Permafrost soils release large quantities of the greenhouse gas nitrous oxide following thawing and re-saturation of the soil, according to a study published online this week in Nature Geoscience.

Twenty-five per cent of the land surface in the Northern Hemisphere is underlain by permafrost, and global warming threatens to thaw these soils. Bo Elberling and colleagues used laboratory experiments to examine the effect of thawing on nitrous oxide production in permafrost soils collected from Greenland. Thawing and drainage of the soils had little impact on nitrous oxide production. However, re-saturation of the drained soils with meltwater from the frozen soils ― as would happen following thawing ― increased nitrous oxide production by over 20 times. Nearly a third of the nitrous oxide produced in this process escaped into the atmosphere.