A couple months ago, I was looking at the patterns over time of sulfur pollution in the atmosphere and global warming. Sulfur emissions have long been known to reduce surface temperatures, as has been shown after large volcanic eruptions.
I noticed that while sulfur emissions were growing in the two decades lasting into the early 1970s, temperatures were cooling slightly. At the time of the first Earth Day in 1970, this cooling led some academics to predict a new Ice Age (though even in 1970, other researchers were worried about global warming because of the longer trend). In response to concerns over sulfur pollution and the acid rain it caused, the U.S. and other countries cut back sulfur emissions substantially, which then corresponded with an increase in temperature.
This led me to wonder about a possible contribution (however small) of pollution control to global warming. It also led me to concoct the goofy idea that perhaps introducing sulfur into the atmosphere could be considered as a way to cut down global temperature increases. Because my ignorance in environmental matters is considerable and my idea was based in part on what might have been a random correlation, I thought that my idea was too strange even to float on this blog.
Then today I saw a news article that reported on a new academic proposal to inject sulfur into the stratosphere. Apparently, the idea of using sulfur to reduce global warming has been kicked around for some years, though I hadn't heard of it.
The author of the paper in the scholarly journal Climatic Change is Nobel laureate Paul Crutzen. I was able to download the paper from this site, but that may have been because of my university's subscription to the journal.
One way to curb global warming is to purposely shoot sulfur into the atmosphere, a scientist suggested today.
The burning of fossil fuels releases carbon dioxide, a greenhouse gas, into the atmosphere. It also releases sulfur that cools the planet by reflecting solar radiation away from Earth.
Most researchers say the warming effect has been winning in recent decades.
Injecting sulfur into the [stratosphere, which is about 9-31 miles above the surface] ... would reflect more sunlight back to space and offset greenhouse gas warming, according to Nobel laureate Paul Crutzen from the Max Planck Institute for Chemistry in Germany and the Scripps Institution of Oceanography, University of California at San Diego.
Crutzen suggests carrying sulfur into the atmosphere via balloons [or] using artillery guns to release it, where the particles would stay for up to two years. The results could be seen in six months.
Nature does something like this naturally.
When Mount Pinatubo erupted in the Philippines in 1991, millions of tons of sulfur [were] injected into the atmosphere, enhancing reflectivity and cooling the Earth's surface by an average of 0.9 degrees Fahrenheit in the year following the eruption.
Crutzen favors Kyoto and restrictions on greenhouse gases as the best approach, but believes that injecting sulfur may be easier to achieve politically. He also claims that injecting sulfur directly into the stratosphere would lead to many fewer health problems to humans than allowing more sulfur fuel burning on the surface of the planet.