Hurricane Stories Full of Holes
USA TODAY, ABC News, and probably other news outlets have published reports that Bill Gates and others have filed patent applications for a plan to weaken hurricanes.
In brief, the proposal is to have a fleet of ships equipped to pump warm water from near the surface of a tropical ocean in the path of a hurricane and pump cold water up from below.
The science behind this idea is sound. As explained in the chapter on hurricanes in the AMS Weather Book, a layer of water warmer than approximately 80 degrees Fahrenheit that’s at least 150 feet deep is needed for a hurricane to form and continue as a hurricane. Warm ocean water and a deep layer of warm, humid air above the ocean supply the energy that drives a hurricane.
But, the stories raise big questions about the engineering, business, and social aspects of the proposal. Since anything Bill Gates does is news the story is legitimate enough, but I think the reporters of the two stories I’ve seen, in USATODAY.com, and ABC News, could have gone much further than they did in raising questions and telling readers about the physical and economic challenges the proposal would have to overcome.
In fact, they missed a chance to use some easy examples of the physics behind hurricanes and potential ways to weaken them.
When I was a beginning reporter editors told me more than once: “This story has a hole in it big enough to drive a semi (tractor trailer) through.” The holes in the hurricane stories are large enough to fly several hurricane hunter airplanes through.
The first big hole is the question of how much energy would be needed to pump up enough cold water to have an effect. Sea water’s density is approximately 64 pounds per cubic foot. The first question to answer is: How much energy is needed to lift one cubic foot of sea water at least 150 feet?
Also, the plan talks about pumping warm water down into the ocean. I wonder how much energy would be needed to force the less-dense, warm water down and what happens when it gets there. The warm water would initially rise, but I wonder how long the resulting convection would take to mix the warm and cold water.
This problem would be a good one for a high school physics teacher to assign. The students would start by calculating the power needed to lift 64 pounds 150 feet. Then they would calculate how many cubic feet of sea water would have to be lifted and then calculate the total energy required.
A good source for ball park figures of the area of ocean that would have to be cooled is found in the NOAA Hurricane Research Division’s FAQ answer to, “Why don’t we try to destroy tropical cyclones by cooling the surface waters with icebergs or deep ocean water?”
This answer notes the challenge of knowing where to cool the water given the errors in hurricane track forecasts, which is a big problem for any scheme to weaken hurricanes.
Once the students, or enterprising reporters, have ballpark figures for the amount of water that would have to be moved, the energy needed to do this, and what kind of engines would do the pumping, they would ready to calculate the cost for fuel and the amount of greenhouse gasses the pumping would add to the atmosphere.
If the pumping ships would use nuclear power for propulsion and pumping the reporter or students could compare the number of such ships to the number of nuclear-powered vessels the U.S. Navy has built in its long history of using nuclear power.
An enterprising reporter or maybe a high school biology class could look into the potential disruptions to ocean life that cooling the top layer of the ocean would cause.
Another environmental effect that could be looked into is the effects on the water cycle of cooling large areas of warm ocean water. Less water vapor evaporates into the air from a cool ocean than from a warm ocean. Could this affect rainfall over land, such as Caribbean islands downwind from an area of cooled water.
Since tropical storms and even hurricanes often bring needed rain to various places, including in the southeastern United States, would successful weakening of hurricanes help beach-front dwellers at a cost to inland farmers?
As for the business plan, the stories mention the possibility of insurance companies paying to weaken a hurricane.
Questions that could be asked include how much would insurance companies stand to lose if, say, a Category 4 hurricane hit Miami compared with a category 2 storm. What share of the savings would they be willing to pay if the storm were weakened to a category 2.
How would this compare with the costs of other ways the companies could save on insurance payments? For example, many insurance companies in some states give discounts to home owners who have hurricane pretection, such as impact-resistant windows. Would giving bigger discounts or even paying home owners to upgrade their homes pay larger dividends for insurance companies?
Finally, for society as a whole, which investment would be best: building an expensive fleet of pumping ships with economic and enviornmental costs, or investing in ways to mitigate hurricane damage such as stronger buildings and paying owners to move away from especially dangerous areas and converting the land to ocean-front parks?