As scientists continue to accumulate data about the details of Global Warming, the denialists/delayers are finding themselves increasingly on the fringes of the conversation. Their disingenuous, worn-out arguments just seem so tired and strained–the latest one to be recycled, that the earth is cooling, can be easily refuted by any intellectually honest person willing to learn a few facts.
Calendar year 2008 was the coolest year since 2000, according to the NASA Goddard Institute for Space Studies (GISS) analysis of worldwide temperature measurements, but it was still in the top ten warmest years since the start of record-keeping in 1880. Given the range of uncertainty in the measurements, the GISS team concluded that 2008 was somewhere between the seventh and the tenth warmest year on record. (The 10 warmest years have all occurred within the 12-year period from 1997-2008.)
Now, a new study published today in Nature has taken away another denialist talking point: “Most of Antarctica is not warming, which means there must be a flaw in the theory of anthropogenic climate change.”
As it turns out, Antarctica has been heating up.
Research has suggested that temperatures across the bulk of Antarctica were either unchanged or dropping in places — findings that run counter to what might be expected if the world is indeed warming. But a team led by a University of Washington scientist has combined satellite data and temperature measurements to find that, on average, Antarctica has gotten a little bit hotter over the past 50 years.
“That means all of the continents are warming, not just six out of seven,” said geochemist Eric Steig, who leads the UW’s Quaternary Research Center.
The effect is particularly strong in West Antarctica, which is lower in elevation and more moderate in climate than the high, frigid plateau of East Antarctica. “West Antarctica is more like Seattle and East Antarctica is more like central North Dakota,” Steig said.
A recent cooling trend that scientists believe is caused by a thinning of the ozone layer continues during some parts of the year in East Antarctica, where sea ice also is expanding, the researchers say. But warming elsewhere on the continent was strong enough to yield a net temperature gain.
Another article on the Nature paper from Physorg.com explains how the study was done.
The researchers devised a statistical technique that uses data from satellites and from Antarctic weather stations to make a new estimate of temperature trends.
“People were calculating with their heads instead of actually doing the math,” Steig said. “What we did is interpolate carefully instead of just using the back of an envelope. While other interpolations had been done previously, no one had really taken advantage of the satellite data, which provide crucial information about spatial patterns of temperature change.”
Satellites calculate the surface temperature by measuring the intensity of infrared light radiated by the snowpack, and they have the advantage of covering the entire continent. However, they have only been in operation for 25 years. On the other hand, a number of Antarctic weather stations have been in place since 1957, the International Geophysical Year, but virtually all of them are within a short distance of the coast and so provide no direct information about conditions in the continent’s interior.
The scientists found temperature measurements from weather stations corresponded closely with satellite data for overlapping time periods. That allowed them to use the satellite data as a guide to deduce temperatures in areas of the continent without weather stations.
“Simple explanations don’t capture the complexity of climate,” Steig said. “The thing you hear all the time is that Antarctica is cooling and that’s not the case. If anything it’s the reverse, but it’s more complex than that. Antarctica isn’t warming at the same rate everywhere, and while some areas have been cooling for a long time the evidence shows the continent as a whole is getting warmer.”
A major reason most of Antarctica was thought to be cooling is because of a hole in the Earth’s protective ozone layer that appears during the spring months in the Southern Hemisphere’s polar region. Steig noted that it is well established that the ozone hole has contributed to cooling in East Antarctica.
“However, it seems to have been assumed that the ozone hole was affecting the entire continent when there wasn’t any evidence to support that idea, or even any theory to support it,” he said.
Oh, well, denialists, you’ve still got sun spots, right? Oops…