Thursday, February 7, 2008


During the documentary “Hot Topic”, they mentioned that in 1991 Mt. Pinatubo erupted, releasing large amounts of aerosols (sulfates) into the atmosphere. The sulfates cooled the Earth by 0.5 deg C [Wikipedia.] This cooling slowed down many efforts made to address the climate change issue.

Taking this idea, there is talk about releasing sulfate particles into the stratosphere to block the sun’s rays and help cool the Earth. I first heard this Monday on the radio program “Earth and Sky Radio”. (On the website you can listen to the radio program in full.)We briefly commented on this idea in class Thursday.

In the program Richard Turco of UCLA is very skeptical of “geoengineering” saying we would have to release tens of millions of tons of sulfates into the stratosphere and somehow have the particles disperse “so that it’s a very, very fine particle to get the adequate optical efficiency that we need, and then doing this on a continuous basis, essentially until the climate crisis is over, a thousand years from now.”

“Geoengineering” doesn’t seem very plausible to me, but we’ve already “engineered” global warming… why not “engineer” global cooling? It was effective back in 1991 with Mt. Pinatubo. Are there ramifications for releasing the sulfate particles? Thoughts?

1 comment:

bhansen said...

I actually heard something on this subject in a recent news story aired on NPR. The gist was that we could invoke a number of volcanic eruptions that would put fine particles in the atmosphere which would block/reflect sunlight and thus slow down or reverse global warming. I couldn’t find the article on the NPR website, but I did find a related article that discussed releasing particles in the atmosphere that would form a ‘parasol’ around the globe: The idea would be to send these particles in the air using artillery shells, airplanes or even hoses from balloons. These delivery mechanisms don’t seem very viable, but it’s essentially the same argument. This really does seem like science fiction, but let’s consider the pros/cons:

Pros – In the short term, this would be a low cost fix to the global warming problem (fixing the causes of global warming will be in the trillions of dollars). This already happens in nature (volcanoes erupting) so the basic science is understood. The lifespan of these fine particles is 1-2 years in the air – if we add too much or too little, the concentration can be adjusted within a few years.
Cons – This is a band-aid for the problem – we just put off fixing the real issue of CO2 emissions or even encourage further emissions. Further, since the planet is a complex system, we have no real idea what the effect will be to add these particles to the air. Who knows what the feedback loops will be. Lastly, we would have no way to control the particle concentration on a local basis. The effects of the particles could be beneficial in some areas and not in others – we have no way to control the localized effects.

Overall, this type of fix seems more like a last case scenario if we run out of time to slow down the cascading effects of global warming. The better answer is to start reforms now to fix the root of the problem before we run out of time.