Tree planting is the most cost-effective plan to combat climate change, scientists have found in a new study.
We just need to plant 1.2 trillion of them on the 1.7 billion hectares of treeless land in the world, said the study out of Swiss university ETH Zurich.
The land area that could support the foliage is approximately 11% of the earth’s land - equivalent to the size of the US and China combined and would be a 50-100 year project.
It would result in removing about a quarter of the carbon in the atmosphere – about 200 billion tonnes.
“The most effective projects are doing restoration for US 30cents a tree,” Professor Tom Crowther, who led the study at the Swiss university ETH Zurich, said.
“That means we could restore the 1 trillion trees for $300 billion USD, though obviously that means immense efficiency and effectiveness,” he said.
“But it is by far the cheapest solution that has ever been proposed,” he said in the report published by Science Mag.
The planting would increase the world’s forested areas by 25% and cut atmospheric carbon by 25%.
“Excluding existing trees and agricultural and urban areas, we found that there is room for an extra 0.9 billion hectares of canopy cover, which could store 205 gigatons of carbon in areas that would naturally support woodlands and forests,” the report said.
The tropical areas of land, making up the rest of the 0.8 billion hectares could receive dense tree coverage.
“We estimate that if we cannot deviate from the current trajectory, the global potential canopy cover may shrink by 223 million hectares by 2050, with the vast majority of losses occurring in the tropics,” the report said.
Professor Crowther believes that the world’s tropical areas could be covered 100% in trees and the rest of the area less densely covered.
He also believes it is so affordable that individuals can make a difference by planting trees themselves, as well as governments creating national strategies on a larger scale.
Senior Research Fellow at the NZ Climate Change Research Institute at Victoria University Dr Judy Lawrence is sceptical that tree planting alone is enough of a solution.
“Yes, tree planting is part of the solution but at the rate we have deforested globally and continue to do so, what hope is there planting at the scale required will happen and that the vegetation stays there permanently.
“The politics just don’t stack up. We must reduce our carbon emissions as the priority to avert the crisis,” Lawrence said.
Satellite images and artificial intelligence technology supported the research to find key soil data to determine where the trees could grow across the earth.
Previous research led by Crowther in 2015 estimated that there were approximately 3 trillion trees worldwide at that time.