For all of human history prior to the industrial revolution the carbon dioxide levels in the atmosphere remained fairly constant due to the natural carbon cycle depicted on the left to the diagram above.
Beginning at the industrial evolution, humans added to the carbon cycle. Coal and oil, which trapped carbon millions of years ago, began to be mined for fuel. This human addition to the carbon cycle is depicted at the right of the above diagram. Thus humans through the natural carbon cycle completely out of wack—it was no longer in balance and more carbon dioxide was been added to the atmosphere than was being removed. This imbalance as esabertated through land clearing as, humans were reducing he number of trees on the planet—removing the natural part of the carbon cycle which removed the carbon from the atmosphere.
In summary then:
In summary then:
- Humans, via using coal and oil as fuels began adding carbon dioxide to the atmosphere at unnatural levels.
- Humans, via removing tree, began removing the natural part of the carbon cycle that removed carbon dioxide from the atmosphere.
- The only possible result, therefore, being that carbon dioxide levels in the atmosphere must continually increase.
The video below describes the carbon cycle and explains how the carbon dioxide layer in our atmosphere acts to warm our planet.
Before the industrial revolution, when the carbon cycle was in balance the "greenhouse effect" of the carbon layer kept the planet warm enough to sustain life. When humans started adding to the thickness of the carbon dioxide layer through using coal and oil as fuel and through removing trees, the "greenhouse effect" meant the only outcome could be continual warming of the planet until life on it becomes impossible.