in 2007 that the short-term temperature increase would be between 1.8 and 5.4 degrees.
"The hottest of the models in the medium-term, they are actually looking less likely or inconsistent with the data from the last decade alone," co-author Alexander Otto from the University of Oxford told BBC News. "The most extreme projections are looking less likely than before."
Climate scientists have been observing a deceleration in the rise of global air surface temperatures, despite the fact that greenhouse gas emissions have continued to climb. The authors of the report attribute this mitigation of temperature increase to the ocean´s ability to absorb heat — a claim that others dispute.
"There is other research out there pointing out that this storage may be part of a natural cycle that will eventually reverse, either due to El Nino or the so-called“¯Atlantic Multidecadal Oscillation, and therefore may not imply what the authors are suggesting," Steven Sherwood, from Australia´s University of New South Wales, told the BBC News.
The authors of the study suggested that many factors that are still being researched play into the global climate, including the roles of atmospheric aerosols and cloud cover.
"We would expect a single decade to jump around a bit but the overall trend is independent of it, and people should be exactly as concerned as before about what climate change is doing," Otto said.
Otto also told the Financial Times that the study´s findings shouldn´t be viewed as a repudiation of global warming as a general issue.
“Our results indicate nothing of the kind,” he said. “With the current emission trends we are still looking at [temperature rises] significantly higher than 2°C. There is no room for relaxing or for rejoicing or anything like that, unfortunately.”
Last week, it was announced that the level of carbon dioxide in the atmosphere passed 400 parts per million, a record-breaking level for human-inhabited Earth. Policymakers also consider the mark to be the maximum level for remaining within the stated goal of keeping average global temperature from rising by more than 2 degrees Celsius.
Despite the rate slowdown, average global temperatures are still much higher than in any year during the 90s, except for the extremely warm year of 1998. The abnormally high temperatures have also been accompanied by the“¯record melting of Arctic summer sea ice and several large storms that experts say have been made more likely by the forces of climate change.