In February, polar climate researchers gathered at the National Center for Atmospheric Research in Boulder, Colorado to discuss the newest updates to models of the Earth’s climate system. The researchers are working together to create better models of the Arctic and Antarctic climates, which will feed into larger models of the whole Earth that help scientists understand how climate will change in the future. What goes into a climate model, and what can scientists learn from models that they cannot learn from observations?
This image shows several aspects of climate, including sea ice, surface winds, and sea surface temperature. This image came from data simulated from NCAR’s Community Earth System Model. Credit: ©UCAR, image courtesy Gary Strand, NCAR
What’s in a model?
Computer climate models are based on scientists’ understanding of Earth’s climate. The models use mathematical relationships to try to quantify the relationships between parts of the climate system. If you tweak one factor in climate, how does the simulated climate system respond? Models that bring many factors together help scientists learn how the climate system works, and let them run simulations on Earth’s climate. They also allow scientists to assess how climate may be affected by present and future changes in greenhouse gases and solar forcing, and how much of a role natural variability plays. Continue reading
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, NSIDC
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
These before-and-after photographs show Petermann Glacier in July 2009, before the calving event, and again in July 2011. Photographs courtesy Jason Box (top), Alan Hubbard (bottom)
Last summer, a chunk of ice three times the size of Manhattan broke off Petermann Glacier in Greenland and floated out to sea. The calving left miles of newly open water in the deep Petermann Fjord, which had been capped in a thick layer of glacial ice. New research out this summer confirmed that it was likely the largest calving in the region since observations began in 1876. What does this event tell us about climate change in the Arctic? Continue reading
This photo, taken during the NASA ICESCAPE mission in summer 2011, shows melt ponds on the surface of Arctic sea ice. Weather patterns in the Arctic this summer have favored ice loss, leading to near-record low ice extent over most of the summer. New research is explaining how much ice loss is caused by variable conditions, and how much can be pinned on human-caused climate change. Credit: NASA/Kathryn Hansen
Arctic sea ice is near its annual low extent for the year. Will it reach a new record low? While many people are watching this year’s ice extent closely, the effect of climate change on ice extent in a single year is different than its effect in the long term. Arctic sea ice has declined more than 30 percent in summer since satellite measurements started in 1979. But from year to year, ice extent jumps up and down quite a lot. Continue reading