carbon cycle

Carbon never stays still. The same atoms are forever passing among the air, the oceans, every living thing, and the rock beneath our feet — looping through the whole planet like money circulating through an economy. A carbon atom in your morning breath might be soaked up by a leaf, eaten by a cow, exhaled, dissolved into the sea, and locked into seashells over millions of years.

Plants pull carbon dioxide out of the air to build leaves and wood; animals eat the plants and breathe some of it back out; the oceans drink it in and burp it back; and slowly, over ages, dead organisms turn to limestone and coal. For the last several thousand years nature kept these flows roughly in balance, so the amount in the air stayed fairly steady from one century to the next — until we came along.

Here's the trouble. When we burn coal, oil, and gas, we dig up carbon that nature spent hundreds of millions of years tucking safely underground, and release it in a few short decades. We are pouring it into the cycle far faster than the oceans and forests can soak it up — so it piles up in the air, traps heat, and warms the planet. The cycle isn't broken; it's simply being overwhelmed.