Europe’s forests are turning brown during the summer months more than ever before, shows a new study. Droughts, wildfires and heatwaves are causing tree crowns to change colour, showing increased stress and a loss of health.
Last year, when the continent faced its hottest summer on record, 37% of forests in the temperate and Mediterranean regions were affected by forest browning, RTBF reports.
The findings were revealed after researchers analysed over 20 years of forest imagery in the Mediterranean and central regions of Europe. The large-scale study involved specialists from the Swiss Federal Institute of Technology in Zurich, the Technical University of Munich and the Swiss Federal Institute for Forest, Snow and Landscape Research.
Not simply an aesthetic concern, the phenomenon of forests losing colour in the summer signals a degradation in older trees, which are the most valuable in terms of carbon absorption. The degradation, also known as forest dieback, is an indicator of ecosystems losing resilience.
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Researchers came to the conclusion that extreme weather events, largely caused by climate change, do not immediately turn the forests brown but rather that the effects are spread over a longer period. A singular instance of drought and intense heat reduces the trees’ ability to survive successive heatwaves and leads to degraded forests in the long run.
“Prior to low forest greenness in central Europe, we usually observed two dry, hot summers in a row,” Mauro Hermann, ETH doctoral student and lead author of the study, told Euronews.
This year’s summer is predicted to be just as extreme in terms of heat as in 2022 so the loss of forest greenness will almost certainly spread.
Forests absorb and store around 10% of the EU’s yearly greenhouse gas emissions, but only 20% of forests in the EU face little to no degradation, according to the European Environment Agency.
