Forest and the carbon cycle

Forests can absorb our CO2 emissions and thus be used as compensation. Tree planting projects are also based on this principle: a tree absorbs CO2 and binds it. Many trees, therefore, absorb a lot of CO2 and bind it. The CO2 content in the atmosphere is reduced and global warming is slowed down. Trees thus compensate for the damage we have caused. That sounds too simple to be true, doesn’t it?

If we make forests our partners in climate protection, this is known as the “Natural Climate Solution”. Research has shown that (re)afforestation is the greatest natural climate protection option available to us. In order to find out how much unused forest potential (such as degraded land, wasteland, fallow land) is available to us, ETH Zurich researchers evaluated almost 80,000 satellite images in their much-acclaimed study before they found: quite a lot! In total, they said, it is an area of 900 million hectares which, excitingly enough, is not primarily in the tropics, where most reforestation programmes are currently concentrated. The countries with the largest unused areas include Russia, the USA, Canada, Australia and China. Man-made CO2 emissions in the atmosphere account for around 300 billion tonnes. According to the study, if trees were planted on the entire available area, more CO2 than previously assumed could be stored in reforested forests. In total, this would save about 200 billion tons (which would relieve our atmosphere by about 100 billion tons).

Trees could absorb 205 gigatons of carbon

Nevertheless, in the project catalogue of the largest German compensation agency “atmosfair”, for example, tree-planting projects are missing. Why is that? In fact, the idea of reforestation is associated with some difficulties:

First, a tree does not live forever. Forest fire, pest infestation, storm, deforestation or the natural life cycle result in the stored CO2 of a tree being released one to one. The climate protection effect fizzles out.

In addition, it takes decades for a tree to have a significant climate protection effect – the longer a tree stands, the older it gets, the more CO2 it stores. Now storms, fires or pest infestation are not something that can be foreseen or even planned for. Nobody knows for sure how long a forest that has been created by a tree planting project will survive. For this reason, more and more trees are being planted in most tree-planting projects. A tree buffer, so to speak.

It also becomes problematic when more and more parties compete for the use of an area. In view of the increasing competition for land and the loss of land due to climate change, land use pressure is increasing, which could lead to more, not less, clearing (of unprotected forests).

Tree planting projects

What should you look for when choosing an organization? Standards such as the Gold Standard (includes guaranteed CO2 compensation as well as the contribution to a sustainable development on site) or the Verified Carbon Standard (calculation method of CO2 compensation, does not consider social and ecological issues) serve as a first orientation. If social and ecological aspects are not reflected in a seal, you should look for additional seals that guarantee this. Another keyword is transparency: Can you reliably understand what is happening with your money? If you are unsure, you should look for another organisation.




ETH paper ( in German)