Hi all, Here, a few articles about cloudiness changes over the Arctic and Northern Eurasia (in addition to Schweiger, GRL, 2004):
http://journals.ametsoc.org/doi/abs/10.1175/JCLI3439.1 http://www.agu.org/pubs/crossref/2007/2007GL030042.shtml http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3492.1 http://iopscience.iop.org/1748-9326/6/3/035202/ Actually, there is a strong contradiction among different datasets on cloudiness trend over this region. 2011/10/17 John Nissen <[email protected]> > Hi all, > > This email from 21st September (see below) seems relevant to our > discussions at the workshop. Cloud effects are extremely important to SRM > geoengineering and its application to cooling the Arctic, which we discussed > on the second day of the workshop. Therefore I hope the geoengineering list > moderator will allow me to post this message to the group. > > Fortunately we did have a cloud expert at the meeting - Jon Egill > Kristjansson. He told us that there was up to 90% cloud cover over the > Arctic in summer. This is important for calculating the overall heat flux > that the SRM geoengineering has to oppose in achieving an overall cooling of > the Arctic. A central purpose of the workshop was to provide an estimate of > the SRM negative flux (i.e. cooling effect) to be achieved - but the > estimate does not have to be accurate - only sufficiently accurate in the > upper end of the range of values for engineering purposes. > > If the cloud cover has increased since pre-industrial times, then the total > heat flux change calculation could be affected by this increase. The cloud > in summer is likely to have an cooling effect, whereas cloud in winter is > certainly having a warming effect. What is the overall effect? This needs > investigation. Does anybody have an idea on this? Note that any cooling > effect of the cloud, giving a negative feedback effect at certain times of > the year, would be important if we could enhance it. > > At the meeting we looked at the graphs of sea ice extent. We noticed a > definite bounce effect on sea ice extent: after years of larger downturn in > sea ice extent, there was an upturn in the following year, and vice versa. > This could perhaps be explained by an overall negative feedback effect of > cloud: in years of greater sea ice retreat (downturn in sea ice extent), > there would be more cooling at the end of the summer as more open water was > exposed to evaporation - and this cooling would allow a greater volume of > sea ice to form for the following year. > > However the alternative explanation for the bounce effect is that the > negative feedback comes from black body radiation: as the sea ice retreats > there is better radiative transfer of heat into space, because the water is > warmer than the ice. This was the preferred explanation at the meeting. > > Now let's go back to heat flux calculation. If, on average over the year, > the cloud is having an overall positive feedback effect, it increases the > amount of flux that is going to be required by the SRM geoengineering to > cool the Arctic. So this one important thing to know from the engineer's > viewpoint. > > Another thing to know is that the increased cloud has different > significance depending on the SRM technique. With stratospheric aerosols, > the cloud cover factor should cancel out - the reduction in SRM effect by > the cloud is balanced by the reduction in insolation from the sun. Or > looking at it another way, the aerosols are high up, so their sunshade > cooling effect is equally over the whole area below them, whether there are > clouds there or not. For cloud brightening techniques, it is simply good > news to have more clouds to brighten! What proportion of summer clouds in > the Arctic can be brightened? It would be useful to know. > > We discussed both cloud brightening and cloud removal techniques. One of > the nice things about cloud removal is that it more directly opposes the > thermal radiation trapping effect of increased CO2. Jon Egill had done > modelling in exploring the balance of the two techniques. I shall put > copies of his and other presentations into the [arctic-methane] yahoo group > as a file. > > Again for cloud removal we need to know the proportion of clouds that could > be removed by the technique, especially in winter. > > Cheers, > > John > > --- > > On 21/09/2011 12:54, John Nissen wrote: > >> >> Hi Stephen, >> >> It's good news that you can do the brightening so far north. But I'm >> quite worried about the warming effect of clouds in autumn and winter. As >> the sea ice is retreating, there is more open water for evaporation, water >> vapour production and cloud formation for the autumn, slowing the >> reformation of the sea ice. As the sun lowers, the heat trapping of clouds >> becomes more important than the reflection of insolation. Could David >> Mitchell's idea of cloud dispersal have some merit at this time of year? >> >> So I am wondering whether we should invite a cloud expert to the workshop. >> According to this [1], the cloud cover has been increasing - and >> approximately linearly up to the last date of measurement they show, 2005 - >> but hardly at all in the North Atlantic where currents flow into the Arctic >> ocean. The trends are provided by Axel Schweiger, of the Washington Polar >> Science Center [2], who is currently investigating the effect of sea ice >> changes on cloud cover. (I am therefore copying this email to him.) >> >> According to [3] the water vapour heat-trapping effect may be more >> important than the overall effect of cloud cover changes. To quote: "Here >> we show that the Arctic warming is strongest at the surface during most of >> the year and is primarily consistent with reductions in sea ice cover. >> Changes in cloud cover, in contrast, have not contributed strongly to recent >> warming. Increases in atmospheric water vapour content, partly in response >> to reduced sea ice cover, may have enhanced warming in the lower part of the >> atmosphere during summer and early autumn." >> >> Of course, as the Arctic warms, the atmosphere is capable of holding more >> water vapour, so this is a positive feedback. Does anybody have an idea of >> the magnitude/significance of this, especially relative to the sea ice >> albedo effect? >> >> BTW, the surface amplification of temperature graphs of [3] support a >> polar amplification of two, whereas others are talking of Arctic temperature >> increases commensurate with a polar amplification factor closer to six. >> >> Cheers, >> >> John >> >> [1] >> http://www.arctic.noaa.gov/**detect/climate-clouds.shtml<http://www.arctic.noaa.gov/detect/climate-clouds.shtml> >> >> [2] http://psc.apl.washington.edu/**wordpress/response-of-cloud-** >> cover-to-changes-in-sea-ice/<http://psc.apl.washington.edu/wordpress/response-of-cloud-cover-to-changes-in-sea-ice/> >> >> [3] http://www.nature.com/nature/**journal/v464/n7293/full/** >> nature09051.html<http://www.nature.com/nature/journal/v464/n7293/full/nature09051.html> >> >> --- >> >> On 17/09/2011 16:55, Stephen Salter wrote: >> >>> John >>> >>> You say that you do not want to rely on cloud brightening because of >>> effects on the gulf stream and affect Europe. I do not want to rely on any >>> single tool. But in the summer we can do cloud brightening north of the >>> lattitude Novaya Zemlya without affecting Europe. The long hours of summer >>> sunlight make the technique very powerful. If we did need to operate south >>> of this line we could limit the effect to sea temperatures to the values we >>> had in happier times. If there was another Pinatubo or if we over do it >>> then we stop in a few days. >>> >>> Stephen >>> >>> Emeritus Professor of Engineering Design >>> Institute for Energy Systems >>> School of Engineering >>> Mayfield Road >>> University of Edinburgh EH9 3JL >>> Scotland >>> Tel +44 131 650 5704 >>> Mobile 07795 203 195 >>> www.see.ed.ac.uk/~shs >>> >>> >>> On 13/09/2011 20:26, John Nissen wrote: >>>> >>>>> >>>>> Dear Stephen, Peter, >>>>> >>>>> 1. Meeting discussions >>>>> >>>>> Yes, please bring drawings, Stephen. We are meeting at my home, so it >>>>> will be a fairly informal affair, to allow maximum brainstorming and >>>>> discussion! Anything you can let me have beforehand would be appreciated, >>>>> because I want to be able to steer the discussion sensibly. Also I want to >>>>> draft a working paper before the meeting, and then be able to slot in >>>>> contributions/decisions easily. >>>>> >>>>> Also bring stuff about the cloud brightening. I would also like to have >>>>> somebody to discuss stratospheric aerosols, because I think the >>>>> geographical >>>>> distribution of the negative forcing effects is going to be crucial, >>>>> especially to cool the ESAS where the methane seems to be in the most >>>>> critical state. I'm copying this to Brian Launder, who worked on the RS >>>>> report under John Shepherd, and might have some ideas. Your welcome to the >>>>> workshop, Brian - 15-16 October - let me know if you're interested. >>>>> >>>>> I'd be very concerned to rely too much on cloud brightening, because to >>>>> produce upwards of 1 petawatt cooling, you'd have to cool the Gulf Stream >>>>> and North Atlantic currents by a significant amount - potentially >>>>> affecting >>>>> weather in Europe perhaps - opening up a can of worms! >>>>> >>>>> >>>>> 2. East Siberian Arctic Shelf (ESAS) >>>>> >>>>> This does seem to be the most critical area for the methane, with 50 Gt >>>>> of the stuff that could be emitted at any time, e.g. as the result of an >>>>> earthquake (and this is a real hazard). >>>>> >>>>> Just in case you've not got it, I attach the Shakhova and Semiletov >>>>> paper, which describes the situation of the ESAS very graphically. Indeed, >>>>> because the whole area was flooded/inundated as the sea level rose, from >>>>> its >>>>> low level at the last glacial maximum (LGM) about 100-120 metres below >>>>> current level, you can see what the seabed looks like! You can also see >>>>> the >>>>> approximate sizes of the places where methane is coming out, etc. >>>>> >>>>> Note that the authors talk about 5 degrees warming in the region (air >>>>> temperature presumably), and 3 degrees warming of the water! It's the >>>>> warming of the water is particularly dangerous. I don't know how we can >>>>> easily cool it. Can we do anything with local clouds? Could we try >>>>> brightening the water with clouds of bubbles, as somebody suggested on the >>>>> geoengineering list? >>>>> >>>>> BTW, it's amazing that people (who should know better) are still >>>>> talking about polar amplification as a doubling of global warming. It's >>>>> clear to me that Arctic warming is accelerating relative to global >>>>> warming, >>>>> so the amplification factor is increasing all the time, and must be well >>>>> over six by now. So Hadley models that put 16 degrees in the Arctic for 4 >>>>> degrees global warming are rubbish (- and anyway they ignore the >>>>> methane). I >>>>> think it's basically the albedo flip that's doing the amplification now - >>>>> the subject of my paper to the EGU in April, Stephen. Let's pray that >>>>> there's not a methane excursion in the next few years and the sea ice >>>>> doesn't retreat faster than PIOMAS trend! >>>>> >>>>> >>>>> 3. Fluxes into Arctic and your comment >>>>> >>>>> Stephen, by "current TO" I assume you mean "turn over". This is what I >>>>> was talking about, when I said: >>>>> >>>>> * /Warming is driven by currents from the Atlantic and the albedo >>>>> effect/. >>>>> >>>>> >>>>> The main driver turns out to be the albedo flip effect, which I've >>>>> labelled 'F' in my calculations. In order to ascertain the forces we are >>>>> up >>>>> against in geoengineering, I've tried to calculate the various heat >>>>> fluxes. >>>>> 'S' is the extra heat flux from the Atlantic since pre-industrial times, >>>>> taking into account that the flow into the Arctic is balanced by flow >>>>> coming >>>>> out, in what is termed AMOC - the overturning circulation. >>>>> >>>>> I could have added the local greenhouse effect, 'C' to the warming >>>>> effect. There is also a cooling effect, 'R', of thermal radiation from the >>>>> open water as the sea ice retreats, but these are relative small fluxes >>>>> and >>>>> roughly cancel out. >>>>> >>>>> And there are some other factors, I asked about recently: the extra >>>>> water vapour from the open water (positive forcing), the extra cloud cover >>>>> (positive forcing) and the extra snow to increase albedo (negative >>>>> forcing). >>>>> I've so far neglected these other factors. And I've ignored atmospheric >>>>> heat >>>>> transfer - water vapour transport into the Arctic could perhaps be a >>>>> significant positive forcing. Otherwise I would expect the total >>>>> atmospheric >>>>> heat transport if anything to diminish, since the Arctic has warmed >>>>> relative >>>>> to the rest of the world. >>>>> >>>>> The rest of this email is copied from a previous email about the flux >>>>> calculation. But I may have underestimated the albedo flip effect, F, >>>>> when I >>>>> wrote it. >>>>> >>>>> -- >>>>> >>>>> Let significant fluxes (extra since pre-industrial times) be identified >>>>> as follows: >>>>> S = Gulf Stream warming via North Atlantic Drift heat transport into >>>>> Arctic [1]; >>>>> C = local warming - net effect of gases and aerosols, mainly CO2 at >>>>> present; >>>>> F = albedo Flip effect, where snow and ice has given way to land >>>>> surface and sea; >>>>> R = thermal Radiation into space as Arctic surfaces warm [2]; >>>>> L = Latent heat for melting ice; >>>>> W = heat absorbed by land, water and atmosphere, as Arctic warms. >>>>> >>>>> The balance of input flux minus output flux goes into melting the ice >>>>> and raising the Arctic temperature. >>>>> >>>>> Thus S + C + F - R = L + W >>>>> >>>>> The geoengineering negative forcing (aka cooling) has to counter S + C >>>>> + F - R. >>>>> >>>>> S is difficult to estimate.But it is observed that the water entering >>>>> the Fram Strait from the Atlantic has warmed by about 2 degrees C [3]. I >>>>> am >>>>> not sure about the flow volume rate into the Arctic Ocean, but it could be >>>>> about 6 Sv [4].Note that the paper [5] gives 2-3 Sv into Fram Strait and >>>>> 2-3 >>>>> Sv through the Barents Sea Opening (BSO).(1 Sv, or sverdrup, is a million >>>>> cubic metres of water per second).This is small compared to the Gulf >>>>> Stream, >>>>> at 55 Sv. >>>>> >>>>> The figure of 2 degrees warming, observed in [3], is not throughout the >>>>> depth of the water, so cannot be used for calculating the heat flux.But >>>>> fortunately there are some figures for the heat transfer from [5]: about >>>>> 20 >>>>> terawatts through the Fram Strait and 50 through BSO, giving a total of 70 >>>>> terawatts for a total current of 5 Sv. >>>>> >>>>> Now we’d expect the NADW from the Arctic to be the same flow as the >>>>> flow into the Arctic, and this is given as just under 25 Sv in [6] (table >>>>> 4).The Gulf Stream is 55 Sv [4], so it is reasonable that just under half >>>>> goes towards the Arctic and returns as NADW. >>>>> >>>>> If 5 Sv is giving 70 terawatts from [5], but we have 25 Sv from [6], >>>>> then the total warming, S, could be as much as 350 terawatts. >>>>> >>>>> In the formula S + C + F - R = L + W, I've estimated the parameters as >>>>> follows: >>>>> >>>>> S = 70-350 terawatts, from Gulf Stream; >>>>> C = 35 terawatts, from current greenhouse warming over Arctic; >>>>> F* = 300-1000 terawatts, from the albedo flip when sea ice has gone; >>>>> R = 34 terawatts, thermal radiation into space as Arctic warms (using >>>>> [2]); >>>>> L = 10 terawatts; and >>>>> W is derivable from the other parameters. >>>>> >>>>> -- >>>>> >>>>> Cheers, >>>>> >>>>> John >>>>> >>>>> [1] >>>>> http://www.sciencedaily.com/**releases/2011/01/110127141659.**htm<http://www.sciencedaily.com/releases/2011/01/110127141659.htm> >>>>> >>>>> [2] >>>>> http://en.wikipedia.org/wiki/**Stefan%E2%80%93Boltzmann_law<http://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law> >>>>> >>>>> [3] http://instaar.colorado.edu/~**marchitt/reprints/** >>>>> spielhagenscience11.pdf<http://instaar.colorado.edu/~marchitt/reprints/spielhagenscience11.pdf>< >>>>> http://instaar.colorado.edu/%**7Emarchitt/reprints/** >>>>> spielhagenscience11.pdf<http://instaar.colorado.edu/%7Emarchitt/reprints/spielhagenscience11.pdf>> >>>>> >>>>> >>>>> /These results reveal a rapid warming by ~2°C of uppermost AWin the FSB >>>>> in the Arctic Gateway during the past ~120 years, consistent with the >>>>> documented sea ice retreat in the Barents Sea (//5//), terrestrial >>>>> Paleoclimate reference records (//6//, //19//) (Fig. 3, C to E), and >>>>> atmospheric measurements./ >>>>> >>>>> [4] http://www3.ncc.edu/faculty/**bio/fanellis/biosci119/** >>>>> currents.html<http://www3.ncc.edu/faculty/bio/fanellis/biosci119/currents.html> >>>>> This has excellent maps showing currents. >>>>> >>>>> [5] >>>>> ftp://ftp.npolar.no/ASOF/**library/pdf/Karcher_etal.pdf<ftp://ftp.npolar.no/ASOF/library/pdf/Karcher_etal.pdf> >>>>> >>>>> [6] >>>>> http://www.atmos.ucla.edu/~**hbrix/papers/brix03jgr.pdf<http://www.atmos.ucla.edu/~hbrix/papers/brix03jgr.pdf>< >>>>> http://www.atmos.ucla.edu/%**7Ehbrix/papers/brix03jgr.pdf<http://www.atmos.ucla.edu/%7Ehbrix/papers/brix03jgr.pdf> >>>>> > >>>>> >>>>> [7] From 1975: >>>>> http://www.sciencedirect.com/**science/article/pii/**0012821X76900728<http://www.sciencedirect.com/science/article/pii/0012821X76900728> >>>>> “The rate of Atlantic bottom water formation is estimated at 18 >>>>> Sverdrups” >>>>> >>>>> --- >>>>> >>>>> On 13/09/2011 10:13, Stephen Salter wrote: >>>>> >>>>>> John >>>>>> >>>>>> I think that warming is driven by current TO not from the Arctic. All >>>>>> the water that goes in must come out but the in flow is warmer than the >>>>>> out >>>>>> flow. >>>>>> >>>>>> Do you want me to bring drawings and calculations about a scheme for >>>>>> methane recovery? >>>>>> >>>>>> Stephen >>>>>> >>>>>> >>>>>> Emeritus Professor of Engineering Design >>>>>> Institute for Energy Systems >>>>>> School of Engineering >>>>>> Mayfield Road >>>>>> University of Edinburgh EH9 3JL >>>>>> Scotland >>>>>> Tel +44 131 650 5704 >>>>>> Mobile 07795 203 195 >>>>>> www.see.ed.ac.uk/~shs >>>>>> >>>>>> On 12/09/2011 23:50, John Nissen wrote: >>>>>> >>>>>>> >>>>>>> Dear all, >>>>>>> >>>>>>> I need to check figures - especially the 20 W/m-2 figures - before I >>>>>>> send more widely. And I'd like to put petawatts against the methane, so >>>>>>> we >>>>>>> have a total petawatt figure for geoengineering to counter! Anything >>>>>>> else >>>>>>> missing? >>>>>>> >>>>>>> Any other comments? Should I consider 'considerations' at all for an >>>>>>> agenda? Do the figures have to be justified here - or can I do that in a >>>>>>> separate document, with references? >>>>>>> >>>>>>> Should I mention that any rise in methane emissions will affect the >>>>>>> carbon budget for CO2 emissions reductions to meet the 2 (or now 1.5?) >>>>>>> degree C global warming target limit? >>>>>>> >>>>>>> Cheers, >>>>>>> >>>>>>> John >>>>>>> >>>>>>> -- >>>>>>> >>>>>>> Agenda for Arctic methane workshop >>>>>>> >>>>>>> Considerations: >>>>>>> >>>>>>> * Arctic warming is much faster than global warming, and the >>>>>>> warming is accelerating >>>>>>> * Warming is driven by currents from the Atlantic and the albedo >>>>>>> effect >>>>>>> * The extra heat flux, which is warming the Arctic with respect to >>>>>>> its pre-industrial temperature, is currently of the order of one >>>>>>> petawatt >>>>>>> * September sea ice volume trend is to zero in 2015, by which time >>>>>>> the heat flux could be of the order of two petawatts, ignoring >>>>>>> increased methane emissions >>>>>>> * Around 1600 Gt carbon is held in terrestrial permafrost >>>>>>> * Around 30% of this permafrost could thaw by 2050, producing >>>>>>> mainly methane >>>>>>> * Methane being a potent greenhouse gas, the corresponding global >>>>>>> forcing could rise to over 20 Watts/m², compared to current net >>>>>>> forcing of 1.6 Watts/m² >>>>>>> * Under shallow seas there is around 500 Gt carbon in sub-sea >>>>>>> permafrost, 1000 Gt methane as methane hydrate and 700 Gt >>>>>>> methane as free gas >>>>>>> * Up to 50 Gt of this methane could be released “at any time” >>>>>>> (e.g. by an earthquake), increasing atmospheric concentration by >>>>>>> up to 11 times >>>>>>> * The global forcing from such a pulse could rise to around 20 >>>>>>> Watts/m² over the course of a single year and then fall only >>>>>>> slowly >>>>>>> * Such forcing could send global warming over 2 degrees C in a >>>>>>> decade >>>>>>> * Such forcing would also lead to further Arctic methane release >>>>>>> in a positive feedback loop, with the prospect of runaway global >>>>>>> warming, disintegration of Greenland and Antarctic ice sheets >>>>>>> and many metres of sea level rise >>>>>>> >>>>>>> >>>>>>> The objectives of the workshop are to: >>>>>>> >>>>>>> * ascertain the scale of the methane excursion threat and >>>>>>> probability over time; >>>>>>> * ascertain the scale of the local engineering and regional >>>>>>> (geo)engineering required to prevent a significant methane >>>>>>> excursion; >>>>>>> * propose a set of techniques which could meet these requirements; >>>>>>> * propose techniques to capture methane in the event of an >>>>>>> excursion; >>>>>>> * decide on priorities for trials and deployment of key >>>>>>> technologies; >>>>>>> * agree a plan for preparations and pilot trials according to >>>>>>> these priorities; >>>>>>> * agree an outline report to AGU in December. >>>>>>> >>>>>>> >>>>>>> Agenda: >>>>>>> >>>>>>> * Introductions of participants >>>>>>> * Terrestrial and marine methane threats >>>>>>> * Local methane management/engineering ideas >>>>>>> * Regional (geo)engineering – cooling technologies and capabilities >>>>>>> * Mixed technology strategy to optimise cooling distribution >>>>>>> * Methane air capture >>>>>>> * Preparation of project plans for preparation, trial and timely >>>>>>> deployment >>>>>>> * Agree outline report for presentation at AGU >>>>>>> >>>>>>> >>> > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to > geoengineering@googlegroups.**com<[email protected]> > . > To unsubscribe from this group, send email to geoengineering+unsubscribe@* > *googlegroups.com <geoengineering%[email protected]>. > For more options, visit this group at http://groups.google.com/** > group/geoengineering?hl=en<http://groups.google.com/group/geoengineering?hl=en> > . > > -- Alexander V. Chernokulsky A.M.Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences 3 Pyzhevsky, 119017 Moscow, Russia Tel.: 7 (495) 951 64 53 Fax: 7 (495) 953 16 52 E-mail: [email protected], [email protected] -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
