The composition of Alaska’s boreal forests is changing in response to rising global temperatures. Photo courtesy Dennis R. Green, Bureau of Land Management.
Drought, fire and insect infestation have been changing forest landscapes for centuries. But unlike these tangible and visible causal agents, the effects of global temperature increases on forests aren’t immediately obvious. The changes are slower at first, and it is difficult to pinpoint what’s causing them. But in Alaska’s cold northern climes, where the growing season has been getting longer and the daytime temperatures staying higher, the effect of climate change is now clearly seen from one season to the next.
“The climate is not changing, it has changed,” says Glenn Juday, a forest ecology professor at the University of Alaska Fairbanks.
The dense choking smoke that hung over Alaska for weeks in the summers of 2004 and 2005 was the result of massive fires that consumed 10 to 15 percent of the state’s boreal forest during a two–year period; in 2004 alone, one–eighth of the Yukon Territory burned. The fires—and their smoke—were just one indicator that rising temperatures are causing massive changes in this vital region.
Juday says that if temperatures continue to rise along the predicted scale, the whole area will be altered, and the effects will expand far beyond the state’s borders. Many of the vital but unseen ecological functions that the boreal forests provide will be lost.
Among the probable changes Juday foresees are:
Carbon sequestration: The boreal forest plays a huge role in regulating environmental carbon levels. If vast acres of trees are lost through fire or increased insect infestations, the mitigating factor of carbon storage will be decreased, exacerbating the effects of global warming on the rest of the world. The amount of carbon involved is many times larger than the reductions that are called for by the Kyoto Protocol.
Species protection: The boreal forest is critical to the survival of nearly half of all North American species of birds. Waterfowl and shorebirds return to the boreal forests each summer along ancient migratory routes that begin in the tropics. On their journey, they face a gamut of threats, including increased exposure to pesticides and shrinking habitat. Arrival in the boreal allows them to enter an intact ecosystem, affording time to offset the negative influences they encounter along the rest of the route. With diminished forests, the birds will not have suitable habitat in which to recover and breed.
Polar ice: Increased flows in the area’s major north–flowing rivers transfer heat to the arctic regions, accelerating the melting of the polar ice cap. An ice–free cap will radically change climate and coastal geography worldwide.