The paper can be read or downloaded from here: http://rsta.royalsocietypublishing.org/content/372/2031/20140134
--- Regarding termination shock, how much is simply repeating things other people have said and how much is based on empirical knowledge? Let's assume something like an RCP8.5 background scenario, in which the most sensitive ecosystems are likely to be substantially damaged by year 2100. Will ecosystems really be in that much worse of a state if they get to year 2100 RCP8.5 conditions smoothly versus at more-or-less constant temperature for the next 65 years and then sudden warming in the last 20 years? Is the amount of damage to these ecosystems really so path dependent? What is the class of species or ecosystems that are likely to be robust to year 2100 RCP8.5 conditions approached smoothly but fragile with respect to year 2100 RCP8.5 conditions approached in a more stepwise manner? Is there any empirical evidence that this class is likely to be large? I am not arguing that sudden termination would not be damaging, but merely pointing out that much of the claim of catastrophic damage is based on simple assertion that has not yet been well supported with reference to empirical facts. _______________ Ken Caldeira Carnegie Institution for Science Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA +1 650 704 7212 [email protected] http://dge.stanford.edu/labs/caldeiralab https://twitter.com/KenCaldeira My assistant is Dawn Ross <[email protected]>, with access to incoming emails. On Sun, Dec 28, 2014 at 12:04 PM, Andrew Lockley <[email protected]> wrote: > Poster's note: interesting alternative deployment model, in which > termination shock risk is potentially much reduced. It would be useful to > get a biologist's perspective on this, as there's a potential risk of a > large excess of extinctions over a scenario in which temperatures were more > robustly supressed. (Swapping termination shock for extermination shock??) > > Solar geoengineering to limit the rate of temperature change > > Douglas G. MacMartin, Ken Caldeira, David W. Keith > DOI: 10.1098/rsta.2014.0134 > Published 17 November 2014 > > Abstract > > Solar geoengineering has been suggested as a tool that might reduce damage > from anthropogenic climate change. Analysis often assumes that > geoengineering would be used to maintain a constant global mean > temperature. Under this scenario, geoengineering would be required either > indefinitely (on societal time scales) or until atmospheric CO2 > concentrations were sufficiently reduced. Impacts of climate change, > however, are related to the rate of change as well as its magnitude. We > thus describe an alternative scenario in which solar geoengineering is used > only to constrain the rate of change of global mean temperature; this leads > to a finite deployment period for any emissions pathway that stabilizes > global mean temperature. The length of deployment and amount of > geoengineering required depends on the emissions pathway and allowable rate > of change, e.g. in our simulations, reducing the maximum approximately > 0.3°C per decade rate of change in an RCP 4.5 pathway to 0.1°C per decade > would require geoengineering for 160 years; under RCP 6.0, the required > time nearly doubles. We demonstrate that feedback control can limit rates > of change in a climate model. Finally, we note that a decision to terminate > use of solar geoengineering does not automatically imply rapid temperature > increases: feedback could be used to limit rates of change in a gradual > phase-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 [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > -- 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 post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
