For several years government meteorologists in cooperation with the Defense Department have made a series of hurricane modification experiments under the rather evocative name Stormfury. Some of the experiments have been conducted by means of computers using mathematical models of how these major storms behave; others through work on actual hurricanes by seeding them with silver iodide from aircraft.
Last September, in the most recent of these experiments, rain-belt clouds 70 to 100 miles from the center of hurricane Ginger were seeded. After these operations R. Cecil Gentry, who is director of Project Stormfury, said, "Observations made reveal that there were changes in the clouds that were seeded and in the structure of the storm." This was only the latest in a series of experimental results that suggest that wind and rain intensity in hurricanes can be altered quite substantially by seeding. There is now talk among some scientists that hurricane modification is a reality and that operational programs can be initiated.
The benefits from hurricane modification could be large. Each year these storms take a number of lives in the United States and cause many millions of dollars worth of damages by wind and flood. Typhoons, their counterparts in the Pacific, are even more destructive of human life.
It can be anticipated that once the efficacy of modification has been demonstrated, pressures for launching operational programs will be immense. When a major storm is bearing down upon a heavily settled land area, it is easy to imagine how difficult it would be for scientists and technicians in a government agency to resist pressures from the Congress and the public do what they can to mitigate damages.
Perhaps a program of hurricane modification would indeed be a boon to the nation. But there is concern that such a program may be launched before all its ramifications are properly examined. Many are not now well understood. Some portions of the United States are substantially dependent on hurricanes for rainfall. In this connection, would modification be a favorable or an unfavorable development? We do not know. It is possible that more gentle and useful rain would fall over large areas as a result of the modification. On the other hand, the reduction in the storm intensity might reduce its capacity to penetrate inland areas. Other ecological effects, such as those on the morphology of streams and estuary areas, have not been carefully examined. Stream systems have evolved in the context of highly variable rainfall and streamflow, including occasional high flood levels. Clearly, some examination of the implications of substantially altering this regimen is needed.
Moreover, it is not certain that hurricane modification would reduce damage or loss of life. Since the mid-1930s the Corps of Engineers has been vigorously engaged in constructing reservoirs and other facilities to control flood damage. As the studies of geographer Gilbert White and his associates have shown, we have at the same time seen no decline in damage but, if anything, increasing amounts of overall destruction. This results from heavier occupation of flood plains, often based on misunderstanding of how much protection has actually been provided. White has long advocated a program of zoning and flood information, which has now, to a small extent, come into practice. Based on this experience, it is fair to speculate that a major result of our ability to modify hurricanes will be a rapidly expanding occupation of hazardous sites in the coastal and river basin areas affected by hurricanes. Unless controls on land use are imposed simultaneously, it could well be that modification would not reduce the amount of damage or loss of life.
Clearly, there is an urgent need to examine the hurricane modification program in a much broader context than has so far been done. Up to now, and perhaps quite properly, the focus has been exclusively on the issue, "Can we modify these huge storms?" Now we must turn to the equally difficult, if not more difficult, question, "If we can modify them, should we?"
A version of this article appeared in print in the January 1972 issue of Resources magazine.
