Huber & Sherwood (PNAS 2010) establishes a hard biological limit to habitability under warming.
http://www.pnas.org/content/early/2010/04/26/0913352107.abstract An adaptability limit to climate change due to heat stress Steven C. Sherwooda,1 and Matthew Huberb Author Affiliations Abstract Despite the uncertainty in future climate-change impacts, it is often assumed that humans would be able to adapt to any possible warming. Here we argue that heat stress imposes a robust upper limit to such adaptation. Peak heat stress, quantified by the wet-bulb temperature TW, is surprisingly similar across diverse climates today. TW never exceeds 31 °C. Any* exceedence of 35 °C for extended periods should induce hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible.* While this never happens now, it would begin to occur with global-mean warming of about 7 °C, calling the habitability of some regions into question. With 11–12 °C warming, such regions would spread to encompass the majority of the human population as currently distributed. Eventual warmings of 12 °C are possible from fossil fuel burning. One implication is that recent estimates of the costs of unmitigated climate change are too low unless the range of possible warming can somehow be narrowed. Heat stress also may help explain trends in the mammalian fossil record. --- Fred Zimmerman Geoengineering IT! Bringing together the worlds of geoengineering and information technology GE NewsFilter: http://geoengineeringIT.net:8080 On Wed, Apr 17, 2013 at 8:15 PM, Ken Caldeira <kcalde...@carnegiescience.edu > wrote: > I am of the opinion that while climate change may pose an existential > threat to those already facing existential threats (i.e., the poor, the > marginalized, etc) it is far less clear how large a threat climate change > poses to those who live in gated communities. > > I was quoted in the New Yorker recently (behind a pay wall, but slightly > misquoted here): > http://stevemasover.blogspot.com/2012/06/human-are-like-rats-and-cockroaches.html > > *"I have two perspectives on what this might mean," he said. "One > says: humans are like rats or cockroaches. We are already living from the > equator to the Arctic Circle. The weather has already become .7 degrees > warmer, and barely anyone has noticed or cares. And, yes, the coral reefs > might become extinct, and people from the Seychelles might go hungry. But > they have gone hungry in the past, and nobody cared. So basically we will > live in our gated communities, and we will have our TV shows and Chicken > McNuggets, and we will be O.K. The people who would suffer are the people > who always suffer. > > "There is another way to look at this, though," he said. "And that is to > compare it to the subprime-mortgage crisis, where you saw that a few > million bad mortgages led to a five-per-cent drop in gross domestic product > throughout the world. Something that was a relatively small knock to the > financial system led to a global crisis. And that could certainly be the > case with climate change."* > > http://www.newyorker.com/reporting/2012/05/14/120514fa_fact_specter > > I think the uninhabitable claim of Hansen is a bit excessive. While such > a world might not be very pleasant, I don't see it as threatening > fundamental habitability. > > In the attached Scientific American article, I wrote: > > *We are re-creating the world of the* > *dinosaurs 5,000 times faster [than it was created in the Cretaceous].* > * > * > *What will thrive in this hothouse? Some* > *organisms, such as rats and cockroaches,* > *are invasive generalists, which can take advantage* > *of disrupted environments. Other* > *organisms, such as corals and many tropical* > *forest species, have evolved to thrive in* > *a narrow range of conditions. Invasive species* > *will likely transform such ecosystems* > *as a result of global warming. Climate* > *change may usher in a world of weeds.* > *Human civilization is also at risk. Consider* > *the Mayans. Even before Europeans* > *arrived, the Mayan civilization had begun* > *to collapse thanks to relatively minor climate* > *changes. The Mayans had not developed* > *enough resilience to weather small* > *reductions in rainfall, and the Mayans* > *are not alone as examples of civilizations* > *that failed to adapt to climate changes.* > *Crises provoked by climate change are* > *likely to be regional. If the rich get richer* > *and the poor get poorer, could this set in* > *motion mass migrations that challenge* > *political and economic stability? Some of* > *the same countries that are most likely* > *to suffer from the changes wrought by* > *global warming* > *also boast nuclear weapons.* > * > * > *Could climate change exacerbate existing* > *tensions and provoke nuclear or* > *other apocalyptic conflict? The social response* > *to climate change could produce* > *bigger problems for humanity than the* > *climate change itself.* > > On Wed, Apr 17, 2013 at 9:32 AM, David Lewis <jrandomwin...@gmail.com>wrote: > >> Jim Hansen is circulating a >> note<http://www.columbia.edu/~jeh1/mailings/2013/20130415_Exaggerations.pdf>calling >> attention to the Hansen, >> et.al. "near final" paper (entitled* Climate Sensitivity, Sea Level, and >> Atmospheric CO2) * presently available on arXiv.org, i.e. >> here<http://arxiv.org/abs/1211.4846> >> . >> >> The concluding sentence of the abstract reads: "*Burning all fossil >> fuels, we conclude, would make much of the planet uninhabitable by humans >> *, thus calling into question strategies that emphasize adaptation to >> climate change." >> >> Over to those putting forward or supporting the McBurger hypothesis... >> >> (The "McBurger Hypothesis" holds that climate change may only become an >> issue of secondary importance to those who matter,* even if all fossil >> fuels are burned*, because it is thought possible or even likely that >> the American middle class will continue to find ways to remain riveted to >> their video game screens while surviving on orders of Chicken McBurgers or >> whatever else is delivered to their climate change proof homes and >> civilization....) >> >> -- >> 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 geoengineering+unsubscr...@googlegroups.com. >> To post to this group, send email to geoengineering@googlegroups.com. >> Visit this group at http://groups.google.com/group/geoengineering?hl=en. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > > -- > 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 geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at http://groups.google.com/group/geoengineering?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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