Thursday, May 29, 2008
Scientists know: Global warming is real
From the RoundTable blog
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James W. Laughner
Laughner lives in Roanoke and teaches physics at Cave Spring High School. He worked for Owens-Brockway in the 1970s, where he used Wien's law every day, and was a researcher in materials processing at Corning Inc. and a professor at Alfred University.
I am a materials scientist now teaching high school in Roanoke, not a political columnist. I'm not competent to comment on the political column titled "'Sound science' is damaging" (May 19). However, I feel I must correct the "sound science" essay printed that same day titled "Global warming or cooling? Who knows?"
In it, Sherwood Thoele showed an ignorance of physics that is disappointing for someone who chose to write about global warming. He quoted "they," "academia" and "certain think tanks" as his opposition, but never actually named a single source.
Because Thoele ignored the basics, this response contains references and gives verifiable facts. I will not just say "some think" or "some claim." My sources will be italicized so you can look them up online, in textbooks or find the original articles.
The Journal of Geoscience Education, v.49, n.3, May, 2001, p. 274-279 gives the history: Joseph Fourier, an atmospheric chemist in the 1800s, learned that light energy comes into the Earth easier than it leaves. In 1896, the Swedish scientist Svante Arrhenius calculated that doubling the carbon dioxide in the atmosphere would raise the average global temperature by about 10 degrees F. Global warming physics is more than 100 years old.
The law behind it, Wien's Displacement Law, dates at least from 1893. This law, verified millions of times, relates the type of light given off by anything to its temperature. The sun temperature is 5,500 degrees C, so the light it gives off peaks in the green waves, not in the infrared, so Thoele's entire commentary is completely off base. The Earth (mostly the surface, not the atmosphere) absorbs this light and heats up, to about 15 degrees C. While the sun gives off mainly visible light, using Wien's law we calculate that the Earth radiates infrared light. Both of these calculations have been verified by direct measurement.
Carbon dioxide lets green light (and most other visible light) pass right through. This has been measured directly and is shown in the Robert Simmon absorption graph and many other direct measurements. So sunlight gets in through the atmosphere easily, heating the Earth. But carbon dioxide blocks the infrared light that the Earth would otherwise give off into space. So the Earth heats up.
No scientist doubts the physics, but other questions came up. Was so much carbon dioxide going into the air? Would other climate changes drown out the CO2 warming? Back in the 1970s, we wanted to believe the effects would not be great, but after the early data from Hawaii, a large change was confirmed. We were wrong. But as good scientists, we had to accept data and not use the "sound science" method of making stuff up when you don't like the real results.
This principle of transmission/absorption/reflection is exactly the principle behind a glass greenhouse, with glass taking the role of the carbon dioxide as a "one-way mirror for heat." This is not rocket science. But some people think conservatism means never changing and making stuff up to justify stasis. Let's be real conservatives and work together to minimize the well-understood greenhouse effect, instead of fighting wars and splitting our economy apart attempting to maintain our destructive over-consumption of energy.
