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Europe’s forests are losing biomass at a rate scientists describe as unprecedented. A new satellite-based study has found that forests across the continent have lost, on average, 46% more aboveground biomass per hectare each year since 2018 than they did during the previous three decades.The change is significant because forest biomass represents stored carbon. When trees are cut, damaged or killed by drought, storms, insects or wildfire, part of that carbon can eventually return to the atmosphere. The findings suggest that Europe’s forests are becoming less reliable as natural carbon sinks at the same time that climate policies increasingly depend on them to absorb emissions.The study titled ‘Accelerating biomass loss from forest disturbances across Europe,’ was published in Nature Geoscience.A new way to measure forest damageResearchers from the Technical University of Munich used satellite observations to assess how much biomass European forests were losing. Earlier studies often measured forest change by tracking tree cover, whether an area appeared to have trees or not. But tree cover alone does not reveal how much wood, vegetation and carbon a forest contains.A young, recently planted forest and a mature woodland may both appear as “forest” from above, even though they store very different amounts of biomass. By combining satellite data on changes in tree cover with information about biomass density, the researchers were able to estimate the scale and carbon significance of forest disturbances across Europe, as per reports.Their analysis covered the period from 1985 to 2023 and revealed a clear turning point around 2018. From that year onward, the amount of biomass lost per hectare of disturbed forest rose sharply. The increase was especially visible in Central Europe, where many forests hold large amounts of timber but are also vulnerable to drought, heat and pest outbreaks.
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Drought weakened the treesThe researchers link the sharp rise in recent biomass loss largely to climate-related disturbances. Severe droughts have become more frequent and intense in parts of Europe, leaving trees under prolonged water stress.A healthy tree can often defend itself against bark beetles by producing resin and other protective compounds. But when the tree is weakened by heat and a lack of water, those natural defenses can fail. Bark beetles can then reproduce rapidly and spread through vulnerable stands, killing trees that might once have resisted infestation.This pattern became particularly visible after the severe droughts that affected Central Europe from 2018 onward. Germany, the Czech Republic and Poland were among the countries where older, biomass-rich forests suffered extensive damage. Scientists say the interaction between drought and insects is more important than either threat considered separately: dry conditions weaken trees, while beetle outbreaks accelerate mortality.Central Europe is a carbon hotspotNot every forest disturbance releases the same amount of carbon. The impact depends partly on how much biomass was stored in the forest before it was damaged.Central European forests tend to contain more standing timber than many Mediterranean or Scandinavian forests. That means a drought, storm or bark beetle outbreak in Central Europe can release considerably more carbon per hectare. In Germany, which has the largest standing timber stock in the European Union, disturbed forests release an average of about 125 tonnes of biomass per hectare each year, equivalent to roughly 230 tonnes of carbon dioxide emissions. Before 2018, the comparable figure was about 170 tonnes of CO₂ equivalents per hectare.This makes Central Europe particularly important for climate planning. If forests in the region lose their ability to keep storing carbon, the effects will extend beyond local landscapes and forest industries. They could also weaken the continent’s wider efforts to reduce net greenhouse gas emissions.Logging still causes most lossesClimate-driven disturbances are responsible for the recent increase, but natural events are not the largest overall source of biomass loss. Across the full 1985–2023 study period, researchers found that approximately 82% of biomass losses resulted from forest management activities, including timber harvesting. Natural disturbances such as insect outbreaks, storms and wildfires accounted for the remaining 18%.However, the balance has shifted in recent years. Natural disturbances represented about 17% of losses between 1985 and 2017, but that share rose to 23% from 2018 to 2023. The change shows why recent forest damage cannot be understood simply by looking at harvesting rates. Drought, insects and extreme weather are now playing a larger role in the amount of biomass being removed or destroyed.There is also an important difference between timber harvesting and natural dieback. Wood removed through managed forestry may be used in buildings, furniture or other long-lasting products, meaning the carbon is not necessarily released into the atmosphere immediately. Biomass destroyed by fire, insects or decomposition can return to the atmosphere more quickly.A warning for Europe’s climate targetsThe findings arrive as the European Union seeks to increase carbon removals from forests and other land-use sectors. The EU has set a target of removing 310 million tonnes of CO₂ equivalents annually from the atmosphere by 2030, partly to offset emissions that are difficult to eliminate in sectors such as transport, industry and agriculture.But Europe’s forests are already absorbing less carbon than they did in the past. Recent assessments have reported a substantial decline in the forest carbon sink between the early 2010s and 2020–2022. One European assessment estimated that the average forest carbon sink fell by about 27% between 2020–2022 and 2010–2014, while the study materials cited by the researchers describe an even sharper decline in carbon storage over those periods.The message is clear: forests cannot be treated as an unlimited climate solution. Their capacity to absorb carbon depends on their health, age, species composition, water availability and exposure to disturbances.Forests can recover, but need helpThe researchers are not suggesting that Europe’s forests are doomed. Forests can regenerate after storms, pest outbreaks and harvesting, and many disturbed areas will eventually begin storing carbon again as vegetation regrows.The challenge is that recovery takes time, while droughts, heatwaves and pest outbreaks may arrive more frequently. Forest managers may therefore need to select tree species better suited to warmer and drier conditions, improve landscape diversity, protect soil moisture and monitor vulnerable areas more closely.The new study also highlights the value of satellite monitoring. Space-based observations can help researchers identify damage across national borders and track whether forests are recovering or continuing to decline. That information could support faster responses to outbreaks and better long-term planning.Europe’s forests remain one of the continent’s most important natural assets. But the 46% rise in biomass loss since 2018 shows that climate change is altering how they function. Restoring damaged forests will matter, but so will adapting them to the conditions they are likely to face in the future.
