A recent study published in Science has reassessed the viability of tree planting to meet climate targets. The study found that vast planted and restored forests, approximately the size of India, could store 40 gigatonnes of carbon by the middle of the century. However, this estimate is lower than previous predictions, as it takes into account the negative impacts of creating new forests on biodiversity, food security, water resources, and regional warming. The study also notes that 90% of the area promised for tree planting is in low- and middle-income countries, with Africa accounting for half of the committed area.
Despite its potential, the study highlights that tree planting can only offset a fraction of vast fossil fuel emissions. Moreover, many tree planting promises have been made without considering environmental and social constraints. When sustainability concerns are taken into account, the estimated land carbon storage from tree planting by 2050 reduces to 12.5 Gt C, which is about one-seventh to one-fifth of previous estimates. This would still cover an area of approximately 120 million hectares, roughly the size of South Africa.
The study emphasizes that the greatest potential for sustainable tree planting lies in South America, where previously cleared forests could be regrown, followed by Asia, particularly in China and India. Brazil alone represents one-fifth of the potentially suitable area. However, the paper also stresses that halting forest loss and protecting existing forests is just as crucial as creating new ones. In fact, stopping global forest loss entirely by 2030 could avoid emissions nearly three times as much as current tree planting commitments.
The study’s corresponding author, Zhanghai Qin, noted that the potential for tree planting to store carbon is enormous, but it must be done with care, taking into account sustainability constraints and environmental safeguards. The study calls for global cooperation, including financing, technology transfer, and carbon markets, to maximize effective climate mitigation. Wealthier economies are urged to increase their domestic policy commitments and provide stronger international support to low- and middle-income countries. Ultimately, the study highlights the importance of a balanced approach to tree planting, one that prioritizes sustainability and environmental protection while also addressing the urgent need to mitigate climate change.