旅居於窮鄉僻壤

Recent satellite data from the U.S. Space agency NASA indicate that sea ice in the Arctic and Greenland is melting at a faster rate than previously projected.  VOA's Paul Sisco has the story.

Arctic melting

"The sea ice is decreasing faster than all the models predicted," says Jay Zwally, the ice satellite project scientist at NASA Goddard, "We not only have the warming of the atmosphere, we have a warming of the ocean that is affecting this.  It has been surprising to everybody, this decrease in area. This is a marked departure, and this is suggesting to us that maybe we are getting at this tipping point."

Jay Zwally

"Up through 2006, in September we've been losing ice at the rate of a little more than nine percent per decade,” says Mark Serreze, a senior researcher at the U.S. National Snow and Ice Data Center in Colorado. “That's equivalent to about 100,000 square kilometers per year, which is quite a bit. What's happened in 2007 has just sent an exclamation point to this."

NASA satellite image shows Arctic over the last 30 years

Zwally says there is clear indication that the remaining is thinning. "The key thing is that this area that is remaining is now thinner," he said. "There used to be a lot of ice here that was three- four, five, six meters thick, and most of that is gone."

All climate models have variability and the possibility that melting trends may lead to results less severe than predicted.

"The other possibility is that it could be worse than the models predict and this is an example, a specific example of the sea ice in the Arctic where what is happening, what we see with the satellite is actually worse than the models predicted," he adds, and he says those models are supported by ground based observations and measurements.