Arctic sea ice is melting. The Greenland ice sheet is losing mass, and the Antarctic Peninsula is one of the fastest warming parts of the planet. But the main part of Antarctica has often been assumed to be pretty safe from extensive surface melting. It’s very cold, and very high. NASA now reports that in January 2005, large parts of the surface of West Antarctica experienced a week long melt, the first time this has been seen.
“The observed melting occurred in multiple distinct regions, including far inland, at high latitudes and at high elevations, where melt had been considered unlikely. Evidence of melting was found up to 900 kilometers (560 miles) inland from the open ocean, farther than 85 degrees south (about 500 kilometers, or 310 miles, from the South Pole) and higher than 2,000 meters (6,600 feet) above sea level. Maximum air temperatures at the time of the melting were unusually high, reaching more than five degrees Celsius (41 degrees Fahrenheit) in one of the affected areas. They remained above melting for approximately a week.”
The picture accompanying the NASA story clearly shows large melt areas – the size of California (how many Belgiums is that?) – over the West Antarctic ice sheet. There hasn’t been a repeat of the event in the last two years, and the period studied only began in 1999, so it’s not clear how unusual the melt was, or if there is any trend. Given the concerns about the stability of the West Antarctic ice sheet in a warming world, this news will add urgency to this year’s International Polar Year effort (which is getting a bit of help from the International Space Station).