Which groups are able to run a chemistry column model? If it's not been done, it's a glaring omission in the science.
On a similar modelling note, does anyone know a group which does modelling of monoterpenes? I had an idea to genetically modify trees, which I'd like to test. A On 28 Jul 2014 06:45, "Govindasamy Bala" <[email protected]> wrote: > Hi Nathan, > > The changes to amount of water vapor in the lower stratosphere, like in > the troposphere, is likely controlled by the stratospheric temperature > change. i.e. follows C-C relationship. Therefore, the source mechanism for > H2O in the low stratosphere may not be that important. I do agree that a > full climate-chemistry investigation is still lacking for aerosol > geoengineering! > > > On Sun, Jul 27, 2014 at 8:40 PM, Nathan Currier <[email protected]> > wrote: > >> >> >> Hi, Ken – >> >> Thanks much for your response. Of course I see how you meant this, and I >> don’t really disagree as long as it’s clearly stated that, given the >> successful achievement of the same radiative forcing impacts with the two >> approaches, then there’s not much difference between the SRM and turning >> down the sun. What I was saying – and, as I said, it was more question than >> comment – grows out of a general sense that we should all still be looking >> for any possible ways that one might not successfully achieve the forcing >> impacts currently assumed, for some reason or another. >> >> So, while you write that the surface temperature is not “super sensitive >> to changes in the stratosphere,” I was referencing one of the possible ways >> in which the surface apparently can be quite sensitive to such changes: for >> me, at least, when I first heard of the Solomon et al paper a few years >> back, what first popped out at me was how, with so little H2O up in the >> stratosphere, changes in it could have such huge impacts on surface >> temperature, comparable with changes in CO2 forcing, I think, over the same >> period. Then later I began wondering whether stratospheric SRM techniques >> could impact this stratospheric hydrology, as opposed to the much more >> frequently discussed surface hydrology SRM impacts. >> >> So, that’s why I brought up the methane issue, since there clearly is an >> interaction at the surface between sulfur chemistry and methane oxidation, >> and methane is very clearly an important source of H2O to the stratosphere. >> Luckily, the methane doesn’t seem to be getting oxidized in the right place >> to have such a big impact, but could *that* somehow or another get >> shifted if you add a bunch of sulfur to the stratosphere? Again, it was >> really a question, where I was asking: have such possibilities been >> explored? >> >> Cheers, >> >> >> Nathan >> >> >> >> >> >> On Saturday, July 26, 2014 3:01:47 PM UTC-4, kcaldeira wrote: >> >>> Nathan, >>> >>> Your questions are interesting but your initial statement is not true >>> when it comes to first order effects on surface temperature and hydrology. >>> [".. the similarity ("turning down the sun" and the SRM) depends on the >>> ability of the models to reproduce, among other things, the stratospheric >>> chemistry correctly. "] >>> >>> Surface temperature and hydrology is not super sensitive to changes in >>> the stratosphere. Key is getting the effective radiative forcing right both >>> in terms of total amount and latitudinal distribution. >>> >>> To repeat what I said in the previous email: >>> >>> *Of course, what tool you use depends on your goals in using a tool. The >>> attached paper shows results indicating that for many purposes, "turning >>> down the sun" is a clear and efficient way of simulating many aspects of >>> solar geoengineering.* >>> >>> *If you are looking at effects on the stratosphere or looking at effects >>> of diffuse radiation, then you would need to simulate aerosols, but if you >>> are just trying to get an idea of temperature and hydrological changes, >>> then it seems that "turning down the sun" does a pretty good job.* >>> >>> Best, >>> >>> Ken >>> >>> _______________ >>> 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 >>> >>> Assistant: Dawn Ross <[email protected]> >>> >>> >>> >>> On Sat, Jul 26, 2014 at 10:57 AM, Nathan Currier <[email protected]> >>> wrote: >>> >>>> This is more question than comment, but it seem to go without saying >>>> that the similarity ("turning down the sun" and the SRM) depends on the >>>> ability of the models to reproduce, among other things, the stratospheric >>>> chemistry correctly. >>>> >>>> Solomon et al, 2010* (see below) concerned the hugely under-represented >>>> impacts of stratospheric water vapor on surfacing warming, and suggested >>>> increased stratospheric water vapor might have accounted for 30% of global >>>> warming in the 90s. They also noted: >>>> >>>> Current global climate models simulate lower-stratospheric temperature >>>> trends poorly, and even up-to-date stratospheric chemistry-climate models >>>> do not consistently reproduce tropical tropopause minimum temperatures or >>>> recently observed changes in stratospheric water vapor. >>>> >>>> >>>> >>>> Their paper only dealt with changes in one of the two ways that the >>>> stratosphere gets its water vapor, but I’ve often wondered about the >>>> potential impacts of sulfur SRM on the other one – that is, stratospheric >>>> methane. Solomon et al, while suggesting that methane’s role is relatively >>>> weak in H2O creation near the tropopause (where it apparently counts most >>>> for surface warming), noted: >>>> >>>> Estimates of the forcing due to (stratospheric) methane oxidation have >>>> varied widely among different studies, perhaps because of different shapes >>>> of the water profile in the region of greatest sensitivity. >>>> >>>> >>>> One of my questions has been whether prolonged use of stratospheric >>>> sulfur SRM, unlike the sudden pulse of a volcano, could potentially give >>>> rise to analogous “competitive” reactions to those seen in the troposphere >>>> involving sulfur chemistry and methane hydroxylation (i.e., Shindell et al >>>> 2007, 2009, 2012, etc), one of the factors that have driven our assumed >>>> increase in the indirect forcing effects of methane over the last half >>>> decade. >>>> >>>> I wonder, if additions of sulfur did actually lead, at the decadal >>>> scale of the methane lifetime, to increases in stratospheric H2O, what >>>> could its maximum impact be? What percentage of all stratospheric H2O comes >>>> from methane, in the first place? Does current SRM modeling account for >>>> such possible interactions? >>>> >>>> Best, >>>> >>>> Nathan >>>> >>>> >>>> >>>> *Solomon et al 2010: >>>> >>>> >>>> >>>> abstract >>>> http://www.sciencemag.org/content/327/5970/1219.abstract >>>> >>>> full paper >>>> http://www.climate.unibe.ch/~plattner/papers/solomon10sci.pdf >>>> >>>> discussions of, from NOAA & RealClimate: >>>> http://www.noaanews.noaa.gov/stories2010/20100128_watervapor.html >>>> >>>> http://www.realclimate.org/index.php/archives/2010/01/ >>>> the-wisdom-of-solomon/ >>>> >>>> >>>> >>>> On Friday, July 25, 2014 11:39:52 AM UTC-4, kcaldeira wrote: >>>> >>>>> Folks, >>>>> >>>>> Andrew wrote something the other day about "turning down the sun" >>>>> experiments NOT being a good analogue for stratospheric aerosol >>>>> geoengineering. >>>>> >>>>> Of course, what tool you use depends on your goals in using a tool. >>>>> The attached paper shows results indicating that for many purposes, >>>>> "turning down the sun" is a clear and efficient way of simulating many >>>>> aspects of solar geoengineering. >>>>> >>>>> If you are looking at effects on the stratosphere or looking at >>>>> effects of diffuse radiation, then you would need to simulate aerosols, >>>>> but >>>>> if you are just trying to get an idea of temperature and hydrological >>>>> changes, then it seems that "turning down the sun" does a pretty good job. >>>>> >>>>> Enjoy, >>>>> >>>>> Ken >>>>> >>>>> >>>>> http://link.springer.com/article/10.1007/s00382-014-2240-3 >>>>> >>>>> >>>>> >>>>> *Modeling of solar radiation management: a comparisonof simulations >>>>> using reduced solar constant and stratospheric sulphate aerosols* >>>>> >>>>> Sirisha Kalidindi · Govindasamy Bala · >>>>> Angshuman Modak · Ken Caldeira >>>>> >>>>> >>>>> Abstract The climatic effects of Solar Radiation Management >>>>> (SRM) geoengineering have been often modeled >>>>> by simply reducing the solar constant. This is most likely >>>>> valid only for space sunshades and not for atmosphere and >>>>> surface based SRM methods. In this study, a global climate >>>>> model is used to evaluate the differences in the climate >>>>> response to SRM by uniform solar constant reduction and >>>>> stratospheric aerosols. Our analysis shows that when global >>>>> mean warming from a doubling of CO2 is nearly cancelled >>>>> by both these methods, they are similar when important >>>>> surface and tropospheric climate variables are considered. >>>>> However, a difference of 1 K in the global mean stratospheric >>>>> (61–9.8 hPa) temperature is simulated between the >>>>> two SRM methods. Further, while the global mean surface >>>>> diffuse radiation increases by ~23 % and direct radiation >>>>> decreases by about 9 % in the case of sulphate aerosol >>>>> SRM method, both direct and diffuse radiation decrease by >>>>> similar fractional amounts (~1.0 %) when solar constant >>>>> is reduced. When CO2 fertilization effects from elevated >>>>> CO2 concentration levels are removed, the contribution >>>>> from shaded leaves to gross primary productivity (GPP) >>>>> increases by 1.8 % in aerosol SRM because of increased >>>>> diffuse light. However, this increase is almost offset by >>>>> a 15.2 % decline in sunlit contribution due to reduced >>>>> direct light. Overall both the SRM simulations show similar >>>>> decrease in GPP (~8 %) and net primary productivity >>>>> (~3 %). Based on our results we conclude that the climate >>>>> states produced by a reduction in solar constant and addition >>>>> of aerosols into the stratosphere can be considered >>>>> almost similar except for two important aspects: stratospheric >>>>> temperature change and the consequent implications >>>>> for the dynamics and the chemistry of the stratosphere >>>>> and the partitioning of direct versus diffuse radiation reaching >>>>> the surface. Further, the likely dependence of global >>>>> hydrological cycle response on aerosol particle size and the >>>>> latitudinal and height distribution of aerosols is discussed. >>>>> _______________ >>>>> 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 >>>>> >>>>> Assistant: Dawn Ross <[email protected]> >>>>> >>>>> -- >>>> 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. >> > > > > -- > 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 3428+91 80 2293 3428+91 80 2293 3428 > +91 80 2293 2075+91 80 2293 2075+91 80 2293 2075+91 80 2293 2075 > Fax: +91 80 2360 0865 > +91 80 2293 3425+91 80 2293 3425+91 80 2293 3425+91 80 2293 3425 > Email: [email protected] > [email protected] > Web:http://caos.iisc.ernet.in/faculty/gbala/gbala.html > ------------------------------------------------------------------- > Call > Send SMS > Add to Skype > You'll need Skype CreditFree via Skype > Call > Send SMS > Add to Skype > You'll need Skype CreditFree via Skype > > -- > 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. 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