Re: Geoengineering - Possible Ways to Counteract Global Warming



BottleBob wrote:
To All:

In this month's (Nov. 2008) issue of Scientific American, there is an article on proposed ways to cool the Earth. Some excerpts follow:

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http://www.sciam.com/article.cfm?id=geoengineering-how-to-cool-earth

#1. Particles in the Stratosphere:

The geoengineering scheme Crutzen and Wigley both defend is the cheapest and most certain to work; The idea is to inject several million tons a year of sulfur dioxide (SO2) into the stratosphere. There it would react with oxygen, water and other molecules to form minute sulfate droplets made up of water, sulfuric acid (H2SO4) and whatever dust, salt or other particles onto which the acid and water condense. Clouds of sulfate droplets would scatter sunlight, making sunsets redder, the sky paler and the earth’s surface, on average, cooler—everyone agrees on all that. In 1991 the volcanic eruption of Mount Pinatubo in the Philippines put 20 million tons of SO2 into the stratosphere, and it had all those effects: it cooled the earth by nearly one degree Fahrenheit for about a year. “So we basically know it works,”

#2. Sea Mist in the Troposphere:

John Latham’s idea for cooling the planet is essentially to whiten existing marine clouds by lacing them with lots of ship tracks—but made in a cleaner way. Latham, a retired English cloud physicist, thinks spraying microscopic drops of seawater into the sky from a fleet of unmanned sailing vessels could do the trick.
In principle, adding particles to the atmosphere makes for more but smaller drops, hence whiter and more reflective clouds.

#3.
A Sunshade in Space:

This proposal calls for placing a sunshade at L1, the inner Lagrangian point, a million miles from the earth in the direction of the sun. (At a Lagrangian point the sun exerts the same pull of gravity as the earth does.) From L1 a sunshade would cast an even shadow over the planet without polluting the atmosphere.
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Now as the article says, these ideas are not without possible unknown risks, and even if they work they are short term stopgap measures. But at least some people are doing more than just complaining about the problem and are generating & offering possible solutions - if only temporary.


Uh... Isn't sulfuric acid in the atmosphere a big part of what's wrong with Venus? And isn't water the "worst" of the so-called greenhouse gasses, in terms of its ability to let sunlight into the atmosphere, and then trap heat before it can escape into space?

KG

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