Europe’s Trees May Be Crying “Uncle”
August 29, 2013
Europe is losing one of its main defenses against rising carbon dioxide emissions linked to global warming, a team of researchers from the Netherlands, Finland, Switzerland, and Italy has reported. Their analysis of data from 29 European countries suggests that the ability of the continent’s trees to absorb and sequester (store) carbon dioxide (CO2), an important greenhouse gas, has nearly reached its limit. Forests, much like oceans, are important natural carbon sinks—that is, areas that sequester large amounts of atmospheric carbon. According to the researchers, the amount of carbon dioxide being absorbed by Europe’s forests has been falling since 2005. The scientists also said that the forests may reach a saturation point by 2030, earlier than previously expected.
The researchers, headed by Gert-Jan Nabuurs of Wageningen University and Research Centre in the Netherlands, listed a number of reasons for the trend. Europe’s trees are aging. Green plants absorb CO2 from the atmosphere as they grow and use the carbon for photosynthesis. However, a tree’s ability to sequester CO2 lessens as it ages. Many of Europe’s trees were planted after World War II (1939-1945), which ravaged the landscape.
Forests cover large parts of Europe, such as the sides of this valley in southern Austria. (© Johanna Huber, SIME/4Corners Images)
Aging trees are more susceptible to wildfires, disease, infestation, and other natural disturbances that return the trees’ sequestered CO2 to the atmosphere, the scientists reported. They also noted that Europe has lost forest because of urban sprawl and deforestation. When trees die or shed leaves, they deposit their trapped carbon into the soil. There, certain bacteria may break down some of the plant matter and release carbon back into the atmosphere as CO2. Trees that are cut down release their CO2 back into the atmosphere as they decay, though turning the wood into paper products delays the release for a a short time.
The researchers suggested that European countries should reevaluate their forestry and land-use policies. “I think policymakers at a national level and within the European Union have to be clear that in certain regions, with valuable habitats, that the focus is on old forests and biodiversity,” Nabuurs told the BBC. “But in other regions, maybe it’s time to concentrate more on continuous wood production again and rejuvenate forests again, so then you have growing forests and a continuous flow of wood products.”
Additional World Book articles:
- Carbon cycle
- The Ocean’s Changing Chemistry (a special report)
