Reducing the global carbon footprint is one of the most significant challenges scientists face in the ongoing effort to fight climate change.
According to a study published in Science, a research team from the Crowther Lab at ETH Zurich in Switzerland claims, “The restoration of trees remains among the most effective strategies for climate change mitigation.”
Specifically, the study finds that planting just under 1 billion hectares of new trees (which is an area about the size of the entire United States), could store up to 205 billion tons of carbon. Researchers noted this figure represents about two-thirds of human-induced carbon emissions since the Industrial Revolution.
However, some responses to the scientific paper express concerns about its conclusions.
A Natural Solution
Approximately 3 trillion trees cover the planet. Sadly, 15 billion trees are cut down every year, and the global number of existing trees has declined 46 percent since the start of civilization.
Stripping trees from the land negatively impacts the carbon footprint. As such, planting a massive number of new trees to help cut carbon dioxide emissions seems plausible. Trees organically remove CO2 from the atmosphere during photosynthesis. In the process, once they suck carbon from the air, they store it in their leaves or bark.
With the push toward ending global warming and conserving vital natural resources, many nations have set aggressive reforestation goals. One leading initiative is the Bonn Challenge. Via this global effort, participating countries aim to restore 350 million hectares of degraded and deforested lands by 2030.
Overall, most researchers would likely agree that trees offer a natural CO2 removal solution.
Global Mapping Methodology
The vast scale of reforestation that researchers recommend in the Science study is more extensive than any current global effort. Notably, the team excluded existing cities or agricultural land when considering potential planting sites.
Moreover, they used Google Earth mapping software and a forest database to produce a predictive model that shows the best places to plant new trees.
Overall, findings revealed the highest potential for tree planting exists across six countries. Russia leads the charge (at 151 million hectares), and the U.S. follows (103 million hectares). The others rank as follows: Canada (78.4 million hectares), Australia (58 million hectares), Brazil (49.7 million hectares), and China (40.2 million hectares).
Professor Thomas Crowther, a study co-author and founder of the Crowther Lab, addressed the study’s results in a press statement.
“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,” Crowther said. “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.”
Planting trees will undeniably help cut carbon emissions. However, the study has prompted several criticisms.
For example, Zeke Hausfather, a climate scientist at U.C. Berkeley and analyst at Carbon Brief, wrote on Twitter that the amount of human-induced carbon emissions to date is around 640 million. So, that would make the study’s carbon storage estimate only one-third of total emissions, instead of two-thirds.
Other considerations also impact the newly planted trees’ potential capacity for carbon removal—for instance, climate shifts in the tropics could decrease canopy coverage. As Crowther noted, new trees won’t be mature enough to remove and store billions of tons of carbon for decades.
Furthermore, Jesse Reynolds, an environmental law and policy fellow at UCLA, called the study “misleading” and “potentially dangerous” in a Legal Planet post.
Reynolds raised several objections. Namely, he notes the study authors don’t consider the high cost of the mass planting endeavor. Moreover, he points out that the study doesn’t address how to manage such a big project. It also doesn’t account for some of the new trees getting cut down.
Notably, Reynolds fears a massive reforestation effort would cause lawmakers and researchers to steer away from fossil fuel reduction plans and other methods of carbon sequestration.
Overall, planting trees has many environmental benefits. However, it will take multiple kinds of efforts to combat climate change in the months and years ahead.