Study shows fundamental ecosystem changes under way
By Summit Voice
Sea ice decline is already changing some Arctic ecosystems in fundamental ways, according to University of Alaska Fairbanks scientists. As part of review team, the two researchers showed, for example, that disappearing sea ice leads to a loss of sea-ice algae, at the very base of the Arctic marine food web. Larger plankton is thriving, replacing smaller, but more nutrient dense plankton. What that means exactly is not yet understood.
“Our thought was to see if sea ice decline contributed to greening of the tundra along the coastal areas,” said Uma Bhatt, an associate professor with UAF’s Geophysical Institute. “It’s a relatively new idea.”
Above water, loss of sea ice has destroyed old pathways of animal migration across sea ice while opening new pathways for marine animals in others. Some animals and plants will become more isolated. In the case of the farthest north and coldest parts of the Arctic, entire biomes may be lost without the cooling effects of disappearing summer sea ice.
Warming soils provide an opportunity for new vegetation to grow where less vegetation occurred previously. This contributes to a general greening of the Arctic that is visible from space. Bhatt, an atmospheric scientist, examined a 1982-2010 time series of remote sensing data to examine trends in sea ice, land-surface temperatures and changes in the vegetation abundance.
“It’s not a simple story here,” Bhatt said. “I’m an atmospheric scientist and Skip (Walker) is a plant biologist. We have had many conversations to understand each other so we might better understand what’s happening in the Arctic.”
A surprise and puzzling finding shows that despite a general warming and greening of Arctic lands in North America, some areas in northern Russia and along the Bering Sea coast of Alaska are showing recent cooling trends and declines in vegetation productivity.
“We don’t know why,” Bhatt said.
This all illustrates the complexity of the arctic system and why scientists from different disciplines should work together to understand it, Bhatt said. The review article is one of the first steps in this direction.
The review appeared in a recent issue of Science magazine. It is a close, comprehensive look at how the losses of northern sea ice affect surrounding areas.