The world’s forests could sequester more than 200 billion tons more carbon than they currently do. This corresponds to approximately twenty times global fossil carbon emissions in 2022. According to a recent study involving hundreds of researchers around the world, restoring damaged forests has greater climate protection potential than planting new ones. forests. However, experts warn that this potential is unlikely to be fully exploited.
The research team, which published its study on Monday in the journal Nature, emphasizes that forests are no substitute for reducing greenhouse gas emissions. “However, our results support the idea that conservation, restoration and sustainable management of various forests can make a valuable contribution to achieving global climate and biodiversity goals,” the researchers write.
Criticism of previous work
It has long been known that forests have potential for climate and species protection. However, it is controversial how much of the greenhouse gas carbon dioxide plants can extract from the atmosphere and then bind the carbon therein over the long term, over centuries or millennia. The main working group led by Thomas Crowther of ETH Zurich published an estimate in 2019 showing a potential through reforestation of 205 gigatons. This value has been criticized by other researchers as significantly too high.
Billions of tons of carbon less stressed forests could absorb them from the atmosphere.
For the current study, the team has now combined data collected in ground studies or via remote sensing from satellites. Terrestrial data is sometimes considered difficult to transfer to other regions, and satellite data is subject to uncertainty. According to current calculations the results differ by only about an eighth, the researchers write. According to the current study, forests that have not yet been converted to settlements or agricultural land currently store 226 gigatons (billion tons) less carbon worldwide than would be naturally possible.
139 gigatons of this potential, almost two-thirds, are found in current forest areas. The additional 87 gigatons could be stored in regions where forest is only partially preserved but hardly used. “These areas are therefore particularly suitable, for example, to be placed under protection and thus fully exploit their natural carbon storage potential,” says Florian Zabel, a geographer at the Ludwig Maximilians University of Munich, who was not involved in the study. the Science Media Center Germany. The climate protection potential could therefore be implemented with “minimal land use conflicts,” according to the study authors.
They have to put up with, for example, criticism from Christian Körner. The emeritus professor of botany at the University of Basel assumes that they have an “otherworldly and static forest concept”. Forests are dynamic systems. Centuries of construction alternate with sudden collapses caused by fire, wind or insects. “There are no forests that permanently have an ideal maximum storage capacity, as assumed here,” says Körner. Furthermore, it overlooks the fact that there is a conflict of objectives: “If you put a gigatonne of carbon into forest biomass, you cannot simultaneously use it to replace fossil raw materials.”
On the other hand, the authors avoid including areas that are currently used as grassland, pasture or arable land or that are densely populated. In theory, these would have a potential of just over 100 gigatons, but reforestation is not realistic. “But there is potential here too, for example through agroforestry or carbon farming,” says Zabel.
In a press release from ETH Zurich, the same authors highlight another limitation: if emissions are not reduced, drought, fires and warming would jeopardize the ability of forests to absorb carbon. Emission reduction and nature conservation must work together. “We need nature for the climate and we need climate protection for nature,” says Crowther.