First Quantification of the Permafrost Heat Sink in the Earth's Climate System

• Published in: Geophysical Research Letters
• Main Authors: Nitzbon, Jan, Krinner, Gerhard, Schneider von Deimling, Thomas, Werner, Martin, Langer, Moritz
• Other Authors: Alfred Wegener Institute for Polar and Marine Research (AWI), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Vrije Universiteit Amsterdam Amsterdam (VU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDE.MCG]Environmental Sciences/Global Changes; Ice; permafrost; Thermokarst
• Online Access: https://hal.science/hal-04191183; https://hal.science/hal-04191183/document; https://hal.science/hal-04191183/file/NitzbonEA_Permafrost_grl2023.pdf; https://doi.org/10.1029/2022gl102053

Due to an imbalance between incoming and outgoing radiation at the top of the atmosphere, excess heat has accumulated 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 used to melt ground ice in permafrost. Here, we diagnose changes in sensible and latent ground heat contents in the northern terrestrial permafrost region from ensemble-simulations of a tailored land surface model. We find that between 1980 and 2018, about 3.9 ^+1.4 -1.6 ZJ of heat, of which 1.7^1.3 -1.4 ZJ (44%) were used to melt ground ice, were absorbed by permafrost. Our estimate, which does not yet account for the potentially increased heat uptake due to thermokarst processes in ice-rich terrain, suggests that permafrost is a persistent heat sink comparable in magnitude to other components of the cryosphere and must be explicitly considered when assessing Earth's energy imbalance.