> Spellchecked & edited repost of the above:
The most interesting insight in Yu, Toon, Robock, et al.'s paper is its confirmation of the "once in a blue moon" rarity of stratospheric smoke injections. The orignal 1983 TTAPS paper- Owen Toon is the second T, presumed stratospheric injection would be the norm, and postulated that teragrams of black smoke from thousands of nuclear attack fires would simultaneously rise past the tropopause, creating a hemispheric optical depth of up to 20, reducing sunlight by roughly 3 to 6 orders of magnitude, dropping surface temperatures by tens of degrees to create a lethal global deep freeze lasting for months or years. Climate communicator Carl Sagan, the S in TTAPS, publicly equated the modeled effects with those of the K-T asteroid impact and wrote that: " The extinction of* Homo sapiens* cannot be excluded." He asserted his "Apocalyptic predictions" to be the "robust" products of a "sophisticated one dimensional model." and wrote in *Foreign Affairs * that , never mind the smoke, cooling from dust alone. even from a 50 megaton a nuclear war 100 times smaller that TTAPS 5,000 megaton "baseline" case would produce equally dire effects. Forest fire experiments were accordingly carried out in Canada in the 80's to test TTAPS 'nuclear winter' hypothesis but they failed to produce produce high optical depths or evidence of solar plume bouyancy or stratospheric smoke transport. It took three decades before one natural wildfire out of hundreds produced either. Black smoke from the appallingly intense Kuwait Oil Fires also failed to penetrate the tropopause. although Sagan warned ABC *Nightline *viewers that their emissions would collapse the Asian monsoon and cause a regional famine. It didn't happen. There was once a case for climate modeling hyperbole in the service of disarmament, but the Cold War is long gone. While Alan Robock remains at liberty to call radiative forcing , and single digit temperature changes from more modern and realistic low optical depth GCM model intercomparisons, "nuclear winter ", the two most salient feature of this study are that, as was objected in the 1980's, photochemisry militates * against * the ooptical depth persistance that TTAPS presumed in adducing the term 'nuclear winter. Smoke plumes that reach the stratosphere remaiin rare outliers- we had to wait more than a generation for satellites to catch one in the act. While it is easy to paint a model's sky black- just tell the systems programmer to adjust the code, models are not things ,and the material world is under no obligation to emulate parameters chosen or guessed at in the name of the precautionary principle. TTAPS and the term 'nuclear winter were criticized as just such a case by climate modelers and statregic policy analyst alike, notably* Climatic Change *founder Steve Schneider, and John Holdren's predecessor as Pugwash president, George Rathjens of MIT. CF https://www.nature.com/articles/475037b -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/b6e7fb33-cee2-426d-839c-b1f1d98f425b%40googlegroups.com.
