- Reducing CO2 emissions, reducing the use of coal and oil are important building blocks in the fight against climate change.
- Planting additional trees would be an efficient measure for climate rescue, according to a new study.
- An area of 900 million hectares would be available on the globe for this purpose.
When trees grow, they absorb CO2 from the air and build the carbon of the greenhouse gas into their biomass. What is bound in the wood cannot harm the climate. Researchers from Switzerland, France and Italy have now surveyed the areas that could be used for afforestation projects worldwide.
900 million hectares are therefore available for this purpose throughout the globe, reports the group around the ecologist Thomas Crowther of ETH Zurich in the scientific journal Science. This would be almost equivalent to the area of the USA or 25 times the area of Germany. The total area of Brazil is 852 million hectares. The earth’s forestation could therefore increase by about a third without affecting cities or agriculture, the researchers write.
Trees planted there could absorb 205 gigatonnes of carbon from the atmosphere in the 30 to 60 years they need to grow. An estimated 300 gigatonnes have risen into the atmosphere through human activity since the Industrial Revolution.
However, hurry is required, the researchers write. As global warming progresses, the regions suitable for afforestation are becoming smaller. In addition, it takes decades for the planted trees to extract noticeable amounts of CO2 from the atmosphere. However, rapid reforemeanwhile even achieves the goal set by the Intergovernmental Panel on Climate Change (IPCC) to limit global warming to 1.5 degrees Celsius, the study states. The researchers deliberately sierly sierly sier-noted cities and existing agricultural land when searching for plantable land. First and foremost, devastated ecosystems should be repaired through afforestation.
Influence of consumers
The countries with the most potential have the most potential, says Felix Creutzig of the Mercator Research Institute on Global Commons and Climate Change (MCC) in Berlin. “At the same time, however, it is even more important that deforestation should be stopped first, especially in Brazil and Indonesia.” European consumers would also have an influence on this. “In the mass animal husbandry, poultry and pigs, but also cattle, are fed mainly Brazilian soya – which in turn is strongly associated with tropical deforestation and catastrophic loss of biodiversity.”
Have a particularly large area for afforestation: Russia: 151 million hectares
USA: 103 million hectares
Canada: just over 78 million hectares
Australia: 58 million hectares
Brazil: nearly 50 million hectares
China: 40 million hectares
“In my opinion, reforestation is an important option in our toolbox of natural climate protection efforts,” says Marcus Lindner of the European Forest Institute (EFI) in Bonn. In principle, however, it should be borne in mind that “forest climate protection measures alone are far too low to achieve ambitious climate protection targets.” However, in view of the afforestation potential in Russia, where huge forest fires have raged in the past, it seems questionable to him whether this potential can be used even in the first place: “The technical means, the workforce and also a reliable institutional support for such measures – unlike, for example, China.”
Julia Pongratz, Chair of Physical Geography and Land Use Systems at the University of Munich, points to other effects that trigger changes in forest areas. Forests, for example, can cool the air temperature in many regions, sometimes by several degrees. Temperature extremes would be mitigated as a result. “Such changes often have a much greater impact on local living conditions than the supra-regional effects of a afforestation measure,” Pongratz said. Ideally, forests should simultaneously serve to adapt on site and reduce global temperature rise.
Humanity has probably already halved the earth’s original tree population, the research by Thomas Crowther in Sciencesuggests. However, the damage done in centuries to repair it through afforestation in the Hauruck process seems unrealistic. “We cannot avoid reducing emissions from the burning of fossil fuels as quickly and comprehensively as possible. This should have happened decades ago and time is running out,” says atmospheric researcher Almut Arneth of the Karlsruhe Institute of Technology. “Despite all its potential, afforestation can only be one of many measures for climate protection,” says Felix Creutzig from Berlin. It would be best not to pump more CO2 into the atmosphere.