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 <p.j.irv...@gmail.com
<mailto:p.j.irv...@gmail.com>> 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
(SO_4 ) stratospheric loading to balance the radiative forcing
of 2 xCO_2 , 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 <tel:%2B1-848-932-5751> Rutgers University
Fax: +1-732-932-8644 <tel:%2B1-732-932-8644>
14 College Farm Road
E-mail:rob...@envsci.rutgers.eduNew Brunswick, NJ 08901-8551 USA
http://envsci.rutgers.edu/~robock
<http://envsci.rutgers.edu/%7Erobock> ☮
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
<rob...@envsci.rutgers.edu> 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:
rob...@envsci.rutgers.edu
New Brunswick, NJ 08901-8551 USA
http://envsci.rutgers.edu/~robock
<http://envsci.rutgers.edu/%7Erobock>
☮ http://twitter.com/AlanRobock
Watch my 18 min TEDx talk at
http://www.youtube.com/watch?v=qsrEk1oZ-54
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Center for Atmospheric and Oceanic Sciences
Indian Institute of Science
Bangalore - 560 012
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