New research suggests that a realistic estimate of the additional global potential for forest carbon storage is around 226 gigatons of carbon, enough to contribute significantly to slowing climate change.
The study, published today in the journal Nature, highlights the critical importance of conservation, restoration and sustainable management of forests to progress towards international climate and biodiversity goals. It was attended by hundreds of scientists from around the world, who highlighted that this potential can be realized by encouraging community efforts to promote biodiversity.
The storage potential of forest carbon is a very controversial subject. Four years ago, a study published in the journal Science found that forest restoration could capture more than 200 gigatons of carbon, which could remove about 30 percent of excess anthropogenic carbon from the atmosphere. A gigaton is equal to 1 billion tonnes.
While this research has sparked debate about the role of nature in combating climate change, it has also raised concerns about the negative environmental impacts of mass tree plantings, carbon offset schemes and greenwashing . While some scientific studies have confirmed the magnitude of this discovery, others have argued that this estimate of forest carbon could be up to four or five times too high.
To tackle this controversial topic, an international team led by the Crowther Lab at ETH Zurich and including a forest ecologist from the University of Michigan Peter Reichconstructed an integrated assessment using a full range of approaches, including extensive terrestrial data and satellite datasets.
Due to ongoing deforestation and degradation, the total amount of carbon stored in forests is approximately 328 gigatons less than its natural state. Of course, much of this land is used for extensive human development, including urban and agricultural land.
However, outside of these areas, researchers found that forests could capture around 226 gigatons of carbon in regions with low human footprints if allowed to replenish.
About 61% of this potential can be realized by protecting existing forests, so that they can return to maturity. The remaining 39% can be achieved by reconnecting fragmented forest landscapes through sustainable ecosystem management and restoration.
“Most of the world’s forests are highly degraded. In fact, many people have never visited one of the few remaining old-growth forests on Earth,” said Lidong Mo, one of the lead authors of the study. “To restore global biodiversity, ending deforestation must be a top priority. »
The dataset revealed that biodiversity accounts for about half of global forest productivity. Thus, the researchers emphasized that, to achieve full carbon potential, restoration efforts should include a natural diversity of species. Additionally, sustainable agricultural, forestry, and restoration practices that promote biodiversity have the greatest carbon capture potential.
“Promoting diverse forests will help us maximize their potential to remove carbon dioxide from the air and store it in tree trunks and soils,” said UM’s Reich, director of the Institute. in Biology of Global Change at the School for Environment and Sustainability. Reich is a co-author of the new study and was part of its main organizing and writing group.
The study authors emphasize that responsible catering is a fundamentally social enterprise. This includes countless actions such as conservation, natural regeneration, rewilding, silviculture, agroforestry and all other community efforts aimed at promoting biodiversity. This requires equitable development, driven by policies that prioritize the rights of local communities and indigenous peoples.
“We need to redefine what restoration means to many people,” said Thomas Crowther, lead author of the paper and professor at ETH Zurich. “Restoration is not about massively planting trees to offset carbon emissions. Restoration means directing the flow of wealth to millions of local communities, indigenous people and farmers who promote biodiversity around the world. Only when healthy biodiversity is the preferred choice of local communities will we achieve long-term carbon capture as a by-product.
The researchers conclude that ecologically responsible forest restoration does not include the conversion of other ecosystems that would not naturally contain forests.
“Global restoration is not just about trees,” said Constantin Zohner, senior researcher at ETH Zurich. “We must protect natural biodiversity in all ecosystems, including grasslands, peatlands and wetlands, which are also essential for life on Earth. »
The new study highlights the critical importance of natural and diverse forests in contributing to 30% of carbon reduction potential. However, forests cannot replace reducing fossil fuel emissions. If emissions continue to rise, the study warns, ongoing droughts, fires and warming will threaten forests and limit their ability to absorb carbon.
“My biggest fear is that companies will misuse this information as an excuse to avoid reducing their fossil fuel emissions. The more we emit, the more we threaten nature and humans. There can be no choice between reducing emissions and protecting nature, because we urgently need both. We need nature for climate, and we need climate action for nature,” Crowther said.