Science & Tech

Planning to save a changing world

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Alaska biologist reviews far north climate change

Climate change is not only altering Alaska’s natural world, it’s also affecting how humans interact with it, particularly those whose culture and traditions have pointed the way for generations to survive in the sometimes inhospitable far north.

Terry Chapin, a professor of ecology at the University of Alaska’s Institute of Arctic Biology, said that climate change is already affecting Alaska in many ways. Sea ice is retreating, salmon are migrating farther north, forest fires are increasing, permafrost is melting, and forest pest outbreaks are becoming more frequent. While those changes are having a dramatic impact on the natural world, Chapin said they’re also affecting the people who live in remote villages around the state.

Chapin gave an overview of global warming’s effects on the United States’ northernmost state during a lecture April 3 at the Science Center. His talk, “Sustainability in a Changing World: Concepts and Policy Strategies to Address Climate Change in Alaska,” was part of the Harvard University Center for the Environment’s Biodiversity, Ecology and Climate Change lecture series.

That the Earth changes is nothing new, Chapin said. The difference now is that all the change is in one direction — toward a warmer world. Most environmental plans discuss how to conserve nature as it is around us now, while taking into account that today’s environment may be different in the coming years. For example, planners might want to consider regulations for a salmon fishery in areas where no fishery exists but where the fish might soon be migrating.

Projections for Alaska’s future show continued warming on the way. When looking at the normal annual variation in temperatures, scientists expect that in the decades to come the coldest years will be warmer than the warmest years today.

That will almost certainly accelerate the changes already being seen in Alaska. Chapin said the increased fires destroy forests, driving out moose and caribou for decades while the forests recover. The early growth following fires favors moose over caribou, which feed on the slow-growing lichens.

In some cases, the shift toward moose-friendly forests is more permanent, as black spruce forests, in which there have been fire suppression efforts for decades, burn hotter and kill seeds on the forest floor. This clears the way for deciduous trees to move in.

The environmental changes are affecting things as basic as local transport. In forests that have burned, treefalls block routes and make travel difficult. And in more remote communities that use snowmobiles for winter travel, often over frozen rivers and lakes, warmer temperatures have thinned ice, increasing the incidence of snowmobiles falling through the ice, according to Chapin.

The warmth is also melting Alaska’s permafrost — the underground layer that remains frozen even in the summer months. Melting permafrost can cause the land to subside, Chapin said, as a patch near the Fairbanks airport illustrates. It was once a birch forest and is now a bog. The subsidence can affect the integrity of infrastructure such as oil pipelines. The melting itself can exacerbate global warming, as it releases the greenhouse gases carbon dioxide and methane, previously locked in the soil, into the atmosphere.

“That could lead to a positive feedback that causes more warming,” Chapin said. “We don’t know how quickly the permafrost will melt once the climate warms.”

Chapin said that change not only brings challenges, but opportunities. Humans, he said, should seek both adaptive and transformative ways to respond to climate change. Forest fires suppression policies could be changed, for example, to adapt to the increased danger of fire, by allowing more frequent smaller fires to burn, clearing out the flammable litter on the forest floor and speeding forest regeneration.

Climate change, in some cases, can be used to restore biodiversity, Chapin said. He cited the example of a heavily logged Swedish forest whose community of decomposers — the bacteria that consume fallen wood and recycle it into soil — had been almost entirely disrupted. Now, with warmer temperatures, decomposer communities from forests to the south can migrate north, restoring the forest.

Added to the mix are the economic realities facing people everywhere, Chapin said. Fuel costs are extremely high in rural Alaska, since most has to be flown in. With costs of $6 and $9 a gallon, he suggested switching to biofuels. Using wood fuel would not only be cheaper, it would also reduce fire risks in the forest and encourage early successional growth near settlements, bringing in moose closer to town for hunting.

Another answer may be to concentrate these smaller communities into fewer, larger ones.

“Alaska is vulnerable to climate change, but also has sources of resilience,” Chapin said.