To stop/stabilize climate change, we need to cut emissions and capture extra amount of carbon from the atmosphere. Restoring trees appears here as a potential natural solution to help capturing an extra amount of atmospheric carbon. Indeed, when growing, trees transform a share of the atmospheric carbon they absorb from the air into wood tissues. But how much can be absorbed with this strategy exactly? And how many trees could the planet actually support respecting the natural balance of each ecosystem?

Trees are capturing atmospheric carbon when growing through a chemical reaction called photosynthesis. With water and energy from light, they are able to convert a significant share of the atmospheric carbon they absorb into wood tissues while releasing oxygen. These principles are known for long.

Trees are present around the world in many different systems, in cities, in agriculture, in savannas and of course, in forests. Trees are therefore not the exclusivity of forest systems and restoring them might participate in the restoration and conservation of all ecosystems.

In each ecosystem though, since the history of time, trees are harvested by humans. First, they were harvest to get space for agriculture and as source of energy for livelihood. This led Europe to be entirely deforested by the mid 19th century.

Source to read: A History of World Agriculture: From the Neolithic Age to the Current Crisis. Marcel Mazoyer, Laurence Roudart

Today, we continue to deforest, but, in other regions and for other purposes. Today’s deforestation hotspots are found in the tropics. The main regions of deforestation are Amazonia, South East Asia and tropical Africa. In Amazonia, deforestation is driven by soy plantation and need of space for pasture, in South Asia it is driven by the conversion of forest into palm plantations and in Central Africa it is mainly driven by small scale shifting cultivation and illegal logging activities.

Despite the important deforestation in the tropics, the total cover of forest has recently increased. Indeed, according to the last FAO Forest Assessment Report we slightly gained, in the last 5 years, some forest cover at a global scale. This confirms scientific reports on the topics. However, the deforestation in the tropics is still happening at an alarming rate.

To protect biodiversity and stop emissions associated with deforestation and forest degradation, we need to protect existing ecosystems and restore depleted ecosystems. To guide actions in that sense, we tried to estimate how many more trees the planet could carry, respecting the natural state of each ecosystem on Earth, and where they could be restored. Assessing the potential tree carrying capacity of the planet might play a key role in the development of key environmental strategies.

Finally, restoring ecosystems is not a simple solution or a silver bullet vs. climate change. We need to cut emissions and to capture atmospheric carbon to stabilize our climate. Restoring ecosystems can help a lot in the capture of atmospheric carbon, but it should be done through a holistic approach.

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