ROBERT SIEGEL, host:
This is ALL THINGS CONSIDERED from NPR News. I'm Robert Siegel.
Researchers say that they're seeing something remarkable in the Arctic, a record low in the amount of sea ice covering the ocean.
NPR's David Malakoff has more.
DAVID MALAKOFF: Since 1979, scientists have been using satellites to pear down on arctic seas and measure the amount of ice that forms each winter and then starts to melt. In recent years, they've noticed a definite trend - less and less ice at the end of each summer. But Mark Serreze says the data they saw this week was especially striking.
Professor MARK SERREZE (Geography Senior Research Scientist, National Snow and Ice Center): Today is a historic day. We've got the least sea ice in the arctic that we've ever seen in our satellite records, and it's only the middle of August. We still have almost another month to go of sea ice melt. So where the system bottoms out this year, we don't know. But it's not looking good.
MALAKOFF: Serreze works at the National Snow and Ice Data Center at the University of Colorado. Overall, he says the arctic has lost about 100,000 square kilometers of summer ice over the last 30 years. That's an area about the size of Alaska. The melting has also been starting earlier in the year. And he says one factor in this year's big melt was that the season began with even less winter ice than usual.
Prof. SERREZE: Part of the reason why we lost so much ice this year is because we started on such a bad footing back in spring, and that bad tone has propagated through the season.
MALAKOFF: Serreze says ice appears to be melting everywhere across the arctic, but some areas are losing more than others.
Prof. SERREZE: Where we have been seeing the biggest loss is, is north of the Siberian coast and north of the Alaskan coast. That's kind of a - have been a picture that we've seen for a number of years.
MALAKOFF: Why is ice melt accelerating in the arctic? Serreze says natural variation in weather may be playing a role. But he also sees human influence.
Prof. SERREZE: I think the best explanation of why it's happening is that we're starting to see now the effects of greenhouse gas that's strongly affecting the ice cover.
MALAKOFF: Those greenhouse gasses include carbon dioxide from burning coal and oil and methane from rice patties and landfills. As those gases build up in the atmosphere, they trap heat, warming the Earth. Now, scientists have long predicted that the arctic is one of the first places we'd see the effects of global warming, and they say that if the trend continues, huge stretches of the arctic ocean could be ice-free each summer within a few decades.
David Malakoff, NPR News.