A new study published in the journal Science has found that the potential of tree planting to combat climate change has been drastically overstated. The research warns that relying on forests to offset carbon emissions could distract from the urgent need to cut fossil fuel use, as nature-based solutions alone are not enough to meet global climate goals.
Overestimated Land and Carbon Sequestration
The study, conducted by a team of scientists primarily based in China, found that the amount of land suitable for forestation is far less than previously thought. After carefully excluding unsuitable areas, such as snowy regions where planting trees can actually cause warming, the researchers calculated that only 389 million hectares worldwide are available for new forests.
Even if this entire area were planted, the amount of carbon absorbed by 2050 would be a mere 40 billion tonnes, significantly lower than prior estimates. The study notes that current forestation pledges only cover a fraction of this land, reducing the expected climate benefit to just 12.5 billion tonnes—a number that is only slightly more than a single year of global fossil fuel emissions.
Pledges Found to Be “Implausible”
One of the most striking findings is that many governments, particularly in Africa, have made “implausible” pledges for forestation. The study found that these pledges often include ecosystems like savannas and grasslands, which are naturally unsuited for forests due to low rainfall and frequent fires. For example, Ethiopia has pledged to reforest 10.2 million hectares, but the study finds only 0.5 million hectares are actually suitable. Attempting to plant forests in these areas is not only unlikely to succeed but also risks damaging unique local ecosystems and biodiversity.
The report concludes that planting trees should serve as a complement to, not a replacement for, rapid cuts in fossil fuel emissions. The authors argue that a more scientific approach is needed to identify where trees will thrive and to ensure that global climate action remains focused on the top priority: reducing carbon pollution at its source.