Why planting new forests could do more harm than good

Why planting new forests could do more harm than good

This article was originally featured on OpenMind.

In the middle of Uganda, there is a large, well-managed stand of pine trees. This forest is an excellent example of “afforestation”, the process of restoring an area that has been deforested by subsistence activities like farming. It is also part the carbon offset business. Green Resources, a Norwegian company that specializes in carbon offset and plantation forestry, can plant trees in Uganda to offset the carbon dioxide emitted elsewhere by planting trees. The Swedish Energy Agency (SEA), which has been planting trees in Uganda for years, paid Green Resources to offset some of its carbon dioxide emissions, a major cause behind climate change.

At first glance, the Green Resources Project sounds fantastic. According to the Oakland Institute, an organization dedicated to environmental and social activism, pine trees are not a common plant in Uganda. Plantation-style agriculture sequesters more carbon , than natural forests and grasslands. The pine trees aren’t actually being planted to address climate change, but rather to be cut into sawlogs or utility poles. And Green Resources, active in East Africa since 1995, evicted thousands of native Ugandans from the land so it could create the plantation in the first place, according to the Oakland Institute’s 2019 expose. Following the institute’s report, the SEA suspended and then ended its relationship with Green Resources in 2020, though Green Resources continues to grow trees and gain investors for its pine plantations in East Africa.

Tree-planting campaigns are a simple and popular way to reduce greenhouse gas emissions. Some tree planting efforts, such as the Green Resources project from Uganda, can be problematic. Many of these tree planting efforts were based on unreliable science, which has been promoted by the media. This may be nothing more than greenwashing, which gives companies cover to pollute while they continue to make money. Trees can absorb carbon dioxide. However, how, where and why trees are planted is a major factor in their climate-mitigating potential. It is not as easy as just planting trees and then walking away to combat climate change.

” “Who could be against tree-planting?” Jennifer Skene is the Natural Resources Defense Council’s policy manager for natural climate solutions. “It seems like such a quaint environmental activity.” Skene has written extensively about the perils of poorly planned reforestation efforts, which can wind up superseding the protection of existing forests. She also notes that many planting campaigns are used as a justification for clearing climate-critical forests elsewhere.

The idea that we could plant our way out of climate change goes back at least to 1976, when physicist Freeman Dyson suggested in a paper that in the face of planetary warming, we could “plant enough trees and other fast-growing plants to absorb the excess CO2 and bring the annual increase to a halt.” Even then, however, Dyson acknowledged that trees and plants alone likely wouldn’t be enough. He wrote that the only long-term solution to a climate catastrophe is to stop burning fossil fuels and to convert our civilization to solar-based or nuclear fuels.

But the idea of using trees as a magic CO2 sponge stuck. In 1989 climate scientist Gregg Marland and his Oak Ridge colleague Thomas Boden testified before the U.S. Senate Committee on Energy and Natural Resources that growing enough trees after cutting down others for fuel could potentially result in net-zero emissions. In 1992 Marland published a paper exploring the idea of sequestering carbon by protecting some forests and harvesting and replanting others.

Then, in November 2006, six months after the climate change documentary An Inconvenient Truth was released, the United Nations Environment Programme (UNEP) announced its “Plant for the Planet: Billion Tree Campaign,” created in partnership with Kenya’s World Agroforestry Centre. The plan, propelled by activist Wangari Maathai, called for at least one billion trees to be planted globally by 2007. In 2009 UNEP reported that more than three billion trees had been planted since the campaign’s launch, far surpassing its original goal.

In 2011, following Maathai’s death, UNEP found a new face for its cause: a charismatic 13-year-old Bavarian boy named Felix Finkbeiner, who had already adopted UNEP’s catchphrase “Plant-for-the-Planet” as the name of a tree-planting nonprofit he had founded at age nine.

Overstating the climate benefits of planting trees can hamper real solutions to climate change.

Despite the high-profile nature of these efforts, scientific justification for mass tree planting remained sparse until 2015, when more rigorous defense began appearing in the peer-reviewed literature. A paper published in Nature that year provided the most comprehensive model of global tree density using satellite imagery and data gathered from a network of on-the ground forest surveys. The first step in determining the current number of trees on the planet was to determine how many more trees could possibly be planted and to what purpose. Researchers estimated that Earth’s surface was covered by approximately three trillion trees.

The big three-trillion figure headlined the paper, press release and interviews with Thomas Crowther (now an ecologist at ETH Zurich). The paper was discussed across social media and, to date, in more than 300 news stories. Many of those stories highlighted another finding from the paper–that there would be nearly twice as many trees around the world without humans. In response, Finkbeiner and the UNEP increased its initial 2007 goal of planting a billion trees to planting a trillion of them.

In 2019 Crowther and a team of researchers at ETH Zurich published a follow-up study in Science stating that restoring Earth’s tree cover was the most effective tool we had to counter the climate crisis. The researchers mapped where trees can grow and in what densities–subtracting known areas of existing forest, cities, and agricultural land–and then calculated the potential carbon storage of planting additional trees using estimates from existing forests.

They concluded that planting more than a half trillion trees could sequester “a considerable proportion of the global anthropogenic carbon burden,” some 205 gigatonnes, over several decades. According to NASA, that would be a reduction of approximately 25 percent of current atmospheric carbon levels, “enough to negate about 20 years of human-produced carbon emissions at the current rate, or about half of all carbon emitted by humans since 1960.” The story was picked up by more than 400 news outlets worldwide.

However, many scientists raised concerns about the analysis. Gregg Marland was one of the many experts who published comments in Science claiming that the paper underestimated trees’ carbon storage capacity and failed to account for nuanced effects such as the impact on grasslands or wetlands, and whether trees would be protected after they were planted. One group of scientists claims that the new study underestimated trees’ ability to capture carbon by five factors.

Crowther, his team eventually admitted a “considerable” margin of error and retracted from the claim in their original paper that tree-restoration was “the most effective way” to combat climate change. “That was incorrect,” see the correction in Science .

Despite the backpedaling, Crowther is listed on Plant-for-the-Planet’s website as its chief scientific adviser. Finkbeiner, a Crowther Lab PhD student, is currently working on an experiment to determine how soil restoration affects tree planting on a privately owned plot on Mexico’s Yucatan Peninsula.

Overstating the climate benefits associated with planting trees can hinder real solutions to climate change. While trees alone won’t reverse the climate effects of burning fossil fuels directly, corporations can claim that they can help. However, this can be misleading as corporations are able to ignore actual climate action and continue to invest in tree-planting projects that could cause more harm than good.

” Offsets are often interpreted as a solution to climate change. However, they are a way for the fossil fuel sector to be able to continue to thrive,” Skene of the NRDC says. Skene says that offsets are not a substitute for cutting greenhouse gas emissions or drastically reducing our dependence on fossil fuels. Furthermore, monitoring and maintenance are virtually non-existent for many tree planting projects. Trees that aren’t planted at the right time or cared for properly after planting can die and sequester very little carbon.

” You can’t plant away the climate change,” says Karen Holl who manages a restoration ecology laboratory at the University of California, Santa Cruz.

“Campaigns would do better if they planned for trees’ permanence and scaled up their quality rather than focus on the quantity of trees put in the ground,” says Karen Holl.

Finkbeiner on the other side, believes in the importance of trees. He says that he doesn’t expect tree planting or forest restoration to solve climate crisis but he believes it is too late for us to rely on reduced emissions. He says, “We are at an all-of the-above point of climate crisis.”

Today Plant-for-the-Planet operates an online platform for tree-planting and forest-restoration. Individuals and groups can post planting projects and solicit donations. According to the organization, all projects posted on its website must meet strict standards set forth by the International Union for Conservation of Nature. It is not clear whether these projects actually sequester carbon, despite all the money being invested in them. An investigation by German news source Die Zeit found that Plant-for-the-Planet’s primary replanting project in Mexico had little to show for all its effort and that the fates of the planted trees was unclear.

Yet, equating trees to carbon sequestered has become an integral part of many tree-planting campaigns. It seems to be a huge business. The world’s top tree buyers today include the cloud-computing company Salesforce, which has bankrolled the planting of nearly 44 million trees, as well as German retail chains REWE and dm-drogerie markt and Staples Europe, each with over one million trees purchased as part of the Plant-for-the-Planet campaign.

Scientists like Holl are focusing on reforestation policies that meet people’s needs and preserve Earth’s diverse ecosystems. These practices are not the only solution to climate change, but they can help in sequestering carbon and bolstering ecosystems. They also support local people.

Holl, a frequently consulted expert in reforestation, collaborated with Pedro Brancalion (Coordinator of the Laboratory of Tropical Forestry, University of Sao Paulo, Brazil) to identify the best practices and weak spots in campaigns that involve protecting and growing trees. They found that a lack of planning often leads to problems like reduced water yield in arid areas, destruction of grasslands and the spread of invasive species. This also causes social conflicts, more forest clearing (ironically), displaced farmers, and loss of livelihoods.

While good planning can help to avoid these problems, the best way for an ecosystem to grow trees is not to plant them. Protecting existing forests and allowing forest ecosystems recover on their own might be the best option. Holl says that allowing trees to grow naturally, without any intervention, is a better option than planting if the main goal of the project is to restore forest areas. Natural regeneration can often be much cheaper than planting. There are other benefits to allowing trees to grow naturally, such as improved biodiversity. Companies like Green Resources do not guarantee biodiversity.

“Campaigns could do better if they planned to preserve trees’ permanence and emphasized their quality over quantity,” Holl says. “We must focus on growing trees, and not planting them.

This story originally appeared on OpenMind, a digital magazine tackling science controversies and deceptions.

Why planting new forests could do more harm than good

Read More