Humans contribute a very small amount of carbon to the atmosphere compared to natural processes. How can it have such a huge impact?
Our planet has a natural cycle that moves huge amounts of carbon— 200 billion tonnes—into and out of the atmosphere every year. When the cycle is balanced, atmospheric carbon dioxide (CO2) levels remain relatively stable. Careful measurements over the past few decades have confirmed that CO2 in the atmosphere is increasing. Human activities are adding about 7 billion tonnes of carbon into the armosphere every year, which is only about 3–4% of the amount exchanged annually. This small addition is enough to upset the fine balance, surpassing nature’s ability to absorb carbon. The oceans and land are currently absorbing half our emissions, but the rest remains in the atmosphere for at least another 100 years.
