In the paper published March 31 in Nature Climate Change, scientists reveal new models projecting that wooded areas in the Arctic could increase by as much as 50 percent over the next few decades. The researchers also show that this dramatic greening will accelerate climate warming at a rate greater than previously expected.
Plant growth in Arctic ecosystems has increased over the past few decades, a trend that coincides with increases in temperatures, which are rising at about twice the global rate. The research team — which includes scientists from the AT&T Labs-Research, Woods Hole Research Center, Colgate, Cornell University, and the University of York — used climate scenarios for the 2050s to explore how this trend is likely to continue in the future.
The models reveal the potential for massive redistribution of vegetation across the Arctic, with about half of all vegetation switching to a different class and a massive increase in tree cover. What might this look like? In Siberia, for instance, trees could grow hundreds of miles north of the present tree line.
In addition, the researchers investigated the multiple climate change feedbacks that greening would produce. They found that a phenomenon called the albedo effect, based on the reflectivity of the Earth’s surface, would have the greatest impact on the Arctic’s climate. When the sun hits snow, most of the radiation is reflected back to space. But when it hits an area that’s “dark,” or covered in trees or shrubs, more sunlight is absorbed in the area and temperature increases. This has a positive feedback to climate warming: the more vegetation there is, the more warming will occur.
“Increased plant growth will not offset this warming effect because plants in the Arctic absorb atmospheric carbon relatively slowly,” said Loranty.
The research was funded by the National Science Foundation. Other authors involved in this study include Steven Phillips (AT&T Labs-Research), Pieter Beck (Woods Hole Research Center), Theodoros Damoulas (Cornell University), and Sarah Knight (American Museum of Natural History and University of York).