Forests and carbon capture under pressure
Forests absorb CO2 from the atmosphere, acting as a natural counterweight to climate change. Yet changes are emerging. The planet gains a large unseen shift, a mismatch in how carbon is stored in key regions. This imbalance worries scientists.
A study published in Nature this week identifies clear signs that carbon sequestration faces destabilization across vast areas of the Earth. The research shows that in some places carbon uptake has changed dramatically in recent years, with periods of high plant productivity followed by weaker phases. The authors warn that this variability signals ecosystems may be at risk of tipping into new states, with sudden shifts possible.
Marcos Fernández, CREAF researcher and University of Barcelona collaborator, is the study’s first author. He notes that in some regions there is a stronger memory signal, meaning each value relates more closely to the one before it. When a measurement declines, the next may fall even more, hinting at deeper systemic changes.
Among the regions most affected, the Mediterranean
The study finds that areas facing the highest risk of destabilization tend to have less forest cover, more agricultural land, warmer conditions, and faster increases in temperature variability. These factors may coincide with more frequent extreme weather events, including heat waves and cold snaps. The Mediterranean region appears prominently, along with the eastern Horn of Africa, the west coast of North America and Central America, parts of India and Pakistan, and Southeast Asia.
To conduct the analysis, researchers used global data from two atmospheric inversion models, CAMS and CarboScope, covering net ecosystem production from 1981 to 2018. They also drew on a set of 12 dynamic vegetation models, TRENDY, to capture baseline production in earth systems.
Unstable patterns and carbon sequestration
Regions showing the greatest destabilization have seen declines in carbon sequestration capacity in recent years. In contrast, areas that tend to be less volatile, such as parts of the Amazon and central to northern Europe, have shown improved carbon uptake.
In the Amazon, for instance, the area loses less carbon over time even as the overall balance remains negative because the system has become less volatile than before, according to Josep Peñuelas, CSIC research professor at CREAF.
Experts emphasize that predicting the carbon cycle is essential for climate action. It remains unclear whether abrupt shifts will alter climate patterns or change the capacity of plants to sequester carbon. The potential for destabilization across large biosphere areas adds a layer of complexity to forecasting.
The researchers highlight that the global scope of the study makes it challenging to disentangle the mechanisms behind these results.
Does biodiversity stabilize ecosystems?
It is often argued that ecosystems with greater species diversity are more stable and productive, boosting carbon sequestration. The study explored this idea globally and found that the highest carbon uptake occurs in regions with moderate biodiversity. In zones with very high biodiversity, such as tropical forests, carbon sequestration can be lower.
The team suggests that the positive effect of biodiversity on decomposition and respiration in tropical ecosystems may offset gains from photosynthesis found in other regions. They also note that the maximum variability in carbon uptake appears in regions with moderate biodiversity. Given the global scope, the exact mechanisms behind these patterns remain difficult to pin down.
Reference: DOI 10.1038/s41586-023-05725-1
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