The study investigated the effect of Arctic sea ice retreat on northward boreal forest advance. Using old aerial photos, satellite images and previously published data from throughout the Arctic, the research team was able to show boreal forest advance has been more common in regions of the Arctic where autumn sea ice has either long been limited or has recently retreated the most. 

The team has also repeatedly visited 20 field sites in the Brooks Range of Northern Alaska, where they collected troves of data and were able to show that retreating Arctic sea ice is associated with increasing winter snowpacks, which protect young trees and insulate soils during winter, leading to greater soil nutrient availability. 

The research team believes the effects of deepening snow are driving the advance of the boreal forest into Arctic tundra, which will have important impacts on wildlife habitat, land surface albedo and the global carbon cycle.  

"Scientists have long thought that the boundary between forest and tundra is simply determined by summer temperature,” said Dr Sullivan. “Our study is novel, not only because we have demonstrated the importance of other factors, but because we have shown that changes occurring in the Arctic Ocean may be driving major changes on land, sometimes more than 100 miles from the coast.”

Check out the full article in Science magazine to learn more about the amazing Arctic research Dr. Sullivan and the team have been conducting.