Doing the math
Introduction Some gases in the atmosphere are transparent for visible light but not for infrared light. The visible sunlight that hits the ground is warming it up, but the IR-light from the ground is prevented from directly radiating back to space because of these gases. This causes a warming of the atmosphere close to the ground. It would be much colder on Earth without this effect, called the greenhouse effect. In the last million years, when human beings have been on Earth, the concentration of the greenhouse gas Carbon dioxide has varied between 160 ppm and 300 ppm (parts per million), low concentration during Ice ages and high during the warming periods as now. Carbon dioxide is the gas of life, it's captured from the atmosphere by green plants, building them up, and return to the atmosphere via the exhauled air when animals eats the plants. However, there is Carbon stored underground, from plants and animals living in the past, that is not a part of the process no more and