Marine cloud brightening
SALTER Stephen
Dear Cynthia
I have seen your comments about marine cloud brightening. It can be used to put sea surface temperatures back to where they used to be. This ought to be better than unbridled increases.
Salt is medicinally benign and free. Clouds are abundant and self-cleaning. All the power comes from the wind. The amount of salt it would use can be compared to the amount already being thrown up by breaking waves in the slide below.
The red dots are all the estimates in a collection by Lewis and Schwartz plotted against the year they were made. The blue circle is the mean value of 5.4 Gigatonne.
Instead of the wide range of sizes of natural spray, we would generate a very narrow spread of diameters at exactly the sweet spot for successful nucleation of cloud drops. The solar energy that is reflected by a cloud drop is many tens of millions of times more than the energy needed to make the nucleus on which it grew.
About 300 spray vessels could offset the thermal damage since preindustrial times. We might need a thousand if we continue to be criminally insane. The amount of salt needed for this is shown by the thickening of the black line on the X-axis between 1960 and 2000. This change may not be detectable on your screen.
The short life of spray, only a few days, and the mobility of spray vessels means that we have a high frequency control system with powerful brakes for an emergency stop. By choosing the place and season of the spraying we can target different objectives such as loss of Arctic ice and coral, hurricane moderation or the balance between floods in Africa and bush fires in Australia. A side effect of any of these would be a reversal of sea level rise. It would take quite a while, about 20 years but the benefit to cost ratio would be attractive. Please let me know if you would like to check the calculations for these or suggest changes to the input assumptions.
I expect that most of your members would approve of these results. Do they realize that your work might prevent them?
Breathe safely
Stephen Salter
Emeritus Professor of Engineering Design
School of Engineering
Mayfield Road EH9 3 DW
University of Edinburgh
Scotland.
Tel 0131 662 1180