Trees can save our climate

About 0.9 billion hectares of land around the world would be suitable for reforestation, which could eventually capture two-thirds of carbon emissions. A study by Swiss scientists shows that planting trees may be the most effective way to combat global warming.

In their study, Zurich scientists have identified for the first time where in the world new trees can be planted and how much carbon dioxide they can absorb from the atmosphere.

Lead study author Jean-François Bastin said: “From our calculations, we excluded cities or agricultural areas from the total restoration potential because these areas are needed for people to live.”

The researchers calculated that about 4.4 billion hectares of forest cover could grow on Earth under current climate conditions. That’s 1.6 billion hectares more than the current 2.8 billion hectares. Of those 1.6 billion hectares, 0.9 billion hectares is land not used by humans that could become potential regions for forest planting. Thus, there is enough space on Earth to plant new trees. This would contribute to an increase in forested area of more than 25%. Such a change could potentially consume the equivalent of 25% of current atmospheric carbon stocks.

Currently, land comparable in size to roughly the area of the United States is available on which trees could grow. These forests could absorb about 205 billion tons of carbon, or about two-thirds of the 300 billion tons of carbon released into the atmosphere by human activities since the Industrial Revolution.

According to Professor Thomas Crowther, a co-author of the study, “restoring forests can play an important role in combating climate change. Planting trees can be a powerful tool to absorb carbon dioxide from the atmosphere. But we need to act fast, because new forests take a long time to mature and decades to reach their full potential as a source of natural carbon storage.

The study shows which parts of the world are best suited for reforestation. The greatest potential can be found in six countries: Russia (151 million hectares) USA (103 million hectares) Canada (78.4 million hectares) Australia (58 million hectares) Brazil (49.7 million hectares) China (40.2 million hectares).

The Swiss analyzed 78,774 direct photo-interpretive measurements (i.e., satellite images with their description), from which they determined what type of soil or climate is found in each area around the world. This helped identify areas that could be reforested.

The researchers also warn against the misconception that climate change will increase global forest cover. According to the researchers, there is a high likelihood of reforestation in areas such as Siberia, where reforestation currently averages only 30 to 40 percent. These gains would offset the loss of dense tropical forests, which typically have 90 to 100 percent tree cover.

These findings are described in the article entitled “The global tree restoration potential” published in the journal Science, 05.07.2019 (Authors: Bastin JF, Finegold Y, Garcia C, Mollicone D, Rezende M, Routh D, Zohner CM, Crowther TW)
DOI: 10.1126/science.aax0848
Translation was done with the assistance of DeepL translator.