evidence: The greenhouse gases in the dry air in Earth’s atmosphere include carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons. While making up around 0.05% of Earth’s total atmosphere, they play major roles in trapping Earth’s radiant heat from the Sun and keeping it from escaping into space. Each is driven directly by human activities. [...] Carbon dioxide is responsible for a third of the total warming of Earth’s climate due to human-produced greenhouse gases. Small increases in its concentration have major effects. A key reason is the length of time carbon dioxide remains in the atmosphere. [...] "Carbon dioxide and other non-condensable greenhouse gases act as control knobs for the climate," said Andrew Dessler, a professor of Atmospheric Sciences at Texas A&M University in College Station. "As humans add carbon dioxide to the atmosphere, small changes in climate are amplified by changes in water vapor. This makes carbon dioxide a much more potent greenhouse gas than it would be on a planet without water vapor."