Will We Control The Weather?

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Removal of vegetative cover also worsens the flooding that occurs during periods of torrential rain. Riverine forests serve as sponges that soak up excess water, preventing it from rushing all at once into rivers and tributaries. In similar fashion, estuarine wetlands and mangrove forests help shield human settlements from the storm surges that accompany tropical cyclones and hurricanes. Biologists estimate that 50% of the world's mangrove forests have already been replaced by everything from shantytowns to cement plants and shrimp farms. Stir in the expectation that rising temperatures will trigger a rise in sea level, and you have a recipe for unprecedented disaster.

Scientists are just beginning to disentangle the myriad levels on which human beings and the natural climate system interact, which only increases the potential for surprise. For example, we now realize that not all the aerosols we are pumping into the atmosphere exert a cooling effect. A notable exception is soot, which is produced by wood fires and incomplete industrial combustion. Because of its dark color, soot absorbs solar energy rather than reflecting it. So when a recent scientific excursion to the Indian Ocean established that big soot clouds were circulating through the atmosphere, a number of scientists speculated that their presence might be raising sea-surface temperatures, potentially affecting the strength of the monsoon.

The monsoon is not the only climate cycle that human activity could alter. Atmospheric scientist John M. Wallace of the University of Washington believes that rising concentrations of greenhouse gases are already beginning to have an impact on another important cycle, known as the North Atlantic or Arctic Oscillation. In this case it's not the warming these gases create in the lower atmosphere that is key, but the cooling they cause in the stratosphere, where molecules of carbon dioxide and the like emit heat to space rather than trapping it in the upper atmosphere. This stratospheric cooling, Wallace and others speculate, may have biased prevailing wind patterns in ways that favor a wintertime influx of mild marine air into Northern--as opposed to Southern--Europe.

Is Wallace right about this? No one yet knows. We are tampering with systems that are so complex that scientists are struggling to understand them. Climatologist Tom Wigley of the National Center for Atmospheric Research, for one, fervently believes the answer to our problems lies not just in improved knowledge of the climate system but in technological advances that could counter--and perhaps reverse--present trends. In other words, the farfetched dreams that prominent scientists like Von Neumann once harbored have not died. Rather they have been transformed and, in the process, become more urgent.