"The study provides more realistic modeling estimates of how much vegetation change will occur over the 21st century and will allow better predictions of future climate change," she said.
The research is also distinctive in that it considers 10 classes of plants and trees, rather than a few, said Song Feng, a climatologist at the University of Nebraska, Lincoln, who did not participate in the study.
Pearson said there already is extensive greening in the Arctic.
Another study this month reported that 32 to 39 percent of the Arctic experienced increased plant growth over the past 30 years (ClimateWire, March 11). Last year, scientists found that plants grew taller and evergreen shrubs increased at 46 Arctic locations between 1980 and 2010.
Pearson cautioned that the study does not mean definitively that a certain amount of tree cover will occur in the Arctic by 2050. It is possible vegetation expansions could move faster, or take longer, considering that there are some uncertainties about the migration patterns of plant species.
A mountain range, for example, could delay the progression of trees into a certain area, even if the climate becomes suitable for them, he said. Another uncertainty -- not measured in yesterday's study -- is how plants and trees will interact with permafrost thaw.
There are recent studies showing that the shading effect of vegetation could also have a cooling effect by helping keep soils cool. That could delay permafrost thaw that further releases stored carbon, said Loranty.
But those prior studies considered small areas, he said. Other research signals that the albedo effect "causes so much warming that permafrost thaws even despite the cooling from shrubs," he said.
Myers-Smith said the interactions among plants and climate are extremely complex, and additional field work is going to be critical to fully understand what is happening in the Arctic.
The vegetation changes, when they do happen, could ripple through the ecosystem, said Pearson. Some bird species, for example, nest in polar regions and require open spaces to do so. More trees could disrupt their life cycles, he added.
"Widespread distribution of Arctic vegetation would have impacts that reverberate through higher tropic levels, affecting wildlife and ecosystem services that are important for human well-being, including food production, access to natural resources, and traditional cultural identity," the study says.
Clarification: This story was updated to clarify the driver of the albedo effect.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500