Summer sea ice is melting in the Arctic, exposing for the first time the fabled Northwest Passage that Europeans sought for centuries. That creates a new frontier for human endeavors ... and potentially a new world of trouble, scientists said this weekend at the annual American Association for the Advancement of Science conference in San Diego.

An Arctic largely free of ice during the summer will mean new opportunities for fishing, oil and gas production, and shipping, in an area that is both extremely sensitive ecologically and highly unregulated.

Shipping seasons will be as much as four months longer, depending on the type of vessel, said Lisa Speer, director of the Natural Resources Defense Council's international cceans program. That could help open huge oil and gas reserves. The Arctic holds almost one-fifth of the world's known reserves, and 80 percent of the petroleum is offshore.

Five nations -- the United States, Russia, Norway, Denmark (through Greenland), and Canada -- have jurisdiction over Arctic waters within 200 nautical miles of their coastlines. Speer noted that this creates a haphazard "patchwork" of regulation and is worrisome if countries (namely Russia) have lax environmental standards.

An oil spill in the Arctic could be devastating (think the Exxon Valdez disaster in Alaska two decades ago),  because people really don't know how to clean up oil in a frozen environment. Even if large stretches of sea become ice-free, a spill would likely coat adjacent sea ice and icy coastlines. And aside from spills, daily discharges from shipping, oil and gas pumping, or other operations could take a heavy environmental toll.

The rapid retreat of summer sea ice will also open up vast tracts of Arctic "high seas" -- international waters that Speer said are not subject to any Arctic-specific treaties that regulate fishing, oil and gas, or shipping, including wastewater discharge from ships.

"There's no international mechanism that presently allows us to integrate those things for ecosystem management," she said. "In systems straddling (for example) the U.S. and Canada or the high seas, we have no way to be sure activities are considered together and protective measures taken."

The five Arctic coastal nations will meet in Quebec on March 29 to discuss "responsible development" of Arctic offshore resources. In 2008, the countries agreed to avoid territorial conflicts and protect the environment in future development. But what that means in practice remains to be determined.

Although the exact manifestations of climate change are often highly unpredictable, observations and modeling indicate that Arctic sea ice has already shrunk significantly and is highly likely to continue that trend in coming decades. Winter sea ice will see relatively little change, said John Walsh, a professor at the International Arctic Research Center in Fairbanks, Alaska. But ice loss over the summer -- with the lowest point typically reached in September -- has already outpaced predictions and is likely to accelerate.

Walsh noted that 2005 through 2008 were the Arctic's warmest years on record, and four of the five warmest Arctic decades have been in the last half century. In 2007, summer ice hit a record low, opening the Northwest Passage. Ice has recovered somewhat during the past two summers, but the overall trend remains intact.

Melting ice creates what scientists call "feedback loops" that accelerate water warming and ice melting. For example, shrinking ice cover last summer opened what Walsh called a "gaping hole" in the Chukchi and Bering Seas, which probably allowed more warm water from the Pacific Ocean to enter the Arctic, meaning more ice erosion. The ice typically refreezes during the winter, which means more ice might actually be produced each year than in the past, but it will be thinner and of a different quality than ice that has survived the summer.

Along with the widely publicized threat to polar bears and the walrus, the ice melt will continue to have significant and often complicated effects on Arctic biology, from the benthic layer of organisms on the sea floor to the plankton and other life forms up the food chain, to the terrestrial creatures (including humans) who feed on them.

Environmental groups and scientists are pushing for a conservation plan for an increasingly ice-free Arctic, but things are in the very early stages scientifically and even moreso politically. An Arctic scientist at the symposium said that 10 times more scientists are working together on Antarctic issues than the Arctic, and getting scientists from different countries to share data has been a struggle.

"We've pressed for discussion at a very high level to develop standards for shipping, fishing, and oil and gas," said Speer. "Additionally, we need a new framework to implement the strategies scientists have told us we need to do. This has to happen as a matter of urgency. We just don't have the time to wait."

Image: Goddard Space Flight Center