A potential measure to combat climate change has always been the restoration of forests. A report by the Intergovernmental Panel on Climate Change suggests that to limit global warming to 1.5°C by 2050, an increase of as much as one billion hectares of forest will be necessary. This number was estimated by considering Google images from around the world.
However, how much of this tree cover might be possible in the planet’s existing conditions has so far remained unclear.
Researchers have also quantified how much land is available around the world for reforestation, and the extent of carbon emissions that can be prevented from being released into the atmosphere.
The study was conducted by researchers of the Crowther Lab of ETH Zurich university which was published in the journal Science. Based on nearly 80,000 images from around the world, it was calculated that for reforestation, about 0.9 billion hectares of land would be suitable.
If this area can be indeed reforested, two-thirds of human-made carbon emissions could be captured, researchers calculated.
“One aspect was of particular importance to us as we did the calculations: we excluded cities or agricultural areas from the total restoration potential as these areas are needed for human life,” The Indian Express quoted lead author Jean-François Bastin as saying in a statement.
Currently, Earth’s continuous tree cover is 2.8 billion hectares. Further, researchers calculated that the land available could support 4.4 billion hectares or an additional 1.6 billion hectares.
The paper suggests that out of this, 0.9 billion hectares fulfil the criterion of not being used by humans.
The calculation revealed that once mature, these new forests could store 205 billion tonnes of carbon, which is about two-thirds of the 300 billion tonnes of carbon that the atmosphere already contains, which was released due to human activity since the industrial age.
“But we must act quickly, as new forests will take decades to mature and achieve their full potential as a source of natural carbon storage,” Crowther said.
According to the Environment and Forest Ministry’s ‘State of Forest Report 2017’, India’s existing forest cover makes up 7,08,273 sq km (about 70.83 million hectares) and tree cover another 93,815 sq km (9.38 million hectares).
There is room for an estimated 9.93 million extra hectares of forest in the country.
Six countries with the greatest reforestation potential are Russia (151 million hectares); the US (103 million hectares); Canada (78.4 million hectares); Australia (58 million hectares); Brazil (49.7 million hectares); and China (40.2 million hectares).
The study, however, has drawn some criticism.
Among several arguments, Jesse Reynolds of University of California’s Berkeley and Los Angeles law faculties noted that the authors do not consider that the land proposed to be reforested is owned and managed by many private persons, companies, nongovernmental organisations, and governments. This suggests that such reforestation cannot come about.
Further, he found that the estimate of carbon removal per area according to the authors is “remarkably high”.
According to him, the research will likely be used to “argue that we can rely more on reforestation to reduce climate change, potentially displacing efforts toward other responses [including] emission cuts”.