House Republicans want to plant trees to combat climate change, but will it work?

As most of the United States is contending with extreme heat, wildfire smoke or flash flooding, and a growing number of Americans say climate change has “made things worse” in their lives, House Speaker Kevin McCarthy, R-Calif., has an answer to those who worry that his caucus’s promotion of expanded fossil fuel production might exacerbate climate change: Plant trees.

“We need to manage our forests better so our environment can be stronger,” McCarthy said last month at a natural gas drilling site in northeast Ohio, as wildfire smoke hung in the air.

Republicans have previously embraced tree planting as an environmental fix: Plant trees, which absorb carbon dioxide, and you can keep producing the planet-warming gas by burning fossil fuels.

In 2021, House Republicans proposed to incentivize growing forests, and the bill’s author, Rep. Bruce Westerman of Arkansas, recently told the Associated Press he expects a similar bill to pass the GOP-majority chamber this year.

To some voters worried about climate change, Republicans seeking climate solutions might seem like progress. But is it a valid solution to climate change?

The climate role of trees

Like all plants, trees absorb and store carbon dioxide as they grow. However, when trees die, are cut down or burn, carbon dioxide is released. According to the World Resources Institute, forests absorb 16 billion metric tons of CO2 every year, but they emit about half that much.

Deforestation, in which trees are chopped down or burned to clear areas for human uses such as housing and farming — or for their natural resources like lumber and palm oil — increases emissions. Stopping deforestation is an important part of combating climate change, according to the Intergovernmental Panel on Climate Change.

But proactive tree planting on a massive scale as a climate solution is more controversial. Some scientists argue that the "1 trillion trees" movement is largely a “greenwashing” effort by companies that pollute to convince the public to let them continue doing so.

The recent boom in tree-planting advocacy was kickstarted by a widely covered 2019 study in the journal Science that suggested there is enough space to plant a trillion trees — which would cover an area the size of the continental United States — and that it could suck up the last 25 years’ worth of carbon dioxide emissions.

The World Economic Forum subsequently launched the One Trillion Trees Initiative. In October 2020, President Donald Trump, a climate change denier and fossil fuel enthusiast, signed an executive order creating an interagency council on tree planting.

The pushback

Many other scientists found fault with the study, leading Science to publish some of their responses. They argued that the initial study made erroneous assumptions about the feasibility of planting trees in areas that are currently covered in other plants, such as grasslands. They also pointed out that planting trees in areas where they don’t grow naturally could destroy ecosystems, with negative consequences for biodiversity and freshwater supplies.

Then there is the difference between merely planting trees and actually raising them to maturity.

“National tree-planting schemes have, historically, come up short,” the New Yorker recently reported. “Studies across countries have found that as many as nine in ten saplings planted under these auspices die. They’re the wrong kind of tree. No one waters them. They’re planted at the wrong time of year. They have not improved forest cover.”

And, of course, even if the most optimistic scenarios were realistic, they wouldn’t solve the problem if we keep producing carbon emissions.

“Reforestation might buy us up to a decade of time,” Zeke Hausfather, a climate scientist at the Breakthrough Institute, a think tank in California, told the Guardian. “It doesn’t really fundamentally change the story: We still need some pretty massive reductions in our emissions. ... You’re going to max out pretty soon if you only try to use forests. Tree planting is not an alternative to mitigation.”

In May 2020, the study authors issued a correction, saying they were endorsing tree planting only in comparison with other ways of capturing and storing carbon, not reducing emissions.

“The authors stated in the abstract and in the main text that tree restoration is the most effective solution to climate change to date. This was incorrect,” they wrote. “They meant that they know of no other current carbon drawdown solution that is quantitatively as large in terms of carbon capture. They did not mean that tree restoration is more important than reducing greenhouse gas emissions or should replace it.”