{"id":12440,"date":"2024-08-25T11:35:48","date_gmt":"2024-08-25T11:35:48","guid":{"rendered":"https:\/\/topat10.com\/?p=12440"},"modified":"2024-08-25T11:35:48","modified_gmt":"2024-08-25T11:35:48","slug":"the-quantum-mechanics-of-the-greenhouse-effect","status":"publish","type":"post","link":"https:\/\/topat10.com\/?p=12440","title":{"rendered":"The Quantum Mechanics of the Greenhouse Effect"},"content":{"rendered":"


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A key question was the origin of the logarithmic scaling of the greenhouse effect\u2014the 2-to-5-degree temperature rise that models predict will happen for every doubling of CO2<\/sub>. One theory held that the scaling comes from how quickly the temperature drops with altitude. But in 2022, a team of researchers used a simple model to prove that the logarithmic scaling comes from the shape of carbon dioxide\u2019s absorption \u201cspectrum\u201d\u2014how its ability to absorb light varies with the light\u2019s wavelength.<\/p>\n

This goes back to those wavelengths that are slightly longer or shorter than 15 microns. A critical detail is that carbon dioxide is worse\u2014but not too much worse\u2014at absorbing light with those wavelengths. The absorption falls off on either side of the peak at just the right rate to give rise to the logarithmic scaling.<\/p>\n

\u201cThe shape of that spectrum is essential,\u201d said David Romps<\/a>, a climate physicist at the University of California, Berkeley, who coauthored the 2022 paper. \u201cIf you change it, you don\u2019t get the logarithmic scaling.\u201d<\/p>\n

The carbon spectrum\u2019s shape is unusual\u2014most gases absorb a much narrower range of wavelengths. \u201cThe question I had at the back of my mind was: Why does it have this shape?\u201d Romps said. \u201cBut I couldn\u2019t put my finger on it.\u201d<\/p>\n

Consequential Wiggles<\/h2>\n

Wordsworth and his coauthors Jacob Seeley and Keith Shine turned to quantum mechanics to find the answer.<\/p>\n

Light is made of packets of energy called photons. Molecules like CO2<\/sub> can absorb them only when the packets have exactly the right amount of energy to bump the molecule up to a different quantum mechanical state.<\/p>\n

Carbon dioxide usually sits in its \u201cground state,\u201d where its three atoms form a line with the carbon atom in the center, equidistant from the others. The molecule has \u201cexcited\u201d states as well, in which its atoms undulate or swing about.<\/p>\n

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