Global environmental forces

Abstract

Greenhouse warming is global in at least two respects. First, carbon dioxide (CO,) and the other gases released or withheld anywhere on earth disperse rapidly into the global inventory. The location of origin makes no difference. Second, the effect will be a change in global circulation of air and water. Although the mean rise in atmospheric temperature is commonly used as an index of climate change, the change in temperature differential between equatorial and polar regions may be a better measure of global environmental forces. The standard point estimate of global warming for a doubling of the concentration of CO2 in the atmosphere is 3°C [ 11. But it is usually estimated that the warming in the polar regions associated with this three-degree average change might be eight or ten degrees, whereas the change in atmospheric temperature near the equator might be closer to one degree [ 11. Offhand this sounds like a welcome dispersion of temperature change: it will mainly get warmer where it is already very cold and warm up the least where it is already hot. But more significant is that it is the temperature gradients between equatorial and polar regions that drive the winds, which in mm drive the oceans, and a change of seven or eight degrees in the mean temperature f some will undoubtedly become cooler. But the observed changes will include not only temperature and temperature variation from season to season and year to year, but also, and probably more importantly, the amounts, the seasonal distribution, and the year-to-year variation in rainfall, snow, wind, fog, sunlight, humidity, and storms. For the purpose of comparing forthcoming changes in climate with changes experienced in the past, the mean global atmospheric temperature is probably not only a reliable index but also something of a measure of magnitude. Using the commonly accepted three-degree rise from a doubling of the atmospheric concentration as an approximation to what may be forthcoming, the ensuing temperature will not only be well outside the range of atmospheric temperatures experienced in the past 10,000 years but may be several times the range of temperature variation experienced in that time. This