Reality check: Will planting 1 billion hectares of trees slow down climate change?

The solution to the accelerating climate change crisis could be as simple as planting more trees, one group of researchers claims in a recent study.

Published in the academic journal Science last Thursday, the study claims that by covering an additional one billion hectares of the planet with trees, the process of global warming could be greatly slowed down.

“We all knew that restoring forests could play a part in tackling climate change but we didn’t really know how big the impact would be,” said Thomas Crowther, the study’s senior author and an assistant professor of ecology at the Swiss Federal Institute of Technology, Zurich, in a statement.

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“We found that there is room for an extra 0.9 billion hectares of canopy cover, which could store 205 gigatonnes of carbon in areas that would naturally support woodlands and forests,” the report reads.

The research team analyzed almost 80,000 satellite photos of tree coverage worldwide, along with data on soil and climate conditions. Trees already take up approximately 3.4 billion hectares of land on the planet and help to mitigate the impact of greenhouse gasses by taking carbon dioxide out of the atmosphere through the process of photosynthesis.

The global potential tree cover, representing an area of 4.4 billion hectares of canopy cover distributed across the world.

The global potential tree cover, representing an area of 4.4 billion hectares of canopy cover distributed across the world.

Science Journal
The global potential tree cover available for restoration.

The global potential tree cover available for restoration.

Science Journal

According to the report, the planet can support a total of 4.4 billion hectares of tree coverage, meaning there is room for an extra 0.9 billion hectares of coverage. The latest special report by the Intergovernmental Panel on Climate Change (IPCC) suggests that an increase of one billion hectares of forest will be necessary to limit global warming to 1.5 C by 2050.

The study found that over the decades, those new trees could suck up nearly 830 billion tons (750 billion metric tons) of heat-trapping carbon dioxide from the atmosphere. That’s about as much carbon pollution as humans have spewed in the past 25 years.

While the strategy proposed in the study is technically possible, University of Alberta Prof. Scott Chang, whose expertise is in forest soils and nutrient dynamics, points out that there are a number of potential obstacles to achieving this goal, starting with whether the land is available to be reforested.

“The strategy proposed is possible, but there are a number of caveats to go with it. It is possible if there is land available for reforestation. If there is no land available then, obviously, that strategy won’t work,” he said.

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He points out that much of the one billion hectares that need to be reforested are probably owned by individuals and businesses, who would require some form of incentive to plant additional trees on their land.

“A lot of them will view having too many trees on their property as a nuisance,” he explained, having attempted a similar strategy in Canada in his own research.

The study outlines specific regions where forest coverage can be increased, over half of which are concentrated in six countries: 151 million hectares in Russia, 103 million hectares in the United States, 78.8 million hectares in Canada, 58 million hectares in Australia, 49.7 million hectares in Brazil and 40.2 million hectares in China.

Then there’s the matter of cost.

In an interview with The Guardian, Crowther said the “most effective projects are doing restoration for US$0.30 a tree,” providing him with an estimate of $300 billion for 1 trillion trees.

However, the price to plant a tree isn’t the same around the world.


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In British Columbia alone, it can cost about C$1 to plant a lodgepole pine seedling in the province’s Interior region, UBC forestry Prof. Sally Aitken told Global News.

Along B.C.’s coast, it can cost anywhere from $3 to $5 to plant and protect a western red cedar. Those trees require the protection of plastic tubes to keep deer from touching them.

“If you are planting trees in areas that will be grazed by animals, you’ll have to protect those trees from grazing and you’ll probably have to start out with a larger tree to begin with,” Aitken said.

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Chang also noted that some of the regions where reforestation is suggested are prone to forest fires and other natural phenomena.

On densely forested land, forest fires and other natural disasters will likely be exaggerated and could even be more frequent.

Chang also noted that some of the regions where reforestation is suggested are prone to forest fires and other natural phenomena. On densely forested land, forest fires and other natural disasters will likely be exaggerated and could even be more frequent.

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Overplanting trees can alter the environment itself and have potentially harmful effects, he added.

“You also have to consider some of the drawbacks with the trees as well because once you have the trees planted, trees can alter the environment themselves,” Chang explained. “If there’s not enough precipitation for the trees to grow, they’ll be taking water from the groundwater.”

This could potentially lead to droughts, killing the trees in the long run.

Perhaps the most significant drawback to the plan, Chang explains, is that it’s only a temporary fix unless society changes its energy usage as well.

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“It’s not a permanent solution,” he explained. “Once you use that up, there’s not much land left available.

“If we don’t curtail the usage of fossil fuels, if we don’t find alternate energy sources and if we continue to burn fossil fuel, we’re still going to be having the same problem so it’s still a temporary solution.

It’s also important to note that it will take decades for the forests to grow and achieve this potential.

Crowther, the study’s author, said in a statement that in order for reforestation to be successful, world governments must act now.

“Our study shows clearly that forest restoration is the best climate change solution available today. 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,” he said.

The study did not estimate the time and costs associated with physically planting the trees necessary for the project to be successful.

© 2019 Global News, a division of Corus Entertainment Inc.

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