Nobel Laureate Offers a Solution to Global Warming

Published October 1, 2006

Nobel Prize-winning scientist Paul Crutzen, professor emeritus at Utrecht University in the Netherlands, has set the scientific community afire with a proposal to address global warming, should it be demonstrated to endanger the planet.

Crutzen, who won a Nobel Prize in 1995 for his work regarding atmospheric ozone depletion, demonstrated in the August issue of Climate Change that sulfur dioxide can be released into the Earth’s extreme upper atmosphere to deflect incoming solar radiation and lower the Earth’s temperature.

Inspired by Mt. Pinatubo

Crutzen’s proposal was inspired in part by sulfur dioxide releases in the 1991 Mt. Pinatubo volcanic eruption, which lowered global temperatures by 0.5 degrees Celsius for a full year. That cooling negated slightly more than half of the Earth’s total temperature gain over the entire previous century.

Crutzen proposes similar releases of sulfur dioxide into the stratosphere, where he says it would be remarkably effective and would reside for an optimal amount of time. Optimizing the location and timing of sulfur dioxide releases would mean far less sulfur dioxide would have to be released to achieve results similar to those from the Mt. Pinatubo eruption.

“Although climate cooling by sulfate aerosols also occurs in the troposphere, the great advantage of placing reflective particles in the stratosphere is their long residence time of about 1-2 years, compared to a week in the troposphere,” Crutzen observed in his proposal. “Thus, much less sulfur, only a few percent, would be required in the stratosphere to achieve similar cooling.”

Safety Valve Available

Importantly, with each sulfur dioxide injection staying in the atmosphere for only two years or so, fine-tuning could be easily done, and there would be no risk of unwanted long-term climate change.

“Such a modification can also be stopped on short notice, which would allow the atmosphere to return to its prior state within a few years,” Crutzen observed.

CO2 Doubling Negated

According to Crutzen, global climate modeling suggests annual releases of sulfur dioxide into the stratosphere would be able to negate as much as a full doubling of atmospheric carbon dioxide. To put that in perspective, carbon dioxide levels have increased by less than 50 percent since the dawn of the Industrial Revolution.

Other options, such as releases of soot or elemental carbon into the stratosphere, might be even more effective than sulfur dioxide, though more research is required into such approaches, Crutzen suggested.

Quick Results Achievable

A significant benefit to sulfur dioxide, soot, or elemental carbon releases, Crutzen reported, is the very quick nature of expected results.

“In contrast to the slowly developing effects of greenhouse warming associated with anthropogenic CO2 emissions, the climatic response of the albedo enhancement experiment would start taking effect within about half a year, as demonstrated by the Mount Pinatubo eruption,” Crutzen wrote.

“Thus, provided the technology to carry out the stratospheric injection experiment is in place, as an escape route against strongly increasing temperatures, the albedo adjustment scheme can become effective at rather short notice,” Crutzen added.

“This whole issue is a reasonable subject of debate,” said Patrick Michaels, professor of natural resources at Virginia Tech University and past president of the American Association of State Climatologists.

“While Crutzen tends to exaggerate climate effects from asserted global warming, he does raise a very reasonable and timely subject,” Michaels continued. “The technology exists to engineer the planet’s climate to our liking, and the subject will increasingly be discussed in public and scientific circles because people who look at the data know that there is very little that can be done to alter the temperature trajectory of the planet merely by curtailing carbon dioxide emissions with present technology.”

Censorship Suggested

In his proposal Crutzen stressed he would prefer to see humans reduce their carbon dioxide emissions, but he observed such an approach may be difficult or impossible to achieve.

“The controversial approach is being taken seriously by scientists because Professor Crutzen has a proven track record in atmospheric research,” the London Independent reported on July 31.

Nevertheless, the Independent reported Crutzen’s proposed atmospheric insurance policy “is so controversial that some scientists opposed its publication in the peer-reviewed scientific press, fearing that it may encourage the view that it is easier to treat the symptoms rather than the causes of climate change.”

“That’s a pretty naked admission that what is scientifically true and credible is being repressed, for political purposes, by ideologues,” observed Michaels. “This is not the way science is supposed to operate. Such behavior speaks for itself regarding how so many alarmists are willing and indeed eager to throw truth under the locomotive wheels of political advocacy.”

James M. Taylor ([email protected]) is managing editor of Environment & Climate News.

For more information …

Paul Crutzen’s July 25, 2006 article, “Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma?” is available through PolicyBot™, The Heartland Institute’s free online research database. Point your Web browser to, click on the PolicyBot™ button, and search for document #19632.

“Scientist publishes escape route from global warming,” London Independent, July 31, 2006,