Since preindustrial times, ambient concentrations of the greenhouse gases have exhibited substantial increases, inter alia CO2 by 30% to about 360 parts per million (ppm), CH 4 by 145% to more than 1700 parts per billion (ppb), and N20 by 15% to more than 300 ppb. The growth rates in the concentrations of these gases in the early 1990s were lower than predicted; while subsequent data indicate that the growth rates are comparable to those averaged over the 1980s. (more…)

Since the early 1960s, climate change and air quality have become major and often controversial issues in many countries and among groups from governments to various scientific communities. Prominent among these issues is the greenhouse effect, in which the gradually increasing tropospheric concentrations of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N20) are believed to trap an excessive amount of solar radiation reflected from the earth. (more…)