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Yosemite National Park in the USA
Photo: HANDOUT / REUTERS
Forests play an important role in climate protection: They serve as large greenhouse gas buffers, release oxygen and store carbon dioxide.
But seen globally, they recently absorbed less CO₂.
There is growing concern that trees and plants are doing this important climate service less and less to mankind and that in the coming years they will rather develop from a CO₂ reducer to a CO₂ emitter (read more here).
Because in the numerous forest fires that recently destroyed forests in many regions of the world, stored CO₂ is released.
In addition, the forests are increasingly under stress for other reasons: droughts, insects and diseases are increasingly affecting them.
The German forest recently absorbed only three percent of the annual CO₂ emissions.
The situation should be better if the forests are very well protected, one suspects.
But that's probably not true.
Because even figureheads of nature such as the Yosemite National Park in the USA or the Blue Mountains in Australia emit more carbon than they absorb. This is due, among other things, to deforestation and forest fires, according to a new report by Unesco. At least ten of the world's natural heritage forests have emitted net carbon in the past two decades, including the tropical rainforests of Sumatra in Indonesia and forests in Russia.
"The fact that even some of the most famous and best-protected forests found in World Heritage Sites can actually contribute to climate change is alarming and shows how serious the climate crisis is," said Tales Carvalho Resende, co-author of the report and Project manager at the United Nations Education, Science and Culture Organization
(Unesco) in a statement.
After all, all 257 world heritage forests taken together still act as a net carbon sink, according to the study, which examines the period from 2001 to 2020. 166 sites were net sinks, while the remaining 81 had nearly neutral balances. Nevertheless, human activities such as deforestation and intense climate-related events such as forest fires impair the ability of forests to bind and store more carbon than they emit. In addition, there are agricultural interventions, droughts and temperature fluctuations.
Forest fires in particular are a disaster for the climate and a downright vicious circle.
With global warming, such fires are increasing.
But with more fires, more CO₂ is created in the atmosphere.
And more CO₂ causes temperatures to continue to rise.
There had already been violent fires in Yosemite National Park, around 2013 when a campfire got out of control and destroyed vast areas of forest.
Even then, experts assumed that the forest would need decades to recover.
190 million tons of CO₂ per year in the storage
For the study, researchers from Unesco and the World Resources Institute (WRI) as well as the International Union for Conservation of Nature (IUCN) evaluated satellite data and combined it with on-site monitoring. They found that the World Heritage sites absorbed a total of 190 million tons of CO₂ per year during the period under investigation. Over the centuries, forests have stored around 13 billion tons of carbon. For their work, the researchers used data from a study published in the journal Nature Climate Change in January that mapped greenhouse gas emissions and absorption by forests around the world.
"I would have expected that such protected forests would remove carbon from the atmosphere, but would not be a source of carbon themselves," said Carlos Sanquetta, professor of forest engineering at the University of Parana in Brazil. "Instead of playing a role in carbon sequestration, they play a role in carbon emissions." However, the expert criticizes the transparency of the report. Although the study provides important results, the methodology could have been presented in more detail, says Sanquetta.
Although only ten of the cultural heritage forests are identified as carbon emitters in the study, other locations also show a clear upward trend in emissions.
"This is another clear sign that even forests that we traditionally believed to be safe are now increasingly threatened," said David Kaimowitz, one of the forest experts for the UN Food and Agriculture Organization.
In his assessment, the report does not place enough emphasis on the support of indigenous and local communities and on the role of activists who fight against forest destruction.
He also doubted that the data were representative of all forests.
joe / Reuters