Scientists, others trying to make sense of Arctic changes
By Jack Williams, USA TODAY
Posted 10/29/2003 9:37 PM     Updated 10/30/2003 10:54 AM

People who live around the Arctic and scientists who study it are seeing clear signs that most of the top of the Earth is getting warmer. Exactly why this is happening, and what it means for the Arctic and the rest of the world aren't as clear.

Satellite temperature measurements show spring is arriving earlier and fall later around the Arctic, according to new research presented last week by NASA scientist Josefino Comiso.

People have been talking about Arctic warming for years, but the NASA study used satellite data to read temperatures over the entire Arctic, not just from a few scattered thermometers as past studies have done. Annual temperatures in parts of the Arctic have warmed as much as 1.9 degrees since 1981. But, some parts have cooled by as much as 0.16 degrees.

Further, Mark C. Serreze, of the University of Colorado, Boulder, reported that in September 2002 less ice covered the Arctic Ocean at the end of summer than any year since satellites began keeping track of it in 1979, and that last month was probably as ice free.

But it's also people, not just satellites and weather instruments, that are seeing the changes. Native hunters around the Arctic report that earlier spring melting and later fall freezing of sea ice is upsetting centuries-old patterns of hunting and fishing since the ice is no longer reliably in sync with the migrations of seals, whales, and fish, Caleb Pungowiyi. of Kotzebue,. Alaska, said Tuesday. Pungowiyi, a Yup'ik. Eskimo and an advocate for native concerns, spoke during a press briefing at the Study of Environmental Arctic Change (SEARCH) conference in Seattle, ending Thursday.

While few people live in the Arctic, what happens there is important: The Arctic is part of Earth's air conditioning system, along with the Antarctic. Warm air and ocean currents flow into these regions; cold air and currents flow out.

Polar changes could affect not only global temperatures, but also things such as rainfall and snow patterns and storm paths. The usual suspect is global warming. But is that what's responsible?

Some, such as Jonathan Overpeck of the University of Arizona, think so. "The changes we are seeing are related to the burning of fossil fuel," he said Tuesday. Burning fuels such as gasoline and coal adds carbon dioxide to the air, which climate scientists agree is tending to increase Earth's overall temperature.

Others such as James Morison, of the University of Washington, say it isn't this simple. The biggest recent changes in the Arctic, including temperature increases and shifts in winds and ocean currents, occurred in the early 1990s, and have since "relaxed," he said.

These big changes "are not related to (global) climate change," but seem to be more like the El Nino pattern of changes in tropical Pacific Ocean temperatures, which have global effects. Scientists have identified such a pattern, called the Arctic Oscillation, which naturally shifts back and forth. with affects on temperatures and sea ice. One result can be that parts of the Arctic can get cooler as others warm.

Still, Morison said, a general warming of the Earth could be pushing the oscillation toward a phase that warms the Arctic.

In fact, Morison said, the oscillation helps explain why summer sea ice is thinner than in years past. Since the 1980s, wind changes associated with the oscillation have pushed ice apart and shoved more ice of it from the Arctic into the Atlantic Ocean between Greenland and Norway.

Ice reflects away most of the sunlight hitting it. When the ice opens up, the now-exposed ocean water absorbs sunlight, which warms it and the air right above it, which tends to melt ice, exposing more water to the sun.

This is what scientists call a "positive feedback" with warming bringing more warming. But, with the ocean exposed, more water can evaporate into the air, increasing cloud cover, which can block sunlight and mitigate warming — a negative feedback. Scientists are still trying to understand the Arctic's feedbacks and how they might play out in the future.

A goal of the Seattle meeting, which is being sponsored by the National Science Foundation, is to bring together scientists, many of whom tend to concentrate on their own research, and native people who live with Arctic changes to learn more about things such as the Arctic's complicated feedbacks, and then use the knowledge to better live with the changes. For example, with better knowledge scientists might be able to predict a few months ahead of time what the spring sea ice will be like, giving native whale hunters time to adjust hunting schedules.

"Each scientist here has learned to play his or her part on their instrument," said Matthew Sturm of the U.S. Army's Cold Regions Lab in Fairbanks, Alaska. "When finally all the parts are played together, a great chord emerges, and it is more powerful and truthful than any individual part. Here, the collective sound is of a region, the Arctic, undergoing profound changes that scientists and society alike need to understand."