As the tectonic plates slide beneath each other, carbon is transported to the Earth’s mantle – a factor in shaping the abundance of surface material. The new study explains why less carbon returns to the atmosphere than some models predict by resolving inequality in how this study lasts. Before reaching the atmospheric carbon mantle it must be deposited on the ocean floor, usually in the form of shells or microorganisms that sink to the bottom of the deep sea.
The process of increasing the rate of fines can keep carbon there for thousands or even millions of years – but until the ocean plate are there, it sits on the subtext below another plate, a process that can bring it back into operation. Some of the trapped carbon eventually returns to the atmosphere through volcanoes – in rare cases it can cause dramatically significant extinctions. Geologists have thought that this is probably the way to go. However, research papers on nature communication makes the case that about two-thirds of the carbon never leaves the coating once it gets there.
About 78 million tons of carbon is pushed into the atmosphere each year for permanent burial – billions of tons of people are released into the atmosphere, but over time it has become a worldwide quantity. Lead author and Cambridge University student Stefan Farsang said in a statement, “We currently have a relatively good idea of carbon’s surface reservoirs and the currents between them, but we know very little about the Earth’s internal carbon stores, which cycle carbon for millions of years.”
Farsang and co-authors sought to bridge this knowledge gap by exploring the chemical reactions that occur when carbon finds itself in the lining heat and pressure. They used a heated “diamond avil” to expose a small amount of carbonate with conditions about 35 kilometers (20 miles) below the earth’s surface. Most of the sunken carbon is locked to the carbonate rock (which contains chalk-like chemical makeup), but researchers have discovered that calcium is replaced by magnesium as the pressure increases. Under the conditions they tested, MGCAO 3 is at least a hundred times less soluble than CaCO3, which inhibits the absorption in its fluids that eventually come out of the volcano. Instead, magnesium-carbonate molecules sink deeper into the mantle, potentially transforming into diamonds.
