Huge carbon stock left out of climate calculations

April 12 () –

A new study urges the incorporation of inorganic carbon in climate change mitigation strategies such as an additional lever to maintain and improve carbon sequestration.

Soil carbon generally refers only to the organic matter component of soils, known as soil organic carbon (SOC). However, soil carbon also has an inorganic component, known as soil inorganic carbon (SIC). Solid SIC, often calcium carbonate, tends to accumulate more in arid regions with infertile soils, which has led many to believe that it is not important.

In a study published in Science, researchers led by Professor Huang Yuanyuan of the Institute of Geographical Sciences and Natural Resources Research of the Chinese Academy of Sciences (CAS) and Zhang Ganlin of the Institute of Soil Sciences of CAS, together with their collaborators, have quantified the global reserve of SIC, challenging the conventional view.

The researchers They found a whopping 2,305 million tons of carbon stored as SIC in the top two meters of soil around the world.or, which is more than five times the carbon found in all the world's vegetation combined. This hidden store of soil carbon could be key to understanding how carbon moves around the world.

“But here's the thing: This huge carbon stock is vulnerable to changes in the environment, especially soil acidification. The acids dissolve the calcium carbonate and remove it as carbon dioxide gas or directly into the water,” said Professor Huang it's a statement.

“Many regions of countries such as China and India are experiencing soil acidification due to industrial activities and intensive agriculture. Without corrective actions and better soil practices, “The world is likely to face a SIC disruption in the next 30 years,” he added.

SIC perturbations accumulated throughout Earth's history have a profound impact on soil health. This alteration compromises the soil's ability to neutralize acidity, regulate nutrient levels, promote plant growth, and stabilize organic carbon. Essentially, the SIC plays a fundamental double role: store carbon and support ecosystem functions that depend on it.

The researchers revealed that approximately 1.13 billion tons of inorganic carbon are lost from soils to inland waters each year. This loss has profound implications, but often overlookedfor the transport of carbon between land, atmosphere, fresh water and ocean.

While society has recognized the importance of soils as a fundamental part of nature-based solutions to combat climate change, much of the attention has been focused on SOC. It is now clear that inorganic carbon deserves equal attention, according to the authors.

This study highlights the urgency of incorporating inorganic carbon into climate change mitigation strategies as an additional lever to maintain and enhance carbon sequestration. International programs such as the “4 per thousand initiative”, which aims to increase (mainly) SOC by 0.4% per year, should also consider the fundamental role of inorganic carbon in achieving sustainable soil management and climate mitigation objectives.

By expanding the understanding of soil carbon dynamics to include organic and inorganic carbon, researchers hope to develop more effective strategies to maintain soil health, improve ecosystem services, and mitigate climate change.