Hi, Peter, I think there are couples things which make the results different: (1) G1 doesn't have diffuse radiation increasing; (2) CLM in Xia et al. is CLM-SP instead of CLM-CN; (3) the climate forcing is quite different.
Lili On Thu, Feb 11, 2016 at 12:11 PM, p.j.irvine <[email protected]> wrote: > Hi, > > I wouldn't be so sure that this is a forcing difference. There are VERY > large differences in the model response to high CO2 scenarios, with much > smaller differences between SRM and no-SRM scenarios. These arise because > different factors act to limit vegetation productivity in the different > models. In Susanne Glienke's paper the only models which included a > nitrogen cycle in GeoMIP, a version of CLM, found the opposite trend to > that reported in Xia et al. They found greater tropical productivity in the > non-SRM scenario than the SRM scenario and only a small CO2 fertilization > effect, likely arising from the fact that nitrogen is the limiting factor > in these regions and it is recycled more rapidly in warmer soils boosting > NPP. > > I think it's still early days in the study of the vegetation response to > SRM. > > cheers, > > Pete > > On Thursday, 11 February 2016 08:44:01 UTC-5, Alan Robock wrote: >> >> Dear Bala, >> >> Actually in our paper we say: >> >> Kalidindi et al. (2015) showed that with a 20 Tg sulfate aerosol >> (SO4) stratospheric loading to balance the radiative forcing >> of 2 xCO2, broadband diffuse radiation would increase >> by 11.2 Wm-2 compared with the reference run. However >> they used a very unrealistic stratospheric aerosol distribution, >> with a very small effective radius of 0.17 μm and uniform >> geographical distribution. >> >> So we did different experiments, and we used a much more "realistic" >> aerosol size and space distribution. I think the differences in the >> results are because of the forcing and not the models. >> >> Alan >> >> Alan Robock, Distinguished Professor >> Editor, Reviews of Geophysics >> Department of Environmental Sciences Phone: +1-848-932-5751 >> Rutgers University Fax: +1-732-932-8644 >> 14 College Farm Road E-mail: [email protected] >> New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock >> ☮ http://twitter.com/AlanRobock >> Watch my 18 min TEDx talk at http://www.youtube.com/watch?v=qsrEk1oZ-54 >> >> On 2/10/2016 10:32 PM, Govindasamy Bala wrote: >> >> Interesting result. The conclusions seem to depend on model >> configurations. >> >> Our paper published last year in Climate Dynamics (attached) did not find >> any such benefit from the enhanced diffused radiation because of the offset >> from a reduction in direct light. In fact we found a net reduction in GPP >> of about 1 PgC >> >> Looks like Multi-model intercomparison would be needed to resolve this >> issue. >> >> On Wed, Feb 10, 2016 at 7:39 PM, Alan Robock <[email protected]> >> wrote: >> >>> Our most recent paper has just been published: >>> >>> Xia, L., Robock, A., Tilmes, S., and Neely III, R. R.: Stratospheric >>> sulfate geoengineering could enhance the terrestrial photosynthesis rate, >>> Atmos. Chem. Phys., 16, 1479-1489, doi:10.5194/acp-16-1479-2016, 2016. >>> >>> http://www.atmos-chem-phys.net/16/1479/2016/ >>> >>> -- >>> Alan Robock >>> >>> Alan Robock, Distinguished Professor >>> Editor, Reviews of Geophysics >>> Department of Environmental Sciences Phone: +1-848-932-5751 >>> Rutgers University Fax: +1-732-932-8644 >>> 14 College Farm Road E-mail: [email protected] >>> New Brunswick, NJ 08901-8551 USA >>> <http://envsci.rutgers.edu/%7Erobock>http://envsci.rutgers.edu/~robock >>> ☮ http://twitter.com/AlanRobock >>> Watch my 18 min TEDx talk at http://www.youtube.com/watch?v=qsrEk1oZ-54 >>> >>> -- >>> 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 https://groups.google.com/group/geoengineering. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> >> >> -- >> With Best Wishes, >> >> ------------------------------------------------------------------- >> G. Bala >> Professor >> Center for Atmospheric and Oceanic Sciences >> Indian Institute of Science >> Bangalore - 560 012 >> India >> >> Tel: +91 80 2293 3428; +91 80 2293 2505 >> Fax: +91 80 2360 0865; +91 80 2293 3425 >> Email: [email protected]; [email protected] >> Web:http://caos.iisc.ernet.in/faculty/gbala/gbala.html >> ------------------------------------------------------------------- >> -- >> 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 https://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 https://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. 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