Storage of existing carbon in Earth’s natural biomes and sediments will be critical to achieving the 2021 United Nations Climate Change Conference (Cop26) goals of keeping rising global temperatures within 1.5 degrees Celsius.
One way to achieve this is to map locations of stored carbon and aiming to keep that stored carbon in a state where it is not released in the atmosphere.
Natural storage of carbon is evident in biomes such as tropical rainforests, forests of giant redwoods, and peatlands. The problem with carbon stored, particularly in rich regions of vegetation, is once the carbon is released, such as through deforestation, then that carbon is almost impossible to recapture in a quick or rapid manner.
At large scales, and if deforestation persists as a major problem, then long-term release of carbon will be a key contributor to climate change.
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Mapping Where Carbon Needs to be Stored
To determine where important carbon needs to be stored, scientists have created a map of the Earth where carbon needs to be stored to keep climate goals from Cop26 possible.
The map, demonstrating what is ‘irrecoverable carbon’ in that such carbon needs to be stored and not lost, indicates about 139 gigatons of carbon that needs to be retained in regions such as forests, mangroves, and peatlands.
This amount contains about 15 years of human carbon dioxide emissions using current levels. While some of that is found in sediments, most of the carbon that is critical in maintaining its storage is found in the Amazon, the Congo Basin, and Insular Southeast Asia.
The map indicates how much total carbon is stored in ecosystems that are vulnerable to human development, while it does not map or indicate carbon or methane stored in regions such as permafrost, which also hold a lot of known carbon and methane.
The map is useful in looking at areas that could be potentially developed in the near future, indicating how much of that carbon needs to be avoided in development in the decades to come to achieve climate goals.
GIS Data and Mapping Carbon Storage
The data are derived from satellite data capturing biomes that contain carbon quantities; satellite data enable sequestration rates by ecosystem type to be calculated using a spatially explicit database called the Global Reforestation Opportunity Assessment (GROA).
Currently, we are losing about 0.45 gigatons of irrecoverable carbon per year.[1] The Intergovernmental Panel on Climate Change (IPCC) estimates that 2,900 gigatons of carbon dioxide can be at most emitted, from 2014 levels, to retain the goal of keeping global temperatures rising less than 2 degrees Celsius.
Protecting Areas of Irrecoverable Carbon
While the study highlights key areas of where irrecoverable carbon is located, key actions are needed to keep most of these areas protected.
For instance, if an additional 8 million square kilometers of protected area for ecosystems that contain irrecoverable carbon is made possible, or about 5.4 percent of the planet’s land surface, that would enable 75 percent of this vulnerable carbon to be under some protection.
The map mainly indicates where efforts should focus in helping to keep carbon in trees and sediments that are critical to maintaining the 1.5 Celsius target.[2]
Trees are a critical part of protection against rapid increase in atmospheric carbon. Currently, there are about 3 trillion trees on the planet, or about half the amount there were about 12,000 years ago, when humans began to significantly alter the planet’s ecosystems.[3]
There are global initiatives supported by different organizations to plant more trees, up to one trillion as one example, as one solution to solving the rising carbon problem.[4] However, most scientists agree that planting more trees without a major reduction of carbon cannot solve the problem of rising global temperatures, as the rate of carbon absorbed is not likely to keep up with emissions.
Overall, the goals that will produce the most beneficial results are a rapid reduction in carbon released through fossil fuels as well as a reduction in the destruction of land that traps much of the irrecoverable carbon, such as rainforests.
Mapping where carbon is irrecoverable is a critical step in demonstrating what areas are likely to be the most impactful in protecting in the decades to come.
If such areas are rapidly lost, then it becomes essentially impossible to keep the 1.5 degree Celsius target governments have set as the tolerable rise in global temperatures. Given that emissions from various human activities, as well as deforestation and land change evident in recent years, we are still significantly contributing to emissions every year.
Protecting key carbon regions as well as limiting emissions will have to be major objectives in the years to come if we are to maintain Cop26 climate goals.
References
[1] For more on the map created to indicate carbon stored in ecosystems and biomes, see: Noon, M.L.; Goldstein, A.; Ledezma, J.C.; Roehrdanz, P.R.; Cook-Patton, S.C.; Spawn-Lee, S.A.; Wright, T.M.; Gonzalez-Roglich, M.; Hole, D.G.; Rockström, J.; et al. Mapping the Irrecoverable Carbon in Earth’s Ecosystems. Nat Sustain 2021, doi:10.1038/s41893-021-00803-6.
[2] For more on mapping ecosystems and carbon that is irrecoverable, see: https://www.sciencenews.org/article/climate-change-natural-carbon-stores-new-map.
[3] For more on the number of trees on the planet, see: https://www.geographyrealm.com/how-many-trees-are-there-in-the-world/
[4] For more on one such group, see: https://trilliontrees.org/.
