Carbon cycle12/16/2023 “That full process would eventually bring it all up-but very slowly,” Rothman says. But mining those fossil fuels and then burning them in cars or factories shortcuts nature’s method. Over thousands or millions of years, the creeping movement of our planet’s tectonic plates brings those fossil fuels back to the Earth’s surface and slowly emits the CO 2 into the air. Hydrothermal vents on the seafloor provide the carbon that-via heat, pressure, and other forces below the planet’s surface-is pressed into fossil fuels such as oil and gas. For example, consider one part of the natural carbon cycle: how fossil fuels are created and released. Time is the key to understanding this problem, Rothman says, because although the natural carbon cycle balances itself, it does so over exceedingly long timescales. This is why the atmospheric level of CO 2 continues to creep up as humans keep burning fossil fuels: Human activities tip the scales by adding carbon to the air faster than the planet’s sinks can absorb it. “What's being taken out by natural processes is more or less equal to what's being put in-other than the extent to which we've disturbed it,” Rothman says. If people emit only a tenth as much CO 2 as nature does, then why are scientists so concerned about our emissions driving climate change? It is because our extra chunk of carbon emissions has tipped out of equilibrium what was once a balanced cycle. That total dwarfs humanity’s contribution, amounting to ten times as much CO 2 as humans produce through activities such as burning fossil fuels. Altogether the planet absorbs and emits about 100 billion tons of carbon dioxide through this natural cycle every year, Rothman says. Meanwhile, natural sources of CO 2 such as undersea volcanoes and hydrothermal vents release carbon. Some parts of the planet, such as the oceans and forests, absorb carbon dioxide and store it for hundreds or thousands of years. The Earth’s natural carbon cycle moves a staggering amount of carbon dioxide (CO 2) around our planet, says Daniel Rothman, MIT professor of geophysics. The problem is that human activities have thrown the Earth’s carbon cycle out of balance. The planet naturally releases and absorbs far more carbon dioxide than humans emit by burning fossil fuels.
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