Polluting the planet to save it?
Readers respond to the idea of injecting sulphur dioxide into the atmosphere to ward off global warming. Some think it’s crazy and dangerous. Others, the real engineers, think they know a better way to do it.

Clearing the air
I am confused. Mr. Teschler, you have previously documented that you do not believe in man-made global warming. However, in your recent editorial, you speak (with some distaste) about a global-warming solution which you surmise will be ignored by politicians, energy-policy folks, and climatologists.

Do you now believe in global warming? What has convinced you of your new position? Or is this another jab at those who do not share your opinions on human effect on the planet? Why the animosity?

Kevin Graney

My point in the editorial is that many of the people who promote discussion of the “problem” of global warming are more interested in using it to further their own agenda than in solving it. Thus, they are not particularly interested in inexpensive but promising ideas that might cure the problem they claim to be concerned about. — Leland Teschler

How can you buy into the argument that a pair of software engineers have “heavy-duty credentials” that justify a massive interference in the Earth’s ecosystem? And if that weren’t going far enough, you had a couple economists ratify the decision as sane. I thought engineers were supposed to be the voice of reason.

Isn’t there enough evidence from hydroelectric projects, introduction of alien species, oil spills, and pesticide use and abuse to suggest we have a poor ability to predict the side effects of many of our actions?

Rajan Ramaswamy

While I found the editorial on SO2 to combat global warming fascinating (“The global-warming solution you’re not likely to hear about,” Oct. 21), I have to say I was disturbed by the blatant and convoluted effort to find some way to attack environmentalists and their ilk.

The global-warming debate is not between those like Al Gore who want to lie and cheat and spend a lot of money fighting it and the clear-headed conservatives who want to come up with cost-effective engineering solutions like SO2. So the dichotomy you set up is false. The debate is actually between those who believe it’s a problem and those, such as tea partiers and most of the Republican party, who don’t. Those who believe global warming is a severe problem that needs to be addressed will be more than happy to consider fixes like SO2 that you describe, and they will not reject such ideas on the grounds that they don’t cost enough or will prevent them from lining their pockets with grant money.

Charles Spungen

I said nothing about tea partiers, republicans, liberals, or democrats. The observation about the cost of Al Gore’s program was from economist Steven Levitt in SuperFreakonomics, not me. I only passed it along. Levitt probably mentioned it because Gore has reportedly called the scheme by IV “nuts.”

As for rejecting solutions to global warming, I will only say that if you make a living studying a specific problem, it is human nature to hope that problem doesn’t get fixed too quickly. And cynics would say there are instances throughout history where politicians decided to turn problems into campaign issues rather than solve them. — Leland Teschler

Your article may have inadvertently pointed to an even cheaper way to inject SO2 into the upper atmosphere. Airliners and military aircraft often fly high enough to serve as injection platforms. They could burn cheaper sulphur-laden fuel above some threshold altitude and cool the Earth while they carry out their military and commercial duties. The scheme proposed in the editorial would threaten aircraft with a maze of wind-blown hoses and put technicians at risk as they try to service 18-mile-long flexible hoses in the sky.

Arnold Haupt

Let’s see. We’ve spent the past 30 years getting sulphur out of our fuels and oils because those nasty engineers who like to burn fuels to make electricity to heat, cool, and light the world were irresponsible. Now we’re in the doghouse again because we’ve successfully removed most of the sulphur and the result is global warming?

Mike Clark

Injecting sulfur dioxide into the stratosphere, an alternative to draconian fuel-economy requirements for cars, undoubtedly will appeal to a lot of us. But wouldn’t deliberately putting SO2 into the air create an acid-rain problem?

Alex Kovnat

You don’t become chief technology officer at Microsoft without thinking about such issues as acid rain in a scheme like this. If you look at IV’s white paper on the idea, you’ll find this passage:

“Scientific studies published so far conclude that any increase in the acidity of rain and snow as several million additional tons a year of SO2 precipitate out of the atmosphere would be minuscule and would not disrupt ecosystems [B. Kravitz, A. Robock, L. Oman, G. Stenchikov, and A.B. Marquardt. Sulfuric-acid deposition from stratospheric geoengineering with sulfate aerosols. Journal of Geophysical Research 114, D14109, 2009].”— Leland Teschler

Symbolic errors and corrections
Thank you for the informative article “The changing face of part inspection” appearing in the Oct. 21, 2010 edition of Machine Design.

I closely monitor developments of companies writing inspection software which can leverage tolerance specifications “built into” solid CAD models to accelerate part inspections. Articles such as this highlight the trend within industry to automate inspection services by comparing measurements of parts and features directly with 3D models annotated with GD&T.

But the side bar “A closer look at 3D GD&T” contains some errors.

The symbol for Flatness is not a straight line. It depicts Straightness. The correct symbol for Flatness is c.

The symbol for Position is not concentric circles. This depicts Concentricity. The correct symbol for Position is j.

Kevin C. Parsons

Thanks for taking the time to point out these errors. And thank goodness for readers such as you who keep me on my toes! Below are the proper symbols and designations. — Leslie Gordon

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