"Antarctic sea ice increases despite warming" (New Scientist, 12 September 2008)
The amount of sea ice around Antarctica has grown in recent Septembers in what could be an unusual side-effect of global warming, experts say.
In the southern hemisphere winter, when emperor penguins huddle together against the biting cold, ice on the sea around Antarctica has been increasing since the late 1970s, perhaps because climate change means shifts in winds, sea currents or snowfall.
At the other end of the planet, Arctic sea ice is now close to matching a September 2007 record low at the tail end of the northern summer, in a threat to the hunting lifestyles of indigenous peoples and creatures such as polar bears.
"The Antarctic wintertime ice extent increased…at a rate of 0.6% per decade" from 1979 to 2006, says Donald Cavalieri, a senior research scientist at the NASA Goddard Space Flight Center in Maryland.
At 19 million square kilometres, it is still slightly below records from the early 1970s of 20 million, he says. Since 1979 however, the average year-round ice extent has risen too.
(link to full article)
"Melting ice caps could suck carbon from atmosphere" (New Scientist, 10 September 2008)
It’s not often that disappearing Arctic ice is presented as good news for the planet. Yet new research suggests that as the northern polar cap melts, it could lift the lid off a new carbon sink capable of soaking up carbon dioxide.
The findings, from two separate research groups, raise the possibility – albeit a remote one – of weakening the greenhouse effect. The researchers say the process of carbon sequestration is already underway. Even so, the new carbon sink is unlikely to make a significant dent in the huge amounts of CO2 pumped into the atmosphere by industrial activities.
Kevin Arrigo and colleagues at Stanford University studied satellite data collected between 1998 and 2007 to see how sea surface temperatures and the quantities of sea ice and phytoplankton had changed during that time.
Phytoplankton produce chlorophyll to obtain energy from the sun and assimilate CO2, and so increased phytoplankton productivity would remove more carbon from the atmosphere.
"We found that as sea ice diminishes, annual productivity goes up," says Arrigo. Satellite remote sensing measures the amount of chlorophyll in surface waters, and so provides an estimate of ocean productivity.
(Link to full article)