How tree planting became a flashpoint in the climate debate

A young mangrove plant. Photo by: REUTERS / Edgar Su

WASHINGTON — The World Economic Forum’s annual meeting in Davos, Switzerland, capped the unlikely rise of a global megastar in the fight against climate change: trees.

“The actual potential to use forest restoration as a climate change mitigation strategy … has been greatly overblown.”

— Joe Veldman, assistant professor, Texas A&M University

Backed by high-profile champions such as Salesforce co-CEO Marc Benioff, big corporations including AstraZeneca and Nestle, and even U.S. President Donald Trump, tree planting, reforestation, and other “nature-based solutions” have managed to capture global attention and donor checkbooks at a time when other pieces of the climate change puzzle are not falling into place.

The argument for making forests a key piece of global climate action is that trees store large amounts of carbon, so increasing the number of trees on the planet can remove significant amounts of greenhouse gas from the atmosphere.

While international climate change negotiations have struggled to keep pace with public demands for faster action, and with the scientific reality of what is required to prevent global warming from exceeding 1.5 degrees Celsius, reforestation and tree planting offer a rare bright spot in an otherwise bleak landscape of international cooperation. Governments and corporations see an opportunity to align with conservation organizations around something positive, instead of warding off accusations about the harm they are inflicting on the planet.

“There is, without question, more consensus on this issue now than ever before,” said Nigel Purvis, president and CEO of Climate Advisers, a Washington-based climate change consultancy.

In Davos, headlines around tree planting and reforestation focused on big numbers. WEF has served as a coordinating hub for a number of large-scale initiatives that share a common goal of increasing the number of trees on Earth under the banner of an initiative for growing, restoring, and conserving 1 trillion trees. That initiative earned its most controversial endorsement to date in Trump’s plenary speech last week.

Amid this groundswell of support for forests, however, a behind-the-scenes battle has been quietly playing out between scientists, policy analysts, advocates, and funders over the potential for reforestation to curb climate change — and how to go about doing it.

The fractures beneath the surface of this seemingly benign conservation agenda point to deeper disagreements about how conservation and development projects should respond to an era of global climate change.

While supporters of large-scale forest restoration and tree planting argue that these are critical to meeting the goals of the Paris Agreement, skeptics charge that these plans overestimate their potential impact while underestimating potential risks. Advocates for the trillion trees initiative and similar campaigns say it is crucial to find visions that will resonate with political leaders and potential funders, while critics argue these messages risk distorting science and creating harmful incentives.

‘It’s all hard, and we’ve got to do it all’

Some climate advocates worry that raising the possibility of using trees to mitigate climate change risks distracting from the urgent need to cut fossil fuel emissions.

That concern was reinforced for many who watched Trump endorse the trillion trees initiative in Davos.

“I’m pleased to announce the United States will join 1 trillion trees initiative being launched here at the World Economic Forum. One trillion trees. And in doing so, we will continue to show strong leadership in restoring, growing, and better managing our trees and our forests,” Trump said.

Trump’s comments were widely seen as an attempt to take credit for environmentalism at the same time that his administration is actively undermining progress on global environmental issues, including climate change, by rolling back regulations and refusing to acknowledge any responsibility to reduce emissions.

“I think President Trump was rightly understood to have been suggesting that if we just focus on trees, we don’t really need to focus on fossil fuels. And of course, that’s totally wrong,” Purvis said.

“But on the other hand, people who say that any discussion of trees is going to somehow stop us from [cutting] fossil fuels are also wrong, because every single scientific analysis that has been done by the international community shows that there is no way to achieve the goals of the Paris Agreement or to protect the climate without stopping deforestation, without maximizing the contribution of reforestation. It is an essential part of any solution,” he said.

The increased attention on forests may not be very reassuring, considering that fossil fuel emissions have continued to increase since the Paris Agreement was forged in 2015, but that does not mean that forests shouldn’t be part of the solution, according to Purvis.

“It’s all hard, and we’ve got to do it all. Unfortunately, that’s what the science tells us,” he said.

Not everyone agrees on whether the science shows that, however.

As the potential for forest restoration and tree planting to slow climate change has gained prominence, some researchers have raised serious doubts about the assumptions and conclusions that support these initiatives.

In July 2019, scientists at the Crowther Lab in Zurich published a paper in the journal Science, reporting that the planet could sustain an additional 0.9 billion hectares of tree canopy cover, that tree restoration is “among the most effective strategies for climate change mitigation,” and that the 0.9 billion hectares has the potential to store 205 gigatonnes of carbon. That equates to roughly one-third of the total amount of emissions produced by humans so far and 20 times what is currently emitted every year.

The Crowther Lab’s findings helped galvanize political and financial support for tree planting and restoration efforts and serve as a scientific backbone for the trillion trees initiative and similar campaigns.

The paper produced a swift reaction, with critics questioning the lab’s methods and conclusions. Joe Veldman, assistant professor at Texas A&M University, was one scientist who submitted a critical response, pointing to what he and his colleagues saw as massive overestimates of land areas that would be suitable for tree planting and restoration.

“The actual potential to use forest restoration as a climate change mitigation strategy … has been greatly overblown,” Veldman said.

“If we’re going to invest in this, it needs to be done with eyes wide open to have a clear idea of what could truly be achieved, and that’s been exaggerated,” he said.

“The fact that smart people want to fund it is actually, to me, a reason to think that the idea may have some merit, rather than a reason to be cynical and suspicious about it.”

— Nigel Purvis, president and CEO, Climate Advisers

Veldman, who studies grasslands and savannas, is particularly worried that enthusiastic advocates of tree planting are laying the groundwork for poorly planned initiatives covering areas that have historically not been forested with trees, thereby destroying natural ecosystems. For people who depend on grasslands and savannas, turning those areas into forests — which some have deemed “arboreal imperialism” — could actually harm their ability to cope with climate change, Veldman said.

“The message that’s being promoted is that these actions or these interventions are only positive,” Veldman said.

“There are trade-offs, and it is actually possible in a lot of scenarios to implement these things that seem like they’re going to be good, and the outcomes are in fact almost completely negative. That’s not the kind of nuance that apparently moves politicians and makes headlines,” he added.

‘Simplicity in the message’

For supporters of big tree planting initiatives, it is partly a matter of faith. Large corporate donors and political leaders who sign on to these efforts may not need to understand the full, complex picture of what ecologically and socially-responsible projects actually require.

Slogans such as “trillion trees” are a useful shorthand for galvanizing political and financial commitments, while the true test of these campaigns will be whether they can help create effective, locally led forest and ecosystem restoration efforts on the ground, supporters argue.

“There’s a place for simplicity in the message,” said Sean DeWitt, director of the Global Restoration Initiative at World Resources Institute, adding that the audience members at Davos are probably not the same as those who will ultimately be planting the trees.

When it comes to implementing the projects, however, they cannot repeat the mistakes of past approaches that saw outsiders come in and try to plant poorly suited trees in places that do not want or need them.

“That’s not modern restoration,” DeWitt said. “It’s about people … and with that comes this kind of complexity.”

The question for the trillion trees initiative and similar movements is whether they can effectively layer the simple messaging and advocacy on top of a more complex and nuanced approach to implementation.

That requires equipping people working in communities where these projects will take place so that when opportunities do arise from multinational funders, for example, they are able to take advantage of them in an effective way, DeWitt said.

The debate over tree planting comes to resemble a litmus test, separating those with faith that simple messages and big numbers can trickle down to more nuanced implementation, and those who fear these are more likely to produce disappointing results, unintended consequences, or some combination of both.

Forrest Fleischman, an assistant professor at the University of Minnesota whose research focuses on India, has seen some ecologically and socially questionable programs implemented in the name of tree planting — and backed by financial incentives.

He described places in central India where regenerating forests were bulldozed in order to plant trees, because that’s what foresters in the area are funded to do. He reported hearing that trees were sometimes planted in places that disrupted local livelihoods and were then surreptitiously cut or burned down. Early findings from his current research include significant evidence of tree planting taking place above 4,000 meters, where trees cannot survive, as well as in dense forests, where there is no need to plant them.

“From my perspective, the big problem with these stories about ‘we need to plant a trillion trees’ is: Why?” he said.

Supporters argue that the scale of the climate emergency demands global action, and they point to some big initiatives that have produced positive results — including a Nobel Peace Prize.

In 2004, Wangari Maathai, founder of the Green Belt Movement, received that accolade for spearheading an effort that combined tree planting with women’s rights and democratic activism. Maathai’s work offers a proof of concept that restoration of degraded lands and tree planting initiatives can improve conditions for people, create employment, and lead to greater resilience to climate change, and nature-based solutions to climate change offer similar potential, Purvis said.

“The fact that smart people want to fund it is actually, to me, a reason to think that the idea may have some merit, rather than a reason to be cynical and suspicious about it,” Purvis said.

About the author

  • Michael Igoe

    Michael Igoe is a Senior Reporter with Devex, based in Washington, D.C. He covers U.S. foreign aid, global health, climate change, and development finance. Prior to joining Devex, Michael researched water management and climate change adaptation in post-Soviet Central Asia, where he also wrote for EurasiaNet. Michael earned his bachelor's degree from Bowdoin College, where he majored in Russian, and his master’s degree from the University of Montana, where he studied international conservation and development.