Atmosphere atmospheres were then modified over time by various complex factors, resulting in quite different outcomes. The atmospheres of the planets Venus and Mars are primarily composed of carbon dioxide, with small quantities of nitrogen, argon, oxygen and traces of other gases. The composition of Earth's atmosphere is largely governed by the by-products of the life that it sustains. Dry air from Earth's atmosphere contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and traces of hydrogen, helium, and other "noble" gases (by volume), but generally a variable amount of water vapor is also present, on average about 1% at
Sustainability at the University of British Columbia Sustainability at the University of British Columbia Climate change is now the most serious global environmental threat. Its potential impacts include global warming, sea level rise, and increased extreme weather events. Climate change is a direct consequence of elevated greenhouse gas concentrations in the atmosphere. Greenhouse gases are gases that trap heat in the atmosphere. Some examples include Carbon dioxide, Methane, and Nitrous oxide. They are emitted from fossil fuel burning. Electricity production generates the largest share of greenhouse gas emissions. Moreover, other sources include transportation, industry, and agriculture. These gases are said to make the planet warmer by “thickening