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, Nitzbon, Jan;, Krinner, Gerhard;, Schneider von Deimling, Thomas;, Werner, Martin;, Langer, Moritz;
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: ddc:551.6; permafrost; Earth’s energy imbalance; essential climate variable; heat sink; CryoGrid; land surface model; Arctic; Climate change; Global warming; Ice; Thermokarst
• Online Access: https://doi.org/10.1029/2022GL102053; http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/10935

Abstract 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 <mml:semantics> 3.9 + 1.4 − 1.6 <mml:annotation encoding="application/x-tex"> $3.9\genfrac{}{}{0pt}{}{+1.4}{-1.6}$</mml:annotation></mml:semantics> ZJ of heat, of which <mml:semantics> 1.7 + 1.3 − 1.4 <mml:annotation encoding="application/x-tex"> $1.7\genfrac{}{}{0pt}{}{+1.3}{-1.4}$</mml:annotation></mml:semantics> 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. Plain Language Summary: In recent decades, planet Earth has received more energy from the sun than it has radiated back into space. This has led to an excess of energy that is causing global warming and climate change. While most of this excess energy is absorbed by Earth's oceans, some of it is used to melt ice in perennially frozen ground called permafrost. However, we do not know how much. In this study, we use a computer model to calculate how much energy the permafrost in the Arctic has absorbed over the past four decades. We find that permafrost has absorbed about 3.9 sextillion Joules of energy between 1980 and 2018. About 44% of this energy was used to melt ice contained in the ground, while the remaining energy was used to warm ...