Diverse forests hold very large carbon potential

Research results published in the journal Nature show that realistic global forest carbon potential is approximately 226 Gigatonnes (Gt) of carbon. Current global emissions are in order of 16 Gigatonne carbon eq/year. The study, which involved hundreds of scientists around the world, highlights the critical importance of forest conservation, restoration, and sustainable management in moving towards international climate and biodiversity targets. The researchers stress that this potential can be achieved by incentivizing community-driven efforts to promote biodiversity.

The forest carbon potential has been a highly controversial topic. Four years ago, a study published in the journal Science found that the restoration of forests could capture over 200 Gt of carbon, which could draw down approximately 30 percent of excess anthropogenic carbon. That study raised concerns around the adverse environmental impacts of mass tree plantations, carbon offsetting schemes, and greenwashing. To address this controversial topic an international team of hundreds of researchers led by the Crowther Lab at ETH Zurich joined forces to build an integrated assessment using a comprehensive range of approaches, including vast ground-sourced data and satellite datasets.

Redefining restoration

The authors stress that responsible restoration is a fundamentally an endeavour that needs to benefit local communities. It includes countless actions such as conservation, natural regeneration, rewilding, silviculture, agroforestry, and all other community-driven efforts. “We are aware that greenwashing can take place”, says Professor Gert-Jan Nabuurs, from Wageningen University & Research and 6 times IPCC coordinating Lead Author, one of the main co-authors of the study. He states: “Restoration is not about mass tree plantations to offset carbon emissions. At some locations though it can, but it is about finding the right measures at the right locations without hampering food production. This study brings to light the critical importance of natural, diverse forests in contributing to 30 percent of carbon drawdown potential. However, forests cannot be a substitute for cutting fossil fuel emissions. If emissions continue to rise, the study warns, then on-going droughts, fires, and warming will threaten forests and limit their ability to absorb carbon.“

Stringent rules and good monitoring needs to be in place to avoid greenwashing and land grabbing, Nabuurs emphasises. “My biggest fear is that corporations misuse this information as an excuse to avoid cutting fossil fuel emissions. The more we emit, the more we threaten nature and people. Under the EU Green Deal we in Wageningen together with European Forest Institute and many partners in Europe, are already testing and executing forest restoration measures across Europe.”

Achieving forest carbon potential

Due to ongoing deforestation, the total amount of carbon stored in forests is ~328 Gt below its natural state. Of course, much of this land is used for extensive human development including urban and agricultural land. However, outside of those areas, this study found that forests could capture approximately 226 Gt C in regions with a low human footprint if they were allowed to recover, reforest them and better manage them. Approximately 61 percent of this potential can be achieved by protecting existing forests, so that they can recover to maturity. The remaining 39 percent can be achieved by reconnecting fragmented forest landscapes through sustainable ecosystem management and restoration. Thus the results actually confirm the previous study in Science, highlighting the important role of forests, but emphasising a much larger variety of measures.

“Most of the world’s forests are highly degraded” says Lidong Mo, the lead author of the study. “To restore global biodiversity, ending deforestation must be a top priority.” As such, the researchers highlighted that, to achieve the full carbon potential, restoration efforts should include a natural diversity of species. In addition, sustainable agricultural, forestry, and restoration practices that promote biodiversity have the greatest potential for carbon capture.