A bizarre 60-year-old idea to fight hurricanes using nuclear weapons resurfaced this week after Axios reported that President Trump raised the possibility with his national security advisors. Trump later denied the report—but regardless, he wouldn’t have been the first to propose it or other wild schemes for stopping cyclones in their tracks.

Hurricane modification is on the scientific fringes today, but in the 1960s and 1970s it was a vibrant area of research, according to Phil Klotzbach, a tropical storm expert at Colorado State University. For several decades, the U.S. government even ran an experimental program aimed at weakening cyclones by misting them with particles of silver iodide. Ultimately, the project was deemed to be fatally flawed and was abandoned.

Other ideas, like using cold water pumps to reduce a hurricane’s strength or soaking up its moisture with a Jell-O-like substance, seem even more far-fetched.

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Project STORMFURY

Possibly the most famous attempt to slay hurricanes was Project STORMFURY, a US government-led program that ran from 1962 to 1983.

In 1949, atmospheric scientist Bernard Vonnegut showed that silver iodide could be used to enhance the formation of ice crystals from supercooled water—water already below the freezing point—inside clouds. By spraying particles of silver iodide on hurricanes, government scientists thought they might be able to induce thunderstorms to form outside of the cyclone’s eyewall. This, they hypothesized, would prompt the eyewall to expand outwards, decreasing its top wind speeds.

Project STORMFURY conducted a range of experiments, including seeding four hurricanes on eight separate days. On half of those days, the hurricane’s winds appeared to weaken by up to 30 percent following silver iodide application. However, these results were later called into question when scientists learned that some hurricanes go through a natural process of “eyewall replacement,” in which outer rain bands form a ring of thunderstorms that migrates inward, weakening and eventually replacing the eyewall. Ultimately, researchers concluded it was this process that likely drove the hurricane weakening they saw in their experiments, not silver iodide.

“The experimental design [of STORMFURY] looked for Category 4 or 5 hurricanes with small eyes,” says Hugh Willoughby, a professor at Florida International University and former director of the National Oceanic and Atmospheric Administration’s (NOAA) Hurricane Research Division. “And those are exactly the hurricanes that are likely to do this.”

Soot and goo

During Project STORMFURY’s heyday, other scientists were thinking about different ways to attack cyclones from the air—like using tiny particles of black carbon, also known as charcoal, to diminish their winds.

Black carbon is a powerful heating agent that absorbs the sun’s energy and releases it into the atmosphere. Tropical storm meteorologist William Gray reasoned that if we used jet aircraft to spray plumes of it into the lower atmosphere, we could crank up the temperature over the ocean, enhancing the evaporation of water and promoting the thunderstorm formation. Similar to STORMFURY, Gray hypothesized that if those thunderstorms formed in the right place, they could weaken a cyclone’s eyewall.

Or, instead of accelerating cloud formation, perhaps we could squeeze hurricane clouds dry. In 2001, entrepreneur Peter Cordani made headlines for sprinkling Dyn-O-Gel—a highly absorbent powder that turns into a slimy goop on contact with water—into a cloud and reportedly making it disappear on radar. Cordani hoped the substance, which his company manufactured for diapers, could one day be used to dry up hurricanes.

But according to Willoughby, the Hurricane Research Division was never able to determine if the physics underpinning Cordani’s idea was actually solid. Even if it were, to have an impact on a hurricane you’d likely need tens of thousands of tons of Dyn-O-Gel. Ditto for black carbon, which may be why neither idea was ever tested on a cyclone.

Cooling the ocean

If we can’t fight hurricanes from the air, what about from the sea? Because cyclones get their energy from heat in the ocean, many scientists and inventors (including Bill Gates) have proposed cooling the ocean’s surface to sap their strength.

In 2011, a team of scientists crunched the numbers on what it would take to deploy an array of “wave-driven upwelling pumps”—pumps that use the vertical motion of waves to force cold, deep water up to the surface through a long tube—around Miami. They found that a system capable of reducing the ocean’s surface temperature by 1 to 1.5 degrees Celsius would cost between $0.9 to $1.5 billion annually. If we got the placement just right, the pumps could weaken a strong hurricane significantly before it made landfall, according to the researchers’ models.

“In principal, that would work,” says senior study author Kerry Emanuel, a professor of meteorology at MIT. The problem, in his view, is the economics of it. “You’d be better off sending people plywood to board up their houses,” he says.

A far more dubious idea that the Hurricane Research Division gets asked about regularly is towing icebergs from the planet’s poles into tropical waters. Beyond the fact that we’d likely need hundreds to thousands of icebergs to make an appreciable dent in ocean heat, there’s a more basic logistical issue with this scheme.

“The iceberg would melt long before it made it to the tropics,” Klotzbach said.

Fatal flaws

After more than 50 years of discussion and experimentation, it’s still unclear if we’ll ever be able to kill or even maim a hurricane. According to Klotzbach, all schemes suffer from two major hurdles: the unpredictability of hurricanes, and their sheer power.

“Hurricanes are just enormous,” Klotzbach says, adding that in a single day, a “typical” cyclone can release more energy than every nation on Earth combined. Put another way, the heat released by a hurricane is comparable to exploding a 10-megaton nuke every 20 minutes. Even if we devised a dissipation method that could match the power of such a storm, there would be the non-trivial task of knowing exactly where the hurricane will be, days in advance, in order to mobilize our defenses.

Finally, there are the potentially significant environmental consequences of fighting hurricanes. Altering the natural mixing of the ocean on a large scale could have enormous effects on marine life. Spraying millions of pounds of tiny soot particles into the atmosphere could create a serious public health hazard for anyone downwind.