A new study published in Science claims that planting trees en masse in an area similar to the size of the United States would reduce the globe’s carbon dioxide levels by two-thirds.
According to the study, the area needed is much larger than first estimated, but would reduce the level of CO2 in the atmosphere by 25%.
The Intergovernmental Panel on Climate Change (IPCC) has previously said that an area of 1-billion hectares - or 2.4-billion acres) of reforestation would be needed to have an impact. Using a combination of photo interpretation and Google Earth’s software engine, researchers at UTH-Zurich were able to analyse 78,000 forests, and have claimed the world can currently accommodate an extra 0.9-billion hectares - or 2.22-billion acres - of tree cover.
When these trees reach maturity, they will photosynthesise 200-gigatonnes of carbon dioxide, according to researchers, two-thirds of extra carbon from human activities since the industrial revolution.
“Our study shows clearly that forest reforestation is the best climate change solution available today and it provides hard evidence to justify investment,” Professor Tom Crowther, senior author of the study said.
“If we act now, this could cut carbon dioxide in the atmosphere by up to 25%, to levels last seen almost a century ago.”
The Zurich-based researchers have also identified prime candidates country-by-country, with Russia leading the way with 151-million hectares. The top-five was rounded out by the US with 103-million, Canada with 78-million, Australia with 58-million, Brazil with 50-million and finally China with 40-million.
Some critics question the efficacy of reforestation as a means of tackling climate change, however. Professor Myles Allen from the University of Oxford says that while ‘reforestation of trees may be ‘among the most effective strategies,’ it is very far indeed from ‘the best climate change solution available,’ and a long way behind reducing fossil fuel emissions to net zero.”
Similarly, Professor Martin Lukac from the University of Reading says that “planting trees to soak up two-thirds of the entire anthropogenic carbon burden to date sounds too good to be true… Probably because it is.”
“This far, humans have enhanced forest cover on a large scale only by shrinking their population size (Russia), increasing productivity of industrial agriculture (the West) or by direct order of an autocratic government (China). None of these activities look remotely feasible or sustainable at a global scale.
In response to the criticism, Professor Crowther says that while “it will take decades for new forests to mature and achieve this potential… it is vitally important that we protect the forests that exist today, pursue other climate solutions, and continue to phase out fossil fuels from our economies.”
The United Nations former climate chief, Christiana Figueres is in full support of the plan. She has said publicly “finally an authoritative assessment of how much land we can and should cover with trees without impinging on food production or living areas.”
“A hugely important blueprint for governments and private sector,” she said.