Due to an imbalance of incoming and outgoing radiation at the top of the
atmosphere, excess heat has been accumulating in Earth’s climate system
in recent decades, driving global warming and climatic changes. To date
it has not been quantified how much of this excess heat is being used
for the melting of ground ice in the terrestrial permafrost region.
Here, we diagnose changes in sensible and latent heat contents in the
northern terrestrial permafrost region from ensemble simulations of a
numerical permafrost model. We find that about 3.9 (+1.5|-1.7)
ZJ of heat, of which 1.7 (+1.4|-1.5) ZJ (45%) were used to
melt ground ice, were taken up by permafrost from 1980 to 2018. This
suggests that permafrost is a persistent heat sink similar in magnitude
to other components of the cryosphere that requires an explicit
consideration in assessments of the Earth’s energy imbalance.