The sea ice cover surrounding the continent of Antarctica is on average thinner than Arctic sea ice, and more susceptible to winds. This photo, from a 2003 research cruise, shows the trail of open water left by a research ship. In the background, an iceberg towers above the thinner sea ice cover. Credit: Ted Scambos, National Snow and Ice Data Center
The Arctic Ocean is not the only place with sea ice. The ocean surrounding the continent of Antarctica also freezes over each winter. But we don’t hear much about sea ice on the bottom of the planet. What’s happening to Antarctic sea ice and why does it matter?
One reason that we hear less about Antarctic sea ice than Arctic sea ice is that it varies more from year to year and season to season than its northern counterpart. And while Arctic ice has declined precipitously over the past thirty years of the satellite record, average Antarctic sea ice extent has stayed the same or even grown slightly. Continue reading
Arctic sea ice extent for September, 2011 was the second-lowest in the satellite record. However, other data sources showed that ice extent perhaps hit a new record low for several days in September. Credit: NSIDC/NASA Earth Observatory
Did Arctic sea ice reach an all-time record low this year—or not? Scientists at University of Bremen in Germany thought it was a new record, while data from NSIDC showed the sea ice at its second-lowest level. The two groups were examining data from two different satellite sensors. Why did the data differ—and if data can vary, does a record low really matter? Continue reading
People sometimes wonder if the weather they are experiencing locally, such as the heavy snow that fell in February 2011 over the Northeastern U.S., is connected to decreasing Arctic sea ice. Scientists are exploring a possible connection. Credit: NASA Earth Observatory.
Over the 2010 to 2011 winter, news stories suggested a potential connection between a warming climate, low Arctic sea ice extent, and unusually cold weather this winter in the U.S. and Europe. What do scientists know about how sea ice affects the weather?
Scientists have been exploring a possible link, but the question is far from settled. It makes sense that changing sea ice conditions could affect weather in the Arctic and other parts of the world. During the colder months, sea ice insulates the relatively warm ocean from the colder atmosphere. As sea ice declines, more heat can escape to the atmosphere in the fall and winter, affecting wind patterns, temperature, and precipitation. Continue reading
Last week, a reader of Arctic Sea Ice News & Analysis asked what we know about Arctic sea ice extent before the satellite records began in 1979. Those records show that Arctic sea ice has been declining at an increasing pace since 1979—enough data to see a strong signal of climate change. But scientists also want to know what sea ice was like before satellites were there to observe it. Mark Serreze, NSIDC director and research scientist, said, “The better we understand how the climate system behaved in the past, the better we can understand and place into context what is happening today.” What do we know about sea ice conditions before 1979, and how do we know that?
Sea ice charts of the Arctic Ocean show that ice extent has declined since at least the 1950s. Credit: NSIDC and the UK Hadley Center
Historical data on sea ice
Scientists have pieced together historical ice conditions to determine that Arctic sea ice could have been much lower in summer as recently as 5,500 years ago. Before then, scientists think it possible that Arctic sea ice cover melted completely during summers about 125,000 years ago, during a warm period between ice ages. Continue reading