Chapter 34: Global Warming and Emission Trading

The earth’s climate is essentially determined by factors that affect the redistribution of energy within the atmosphere, or between the atmosphere, land, and the ocean. The primary source of energy that drives the earth’s climate is radiation from the sun. To maintain its long-term equilibrium temperature, the earth must radiate back into space, on average, the same amount of energy that it absorbs from the sun.

Global warming occurs when human activities and natural processes release greenhouse gases (GHGs) such as carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF₆) into the atmosphere. These gases prevent some of the heat radiated from the earth’s surface from escaping into outer space, so that the earth’s surface will tend to get warmer. It has been estimated that the earth’s average surface temperature has increased by about 0.6 ± 0.2°C since the late nineteenth century, and it is very likely that the 1990s was the warmest decade of the millennium in the northern hemisphere, with 1998 being the warmest year in the instrumental record since 1861 (Intergovernmental Panel on Climate Change, 2001). There is strong scientific evidence to suggest that most of the warming observed over the last 50 years is attributable to human activities and is likely to have been due to the increase in GHG concentrations in the earth’s atmosphere. Furthermore, if no action is taken now to reduce the current and future levels of GHG emissions into the atmosphere, which will add to these concentrations, current climate models predict that the earth’s average surface temperature will rise by about 1.4–5.8°C over the period 1990–2100. This has the potential to cause significant climate change that could result in severe damage to the natural and economic environment and affect the well-being of humans as well as many other species.