The global potential for increased storage of carbon on land

Abstract

Significance Despite increased interest in land-based carbon storage as a climate solution, there are physical limits on how much additional carbon can be incorporated into terrestrial ecosystems. To effectively determine where and how to act, jurisdictions need robust data illustrating the magnitude and distribution of opportunities to increase carbon storage, as well as information on the actions available to achieve that storage. Here, we provide globally consistent maps for directing additional carbon storage under current and future climate, as well as a framework for determining how that storage could be gained through restoration, improved management, or maintenance of woody biomass and soil organic matter. Our estimates provide an upper bound on how improved land stewardship can mitigate the climate crisis.

Carbon uptake in Eurasian boreal forests dominates the high‐latitude net ecosystem carbon budget

“…As with this assessment, other reports have highlighted the importance of the boreal CO 2 sink—perhaps on par with the tropical forest sink (Tagesson et al, 2020)—and indicate a large unrealized potential of boreal forests to sequester additional carbon (approximately 46 Pg C total) through protection and restoration (Walker et al, 2022). Although some studies estimate that this NEE sink will continue to increase through 2100 (Holmberg et al, 2019; White et al, 2001), it is very likely that an increase in fire activity, already observed in more recent years, will threaten historic carbon gains (Walker et al, 2019).…”

Mechanisms driving interspecific variation in regional synchrony of trees reproduction

“…The ecological consequences of the interspecific variation in regional synchrony of masting are diverse and potentially great. For example, reforestation strategies widely planned to mitigate climate change (Walker et al, 2022) require a large seed supply that is difficult to meet, especially in masting species (Jalonen et al, 2018; Kettle et al, 2010; Whittet et al, 2016). Species characterized by large‐scale regional synchrony will share nil seed production years over entire subcontinents, which requires planning to stabilize the supply of seeds to nurseries (Kettle et al, 2010).…”

Releasing global forests from human management: How much more carbon could be stored?

“…Nevertheless, recent research shows that reducing harvesting intensity has strong climate mitigation benefits, especially at shorter timescales, even after accounting for such substitutions ( 15 ). However, on the long term and at a global scale, the total amount of carbon that could realistically be stored in forests remains poorly understood ( 16 ).…”

“…This hypothetical scenario defines the upper bound of carbon storage in existing forests and implies the removal of all direct human management from forests (meaning any human-caused physical changes in forest structure, carbon storage, or species composition that are due to harvesting, fire suppression, plantation, or other factors). Throughout this text, we refer to forests that have been altered by direct human action simply as “managed forests” as opposed to “intact forests.” Some human interventions, such as active fire suppression, could in practice enhance carbon stored in forests, but from a global perspective, managed forests contain substantially less carbon than their intact counterparts ( 11 , 16 ). We focused on existing forests because other studies suggest that they hold most of the additional carbon storage potential of forests, considering management as well as afforestation and reforestation when accounting for competition with other land uses ( 16 ).…”

“…Throughout this text, we refer to forests that have been altered by direct human action simply as “managed forests” as opposed to “intact forests.” Some human interventions, such as active fire suppression, could in practice enhance carbon stored in forests, but from a global perspective, managed forests contain substantially less carbon than their intact counterparts ( 11 , 16 ). We focused on existing forests because other studies suggest that they hold most of the additional carbon storage potential of forests, considering management as well as afforestation and reforestation when accounting for competition with other land uses ( 16 ).…”