Too many people deny that our atmosphere is warming. Many of these do so because they are making lots of money contributing to global warming. They also spend lots of money convincing people of a certain political view that the promotion of the idea of global warming is the plot of people of a certain other political view.
It is relatively simple to prove that there is global warming with one simple assumption: increased carbon dioxide in the atmosphere will cause the globe to be warmer.
For centuries there has been a certain balance of carbon dioxide in the atmosphere. People have used plants for food and fuel for eons. As people use the plant carbon as food, they breathe out carbon dioxide. As they use plant carbon as fuel, their fires give off carbon dioxide. Plants, in turn, use the atmospheric carbon dioxide as food to grow. The balance is such, that even with huge forest fires and volcanoes, the excess carbon dioxide is used up over a few years or decades with the new growth of plants.
We could express this as
CB-CU=0
That is, carbon burned minus carbon used by plants equals zero. That is, we have a long term balance.
Then people took coal, oil, and gas from under the ground. Now are equation is
CB-CU=CG
where CG is carbon from underground: coal, oil and gas. That is, the carbon from coal, oil, and gas is not used up by the existing plants.
To make matters worse, human activity doesn't increase the amount of plant life to absorb the extra carbon. To the contrary, human activity reduces the volume of plant life. Humans cut down huge forests without replacing them with plants of equal volume. Sometimes they replace the huge forests with sugar cane, coffee plants, or corn. Sometimes they don't even replace the plants but cover the same ground with highways, parking lots, and mammoth buildings. Now our equation becomes
CB-CU=CG+CL
where CL is carbon uptake lost. CB, CG, and CL keep getting bigger, and CU keeps getting smaller.
If you assume the increase of atmospheric carbon dioxide doesn't cause global warming, consider that residents of many cities are having breathing problems because of all the pollutants, including carbon dioxide, that are in the air because of the cities' dependence on fossil fuels.
