Monthly Archives: October 2007

The question of where and how to get our energy without causing unacceptable environmental and other impacts is probably the most burning problem of our time. It is beginning to sink in that the large coal deposits buried on the North American continent and all the oil buried in Iraq and elsewhere are only part of the answer. At least a supplementary source of fuel is needed to put a cap on burning fossil fuels. Unexplained accelerated melting of polar ice caps adds an incentive to come up with solutions fast. If we should succeed in melting the entire Antarctic ice cap we would gain a new continent, but, in the process, large land areas would be lost to a sea level rise of up to 70 m. People living in present coastal areas have no clue that their domiciles

would wind up at the bottom of a new ocean shelf. Cities like Augusta, Columbia, Richmond, and others would go partly under water and partly become coastal cities. Even a fraction of the estimated rise would be quite disastrous. The densely settled Ganges and Yangzi deltas would go under and drive out millions of people. A consoling factor is that it will take some time for this to play out and probably none of us who contributed to this potential calamity will be around.

There seems to be a consensus now that global warming is

in progress. How far will it go? Will it be a Venusian run-away process or will it perhaps reverse itself after some time to global cooling? Climate excursions and reversals, such as the ice ages and the intervening warm periods, have happened repeatedly in geologic history. We can

only guess what triggered them,.

The presently increased warming of the

troposphere (the lowest 10 km from the ground up) strengthens vertical turbulent air movements. They may get organized in updrafts that become visible as towering cumulonimbus clouds. These vertical updrafts are fed by heat energy and water vapor condensation and penetrate deeply into or through the troposphere to its very upper limit and even beyond. As the water vapor condenses the rising air is freeze-dried at the low temperature of high altitudes, and the updraft literally loses its steam, and spreads horizontally like under an invisible barrier into an anvil cloud. Every air traveler has seen such anvils from the air plane window and pilots circle respectfully around them. The tropopause is the altitude at which the air temperature reaches its minimum of around – 70 C. It occurs at about 9 km at the poles and 16 km at the equator. Beyond the tropopause, the air temperature rises again, thus adding resistance to vertical air movement in the lower stratosphere. This enhances horizontal air movement and for good reason this level is the home of the fast moving horizontal jet streams. Some thin ice clouds and with them air pollutants make it beyond that level into the stratosphere where they are out of reach of the weather, in other words, they cannot be washed out by rain. This sets the stage for an accumulation of pollutants and a possible reduction of solar radiation transmission in the stratosphere. It is like slowly pulling the straw mat over the greenhouse, and it may bring on a cooling trend on Earth. The ozone decay by chlorofluorocarbons that threatened exposure of life to lethal ultraviolet radiation was a warning signal in the 1990’s and indicated the presence of stratospheric pollution. It would seem that the stronger global warming will be, the more pollution will be pumped in the lower stratosphere, and the stronger global cooling could be. Historic volcanic eruptions have demonstrated that stratospheric pollution is capable of rapid

climate cooling. Surprisingly little is presently known about the troposphere-stratosphere transition layer and its effect on global climate. At that altitude only special planes can fly making sampling and investigating difficult and costly (EOS, 7/10/07, p. 286; www.espo.nasa.gov/tc4).