The short carbon cycle
The short carbon cycle involves the movement of carbon (C) atoms over a relatively short period of time. This is the movement of CO2 taken up from the air by living organisms such as plants or bacteria. These organisms convert the CO2 into glucose through photosynthesis.
When the plant or bacterium is eaten, or consumed in some other way, it becomes food for the 'consumer'. Who converts it into, for example, body weight and combustion. The combustion has as a residual product which is CO2, so the cycle is complete again. If plants or trees fall, die and/or burn, the stored carbon is released back into the atmosphere. Hence, when we plant a tree, which falls over due to a wind gust 15 years later, no carbon is captured and stored at the point that the tree is perished.
The long carbon cycle
As the name suggests, the long carbon cycle takes a long time compared to human life. Some dead plants or animals end up under layers of earth. This way, they do not rot (consumed by fungi and bacteria), but form almost permanent storage of C-atoms. This storage took place over millions of years and transformed into what we now know as coal, oil and gas. This long-term storage of all this carbon created the climate as we know it today.
By removing these layers of coal, oil and gas to satisfy our energy needs, we tap into these long-term carbon sinks. This, at least for human terms, should not take place. It results in the re-entering of the carbon into the atmosphere. This in returns leads to hot and dry temperatures like our planet has seen long before mankind existed.
To further prevent the consequences of this carbon cycle disruption, we have made global agreements on CO2 reduction. One way of gaining insight into emissions is to calculate your carbon footprint. A carbon footprint shows exactly what are the greenhouse gas emission sources in your organisation.