Scientists have conducted the first research to determine the number of trees the Earth can hold, the location, and the amount of carbon they could store. They reported that the Earth can hold enough additional trees to reduce the atmospheric carbon levels by almost 25%, which is lower than any levels observed for around a century.
We all knew restoring forests could play a part in tackling climate change, but we had no scientific understanding of what impact this could make. Our study shows clearly that forest restoration is the best climate change solution available today.
Thomas Crowther, Study Co-Author
As trees absorb and eliminate carbon dioxide (CO2) from the atmosphere, extensive reforestation is regarded as one of the most powerful weapons against climate change. The latest Intergovernmental Panel on Climate Change (IPCC) report states that an extra 1 billion hectares of forest will be needed to reduce global warming to 1.5 ○C by 2050.
Yet, it is still not clear whether these restoration objectives can be realized, as scientists are not aware of how much tree cover might be possible under existing or future climate conditions.
In order to study this, Jean-Francois Bastin, Thomas Crowther, and team exploited a unique global dataset of forest observations covering around 80,000 forests, integrated with the mapping software of Google Earth Engine. They used this to produce a predictive model to map prospective tree cover across the world under present conditions.
As well as the existing trees, urban and agricultural regions, the researchers propose that Earth’s ecosystems could hold an extra 0.9 billion hectares of tree cover that, upon maturing, could confiscate over 200 Gigatons of carbon, which equates to two thirds of manmade carbon emissions.
The authors state that the global map of reforestation offered by their work is important for creating more effective global-scale restoration targets, as well as for directing local-scale restoration projects.
In a related Perspective, Robin Chazdon and Pedro Bancalion emphasize the need to take swift measures within a narrowing window of time, since existing forested regions continue to reduce, and as reforestation efforts become more demanding in a warmer world.