With no permanent research stations, the scientists lacked reliable long-term records, Steig said.
"We recognized that to get an idea of what was happening in western Antarctica, we would have to rely on using weather station data from other parts of Antarctica."
Because weather stations are so sparse, past studies relied weighted averages, for the missing areas that are based on temperatures from surrounding locales.
"In our case, we recognized that there was a better way to [connect data] between weather stations in Antarctica, which was to use satellite data," said Steig, whose results appear in this week's issue of the journal Nature.
The team combined spotty weather station records and satellite data between 1957 and 2006.
"In retrospect, it is pretty obvious that ignoring the satellite data, as others had done, was really missing the forest for the trees," Steig said.
The researchers found that the temperature over western Antarctica is rising 0.31 Fahrenheit (0.17 degree Celsius) per decade, with a continental increase of 0.18 Fahrenheit (0.1 degree Celsius).
Worldwide, the temperature has climbed an average of 1.08 Fahrenheit (0.6 degrees Celsius) over the past 50 years, said study co-author Drew Shindell of NASA's Goddard Institute for Space Science.
A hole in the ozone layer over eastern Antarctica drives winds that help keep temperatures down, but that effect is likely to lessen as the layer heals, leading to still more warming, Shindell added.
In 2002, Peter Doran, an earth and environmental scientist at the University of Illinois at Chicago, published results that showed more parts of Antarctica than not were cooling.
But Doran wrote a 2007 op-ed in the New York Times lamenting that his earlier study had been cited by global warming skeptics, including the late Michael Crichton in his 2004 novel State of Fear.
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Doran also wrote that more weather stations on Antarctica and longer-term data would be needed to demonstrate a clear trend in Antarctica.
This week, Doran called the new Nature paper "an excellent and thorough study by a top-notch group."
"First, they have brought in a combination of data sources and added another decade and a half to what we reported on. The argument for an expanded warming in [western] Antarctica based on this seems reasonable."
Continued satellite measurements, more weather stations, and core samples to reconstruct historic temperatures are all needed to complete the Antarctic climate picture, Steig said.
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