The risks of overstating the climate benefits of ecosystem restoration

mangrove shoots in shallow water
The feasibility of the restoration options and estimate accuracy of converted land carbon stocks are highlighted by Doelman & Stehfest.

Doelman, J.C. & Stehfest, E. 2022

A recently published Matters Arising response to the 2020 Nature paper, Global priority areas for ecosystem restoration (Strassburg et al., 2020), asserts that overstating the role of restoration in preventing climate change may undermine mitigation efforts and distract from the core task of reducing carbon emissions.

Strassburg et al. presented a high-resolution method to identify optimal locations for ecosystem restoration globally for conserving biodiversity and increasing carbon sequestration, and present as one conclusion that 30% of total CO2 increase in the atmosphere since the Industrial Revolution can be sequestered by restoring 15% of converted lands. Doelman & Stehfest argue that this is an overly optimistic message that is partly based on inaccurate assumptions, and that this creates unrealistic expectations for the contribution of restoration to the mitigation of climate change.

For converted lands, Strassburg et al. assume that current aboveground carbon stocks are 6 tonnes of carbon per ha (tC ha−1). However, especially in locations identified as priority areas, such as southeast Asia, the western African coastal area and the Caribbean, carbon stocks in converted lands are in fact much higher because they mostly consist of mosaic and agroforestry-type landscapes. Such areas make up a large share of the highlighted 15% priority areas by Strassberg et al., and therefore, the higher reference carbon stocks result in substantially reduced carbon-sequestration potential.

The response also highlights the feasibility issue of unconstrained restoration with large-scale abandonment of agriculture in high priority locations that are mostly located in tropical regions. About 50% of all agricultural land in southeast Asia, Central Africa, the Caribbean and Mesoamerica would need to be restored in the case proposed by Strassberg et al., which would have enormous impacts on the agricultural system and beyond. Doelman & Stehfest suggest that the case with national targets (a maximum of 15% agricultural abandonment) represents a more realistic approach to restoration and mitigation potential.

Read more in the full Nature Matters Arising article, The risks of overstating the climate benefits of ecosystem restoration. A response to this from Strassberg et al. can be found at Reply to: The risks of overstating the climate benefits of ecosystem restoration. In the response Strassberg et al. counters the analysis from Doelman & Stehfest regarding estimates of land-use and carbon stocks, and summarises that: ‘Achieving ecosystem restoration at planetary scales targeted by multiple international agreements and processes will be very complex, involving multiple practical, ecological, social and ethical considerations that need to be dealt with appropriately. However, the resulting contributions to some of our greatest global challenges, as shown in our Article and reaffirmed in the analyses summarized here, are vast and can hopefully motivate all relevant stakeholders to take appropriate actions towards realizing this potential.’

A previous response to Strassburg et al., 2020 was also published in July: Fleischman, F., et al. Restoration prioritization must be informed by marginalized people. Nature 607, E5–E6 (2022). Fleischman et al. warn that the large-scale, broad characterization of areas as ready for restoration, such as by Strassburg et al. 2020, risks displacing marginalized people, compromising food security and undermining democratic processes.

The concerns raised by Fleischman et al. and Doelman & Stehfest highlight the importance of including local and Indigenous communities in nature-based solutions such as ecosystem restoration. IPLCs depend highly on nature-based resources for their livelihood and have extensive, traditional knowledge about nature conservation. Therefore, the collaboration of scientists and policy-makers with organizations representing people who live on and manage lands is likely to provide the best identification of land-use priorities in the face of ongoing climate change.