Across our northernmost state, ponds and wetlands vital to wildlife are draining away as global warming melts underlying permafrost
Lisa W. Drew
ORVILLE HUNTINGTON'S childhood summers were full of water. An Athabascan Indian from the interior Alaska village of Huslia, Huntington grew up next to the Koyukuk River in a landscape dotted with lakes and wetlands. "When I was a boy hunting here, all these hills were full of lakes," he says. But during the past two decades, much of that water has become only a memory. More than half the area's lakes, Huntington estimates roughly, have simply vanished. "They turn into meadows," he says. "Then they turn into grass."
The Huslia region is not alone. Bodies of water reportedly are drying up all over Alaska. "I've heard it everywhere," says Huntington, who has traveled the state working as a liaison between the U.S. Fish and Wildlife Service and Native groups. "Not just in the interior but in all the villages I've gone to."
In recent years, scientists too have taken notice of the phenomenon. "Evidence has mounted really quickly that this is a large-scale problem," says ecologist Brad Griffith of the Alaska Cooperative Fish and Wildlife Research Unit. Although much remains to be learned, big changes clearly are taking place in the plumbing of the Far North, and the effects are sure to reverberate through entire ecosystems. "If we begin to think it's happening in a lot of places, then the implications for wildlife and subsistence resources are pretty substantial," Griffith says.
More than half of Alaska's surface, including its water, sits on perennially frozen soil or ice--called permafrost--that has long served as a pool liner. As University of Alaska–Fairbanks (UAF) permafrost scientist Vladimir Romanovsky likes to point out, "The stability of Arctic ecosystems depends on the ice that holds them together." And there's the rub: As our planet heats up with global warming, permafrost is starting to thaw. The effect for many bodies of water has been "to pull the cork out from underneath," says ecologist Torre Jorgensen of the Fairbanks biological research firm ABR, Inc.
Other factors too are probably playing a role, as evidenced on Alaska's permafrost-free Kenai Peninsula, where lakes and wetlands are giving way to woodlands. Evaporation caused by higher temperatures and a drier climate may be among the reasons, but degrading permafrost looks like a major factor in the drying trend elsewhere in the state.
Not all permafrost is the same. It can be solid ice or frozen soil, and it varies greatly in depth and temperature. On the Arctic coastal plain north of the Brooks Range, the permafrost tends to be extremely deep. But in most of the rest of the state, it is relatively shallow and generally grows spottier toward Alaska's southern end. In much of the interior, the permafrost has warmed near the surface to within a few degrees Centigrade of zero, the melting point. In some places, including spots along the Trans-Alaska Pipeline, it is within one degree of zero.
The drying effect of continued thawing is likely to lead to more wildfires. Two summers ago, Alaska experienced its largest wildfire season on record. Combined, the areas that burned exceeded the size of Massachusetts. Last summer too was a big wildfire year, the third largest on record. If the organic matter in the tundra burns through, little is left to insulate the frozen layer below from the warm air above. "After fires, permafrost is not recovering in many areas," says UAF hydrologist Larry Hinzman. "People think climate change is going to be gradual, but this is a phase change." In other words, the ecosystem in those areas could be shifting within just a few years to an entirely different system. Adds ecologist Dave Klein, also of UAF, "So you could likely have a rapid transition from boreal forest to a grassland savannah, with groups of trees scattered around."
One of the first studies to report that lakes were dwindling actually was intended to help researchers track the effects of fire cycles. The idea was to inspect satellite images for differences in land cover, such as trees and other vegetation. But as the researchers looked at their first sets of images, taken of Wrangell-St. Elias National Park in 1986 and 1995, they noticed an astonishing change: Out of 242 ponds and lakes, 156 had noticeably shrunk. Many had simply disappeared. "It was sort of like, 'Whoa, check this out,'" recalls Dave Verbyla, a UAF forestry and remote-sensing expert.
In 2001, another UAF team reported that 22 of 24 lakes in a study area on Alaska's Seward Peninsula had shrunk noticeably between 1951 and 2000. "Many climate-change models say it's going to get wetter," says hydrologist Hinzman, who led the study. "We say it's going to get dryer."
Meanwhile, one of Verbyla's students, Brian Riordan, studied nine other sites around the state. In 2004, he reported in his master's thesis that at six of the sites, some lakes dwindled noticeably during the last half of the last century. The lakes with the most loss were the southernmost, in the Copper River Basin. Yet another study, published in spring 2005, found that lake loss is not confined to Alaska. During a 30-year period starting in the 1970s, a lake-studded part of northern Siberia lost 360 square miles of lake surface from a region covering 44,400 square miles. Although melting permafrost is not the complete explanation, wrote the researchers, led by University of California–Los Angeles geographer Laurence C. Smith, "the ultimate effect of continued climate warming on high-latitude, permafrost-controlled lakes and wetlands may well be their widespread disappearance."
The anecdotal evidence, too, has been adding up. "I've gone out with 1960s topo maps and walked to a lake expecting it to be a single lake and found it broken up into two or three small lakes," says UAF biologist Mark Lindberg, who has studied birds in the Yukon Flats. "You go, 'Hold it. This isn't right. I should be able to paddle from this lake to that lake.' Instead, you find yourself dragging a canoe. Some lakes shown on the map don't even exist anymore."
Of course, Alaska for now contains an almost unfathomable amount of standing water. At last count, the state was dotted with no fewer than 3 million lakes. That water supports a wilderness spectacle almost unchanged by humankind.
Millions of migrant birds--ducks, geese, loons and shorebirds--use the Far North's lakes and wetlands for breeding, nesting, feeding, staging or molting. They are joined by other creatures large and small, from 1,500-pound moose to tiny wood frogs. In early spring, just after the ice melts, the 3-inch-long frogs come out of a suspended-animation deep freeze to congregate at water's edge and sing symphonies during a brief mating season. Throughout the summer, moose lumber into ponds to feed on mineral-rich, easy-to-digest underwater vegetation.
No one knows for sure how the drying may be affecting, or could eventually affect, these species. How deep a lake freezes, or even for how long, can determine what life it supports. Fish need deep water so they can huddle in unfrozen pockets. When a lake becomes so shallow that it freezes solid, it no longer supports fish or the animals that eat them. As it drains further, it fosters surface vegetation that supports grazers rather than divers. And if it dries up altogether, it will not even support birds like the Arctic tern, the world's champion migrant, which is not a picky eater: From its hovering position over ponds, the Arctic tern spies and dives to feed on a varied menu of fish, insects and other invertebrates.
Conservationists are particularly concerned about the yellow-billed loon, which nests close to water, does not cope well with disturbance and ranks as North America's rarest loon. "Any slight rise in the water level or slight lowering of the water level can make an otherwise good nesting area a bad nesting area," says Mike Frank, an attorney with the environmental law firm Trustees for Alaska. "If the shoreline is underlain with permafrost, and the permafrost melts, the shoreline may subside, and the nesting area may be lost." A coalition of conservation groups is petitioning the U.S. Fish and Wildlife Service to list the species as threatened or endangered.
Almost all of the reports of vanishing lakes come from parts of the sub-Arctic where permafrost is spotty, or discontinuous. In the most northern regions of very deep permafrost, the frozen pool liner underneath the lakes will support the water for a very long time to come. But that doesn't mean all of those ecosystems are stable. In western Siberia, where the permafrost is ice-rich and extremely deep, an astonishing 390,000 square miles is becoming wetter, not drier. As the ice melts from the top down, the region is turning into an enormous bog. For other reasons, lakes also are growing in some parts of Alaska, including areas along the Koyukuk River, where warming water is thawing the permafrost edges.
Thawing permafrost also produces other effects. Researchers and other observers have reported seeing more landslides, with sheets of tundra sliding off hillsides and coming to rest in bizarre folds. In Fairbanks, the interior's largest city, sinkholes from melting permafrost ice wedges are opening up along roadsides and in yards. Some roads and bike paths look like roller coaster rides.
Even on the northern coastal plain, Inupiat Eskimos are noticing that permafrost is melting as they have never seen before. Last summer, when subsistence hunter Roy Nageak of Barrow and his son tried to retrieve muktuk--a whale-skin-and-blubber delicacy--and whale meat from their permafrost cellar for guests, they found that dripping water had coated their ladder with ice and that stalagmites of ice rose from the cellar floor. Nageak and others in the region are also starting to see water from their lakes escaping through channels in the permafrost. "Water," Nageak says. "When it finds a way, it will drain out."
Lisa W. Drew learned about ice wedges and permafrost sinkholes firsthand from scientists in Fairbanks, Alaska.
Hazardous Melting: The Danger Is in the Dirt
The melting of Arctic permafrost raises scientific concerns about something less visible than the demise of lakes and ponds but potentially much more catastrophic. At the heart of these concerns is a colorless, odorless gas called methane. One of the gases that contributes to global warming, methane remains in the atmosphere about 10 to 15 years after release and traps heat at least 20 times more effectively than does carbon dioxide, the primary greenhouse gas. About 60 percent of the methane currently going into the atmosphere comes from human sources, such as the burning of fossil fuels, but methane also rises from natural sources, such as bacterial decomposition of plants and from termites (fully 11 percent of naturally occurring methane comes from the digestive tracts of these wood-devouring insects).
A massive amount of natural methane has been trapped for millennia in the frozen arctic tundra--400 billion tons. Northern mud contain 3,000 times as much methane as is currently found in the atmosphere. Melting permafrost could release that methane, which would enter the atmosphere, increase the rate and intensity of global warming and spur the release of yet more methane from ocean bottoms.
"Nations can make a difference if they act soon to reduce carbon dioxide emissions," says Jeremy Symons, director of NWF's global warming campaign. "But once global warming reaches a level that speeds methane into the atmosphere, there may be no turning back."
How deadly is this threat? Scientists believe that a release of massive amounts of methane into the atmosphere some 250 million years ago caused the extinction of 94 percent of all marine species known from the fossil record. In the seas, coral reefs almost vanished, as did forests on land. Some areas did not recover their biological diversity for more than 100 million years. "The vanishing ponds of Alaska and Siberia may be a warning for all nations to take a preemptive strike against global warming rather than wait until the warning signs turn to disaster," Symons says.
NWF Priority: The Global Warming Fight
Global warming is posing a pronounced threat to Alaska, changing habitats, melting Arctic ice and jeopardizing animals from walruses and polar bears to seals and whales. In the Lower 48, threats include increased drought, more frequent wildfires and increasingly severe storms, including more frequent high-category hurricanes. Combating this global danger is a top priority for NWF, which has backed bipartisan congressional legislation to reduce greenhouse gases, supported youth activities to persuade elected officials to address global warming, published reports on the effects of global warming on wildlife and worked with state affiliates on climate issues. The NWF Alaska Natural Resource Center in Anchorage is helping to lead the battle against global warming in the 49th state. For more information, go to www.nwf.org/globalwarming.