In addition to carbon dioxide, several other gases contribute to the Greenhouse effect, including methane, ozone, water vapour, and nitrous oxide. Steitz believes that a "natural greenhouse effect" exists, and has the ability to raise the Earth's average temprature due to the natural prescence of water vapour and carbon dioxide. Steitz claims that these two substances are essential for human health.
Steitz explains that the rise in ocean temperature typically increases the concentrations of carbon dioxide in the atmosphere; it takes approximately five months for a rise in ocean temperature to lead to a rise of carbon dioxide in the atmosphere.
Furthermore, Steitz discusses the importance of a carbon dioxide equilibrium (balance). Any carbon dioxide which is injected into the troposphere (the lower section of the atmosphere) comes to equilibrium with reservoirs of gas held in molecular form in the seas and land. The carbon dioxide held in solution in the upper layer of the ocean is the most important reservoir.
The time required for this equilibrium to occur on a global basis is estimated at 10 years. This process involves the carbon dioxide generated by burning fossils fuels to come to balance with the intermediate global reservoir in the upper layer of the ocean.
Therefore, only a fraction of the increase in atmospheric carbon dioxide observed in the last 100 years can be of fossil fuel origin, and thus global warming can be contributed to natural fluctuations. These natural fluctuations include an increase in ocean temperature (the reasoning was unclear behind the increase in ocean temperature), and the carbon dioxide equilibrium.
