Despite rising temperatures in the Arctic, permafrost has been expanding around some lakes, probably because of vegetation springing up nearby.

Twelvemile Lake in Alaska has been shrinking, causing permafrost and willow-shrub growth to expand along its shores. A team led by Martin Briggs of the US Geological Survey in Storrs, Connecticut, modelled the response of ground ice to shading and transpiration by plants. The simulations show that, thanks to the effects of vegetation (for example, by cooling and drying the surface), shallow permafrost can persist and even expand in warmer temperatures.

However, the team calculates that, within 70 years, rising air temperatures will win out and cause this permafrost to thaw.

Geophys. Res. Lett. http://doi.org/rmp (2014)