At the Poles, Melting Occurring at Alarming Rate
For scientists, global warming is a disaster movie, its opening scenes set at the poles of Earth. The epic already has started. And it's not fiction.
The scenes are playing, at the start, in slow motion: The relentless grip of the Arctic Ocean that defied man for centuries is melting away. The sea ice reaches only half as far as it did 50 years ago. In the summer of 2006, it shrank to a record low; this summer the ice pulled back even more, by an area nearly the size of Alaska. Where explorer Robert Peary just 102 years ago saw "a great white disk stretching away apparently infinitely" from
Animals are on the move. Polar bears, kings of the
"It affects everyone," said Carin Ashjian, a Woods Hole Oceanographic Institute scientist who spent early September with native Inupiats in Barrow, the northernmost town of
At the South Pole, ancient ice shelves have abruptly crumbled. The air over the western
Antarctica's signature Adelie penguins are moving inland, seeking the cold of their ancestors, replaced by chinstrap and Gentoo penguins, which prefer open water. Krill, the massive smorgasbord for a food chain reaching to the whales, are disappearing from traditional spawning grounds.
The scenario is not new. What is most alarming to the scientists is the speed at which it is unfolding. A decade ago, melting at the poles was predicted to play out over 100 years. Instead, it is happening on a scale scientists describe as overnight.
When the Larsen B, an Antarctic ice shelf the size of Rhode Island, collapsed in 2002, "it was a big glaring clue that something not natural was happening," said Hugh Ducklow, director of ecosystems for MBL Laboratories in Woods Hole, Mass. "The geological evidence suggested that was stable for at least 10,000 years, back to the last ice age. And it literally disintegrated in three weeks."
The scientists say the coming scenes in the movie, as described by the historic melding of research assembled by the Intergovernmental Panel on Climate Change, will be even more disturbing:
As the air warms over Canada,
The ice shelves collapsing in western
"I just don't see a happy ending for this," said Ted Scanbos, who studies the polar ice at the National Snow and
Most scientists say the changes anticipated at the poles in the next 30 to 40 years are inevitable, and averting more severe effects will take a drastic reduction in emissions of greenhouse gases. Some have advanced controversial ideas to exploit the polar systems. At least three companies have plans to "fertilize" the Southern Ocean with iron try to soak more carbon dioxide out of the air.
"We are just leveraging a natural process," said Dan Whaley, founder of Climos, a San Francisco company. Other scientists gathered recently at the Woods Hole Oceanographic Institute were skeptical of the idea. "There will be scientific consequences we cannot predict," warned John Cullen, an oceanographer at
The polar regions have been regularly described as the canaries in the coal mine of global warming: remote bellwethers that could give mankind a heads-up when important changes are coming.
Some even see positive opportunities in the warming. The legendary
But it turns out that the polar regions are far more than simple alarms. What happens at the poles will -- and is -- affecting the rest of the world.
Consider the permafrost. The vast Arctic region in the north encompasses land on three continents that has been deeply frozen since the last ice age. A thin layer thaws each summer. By mid-century, half of it will thaw to 10 feet, according to computer models of the
Already, the melting in
"That's a serious runaway," Scanbos said. "A catastrophe lays buried under the permafrost."
Or consider the ocean currents. The weather in the Northern Hemisphere is controlled by the temperature of currents that circulate on a giant treadmill, in which water cooled at the icy poles sinks to the bottom, and moves slowly toward the equator, where it heats and rises to flow northward again, mixing the seas. That is why Europe's climate is relatively moderate.
As the Arctic ice melts and ice shelves collapse in the Southern Ocean, vast areas of open water are exposed. The water absorbs heat from the sun that until now was reflected by the ice. As that heat warms the seas, the treadmill is expected to slow, the IPCC has reported. In the worst case, it could stop. The previous time that happened, 15,000 years ago, the Northern Hemisphere was plunged into a brief and brutal ice age, apparently within decades.
"It's like having a pool of warm water sitting in the middle of what is supposed to be the air conditioner of the north," Scanbos said. "And it will be within our lives, not our grandchildren's."
The Antarctic has sent complicated signals, she said. The interior is "a monstrously large ice sheet that creates its own microclimate." Winds circling
Furthermore, Antarctica's ice sits on land, and the warming of even the most gloomy predictions is unlikely to make a big dent in that huge ice pack very soon.
"We thought the Southern Hemisphere climate is inherently more stable," Scanbos said. But "all of the time scales seem to be shortened now. These things can happen fairly quickly. A decade or two decades of warming is all you need to really change the mass balance.
"Things are on more of a hair trigger than we thought."