Climate impact

Draft a response of no more than 250 words and send it to us this week

Q. Climate scientists are returning home after delivering a presentation about cirrus clouds. The pilot announces, “Ah, folks, we’re taking the shortest possible route from Washington Dulles to Vienna this afternoon, so sit back and relax, knowing we’ve done all we can to reduce this flight’s climate impact.” The scientists let out a collective groan. Why?

Draft a response of no more than 250 words and email it by midnight March 3 to for a chance to have it published in the April issue.


We asked you whether it’s true or false that water vapor would be the only emissions from the Space Shuttle Main Engines or a hypothetical hypersonic air-breathing vehicle fueled by liquid hydrogen.

WINNER: The statement as written is false. The shuttle main engines burn liquid oxygen, so as long as the hydrogen and oxygen are pure, the exhaust is water. But for the air- breathing vehicle, a large amount of nitrogen goes into the engine, and the heat will produce nitrogen oxides, which are a pollutant. There MIGHT be some other compounds created outside the shuttle engine itself, if the hot exhaust is enough to trigger some reactions in the surrounding air.

Bob Parks
San Jose, California
AIAA associate fellow

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Climate impact