Letter writer: Science makes the case for limiting CO2

Graphic by Lori Deaton

In his [July 8] letter, [“Climate-change Believers Betray Their Naiveté“], Michael Ivey lectures others on climate change. First, he claims that “CO2 is not a “pollutant. There’s simply not enough of it in the atmosphere.” By this logic, you could drink a glass of water spiked with cyanide: It can’t possibly harm you, since “there is not enough of cyanide compared to water,” right?

Next: “Atmospheric CO2 attributable to all human activities is extremely small compared to natural sources.” That’s easy enough to test: The preindustrial (natural) CO2 was 280 parts per million. Today is greater than 400 ppm. A 45 percent increase [is] “extremely small”?

Next ditty: “Around 98 percent of all ‘greenhouse gas’ is water vapor.” First, the number of 98 percent is a fake, invented by climate-change deniers and referenced only by other deniers. The reality is quite different.  Water vapor is responsible for “between between 36 percent and 66 percent“of the the greenhouse effect (see http://avl.mx/1bu).

But that’s not even half of a story, as the 36 to 66 percent is mainly about the preexisting (preindustrial) greenhouse effect, while in the context of the climate change, only the factors  that change matter. And unlike CO2, the concentration of water vapor hardly budged, mainly following the temperature, which means that water vapor is not the driver of climate change, but merely a passive feedback, an amplifier of other factors that do initiate the climate change: Warm the Earth a bit by other means (like extra CO2), and water vapor would amplify this warming; cool the Earth a bit, and water vapor would amplify the cooling too.

All this means that the water vapor makes the climate not less, but MORE sensitive to human emissions of CO2, since even a small increase in CO2 heating would be made worse by additional heating by water vapor.

Therefore, unwittingly, Mr Ivey made a strong argument for limiting our CO2 emissions: Thanks to the amplifications by water vapor, such CO2 cuts would have larger effects on the climate than on their own.

But don’t let your ignorance of elementary climatology, Mr. Ivey, stop you from lecturing others about “naivete” and “ridiculous assertions.”

— Piotr Trela, Ph.D. (oceanography)
St. John’s, Canada

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