TUM Study Finds Europe’s Forest Carbon Sinks Under Growing Pressure From Accelerating Biomass Loss

The researchers argue that forest management should be adapted to climate change to strengthen the forests’ role as a carbon sink.

(IN BRIEF) Researchers at the Technical University of Munich have identified an unprecedented rise in aboveground biomass loss across Europe’s forests since 2018, using satellite data to assess changes in forest biomass rather than only tree cover. The study found that Europe has lost 46% more biomass per year per hectare since 2018 than during the period from 1985 to 2017. Central European forests have been especially affected because they contain high levels of biomass and are vulnerable to drought, bark beetle outbreaks and storms. The researchers link the sharp increase primarily to climate change-related disturbances. Natural disturbances accounted for 23% of biomass losses between 2018 and 2023, compared with 17% from 1985 to 2017. The findings raise concerns about the European Union’s target to increase annual forest carbon removals to 310 megatonnes of CO₂ equivalents by 2030, and underline the need for forest management strategies adapted to future climate conditions.

(PRESS RELEASE) MUNICH, 5-Aug-2026 — /EuropaWire/ — Researchers at the Technical University of Munich, known as TUM, have identified an unprecedented loss of aboveground biomass in Europe’s forests since 2018, raising concerns about the ability of forests to continue acting as reliable carbon sinks.

Using satellite data, the research team carried out the first large-scale assessment of forest biomass loss across Europe.

The study shows that forests in Central Europe have been particularly affected, with drought, bark beetle outbreaks and storms contributing to significant losses of carbon stored in forest ecosystems.

Unlike earlier studies that focused mainly on changes in tree cover, the TUM analysis combines satellite-based information on tree cover change with data on the amount of biomass stored in forests.

This approach allowed the researchers to assess not only where forests were disturbed, but also how much biomass and stored carbon was lost.

The findings point to a clear shift since 2018.

Since then, biomass losses have increased sharply, resulting in substantially higher carbon losses from European forests.

The increase coincides with a major rise in bark beetle outbreaks linked to worsening drought conditions.

According to the study, Europe has lost on average 46% more biomass per year per hectare of forest area since 2018 than during the period from 1985 to 2017.

While timber harvesting and natural disturbances both contribute to biomass losses, the researchers attribute the sharp increase since 2018 primarily to climate change-related events.

Katja Kowalski, researcher at the Professorship of Earth Observation for Ecosystem Management at TUM and lead author of the study, said the changes since 2018 are difficult to explain without climate change.

She said that as droughts become more frequent and severe, trees become weaker and bark beetles benefit from increasingly favourable conditions.

Kowalski added that such events are expected to become more frequent in the future and should therefore be considered more strongly in forest management planning, particularly if Europe intends to rely on its forests as carbon sinks.

The study also highlights the importance of geography in determining the amount of carbon released by forest disturbances.

Central European forests contain especially high levels of biomass, but they are also particularly vulnerable to drought, bark beetles and storms.

In Germany, which has the largest standing timber stock in the European Union, disturbed forests now release an average of about 125 tonnes of biomass, equivalent to roughly 230 tonnes of CO₂ equivalents per hectare each year.

Before 2018, the figure was approximately 170 tonnes of CO₂ equivalents per hectare.

By contrast, Mediterranean and Scandinavian forests generally contain less biomass per hectare because of their ecological characteristics and growing conditions.

Disturbances in those regions therefore release less carbon per hectare than disturbances in Central Europe.

The researchers said rising disturbance rates in Central Europe have especially serious implications for the carbon sink capacity of Europe’s forests.

Across Europe, 18% of all biomass losses between 1985 and 2023 were caused by natural disturbances, including insect outbreaks, storms and wildfires.

Between 1985 and 2017, natural disturbances accounted for 17% of biomass losses.

From 2018 to 2023, their share increased to 23%.

The much larger share of biomass loss, 82% over the full 1985–2023 period, resulted from forest management activities.

Cornelius Senf, Professor of Earth Observation for Ecosystem Management at TUM, said that unlike natural disturbances, human interventions in forests can be influenced.

He also noted that biomass removed from forests does not usually enter the atmosphere immediately as CO₂, because it is often used as raw material for buildings, furniture and other products.

The study found that timber harvesting increased steadily over the period analysed, but the increase was moderate compared with the more abrupt rise in losses linked to disturbances after 2018.

The researchers also place their findings in the context of European climate policy.

The European Union has set a target of increasing annual carbon removals from forests to 310 megatonnes of CO₂ equivalents by 2030, in order to offset emissions that are difficult to avoid in other sectors.

However, the performance of Europe’s forests as carbon sinks is already declining.

Recent studies show that Europe’s forests stored about 72% less CO₂ equivalents during 2020–2022 than they did between 2010 and 2014.

The TUM study suggests that this weakening trend could become even more pronounced.

Senf said forests are capable of recovering from disturbances and that there is reason for optimism, because most disturbed areas will eventually regain their role as carbon sinks.

He said the task now is to restore forests’ capacity to store carbon and adapt them to future conditions.

The research was supported through the European Space Agency’s Climate Change Initiative as part of the RECCAP-2 project, as well as through the EU-funded ForestPaths project.

Both initiatives use satellite data to quantify changes in Europe’s forests and assess their role as carbon sinks.

The findings were published in Nature Geoscience in the paper titled “Accelerating biomass loss from forest disturbances across Europe” by Katja Kowalski, A. Viana-Soto, M. Brandt, P. Ciais, W. De Keersmaecker, R. Fensholt, T.A.M. Pugh, Y. Xu and Cornelius Senf.

Senf is a member of the TUM School of Life Sciences and the Center for Alpine Forest Management at TUM.

In 2026, he was appointed by NASA and the U.S. Geological Survey to the Landsat Science Team, an interdisciplinary group of international experts working with long-term satellite observation data.

Through the study, TUM researchers provide new evidence that Europe’s forest carbon sinks are under increasing pressure, particularly in Central Europe, and underline the need for climate-adapted forest management to protect the long-term carbon storage role of European forests.

Publications

Kowalski, K.; Viana-Soto, A.; Brandt, M.; Ciais, P.; De Keersmaecker, W.; Fensholt, R.; Pugh, T.A.M.; Xu, Y.; Senf, C.: Accelerating biomass loss from forest disturbances across Europe. Nature Geoscience 2026. DOI: 10.1038/s41561-026-02032-y

Further information and links

• The research was supported through the European Space Agency’s Climate Change Initiative as part of the RECCAP-2 project, as well as by the EU-funded ForestPaths project. Both projects use satellite data to quantify changes in Europe’s forests and their role as carbon sinks.
• Cornelius Senf is a member of the TUM School of Life Sciences and the Center for Alpine Forest Management at TUM.
• In 2026, he was appointed by NASA and the U.S. Geological Survey (USGS) to the Landsat Science Team, an interdisciplinary group of international experts. For more than 50 years, the Landsat program has provided a continuous record of satellite observations, serving as a foundation for research on climate change, land use, ecosystems, agriculture, and urbanization.
• Lecture by Prof. Cornelius Senf at TUM@Freising

Media Contacts:

Corporate Communications Center
Anja Lapac
anja.lapac@tum.de
presse@tum.de

Prof. Dr. Cornelius Senf
Technical University of Munich
Earth Observation for Ecosystem Management
Tel. +49 8161 71 4371]
cornelius.senf@tum.de

Dr. Katja Kowalski
Technical University of Munich
Earth Observation for Ecosystem Management
Tel. +49 8161 71 4370]
katja.kowalski@tum.de

SOURCE: Technical University of Munich