Everyone likes to talk about the weather, and maybe someone could do something about it someday. From the dances and prayers of the past, we get to the weather-modification technology of the 24th century (at least, that's what I recall from an episode of Star Trek: The Next Generation).
Controlling cyclones is an effort entirely different from, say, making it rain. A storm as massive as Hurricane Irene would seem to defy any attempts by mere mortals to deflect it. Yet the idea isn't as farfetched as it might seem, thanks to chaos theory.
Ross N. Hoffman, a principal scientist at Atmospheric and Environmental Research in Lexington, Mass., described in the October 2004 issue (sorry, pay wall) of Scientific American how models showed it was indeed possible to re-route storms. Being chaotic systems, hurricanes are highly sensitive to initial conditions, so adjusting humidity or temperature could be enough, as the storms grows, to send them away from sensitive areas.
Here's how Hoffman described what he found in a simulation of the Hurricane Iniki, a 1992 storm that was the most powerful ever to hit the Hawaiian islands:
The most significant modifications proved to be in the starting temperatures and winds. Typical temperature adjustments across the grid were mere tenths of a degree, but the most notable change—an increase of nearly two degrees Celsius—occurred in the lowest model layer west of the storm center. The calculations yielded wind-speed alterations of two or three miles per hour. In a few locations, though, the velocities changed by as much as 20 mph because of minor redirections of the winds near the storm’s center.
Although the original and altered versions of Hurricane Iniki looked nearly identical in structure, the changes in the key variables were large enough that the latter veered off to the west for the first six hours of the simulation and then traveled due north, so that Kauai escaped the storm’s most damaging winds. The relatively small, artificial alterations to the storm’s initial conditions had propagated through the complex set of nonlinear equations that simulated the storm to result in the desired relocation after six hours. This run gave us confidence that we were on the right path to determining the changes needed to modify real hurricanes.
Of course, just how to change those initial conditions is another matter. Proposals abound, including one that made headlines in 2009 because the patent holders included Microsoft founder Bill Gates. The key is to change the ocean's local surface temperature, say, by pumping up deep, cold water or using giant plastic tubes to help mix the ocean layers. Other ideas appear in the graphic below, from Hoffman's article.
Thinking that humans can manipulate nature in this way seems hubristic. But considering the danger from hurricanes and the enormous costs they exact, it may be worth a try.