By David L. Brown
One of the big questions about “global warming,” or climate change as I prefer to call it, revolves around the future of Antarctica. The two largest ice sheets in the world sit atop this southern continent, containing enough frozen water to raise sea levels substantially. Until recently it has been argued that Antarctica has not experienced warmer temperatures, even though the Larson B ice shelf collapsed entirely a few years ago and evidence has been seen for increased glacial speeds and developing lakes beneath the ice.
Now a report from NASA says that an area of the West Antarctic ice sheet larger than the state of California melted, then refroze during a warm spell in 2005. Here is a map the space agency provided, showing the melt area in red and yellow:
According to a story posted today on FoxNews.com (see story here):
Satellite data collected by the scientists between July 1999 and July 2005 showed clear signs that melting had occurred in multiple distinct regions, including far inland and at high latitudes and elevations, where melt had been considered unlikely.
“Antarctica has shown little to no warming in the recent past, with the exception of the Antarctic Peninsula,” said Konrad Steffen of the University of Colorado, Boulder. “But now large regions are showing the first signs of the impacts of warming as interpreted by this satellite analysis.”
The melted snow refroze after the week-long warm spell which brought unusual temperatures of about 41 degrees F. to the region. However, according to NASA scientists, “Water from the melted snow can penetrate cracks and the ice, lubricating the continent’s ice sheets, sending them toward the ocean faster and raising sea levels.”
“Increases in snowmelt, such as this in 2005, definitely could have an impact on larger scale melting of Antarctica’s ice sheets if they were severe or sustained over time,” Steffen said.
It seems that even the vast frozen mass of the Antarctic ice could be joining the Greenland ice sheet in a steady slide toward increasing melting. In Greenland, where it was recently believed that the two-mile thick ice would take hundreds or even thousands of years to melt, it has been discovered that crevasses, deep cracks in the ice, are allowing warm, melted water from the surface to quickly flow to the bottom of the ice sheet, creating huge waterfalls and rivers inside the ancient ice. Something similar is apparently happening now in the Antarctic. Between them, the Greenland and Antarctic ice could raise sea levels by as much as several tens of meters, flooding wide areas of coastal regions where a large proportion of the world’s population now lives.