The question arose from research from research at Lawrence Livermore National Laboratory near San Francisco, by Lowell Wood, a protégé of the brilliant and controversial hydrogen bomb inventor Edward Teller. The idea was simple: Inject sulfur dioxide into the stratosphere to reflect a portion of the sun’s rays back into space, thus cooling the planet. It also seemed to be within the realm of possibility to some.
Here is how it works:
Graphic and text below adapted from Wired magazine article
1. Make sulfur dioxide
A million tons of sulfur dioxide would be needed to begin the cooling process. Luckily SO2, a byproduct of coal-burning power plants, is a common industrial chemical.
2. Inject it into the stratosphere
Load the sulfur dioxide into aircraft — converted 747s, military fighters, or even large balloons — and carry it up to the stratosphere. This will cost about $1 billion a year.
3. Wait for the chemical reaction
In a series of reactions, sulfur dioxide combines with other molecules in the atmosphere, ultimately forming sulfuric acid. This H2SO4 binds to water to form aerosol droplets that absorb and reflect back into space 1 to 3 percent of the sun’s rays. (The particles also contribute to the depletion of the ozone layer, but scientists are researching alternate chemicals.)
4. Let the planet cool
Results will be quick, especially over the Arctic.
And just a few days ago, over a million tons of sulfur dioxide (SO2) was in fact injected into the atmosphere over the Pacific Ocean, here is a satellite sounder derived image of the cloud that has been released:
The Terra/MODIS satellite snapped a nice image of the release, notice the obvious brown trail as the plume becomes airborne over the Pacific ocean:
Here is a photo of where the experiment took place:
The Kasatochi volcano as seen from space, and location map below:
“The August 7-8 eruption of Kasatochi volcano (Aleutian Islands)produced a very large stratospheric SO2 cloud – possibly the largest since the August 1991 eruption of Hudson (Chile). Preliminary SO2 mass calculations using Ozone Monitoring Instrument (OMI) data suggest a total SO2 burden of ~1.5 Tg. This figure will be revised in the coming weeks but is more likely to go up than down. The SO2 cloud has drifted over a large area of North America and is now (August 14) reaching Europe.“
With the released SO2 at ~ 1.5 Tg (Teragrams, a unit of mass approximately equal to one megaton) this is actually 50% more than mass in the experiment proposed by Wood and Teller.
With this eruption coming on the heels of a short term global cooling trend that we’ve seen in the last 18 months, it will be interesting to see if this real-world experiment being performed by nature will add to the trend we’ve already seen.
Click for a larger image
Reference: UAH lower troposphere data
This type of “experiment” has already been seen before in recent times, as the Wired article mentions:
Pinatubo’s eruption didn’t just unleash huge mud slides and lava flows; it also fired an ash stream 22 miles into the air, injecting 20 million tons of sulfur dioxide into the stratosphere. Over the following months, a massive haze gradually dispersed across the globe. Meanwhile, the sulfur dioxide component underwent chemical reactions to form a particulate known as sulfate aerosol (in essence, droplets of water and sulfuric acid), which absorbs sunlight and reflects some of it back into space.
The climatic effect of this volcanic eruption was rapid, dramatic, and planetary in scale. In a year, the global average temperature declined by half a degree Celsius, and researchers observed less summer melt atop the Greenland ice sheet.
An interesting passage in the article on SO2 injection suggests:
Until large-scale experiments are funded, the only way to explore the potential consequences is through computer simulations. By turning down the virtual sun or cranking up the digital carbon, we can create any planetary future we want.
It looks like nature has stepped up and eliminated that need for computer simulation.
Based on Carn’s estimate, when the data is all in on Kasatochi, it will likely be about 10 times less than Pinatubo in total mass of SO2 ejected. But we’ll watch, measure, and see what this smaller event does for our global climate. Unfortunately, most any global cooling we see in the next couple of years, no matter what the true cause of it is, will probably be labeled as “volcanically induced” due to this event.
h/t to Philip_B for comments that lead to this article’s creation
UPDATE: 8/19/08 10:20 AM PST There has some been some questions in comments as to whether or not the plume reached stratospheric levels. This press release from USGS notes that the plume has reached more than 35,000 feet altitude, which would put the plume into the lower stratosphere.