The news on the cryosphere hasn’t been good at this year’s EGU meeting, with poor prognoses for mountain glaciers, Arctic ice shelves and permafrost.
The situation seems particularly bleak for the ice shelves in Canada’s far north. Luke Copland of the University of Ottawa, Canada, has been studying the northern coast of Ellesmere Island. Records from an expedition to the region in 1906 indicate that the ice shelves had an area of 10,000 square km. But by early 2008 there were only five ice shelves left, with a total area one-tenth of the figure a century ago. And by September of 2008 the Markham ice shelf had disappeared, leaving four ice shelves with a total area of just 750 square km.
Copland says there are several reasons for the changes, including the increase in winter temperatures of one degree C per decade, which prevents the ice shelves from rebuilding over the winter, the decreased extent of sea ice, which used to protect the outside edges of the shelves from tides and waves, and very warm summers and high winds in 2005 and 2008. He reckons it would take centuries to rebuild the ice shelves even if we stabilize temperatures at current levels and he would be surprised if the Arctic ice shelves survive.
Smaller and thinner than those in the Antarctic, these northern hemisphere ice shelves have become disconnected from the glaciers that created them. This has allowed freshwater pools around 40 m deep and known as epishelf lakes to build up behind the ice shelves on top of oceanic water, creating unique ecosystems. These ecosystems will disappear if the remaining Arctic ice shelves go.
Meanwhile Wilfried Haeberli of the University of Zurich, Switzerland, reported how he believes it’s a realistic scenario that all mountain glaciers could have disappeared by 2050. The Pyrenees have lost 90% of their ice cover over the last few decades, for example. This will have big implications for water as rivers such as the Rhone and Rhine gain most of their water from glacier melt in July and August. “Most of my students will experience the loss of most of the European glaciers by the middle of the century,” said Haeberli. “There is practically no hope for glaciers in the mountains.”
There was further worrying news about the Arctic at the AGU Meeting this
morning. Igor Semiletov of the University of Alaska Fairbanks detailed results from a 12,000 nautical mile long survey of the
entire Eurasian Arctic continental shelf for International Polar Year.
Worryingly, the International Siberian Shelf Study (ISSS-08) found that methane is emerging from the East
Siberian Arctic Shelf, as evidenced by bubble clouds of methane in the sea and
methane bubbles trapped in sea ice in the winter. It looks like the sub-sea
permafrost is failing due to warmer ocean temperatures and allowing methane to
escape; because the Siberian Sea is very shallow the methane isn’t oxidized as it travels to the
surface. “We didn’t know that the huge carbon pool there is extremely
vulnerable,” said Semiletov. Some have predicted that a 6 ppm increase in
atmospheric methane concentrations could induce abrupt climate change –
Semiletov says that would require the release of only 1-2% of the methane
stored under the East Siberian Arctic Shelf.
By Liz Kalaugher
On the way home from the Amundsen I take part in a whale survey.
I depart from the Amundsen with mixed feelings. I’m sad to be leaving the scientists and crew on board, who have been incredibly welcoming over the last week, but I’m looking forward to being able to walk around on dry land.
Ice surface reflectivity results and a successful catch of Arctic cod larvae.
Researchers hit the onboard laboratories as the Amundsen moves to another sampling station.
Ocean sampling takes off in earnest.
The icebreaker refuels and the researchers move their equipment ready for the move into open water.
Today researchers take measurements out on the ice, perhaps for the last time this trip.
After waiting for the fog to clear, today I join researchers on board the Amundsen.
Just one flight into my epic six-flight
trip to join the Amundsen icebreaker in the Canadian Arctic and I had already
seen a polar bear. Admittedly it was made of plastic and a little closer than
I’d like to get to any real ones I come across during the next week, but I’m
taking it as a good omen.