Northern Hemisphere forests carbon sink is under threat

Posted 10.06.2025

A recent study* supported by EYE-CLIMA shows that the carbon sink of Northern Hemisphere forests has declined since 2016 most likely due to drought and increased disturbances such as wildfires and insect outbreaks. Northern Hemisphere forests across North America, Europe and Siberia contribute an estimated 1.4 to 2.0 petagrams of carbon per year (PgC y^-1) to the global terrestrial carbon sink and thus help offset some of the carbon dioxide (CO₂) emitted through the use of fossil fuels.

In this study, Xiaojun Li and colleagues used satellite observations of L-band Vegetation Optical Depth (L-VOD) from the SMOS satellite to determine changes in above ground living biomass in northern forests (>30°N) from 2010 to 2022. From 2010 to 2016, there was an increasing trend in living biomass meaning that these forests were taking up carbon from the atmosphere. However, from 2016 the annual losses of living biomass outweighed the gains and the forests lost carbon at a rate of 0.2 PgC y^-1. Also in Europe, losses in living forest biomass were observed from 2016, in particular in Western Europe, while some gains were still seen in Northern Europe.

A longer article about this study is available from the European Space Agency (ESA) climate office.

*Reference: Li, X., Ciais, P., Fensholt, R. et al. Large live biomass carbon losses from droughts in the northern temperate ecosystems during 2016-2022. Nat Commun 16, 4980 (2025). https://doi.org/10.1038/s41467-025-59999-2