Hi, Peter, The evaporation reduction due to cooler environment would balance the effect of the reduced precip to some extent. The change of evapotranspiration may help. I think more studies are needed to work on all the details.
Lili On Thu, Feb 11, 2016 at 6:38 PM, Peter Irvine <[email protected]> wrote: > Interesting study Lili! One surprise for me was the large increases in > productivity in the amazon - do you think that the temperature reduction > and reduced evaporative demand more than make up for the reduced precip? > > I'm looking forward to the next-gen of nitrogen-limited models getting > into this debate, they produced a different sign of change in Susanne's > study. Cooler was worse for productivity in the tropics rather than better, > despite the factors you identify in your study due to the greater > availability of nitrogen in the warmer soils. This effect is obviously > missing from models without interactive nitrogen cycles > > Pete > > Pete > > Peter J. Irvine > > Postdoctoral Fellow > Harvard University > John A. Paulson School of Engineering and Applied Sciences (SEAS) > One Brattle Square, Office 492, Cambridge, MA 02138, USA > > Email: [email protected] <[email protected]> > https://scholar.google.de/citations?user=7asLSCEAAAAJ&hl=en > > On 11 February 2016 at 15:35, Lili Xia <[email protected]> wrote: > >> 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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