Extreme weather and bark beetles have devastated many trees in the Harz Mountains, Germany
Rob Cousins/Alamy
The abrupt and significant drop in carbon absorption by European forests has ignited concern among scientists, who fear that a marked decline could hinder efforts to combat global warming.
For many years, European forests, which span around 40% of the continent’s land area, have played a dual role as sources of timber and as carbon sinks. However, increasing extreme weather events are pushing these forests beyond their limits, swiftly altering the landscape.
“Many [European Union] countries will struggle to meet their [land-use climate] targets due to this sink reduction,” states Glen Peters from the Cicero International Climate Research Centre in Norway.
Earlier this year, Finnish officials revealed that their forest ecosystem had shifted from functioning as a net carbon sink to becoming a net carbon source. This development follows Germany’s declaration that its forests became the first in the country’s history to record a net increase in carbon emissions. Additionally, the Czech Republic has reported its forests as net carbon sources since 2018.
While these instances are particularly severe, carbon absorption rates are dwindling rapidly in many other nations. For instance, in France, the carbon uptake by forests has nearly halved in just 14 years, with a study released last month documenting a decrease from a peak of 37.8 million tonnes of carbon dioxide annually in 2008 to 74.1 million tonnes in 2022. Concurrently, Norway’s carbon absorption has plummeted from 32 million tonnes in 2010 to 18 million tonnes in 2022.
“The trend had remained relatively stable from 2013 to 2015,” comments Korosuo at the European Commission’s Joint Research Centre in Belgium. “This is a widespread issue, not confined to just one or two countries. Similar patterns are observable across nearly all forested nations.”
Many forests in Europe are privately owned and commercially managed. Some of the decrease in carbon sinks has been linked to increased logging, particularly following the sanctions on Russian timber imports due to the invasion of Ukraine in 2022. For example, Finland has seen strong demand for wood, leading to heightened harvesting levels, notes Raisa from the Natural Resources Institute of Finland.
However, scientists also attribute the rapid decline in carbon storage to the escalating impacts of climate change.
Europe has faced several droughts in recent years, with 2018 and 2022 marking the harshest conditions. Wouter Peters at Wageningen University in the Netherlands highlights that his research indicates the 2022 drought caused a significant reduction in carbon intake by European forests during summer months. “We’re observing immediate effects; the trees are under stress,” he comments.
Researchers had expected that as global temperatures rise, European forests would diminish in health, yet the extent of the recent decline is still astonishing. Wouter Peters explains, “The impact seems to be more severe than anticipated.”
This downturn could be a result of successive droughts occurring within a few years, exacerbated by other extreme weather events such as storms that disturb forests. “We see not just one drought in 2018, but additional ones in 2021 and 2022,” Wouter Peters notes. “Our models have not effectively accounted for this concentration of drought events over such a short time frame.”
Moreover, rising temperatures are leading to more frequent and widespread infestations of bark beetles across Europe, which are severely damaging spruce forests. The Czech Republic, in particular, has faced seven major bark beetle outbreaks from 2018 to 2021.
A declining carbon sink poses a threat to the EU’s climate objectives, which depend on forests to absorb the bulk of emissions generated by other sectors. The EU is even aiming to enhance this carbon sink to support its climate ambitions, targeting a removal of 310 million tonnes of CO2 equivalents annually by 2030, a significant increase from the approximately 230 million tonnes currently removed.
However, a recent analysis published in April warns that European carbon sinks are projected to decrease by around 29% below the 2030 target, with researchers cautioning that the capability of European forests to absorb carbon will “gradually deteriorate.”
Preventative measures can help mitigate this decline, such as reducing harvesting rates and prohibiting clear-cutting in plantations, which can maintain carbon stocks. Additionally, increasing species diversity and retaining some deadwood can enhance forest health and resilience against pests and droughts.
Nonetheless, Wouter Peters argues that policymakers are overestimating the carbon absorption potential of forests in warmer climates. “There has likely been an over-reliance on forests, particularly in the context of greenhouse gas emissions,” he contends. He emphasizes that other sectors must rapidly reduce emissions to meet European climate goals. “This implies that we need intensified efforts in other areas.”
Carbon dioxide levels in the atmosphere are rising at unprecedented rates, despite an overall stagnation in greenhouse gas emissions. Scientists attribute this acceleration to slower carbon absorption rates in forests, wetlands, and peatlands globally, compounded by deforestation and increased emissions from wildfires and droughts that weaken global land sinks.
This issue is most pronounced in mid-latitude regions. Alongside Europe, significant declines in carbon sink capacity have also been recorded in boreal forests of Alaska and Canada. Tropical forests are facing challenges from both deforestation and diminished carbon storage capacity, primarily due to wildfires.
This poses a serious challenge to global efforts to achieve net-zero emissions. “In a broad global context, the entire concept of net zero hinges on the functionality of forests and oceans. If these systems cease to effectively sequester carbon, it will lead to increased atmospheric carbon levels and accelerated global warming.”
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Source: www.newscientist.com
