The carbon cycle | Middle school Earth and space science | Khan Academy

Take a deep breath in and out. The carbon dioxide you just exhaled, it might end up in a tree. A few years later, it could settle in a soil. And millions of years from now, it might even become coal. But wait, how does carbon move through all these places? Let's find out. Carbon is stored in

different parts of the environment called the carbon reservoirs. Organic reservoirs include living organisms like plants, animals, and even microbes. This also includes their remains after they die. Now, inorganic reservoirs include non-living parts of the environment like rocks, sediments, water, and even the atmosphere. But what's interesting is that the carbon moves from one reservoir to another in a

cycle. So we call this the carbon cycle. But how does it move you ask? Well, there are four main processes that move carbon through the environment. We have photosynthesis, respiration, decomposition, and combustion. Let's start with photosynthesis. Plants use sunlight to convert carbon dioxide from the atmosphere into glucose, a type of sugar. Now processes that remove carbon

from the atmosphere are called carbon sinks. So through photosynthesis, plants act as a carbon sink. Next up, respiration. Respiration is a process in which plants and animals break down glucose to get energy. This process releases carbon dioxide back into the atmosphere. Any process that adds carbon to the atmosphere is called the carbon

source. So respiration is a carbon source. But what happens when plants or animals die? That's where the decomposers come in. Organisms like bacteria and fungi. They break down dead organisms to get energy. This process is called decomposition and it also releases carbon dioxide back into the atmosphere. So decomposition is a carbon source as well. Now these three