Boreal forests shade northern permafrost so effectively that summer thaw stays about one metre shallower; researchers estimate their canopies keep 59 billion tonnes of carbon frozen

• Spruce and birch trees are seen tilting along the edge Stevens Pond on the University of Alaska Fairbanks campus on Sept.
• Thick green tree canopies across northern forests act as giant sunshields, keeping permafrost cool enough to hold 59 billion tonnes of carbon safely in the ground.
• The discovery reveals that the forest canopy reduces summer soil thawing by roughly one metre compared to open, treeless land.