More work has been done on PSC equable climate theory since Sloan et al.
(1998). For those interested in this topic, see the reference:
Daniel B. Kirk-Davidoff, Daniel P. Schrag, and James G. Anderson, 2002: On the
feedback of stratospheric clouds on polar climate. GEOPHYSICAL RESEARCH
LETTERS, VOL. 29, NO. 11, 1556, 10.1029/2002GL014659.
ABSTRACT:
Past climates, such as the Eocene (55 - 38 Ma), experienced
dramatically warmer polar winters. Global climate models run
with Eocene-like boundary conditions have under-predicted polar
temperatures, a discrepancy which has stimulated a recent
hypothesis that polar stratospheric clouds may have been
important. We propose that such clouds form in response to
higher CO2 via changes in stratospheric circulation and water
content. We show that the absence of this mechanism from
models of Eocene climate may be attributable to poor vertical
resolution in the neighborhood of the tropical tropopause. This
may cause the models to underestimate future greenhouse warming.
From: [email protected] [mailto:[email protected]]
On Behalf Of Michael Hayes
Sent: Wednesday, September 09, 2015 6:22 PM
To: Adrian Tuck
Cc: geoengineering; Greg Rau; R. D. Schuiling (Olaf); Ronal Larson; Mike
MacCracken
Subject: Re: [geo] (must read) Geoengineering as a design problem
Adrian et al.,
Thank you for posting your work on this subject and doing so in such short
time. However, the paper's conclusion clearly states that:
1) The work is limited to the "[...] southern hemisphere.". Aggressive Arctic
methane release, due to marine and atmospheric warming, seems to present the
most critical concern relative to the long list of polar warming issues. And,
methane does seem to effect the "frequency and the optical thickness of PSCs to
increase substantially" per (Sloan
1998<http://onlinelibrary.wiley.com/doi/10.1029/98GL02492/pdf>).
In simple words, we do need qualitative and quantitative investigations of both
polar regions, specifically on the PCS/H2SO4 connection (and other sulfur
compounds), as the dynamics of each polar region offers distinctly different
biogeochemical scenarios.
2) The conclusion in your paper also states that "PSCs always increased the
short-wave heating [...]". On that point, it is easy to beg the question of; If
PSCs increase short-wave heating, should not the increase of the number and
thickness of PSCs, which can be induced with additional H2SO4 and other sulfur
compounds, be avoided in any geoengineering scheme?
Also, your paper seems to suggest that PSCs play a meaningful role in
tropospheric cloud formation and I find in Wang et al.
2008<http://www.atmos.uwyo.edu/~deshler/articles/Wang&_08_GRL.pdf> the
following:
"[...] These new findings suggest that Antarctic PSC formation is closely
connected to tropospheric meteorology and thus governed by synoptic scale
dynamics, local topography, and large-scale circulation. More dedicated studies
are still needed to better understand Antarctic PSC formation."
The latitudinal variances which your paper points out, in respect to ground
temperature, tropospheric cloud cover and stratospheric temperature, as well as
the issues Wang et al. bring to the table, indicates that predictive modeling
of the full spectrum of the biogeochemical response(s) (within the polar
regions and specifically in regards to PSCs) to stratospheric aerosol injection
(SAI) of H2SO4 and other sulfur compounds may simply be beyond our current
modeling abilities.
To conclude, any significant intentional anthropogenic increase in polar
warming, from any biogeochemical avenue, such as SAI, should be viewed as being
too unpredictable to deploy....at this time.
In the most simplistic terms, to our best collective knowledge, SAI can just as
easily warm the polar regions as not. Tough gamble!
Best,
Michael
Michael Hayes
"How inadequate it is to term this planet "Earth", as it is evident that it
should be called "Ocean". Arthur C. Clarke.
US Plan: Chemosynthetic Management of the Water/Energy/Nutrient Nexus
(WENN)<http://climatecolab.org/web/guest/plans/-/plans/contestId/1302001/planId/1318702>
On Wed, Sep 9, 2015 at 4:31 PM, Adrian Tuck
<[email protected]<mailto:[email protected]>>
wrote:
I suggest reading the attached paper before hanging too much on the heating
effect of PSCs at the poles.
Adrian Tuck
'ATMOSPHERIC TURBULENCE: A Molecular Dynamics Perspective'.
Oxford University Press, 2008. ISBN 978-0-19-923653-4.
http://www.oup.com/uk/catalogue/?ci=9780199236534
***************************************************
Adrian Tuck
[email protected]<mailto:[email protected]>
On 9 Sep 2015, at 22:19, Michael Hayes
<[email protected]<mailto:[email protected]>> wrote:
Hi Folks,
Regretfully, the authors have relegated the use of the word Geoengineering to
simply include SRM concepts. However, to their collective credit, they do
explain that they purposefully picked the easiest concept to model.
With that said, their efforts at viewing the challenge(s) from a
multi-latitudinal perspective is a refreshing break from the belief that
attaining a reduction in the 'Average Global Temperature' is some sort of gold
standard in Geoengineering.
Creating an equitable
climate<http://www.seas.harvard.edu/climate/eli/research/equable/climate.html>
(a.k.a. an averaged out climate) must be avoided at all
costs<https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=equable%20climate%20problem>
and stratospheric aerosol injection (SAI), using sulfuric acid (H2SO4) or
other sulfur compounds, can lead to the formation of Polar Stratospheric Clouds
(PSC) and thus warming of the polar regions
(a<http://www.ncbi.nlm.nih.gov/pubmed/17745351>)(b<http://www.atmos-chem-phys.net/3/987/2003/acp-3-987-2003.pdf>)(c<https://www.nasa.gov/centers/langley/news/factsheets/Aerosols.html>)(d<http://geotest.tamu.edu/userfiles/231/p19.pdf>)(e<http://onlinelibrary.wiley.com/doi/10.1029/91JD02740/abstract>)(f<http://www.seas.harvard.edu/environmental-chemistry/publications/97GL03408.pdf>)(g<http://wind.sjsu.edu/papers/PhysToday.pdf>)(etc.).....while
cooling of the lower latitudes a.k.a. an equitable climate.
The hazards of warming the polar regions through increasing polar stratospheric
clouds is well covered by LC Sloan et al.- 1998 "Polar stratospheric clouds: A
high latitude warming mechanism in an ancient greenhouse
world<ftp://ftp.tudelft.nl/pub/TUDelft/irctr-rse/Mieke/Papers/SloanPollard98-PSCforHighLatPTMwarmArctic.pdf>"
Abstract:
The presence of water vapor clouds in the stratosphere produces warming in
excess of tropospheric greenhouse warming, via radiative warming in the lower
stratosphere. The stratospheric clouds form only in regions of very low
temperature and so the warming produced by the clouds is concentrated in polar
winter regions. Results from a paleoclimate modeling study that includes
idealized, prescribed polar stratospheric clouds (PSCs) show that the clouds
cause up to 20°C of warming at high latitude surfaces of the winter hemisphere,
with greatest impact in oceanic regions where sea ice is reduced. The modeled
temperature response suggests that PSCs may have been a significant climate
forcing factor for past time intervals associated with high concentrations of
atmospheric methane. The clouds and associated warming may help to explain
long-standing discrepancies between model-produced paleotemperatures and
geologic proxy temperature interpretations at high latitudes, a persistent
problem in studies of ancient greenhouse climates.".(My highlight)
[http://eeclat.ipsl.jussieu.fr/wp-content/uploads/2011/05/t4_PSC.png]<http://eeclat.ipsl.jussieu.fr/wp-content/uploads/2011/05/t4_PSC.png>
[https://pubweb.bnl.gov/~xujun/99post/strato_freezing.gif]<https://pubweb.bnl.gov/~xujun/99post/strato_freezing.gif>
[http://www.thetruthdenied.com/news/wp-content/uploads/2012/12/stratospheric-chemistry.jpg]<http://www.thetruthdenied.com/news/wp-content/uploads/2012/12/stratospheric-chemistry.jpg>
[http://www.nature.com/ngeo/journal/v3/n12/images/ngeo989-f2.jpg]<http://www.nature.com/ngeo/journal/v3/n12/images/ngeo989-f2.jpg>
(Side note: To keep things simple, I'm leaving the ozone destruction potential
of the PSC/H2SO4 combination off the table for now and simply ask the reader to
focus upon the thermal issues presented by SAI.)
Hopefully, the Kravitz et al. work will give us a detailed way to predict
simply the thermal hazards of SAI. With equal hope, once the hazards of SAI
induced polar warming (as well as the hazard to ozone) is well repeated in both
peer reviewed papers and popular press, the highly productive and appropriate
'Other' form of Geoengineering, which I believe is called Carbon Dioxide
Removal (CDR), can gain footing in the debate.
Regrettably, expanding the Kravitz model to cover more complex concepts, other
than the simplistic SAI concept, will not be easy. The authors clearly point
out in their 'Discussion and Conclusion' section that "Understanding the
boundaries of what is achievable, as well as what robust conclusions can be
obtained about any particular strategy, are open questions that require further
research.".
In brief, the work of Kravits et al. needs to be expanded upon as it would be
interesting to see this same detailed analytical tool applied to the other
Geoengineering concepts such as biochar, olivine, advanced weathering of
limestone and vast scale marine biomass production. Deployed individually and
or in concert, such efforts can clearly produce a "[...] deliberate large-scale
intervention in the Earth’s natural systems to counteract climate change."
(http://www.geoengineering.ox.ac.uk/what-is-geoengineering/what-is-geoengineering/).
Best,
Michael
On Tuesday, September 8, 2015 at 4:20:57 PM UTC-7, andrewjlockley wrote:
http://www.earth-syst-dynam-discuss.net/6/1635/2015/esdd-6-1635-2015.html
Geoengineering as a design problem
08 Sep 2015
Abstract. Understanding the climate impacts of solar geoengineering is
essential for evaluating its benefits and risks. Most previous simulations have
prescribed a particular strategy and evaluated its modeled effects. Here we
turn this approach around by first choosing example climate objectives and then
designing a strategy to meet those objectives in climate models.
There are four essential criteria for designing a strategy: (i) an explicit
specification of the objectives, (ii) defining what climate forcing agents to
modify so the objectives are met, (iii) a method for managing uncertainties,
and (iv) independent verification of the strategy in an evaluation model.
We demonstrate this design perspective through two multi-objective examples.
First, changes in Arctic temperature and the position of tropical precipitation
due to CO2 increases are offset by adjusting high latitude insolation in each
hemisphere independently. Second, three different latitude-dependent patterns
of insolation are modified to offset CO2-induced changes in global mean
temperature, interhemispheric temperature asymmetry, and the equator-to-pole
temperature gradient. In both examples, the "design" and "evaluation" models
are state-of-the-art fully coupled atmosphere–ocean general circulation models.
Citation: Kravitz, B., MacMartin, D. G., Wang, H., and Rasch, P. J.:
Geoengineering as a design problem, Earth Syst. Dynam. Discuss., 6, 1635-1710,
doi:10.5194/esdd-6-1635-2015, 2015.
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