The same amount of carbon dioxide (CO2) may be emitted by the natural process of weathering rocks.2) Take to the air like the world’s volcanoes.a The study was published in the journal Oct. 4 Nature We found that natural weathering can also be a major contributor to greenhouse gas emissions. Understanding the natural sources of this greenhouse gas can have important implications for modeling climate change scenarios.
[Related: The truth about carbon capture technology.]
The idea of storing excess carbon in rocks to combat climate change is hotly debated. Although rocks can act like carbon sinks in some scenarios (in practice, preliminary success 1 and icelandic company (Sucking carbon dioxide out of the air and storing it in rocks) is still not a silver bullet for the carbon problem.
Earth’s rocks contain large amounts of carbon from the remains of plants and animals that lived millions of years ago.of geological carbon cycle It also helps regulate the Earth’s temperature. During chemical weathering, where chemicals in rainwater change the rock’s mineralogy, stones can absorb carbon dioxide when certain minerals are attacked by weak acids in the rainwater. Chemical weathering helps combat the carbon dioxide that continues to be emitted by volcanoes around the world and is part of Earth’s natural carbon cycle.
this new research We measured additional natural processes that release carbon dioxide from rocks to the atmosphere. The newly analyzed process occurs when rocks that formed on the ancient ocean floor are pushed back to Earth’s surface. This type of event occurs when a mountain forms. In this event, organic carbon from the remains of long-dead organisms in the rock is exposed to oxygen in the air and water. The carbon then reacts with oxygen to release carbon dioxide. This means that rather than acting like a carbon sink, weathered rocks can become a source of carbon dioxide.
To study the weathering of organic carbon in rocks, the researchers used a tracer element called rhenium. rhenium When organic carbon in rocks reacts with oxygen, it is released into the water.
The researchers first determined how much organic carbon was present in rocks near the water’s surface, then determined where rocks were being exposed most rapidly through erosion.
“The challenge was how to combine these global maps and river data while taking into account the uncertainties. , we simulated the complex interactions of hydrological processes,” said study co-author Jesse Zondervan, a geoscientist at the University of Oxford. stated in a statement. “By piecing together this giant planetary jigsaw puzzle, we were able to finally estimate the total amount of carbon dioxide released as these rocks weather and release ancient carbon into the air. .”
They then compared how much carbon dioxide was released through weathering of silicate materials in natural rocks and identified many large areas where weathering was a source of carbon dioxide. These hotspots of carbon dioxide emissions include high-elevation mountain regions such as the eastern Himalayas, the Rocky Mountains, and the Andes. The global carbon dioxide release rate from organic carbon weathering in rocks has been found to be 68 megatons of carbon per year, slightly more than the amount of carbon dioxide on Earth. Carbon dioxide emitted during heating and cooling of buildings under abnormal weather conditions in the US in 2022.
[Related: Ancient rocks hold the story of Earth’s first breath of oxygen.]
“This is about 1/100th the current human carbon footprint.”2 Emissions from burning fossil fuels, similar to the amount of carbon dioxide2 “Carbon is emitted from volcanoes around the world, which means it plays a key role in Earth’s natural carbon cycle,” says study co-author Robert Hilton, a geochemist at the University of Oxford. stated in a statement.
The authors cautioned that these events may have changed in Earth’s past, perhaps during mountain building periods when the influx of rocks to the surface could have released enough carbon dioxide to affect Earth’s climate. are doing.
The research team is now investigating how this natural release of carbon dioxide is likely to increase over the next century, as anthropogenic climate change and erosion can increase natural leakage of carbon. ing.
“Although the amount of carbon dioxide released by weathering rocks is small compared to current human emissions, a better understanding of these natural processes will allow us to predict carbon budgets more accurately.” said Zondervan.
