A study conducted by the University of Oxford (UK) disproved the idea that natural erosion of rocks acts as a basin CO2On the other hand, this gas can also act as a major source of emissions.It can even rival the amounts emitted by volcanoes. The results were published in the journal NatureIt may have important consequences for climate change management.
Rocks contain large stores of carbon derived from the ancient remains of plants and animals that lived millions of years ago. This means that what is called the “geological carbon cycle” acts as a thermostat that helps regulate the Earth’s temperature.
For example, during chemical weathering, rocks can absorb CO2 when the acid present in rainwater attacks certain minerals. This process helps offset the CO2 constantly released by volcanoes around the world, and is actually part of the Earth’s natural carbon cycle, which helps keep the surface habitable for life for a billion years or more.
For the first time, a scientific study has revealed that the release of CO2 from rocks into the atmosphere is a natural process.
But for the first time, a scientific study has revealed that it is a natural process of CO2 being released from rocks into the atmosphere. Not only that. Researchers discovered that This emission is as significant as the CO2 released by volcanoes around the planet.. Currently, due to the novelty of the discovery, this process is not included in most models examining the natural carbon cycle.
Rocks that emit gas instead of sequestrites
The process occurs when rocks formed in ancient seabeds (where plants and animals were buried in sediments) are pushed towards the Earth’s surface when mountains, such as the Himalayas or the Andes, form. This exposes the organic carbon in the rocks to oxygen in the air and water, which can react and release CO2.. This means that eroded rocks could be a source of CO2, rather than trapping this gas as assumed so far.
Until now, it has been difficult to measure this CO2 release from the erosion of organic carbon in rocks. But in the new study, researchers They used a trace element (rhenium) that is released into the water when organic carbon in the rock reacts with oxygen.
Sampling river water to measure rhenium levels allows CO2 emissions to be measured. But the study’s authors acknowledge that sampling all the water in the world’s rivers to obtain a global estimate would be a significant challenge.
To scale this up and apply it to the Earth’s surface, the researchers did two things. First, they determined how much organic carbon was present in rocks near the surface. Secondly, they investigated which places were most exposed to erosion, especially because they were mountainous and very steep.
Professor Jesse Zondervan, a researcher at the University of Oxford’s Department of Earth Sciences who led the study, said: “The challenge was how to combine these global maps with river data, taking into account uncertainties. By transferring all our data to a supercomputer in Oxford, we simulated the complex interplay of physical, chemical and hydrological processes.. “By putting the pieces of this giant planetary puzzle together, we were finally able to estimate the total amount of carbon dioxide emitted as these rocks eroded and released their old carbon into the air.”
This is comparable to the amount of CO2 that can be obtained through the natural erosion of silicate minerals from rocks. The results identified many large areas where weathering is a source of CO2 and challenged current views on how weathering affects the carbon cycle.
Vast mountain ranges that emit CO2
According to the results, the critical points of CO2 emissions are concentrated in mountain ranges with high elevations that expose sedimentary rocks. Eastern Himalayas, Rocky Mountains and Andes. Global CO2 emissions from the erosion of organic carbon in rocks have been found to be: 68 megatons of carbon per year.
Professor Robert Hilton (Department of Earth Sciences, University of Oxford), who led the ROC-CO2 research project supporting the study, said: “This is approximately 100 times less than current human CO2 emissions from burning fuels.” This is similar to the amount of CO2 released by volcanoes around the world.“This means it is a key player in the Earth’s natural carbon cycle.”
These flows may have changed during Earth’s history. For example, during periods of mountain building when many rocks containing organic matter were exposed, CO2 emissions may have been greater and may have affected global climate in the past.
Studies still ongoing, explores how erosion is changing due to human activitiesThis natural carbon emission may also increase as the heating of rocks increases due to anthropogenic climate changes.
One of the questions the team is now asking is whether this natural CO2 emissions will increase over the next century. “We don’t know right now; our methods allow us to provide a robust global forecast, but we haven’t yet assessed how this might change,” says Hilton.
Reference work: https://www.nature.com/articles/s41586-023-06581-9
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