Limited carbon sequestration potential from global ecosystem restoration
Csaba Tölgyesi
University of Szeged
DOI: 10.25453/fpprize.32066187
Limited carbon sequestration potential from global ecosystem restoration (Nature Geoscience, 2025)
“Our findings challenge the narrow focus on tree planting and carbon capture for climate mitigation.”
The twin crises of climate change and biodiversity decline are threatening the well-being of all humanity. Droughts, flash floods and hurricanes, fuelled by an overheated atmosphere, are inflicting severe damage to crops, infrastructure and directly to our health. At the same time, we have destroyed or severely transformed roughly three-quarters of natural ecosystems, diminishing their capacity to provide essential ecosystem services. The decline of pest-controlling insects and pollinating bees, the loss of fish stocks and game species, pose tangible risks to economies at all scales, and hit marginalized people who are particularly reliant on nature. These issues are no longer gloomy forecasts but our reality we are living in today. As a result, there is a growing, albeit still not universal, consensus that we need to join forces and find solutions.
Climate action has received great international attention and rests on two major pillars: reducing greenhouse gas emissions and removing carbon dioxide from the atmosphere. Among so-called nature-based solutions, tree planting has attracted enthusiasm from researchers, policy-makers, business and civil society, as a promising method to mitigate climate change by reducing the carbon burden in the atmosphere. Influential studies suggested that, in theory, up to two-thirds of human carbon emissions could be recaptured by expanding global tree cover. However, the critical difference between the reforestation of formerly cleared forest landscapes and the afforestation of historically open landscapes, such as savannahs and alpine tundra vegetation, remained blurred. Planting trees in the wrong places can reduce surface albedo, thereby offsetting the cooling effect. Misplaced tree planting can also compromise native biodiversity and related ecosystem services, increase wildfire risk, and intensify water scarcity in dry regions.
These potential adverse effects, and the recognition that we tend to neglect the carbon capture potential of open ecosystems in their soils, call for a more comprehensive concept of ecosystem restoration to support climate change mitigation. However, we had little idea how much carbon we could actually capture by expanding the set of potential target ecosystems, considering all constraints for restoration site availability, and getting access to improved methods and source data for modelling.
In our study, we aim to fill this crucial knowledge gap by developing an improved, more policy-relevant global model to predict the carbon sequestration potential of ecosystem restoration. We not only estimate the potential carbon stock that can be built up by a distant time point in future – a common limitation of earlier models – but set up a realistic timeline for both the restoration itself and the subsequent carbon sequestration by considering annual rates until 2100.
Our model had some eye-opening results. First, restoring open ecosystems has a comparable carbon capture potential to forest restoration globally. This challenges the widespread perception that forests are the singular cornerstone of nature-based climate change mitigation. Second, there is substantial land available for restoring both open ecosystems and forests in temperate zones of the northern hemisphere, reducing the pressure on tropical countries and the Global South to offset emissions that the Global North was historically more responsible for. However, despite fine-tuning restoration targets and their global distribution, the maximum amount of carbon we can capture by 2100 is limited. We estimated a cumulative amount of 96.9 Gt, equivalent to approximately 17.6% of anthropogenic emissions between the Industrial Revolution and the present. In addition, if considering future emissions until 2100, the number dropped to 3.7–12.0%. The upper bound of 12% would require a coordinated global shift toward sustainable, low-carbon economies. Given current geopolitical rivalries, deep-rooted economic interests, and uneven development priorities, such a scenario cannot be taken for granted.
Figure 1: Priority regions for ecosystem restoration to mitigate climate change
So, what should we do if neither tree planting nor a more comprehensive approach of ecosystem restoration can be our silver bullet to mitigate climate change? First, we need to put more effort into emission reduction: The convenient assumption that someone, somewhere, will plant trees to offset our emissions should be abandoned, and emissions should be reduced, regardless of restoration activities. Second, reset the priorities. Measures against climate change do not only include mitigation but also adaptation, for which ecosystem restoration is a prime tool. For example, restoring forests upslope of settlements can make them resilient to flash floods intensified by climate change. So, the most strategic restoration site may not be the one with the highest carbon gain per unit cost, but the one that provides the greatest protection for vulnerable communities. Prioritizing adaptation over pure carbon optimization does not imply abandoning mitigation benefits. Every restored ecosystem sequesters carbon to some degree. The challenge is not to choose between mitigation and adaptation, but to integrate both objectives in restoration planning. Moreover, independent of its carbon sequestration potential, ecosystem restoration remains one of the most effective measures to halt the biodiversity crisis and thus to secure ecosystem services, as recognized by recent international agendas, such as the United Nations’ Decade on Ecosystem Restoration and the EU’s Nature Restoration Law.
Our findings therefore contribute to a more nuanced understanding of the climate change – biodiversity decline – ecosystem restoration nexus. We call for a stronger integration of ecosystem restoration and climate adaptation in research and policy-making. Future modelling efforts should identify priority areas for restoration, such as upslope regions, where reforestation can reduce flood risks, or degraded floodplains where wetland restoration can buffer against droughty periods. These priority areas could be explicitly incorporated into National Restoration Plans during the implementation of the Nature Restoration Law in Europe and similar instruments worldwide.