Should we throw salt from the ocean into the air? Ask Carter.


An up close view of one of Purdue’s supercomputers Carter. (Credit: Purdue University/Andrew Hancock)

Miles Evans

The world’s largest surface, the ocean, may be the answer to reversing rising temperatures and its negative effects.

After a period of lots of work, failed attempts to get the code working, research, and collaboration, I have three models running. They will continue to run almost continuously on Purdue’s supercomputer, Carter*, until the end of July, when I will analyze their output and report the results.

The first model is pretty standard and will fit in with the work of the other interns’. It will be a scenario that outlines the climate should humanity take modest carbon emission mitigation actions. The other two models are my individual work and go together. One of the remaining models is a control scenario that will predict what the climate will be like in the future if we, as a species, take little action to mitigate emissions or their impacts. The other model will test a strategy for lowering the temperature of the earth by kicking a lot of salt from seawater into the atmosphere. Because the salt in aerosol form reflects light, it will have the effect of scattering sunlight back into space before it can warm the planet. In addition, it will seed clouds and hopefully make the Earth even more reflective. At least, this is the idea currently.

Strategies to lower the temperature of the Earth without controlling carbon emissions are generally called geoengineering strategies. Many of these strategies can be relatively mundane, such making all roofs white, while others are more exotic, such as floating big, reflective mirrors in the upper atmosphere or firing clouds of dust into orbit to block sunlight. Even within the category of increasing the amount of aerosols (like sea salt) in the atmosphere, there is much variety. Most commonly, people are looking at mimicking volcanoes by injecting aerosols of sulphur compounds into the stratosphere. Others look at injecting salt directly into the stratosphere by means of a system of boats, balloons, and pumps.

My model involves a simpler scenario where we use boats or rafts to spray sea water around on the surface of the ocean. While being easier to do, much of the salt aerosol that gets produced will fall to the ocean or be caught by rain very quickly. Only a very small percentage of it will complete the journey to the stratosphere, where it will do the most good. It will be interesting to see if this geoengineering strategy will have much of an impact.

*Speaking of supercomputers, Purdue and Indiana University’s rivalry has found another way to manifest itself. Earlier this summer, IU unveiled the fastest supercomputer only to be put to shame two months later by Purdue.

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