Global ecosystems are at risk of losing carbon storage ability, study says

Several regions of the world are at risk of losing their ability to store carbon, which could result in the drastic transformation of ecosystems and accelerated climate change, one recent study has found.

Across the globe, landscapes are showing signs of losing their ability to absorb the amount of carbon they once could, according to a study called “Diagnosing destabilization risk in global land carbon sinks,” published in Nature last month. That would pose serious obstacles to the fight against climate change, as carbon storage in forests, peatlands and other ecosystems is key to keeping the global temperature below 1.5° Celsius (2.7° Fahrenheit).

“For the first time, we’ve demonstrated that for certain regions of the world, the land might be reaching a tipping point in terms of its ability to host significantly forested land and absorb significant amounts of carbon,” said co-author Patrick McGuire, a staff meteorologist at the University of Reading and the National Centre for Atmospheric Science in the UK.

The study reviewed the productivity of carbon storage of global ecosystems between 1981 and 2018, finding that many fluctuated greatly from year to year. So much fluctuation means that some parts of the world are at risk of turning into scrubland that’s unable to host forests and other ecosystems that act as carbon sinks.

One reason for this, the researchers said, is that landscapes have a “memory” of which years had high carbon storage and which were low. Low years are more likely to be followed by additional low years, meaning that as carbon storage potential diminishes, a landscape is more likely to permanently become scrubland.

The phenomenon can be thought of as a “spiraling” effect, researchers said, in which landscapes absorb less carbon that in turn worsens climate change, which then destabilizes additional landscapes and puts them at higher risk of turning into scrubland.

“If we destabilize the carbon net uptake, that will destabilize climate even more,” said lead author Marcos Fernández, researcher at the Center for Ecological Research and Forestry Applications (CREAF). “It’s like a positive feedback loop. As you destabilize the carbon balance, then the climate becomes more unstable, as well.”

The most-affected regions include the Mediterranean Basin, South and Central Asia, East Africa and the west coasts of North and Central America. More specifically, mapping suggests that Kenya, India, Pakistan, Russia, Kyrgyzstan and Iraq are losing their ability to store carbon while in the Americas, it’s the Northern Triangle, Mexico and the west coast of the United States that are the most affected.

Researchers noted that certain parts of the world, such as the Amazon and central and northern Europe, are less likely to see this destabilizing effect. In fact, their capacity for carbon storage has increased in recent years, they said. Nevertheless, they stressed that the countless landscapes across the globe that are at risk of losing carbon storage capacity need to be addressed.

“We need to take care of our land better and not let all the trees get cut down and converted to cropland,” McGuire said. “Trees can hold a lot more carbon than crops or grasslands.”

Banner image: A redwood forest in California. Photo by Rhett Butler. 

CITATION: Fernández-Martínez, M., Peñuelas, J., Chevallier, F. et al. Diagnosing destabilization risk in global land carbon sinks. Nature (2023). https://doi.org/10.1038/s41586-023-05725-1

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