Atmosphere of Earth years ago. About 3.4 billion years ago, nitrogen formed the major part of the then stable "second atmosphere". The influence of life has to be taken into account rather soon in the history of the atmosphere, because hints of early life-forms appear as early as 3.5 billion years ago. How Earth at that time maintained a climate warm enough for liquid water and life, if the early Sun put out 30% lower solar radiance than today, is a puzzle known as the "faint young Sun paradox". The geological record however shows a continuous relatively warm surface during the complete early
Greenhouse gas footprint and constant deforestation, the amount of greenhouse gas in the atmosphere is increasing, which makes reducing a greenhouse gas footprint harder to achieve. However, there are several ways to reduce one's greenhouse gas footprint, such as using more energy efficient household appliances, increase usage of fuel efficient cars, and saving electricity. Greenhouse gases (GHGs) are gases that increase the temperature of the Earth due to their absorption of infrared radiation. Although some emissions are natural, the rate of which they are being produced has increased because of humans. These gases are emitted from fossil fuel usage in electricity, in heat