 So why do we care about carbon? So carbon is the foundation for all life on earth including plants animals bacteria and so on and it also plays an important role in regulating the climate in particular temperature as well as affecting the acidity of rain rivers and lakes and the ocean. The carbon cycle describes the continual movement or flux of carbon through different reservoirs on the earth. So the four major reservoirs are the atmospheres, the oceans, the terrestrial biosphere, which includes plants, animals and soils and the geosphere, so things like sediments. There are two aspects to the carbon cycle. There's fast carbon, so that's carbon that moves between reservoirs at a rapid pace and the slow carbon. Fast carbon describes processes by which carbon moves between reservoirs such as the atmosphere the oceans and the terrestrial biosphere. So these processes would be things like diffusion of atmospheric carbon into the oceans, degassing from the oceans into the atmosphere. So slow carbon describes carbon in the geosphere and these are things like limestones, extractable hydrocarbons, so oil, gas, coal, as well as sedimentary rocks and also huge amounts of carbon that are stored within the earth's interior in the mantle. Most of the carbon is locked away in rocks and only really a tiny fraction of the carbon in the earth exists on the surface. The atmosphere contains about six hundred gigatons of carbon. The terrestrial biosphere is bigger. It contains about 2.3 thousand gigatons of carbon and the oceans are a massive reservoir, so they contain 39,000 gigatons of carbon and 38,000 of those are stored in the deep ocean, so only a fraction of it is in the surface. In addition to that, hydrocarbons that we're able to extract consist of about 10,000 gigatons of carbon. So these rapid fluxes dwarf even the fluxes that we see through anthropogenic carbon emissions.