Satellites show: Europe’s forests have lost significantly more biomass since 2018

Since 2018 Europe’s forests have experienced considerably stronger biomass losses than previously assumed. Current analyses of Earth observation data point to this trend. Affected areas include not only weakened or young stands but also old, previously stable forests. The decline in woody biomass — in trunks, branches and roots — reduces forests’ CO2 uptake capacity and can release stored carbon back into the atmosphere.

What the data show

Spatially consistent analyses indicate a new pattern of large-scale losses since 2018 that cannot be explained solely by regular management. In several regions, damage has become more frequent and extensive, visible as reduced stand densities and sparser crowns.

How remote sensing measures it

Modern satellites combine radar, lidar and multispectral measurements. From these signals, woody biomass can be estimated across large areas and compared over years. Long-term, wall-to-wall observation makes it possible to rapidly identify trends and hotspots — independently of local inventory cycles.

Drivers: drought and pests

Prolonged dry periods weaken trees’ defenses. Insect pests such as bark beetles simultaneously benefit from warm, dry winters and longer growing seasons. Disturbances often overlap: drought facilitates infestations, the resulting canopy gaps dry out further and become more susceptible to erosion and structural shifts. Such cascades produce nonlinear damage — the combined effect of multiple stressors exceeds each one individually.

Why old forests suffer particularly

Older stands store large amounts of woody biomass but react sensitively to sudden water shortages. Historically shaped, even‑aged structures increase vulnerability when extensive areas reach advanced age at the same time. Conditions are aggravated on sites with shallow soils or at mountain margins, where persistent drought depletes soil moisture. Pure non‑intervention does not reliably protect everywhere under changed climatic conditions.

Consequences for climate, economy and biodiversity

As biomass declines, net carbon uptake falls. Locally, forests can temporarily become carbon sources when dying wood decomposes. For the timber sector this means lower predictable harvest volumes alongside more damaged timber — a combination that strains quality, logistics and profitability. Ecologically, structure, light regimes and species composition change: some species may benefit in the short term from increased deadwood, others lose habitat; in the long term, there is a risk of losing stable, species‑rich forest communities.

What to do now

Satellite‑based monitoring serves as an early warning system and should be linked with targeted field inventories. Adaptation strategies include structurally diverse mixed stands, regeneration with heat‑ and drought‑tolerant species and soil management measures to improve water retention. Where damage is severe, interventions are warranted: site‑adapted reforestation, selective removal of diseased trees and effective, ecologically sound protection against pest insects. At the same time, the sector needs flexible supply chains and methods to use damaged timber while limiting ecological risks.

Adjusting policy

Continuous Earth observation combined with local inventories provides the data base needed to set priorities: which stands are chronically affected, where are short‑term measures required? Support instruments for climate‑resilient management, stand diversification and assistance for adaptation measures gain importance. Europe’s forests remain central actors in climate protection — their role as carbon stores must, however, be actively secured.