View: | Click here to view the article |
Title: | New Research for Week #21 2022 |
Date: | 5/26/2022 |
Summary: | A cloudless sky on a sunny day looks featureless and inactive to our eyes. In reality, invisible to us a perfect frenzy of chemistry is happening in the daytime sky. For people interested in tracking the life history of a given compound in Earth's atmosphere there are many details to capture and account for. In connection with climate change, we're of course interested in the effective residence time of the most important "greenhouse gases" or GHGs, which include not only CO2 but also methane (CH4) and nitrous oxide (N20). Methane is not only a much more potent GHG than CO2 but is also (and unlike CO2) chemically very busy in the atmosphere, too active and too generous for its own good. CH4's trip into the air is essentially on a one-way ticket; all methane entering the atmosphere is also ultimately destroyed there. Destruction mostly happens in interactions with OH and Cl radicals hungry for electrons on offer by CH4. Careful accounting for availability of radicals is needed to predict the lifespan of methane in the atmosphere. Qinyi Li et al. have paid particular attention to the various roles of various compounds and elements acting in concert and opposition to act on and destroy methane, in Reactive halogens increase the global methane lifetime and radiative forcing in the 21st century (Nature Communications). In particular the authors note that the radical compound OH is a main "consumer" of methane, but OH itself requires 03 (ozone) as a feedstock. Full accounting reveals that 03 is destroyed in suffiicent quantity by halogens such as bromine, iodine and chlorine so as to limit the supply of OH radicals. This is a previously unidentified and hence unconsidered factor, and one that is quite significant. The above atmospheric chemistry description is highly simplified and paraphrased by somebody who did their 3 semesters of university chemistry about 40 years ago. The upshot is pretty easy for all of us to understand. From the... |
Organization: | Skeptical Science |
Date Added: | 5/26/2022 6:37:14 AM |
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