When it comes to global warming, greenhouse gases, such as carbon dioxide, have long been considered the main offender.
University professor Joseph McFadden is among a team of researchers studying Arctic warming. The team has found two more culprits: snow and shrubbery.
The team’s report, which will be published in the magazine Science, outlines systems in Alaska that could dramatically amplify Arctic warming.
McFadden said scientists have long been concerned with the Arctic’s effect on the global climate.
“The physical structure of Arctic ecosystems is changing,” he said.
Researchers found that increased temperatures in the far north are causing significant increases in shrub growth. Shrubs absorb solar energy, which, in turn, adds to the warming effect, he said.
Warming in the high latitudes also causes the snow to melt a bit earlier each year.
Snow on the ground reflects a large amount of solar energy into space. With fewer “snow days” in a year, more energy is absorbed by the ground, again warming the atmosphere, he said.
McFadden, an assistant professor in the department of ecology, evolution and behavior, said that 10 years ago, greenhouse gases were the focus of research on the Arctic ecosystem. Now, the study shows, many more factors are in play than previously thought.
He said the range of the boreal forest – a biome consisting of mainly coniferous evergreen trees – is also creeping north, adding to the cycle of warming.
University of Alaska ecology professor Terry Chapin, also a lead author of the report, said the warming climate has had substantial effects on native Alaskan communities.
Chapin said many Alaskans travel on snowmobiles in the winter, and thinning river ice has caused problems.
“There are a lot more deaths, a lot more problems maintaining subsistence lifestyles,” he said.
Some critics disagree on the level of concern that should be given to climate change, with some saying global warming rhetoric is too alarmist.
Levels of concern vary among different groups, but the effects of warming are being seen locally, one group contends.
In the last century, the average temperature in Minneapolis has increased by 1 degree Fahrenheit and some areas of the state have seen as much as a 20 percent increase in precipitation, according to the governmental Minnesota Pollution Control Agency.
A 2003 University of Wisconsin study showed that 37 of 39 monitored lakes experienced warming trends over more than a century. Lakes took longer to freeze in the winter and the ice broke up sooner in the spring.
Chapin said the far northern latitudes feel climate change sooner than more southerly latitudes, which leads to problems in addressing the warming issue.
He said that since climate changes are proportionately smaller in the south, he thinks people don’t take the climate too seriously because they don’t believe the changes will have a significant effect on their lives.
McFadden said increasing energy efficiency and reducing the use of fossil fuels is the key to reducing greenhouse gases.
Because any gases released into the atmosphere are mixed around the globe within a year, the problem is a global concern, he said.
“This whole biome, which covers huge amounts of land, is really at the mercy of the choices and decisions people make everywhere else on the Earth,” he said.