Climate manipulation ideas have been around for quite a while. In the middle of the last century, Nobel Laureate Irving Langmuir at General Electric came up with the idea of seeding clouds with iodide crystals or dry ice to produce rain in specified areas and he achieved a certain degree of success. During the cold war, the U.S. was intent on controlling space as it was speculated that detonating a chlorine or bromine bomb could rip a giant hole in the earth’s ozone layer and that dozens of megaton bombs seeding the earth’s magnetic field could lead to an eventual solution to the probem of climate control.
When a number of scientists started to believe that the rapidly increasing concentrations of carbon dioxide were responsible for global warming and climate change, they considered two approaches to moderate the effects. One of these was to reduce the amount of CO2 already in the atmosphere by sequestering it it in some way. This might involve dumping thousands of tons of iron dust into the ocean to cause iron-eating planktons to bloom, which would suck unwanted CO2 from the atmosphere and drag it to the bottom of the sea. The other appraoch was to offset the effects of increased greenhouse gas concentrations by reducing the absorption of solar radiation or deflecting sunlight.
This gets me to last October (Chem & Eng. News, Dec. 17. 2102)., when a Canadian firm tried to promote salmon growth offshore British Columbia by dumping large quantities of iron dust into the ocean that would promote plankton growth through CO2 absorption. According to the firm, Haida Salmon Restoration Corp, this resulted in attracting an unusually large number of fish, seabirds and marine mammals. It turns out that this “experiment” was illegal under the Canadian Environmental Protection Act which prohibits ocean fertilization except for legitimate research projects. The United Nations has passed a similar act. Also, the firm was expecting to get offset carbon credits for its carbon sequestering action, which would pay for buying and dumping the iron dust to seed that part of the ocean. To revert to use of this technique in a broader way to mitigate global warming, calculations show that, even if successful, this would require impractically large amounts of iron dust.
The other geoengineering approach, solar radiation management, involves reflecting sunlight. thus mitigating global warming while ever increasing amounts of CO2 are spewing into the atmosphere. Ideas include space mirrors, releasing swarms of sulfur particles to form stratospheric aerosols, or spraying millions of gallons of seawater into the air to make clouds thicker and white. The 1991 eruption of Mount Pinatubo, which temporarily lowered global temperatures by 0.4 to 0.5 degrees, gave birth to some of these ideas. Still, all of these approaches cause major concerns about possible or likely side effects that may have unforeseen catastrophes. Injecting aerosols into the stratosphere could deplete polar ozone (making even bigger holes then those attributed to (now-banned) refrigeration fluorochemicals) and decrease global rainfall.
Then there is another issue. One country or region might decide to use geoengineering to achieve some beneficial effect that might have negative consequences for another region (eg. more rain here, less rain there). That might lead to war in extreme cases.
So, we are back to the need to reduce the amount of CO2 we are releasing into the atmosphere every day. Geoengineering is considered a last resort, but we can hope that the situation will not become as dire.