By Liz Kimbrough
Plants absorb carbon dioxide from the air and store it in their leaves, stems, roots and the soil. But as climate change and human activities drive more plant species toward extinction, that stored carbon could be released back into the atmosphere, potentially accelerating climate change. A new study published in Nature Communications suggests this biodiversity-driven carbon loss may be a major overlooked source of future emissions.
The researchers used computer modeling to estimate that losing plant diversity around the world could release between 7 billion and 146 billion metric tons of carbon from vegetation. At the upper end, that’s equivalent to more than 12 years’ worth of carbon dioxide emissions from all the cars in the world.
“The magnitude was surprising to me,” study lead author Sarah Weiskopf, a research ecologist at the U.S. Geological Survey, told Mongabay. “Those higher-level estimates for how much carbon emissions we could see with plant diversity loss are pretty high.”
The study looked at how the number of different plant species found in a specific areas or ecosystems worldwide could decline under future climate change and land use scenarios. The scientists then calculated how much carbon storage would be lost as plant species disappear.
They found that biodiversity hotspots in the Amazon Rainforest, Central Africa and Southeast Asia could be hit hardest by both species loss andbiodiversity-drivencarbon storage declines, as these regions have high species richness and large vegetation carbon stocks. Southern Australia also showed significant potential biodiversity loss, but with lower total biomass.
“You can see there’s a lot of plant species loss in the models, but then when you look at the carbon storage, it’s not that high,” Weiskopf said. However, she noted that even moderate diversity losses over large areas can add up to major carbon emissions.
The results suggest a dangerous feedback loop: higher levels of climate change cause more plant extinctions, releasing more carbon and further exacerbating climate change. This effect was much more severe in a high-emissions, limited-conservation scenario compared to a moderate-emissions, proactive-conservation scenario.
The last known remaining Abutilon pitcairnense was destroyed by a landslide on Pitcairn Island in the southern Pacific Ocean. It is now considered extinct. Photo by Marcella Corcoran.
Comparing these biodiversity-driven emissions to other sources like fossil fuel burning is challenging, though. The plant diversity losses and resulting carbon releases are gradual, long-term processes unfolding beyond 2050.
“We don’t want to do a one-to-one comparison, because deforestation is carbon that you’re losing right away,” Weiskopf said. “So it’s not exactly the same, but even with our range of uncertainty, biodiversity-driven carbon loss has the potential to be quite high.”
The study relied on localized experimental data to model large-scale biodiversity-carbon relationships, and estimating species’ climate adaptations remains difficult. However, the approach likely offers a conservative estimate of future losses.
The researchers also didn’t fully assess soil carbon, which stores more carbon globally than vegetation. Plant diversity is known to increase soil carbon storage, so the belowground impact could be substantial.
“Ecosystem management that restores plant diversity likely enhances soil carbon sequestration, particularly in warm and arid climates,” Marie Spohn, an ecologist at the University of Bayreuth in Germany, who was not involved in the study said in an interview.
Beyond carbon cycling, the findings highlight the urgent need to address the interconnected biodiversity and climate crises. As the researchers write, “Biodiversity conservation and restoration can help achieve climate change mitigation goals.”
“As we continue addressing climate change and biodiversity loss, it’ll be more effective to think about these issues together,” Weiskopf said. “It’s not just how much land we conserve, it’s also about biodiversity.”
Banner image of trees in Colombia by Rhett A. Butler.
Liz Kimbroughis a staff writer for Mongabay and holds a Ph.D. in Ecology and Evolutionary Biology from Tulane University, where she studied the microbiomes of trees. View more of her reporting here
Citations:
Weiskopf, S. R., Isbell, F., Arce-Plata, M. I., Di Marco, M., Harfoot, M., Johnson, J., … Ferrier, S. (2024). Biodiversity loss reduces global terrestrial carbon storage. Nature Communications, 15(1), 4354. doi:10.1038/s41467-024-47872-7
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This article was originally published on Mongabay
