On Fri, Mar 14, 2014 at 2:34 PM, John Nissen <[email protected]> wrote: > Hi all, > > I think there is a connection between irreversibility and tipping points. > If a system is past its tipping point, the only way of returning the system > to its prior state (before the tipping point) will be by geoengineering. > For example, the Arctic sea ice is arguable well beyond its tipping point > (see paper by Lenton et al [1]), so geoengineering is required to restore > the sea ice to a previous level. Without SRM-type geoengineering to cool > the Arctic, increased albedo loss will further accelerate Arctic warming > through positive feedback until the whole Arctic ice cap has gone, with dire > consequences for sea level rise,
Wait a second. Maybe you meant something different, like Greenland, but the melting the floating Arctic ice doesn't cause the sea level to go up. > methane release and extreme weather. In > this sense, the positive feedback cycle leading to complete Arctic meltdown > is irreversible without geoengineering to cool the Arctic and break the > cycle. Hmm. Personally I would say the more important thing to do would be tapping a really large non-carbon energy source. You really need to plug the hole before bailing out the boat. If you really want to raise the albedo, another trick might be floating thermal diodes. Those are not likely to raise the awful political objections to sulfuric acid clouds. BTW, Gregory Benford was talking about SO2 in the sky a *long* time ago. Does he ever post here? Keith > The AR5 carbon budget is being used up rapidly, implying commitment to > dangerous global warming and dangerous ocean acidification. Arguably, these > dangers can only be mitigated by CDR-type geoengineering to remove CO2 from > the atmosphere. In this sense, one could say that global warming and ocean > acidification are irreversible without geoengineering to remove CO2 from the > atmosphere. > > Cheers, > > John > > [1] http://arxiv.org/abs/1204.5445 > > -- > > > On Fri, Mar 14, 2014 at 12:36 AM, Ronal W. Larson > <[email protected]> wrote: >> >> Keith etal >> >> The people who are saying climate change is irreversible would >> probably agree with your arithmetic on electricity from solar power >> satellites to turn CO2 into a wax.. However, I feel they are making a >> different point - and they are not ignorant. I just haven't understood what >> word they would want to use for what "Geoengineers" know can be accomplished >> with a small part of our solar input. There is some subtlety in >> nomenclature we should try to work out that is unrelated to how we do it or >> how much it will cost. >> >> Ron >> >> >> On Mar 13, 2014, at 12:55 PM, Keith Henson <[email protected]> wrote: >> >> > The mass of CO2 in the atmosphere is about 3.09 x 10^12 tons. [Watch >> > the conversion from ppm (vol) to molar mass.] >> > >> > Long chain wax is close enough to CH2. >> > >> > CO2 + 3H2 -> CH2 + 2H2O >> > 44 6 >> > >> > I.e., to reduce 44 units of CO2 to synthetic oil would take 6 units of >> > hydrogen. >> > >> > That's 0.421 x 10^12 tons of hydrogen to take all the CO2 out of the >> > air, 0.105 x 10^12 tons to take out 100 ppm. >> > >> > It takes 33.3 MWh/ton to make electrolytic hydrogen. Call it 40 >> > MWh/ton considering efficiency. The energy cost to sort CO2 out of >> > the air is negligible compared to making the hydrogen. So the energy >> > cost to take out 100 ppm would be ~4.21 x 10^12 MWh, ~4.21 x 10^6 TWh. >> > Or ~480 TW years. >> > >> > Taking the time as 20 years, we would need 24 TW of power to do it. >> > >> > Current human use is around 16 TW/years/year. So we would need about >> > 1.5 times the current energy production to take out 100 ppm in 20 >> > years. Even if we kept burning coal (why?) a project at this scale >> > would still reduced the CO2 by around 3 ppm/year. >> > >> > Considering that geosynchronous orbit will hold at least 177 TW of >> > power satellites, 24 TW dedicated to taking out CO2 seems feasible. >> > >> > Most of that CO2 went into the atmosphere over the past 30 years from >> > burning coal, so taking it out at about the same rate should take >> > about the same time. >> > >> > The oceans will out gas CO2 for ages. That's OK. Run it beyond 20 >> > years. >> > >> > This probably isn't the best idea, and it might not even be a good idea. >> > >> > It's just an exercise to show that people who say CO2 is >> > "irreversible" haven't thought it through or worked the numbers. >> > >> > Keith >> > >> > PS. If any of you are inclined to work the numbers and find I made an >> > error, please let me know. >> > >> > On Wed, Mar 12, 2014 at 9:40 PM, Keith Henson <[email protected]> >> > wrote: >> >> There are a couple of points re irreversible. First, we might not >> >> want to reverse it. Around 1/3rd of crop yields is due to the higher >> >> concentration of CO2. >> >> >> >> But let's take reversing as taking out 100 ppm, and the time frame as >> >> 20 years. It's actually not that expensive in energy terms to >> >> sequester 100 ppm, but say we really wanted to be sure. Like turn the >> >> carbon dioxide into synthetic oil that we could pump back into old oil >> >> fields. Humans currently use around 15 TW. What multiple of that >> >> would it take in 20 years to pull 100 ppm out of the air? >> >> >> >> If it's a small number, then it's just a matter of tapping enough >> >> energy to do it. It's not going to take more than a tiny fraction of >> >> what the Sun puts out. >> >> >> >> On Wed, Mar 12, 2014 at 7:53 PM, Ronal W. Larson >> >> <[email protected]> wrote: >> >>> Greg and list >> >>> >> >>> This is a return to this list's discussion of the terms "reversible" >> >>> and >> >>> "irreversible". Until the last few days I have wanted only to agree >> >>> with >> >>> you - I have wanted to argue for "reversibility" and against >> >>> "irreversibility". >> >>> >> >>> The folks using the term "irreversible" are intelligent however. So >> >>> why are >> >>> we having this disagreement? >> >>> >> >>> I now think it is because the deep ocean part of climate change is >> >>> going to >> >>> be with us for a long time (i.e. we have caused changes that are >> >>> indeed >> >>> "essentially irreversible"). They are perhaps saying that if the deep >> >>> ocean >> >>> part of global climate changes cannot and will not be reversed over >> >>> millennia, that is enough justification for using the term >> >>> "irreversible". >> >>> Persons in this camp will agree that, at least hypothetically, we can >> >>> get >> >>> surface temperatures and even ocean surface pH and delta-T to very >> >>> near >> >>> their values 150 years ago. They would presumably still say that this >> >>> doesn't permit use of the term "reversible" - because a huge ocean >> >>> energy >> >>> gain (i.e. 4 nuclear bombs per second) has occurred. Let me call this >> >>> group >> >>> 1. >> >>> >> >>> Those of us in Group 2 see the present and near-term deep (repeat >> >>> deep) >> >>> ocean percentage changes in pH and temperature as being very small and >> >>> of >> >>> little present or future practical importance; we feel that this >> >>> should be >> >>> driving us towards the word "reversible". I am assuming that if we >> >>> get back >> >>> near 280 ppm that we can regrow arctic ice and glaciers - and the >> >>> present >> >>> ocean levels can return a bit, but not to pre-Anthropocene levels for >> >>> many >> >>> millennia. These arguments probably aren't going to satisfy Group1 >> >>> over >> >>> using the term "reversible". >> >>> >> >>> So, I wonder if we as a composite of Groups 1 and 2 can come up with >> >>> a term >> >>> or terms with which both groups are comfortable. Perhaps >> >>> "Reversibility >> >>> Types 1 and 2" where "1" and "2" denote group labels? >> >>> >> >>> Or announce that the word "reversible" means "atmospherically", >> >>> shortened to >> >>> "AR"; to be contrasted with "OI" for "Ocean Irreversible". At least >> >>> the >> >>> extra "A" and "O" are floating in the background. >> >>> >> >>> Or ?? >> >>> >> >>> The most important part of this is to make sure we all understand why >> >>> we are >> >>> not agreeing on a very fundamental topic - the ability to reverse land >> >>> and >> >>> ocean surface temperatures and ocean pH back to non-worrisome levels, >> >>> even >> >>> if a relatively small ocean rise is irreversible. >> >>> >> >>> Ron >> >>> >> >>> >> >>> On Mar 8, 2014, at 12:53 PM, Greg Rau <[email protected]> wrote: >> >>> >> >>> Thanks again for the detailed reply. Good to see that the IPCC at >> >>> least >> >>> acknowledges the possibility of CDR, though seems to then dismiss it >> >>> by >> >>> raising "limitations" and "uncertainties". Meantime, the rise in >> >>> atmospheric >> >>> CO2 is temporarily reversed every year by some 5 ppm due to natural >> >>> CDR, >> >>> though not without environmental impact (OA) and with no guarantee >> >>> that such >> >>> highly beneficial CDR will continue. >> >>> >> >>> So I'm sticking with my story, the rise in atmospheric CO2 is >> >>> reversible. >> >>> Whether it can be achieved over a sustained period via enhanced CDR in >> >>> amounts and on timescales relevant to humans/biology is an open and >> >>> important question given the ongoing failure of other methods of CO2 >> >>> management. And yes, effective CDR must increase CO2 removal from the >> >>> atmosphere and/or reduce CO2 emissions from ocean and land reservoirs. >> >>> Further research is needed, but that is guaranteed not to happen as >> >>> soon as >> >>> policy-/decision-makers read "irreversible" in the exec summary. >> >>> Under our >> >>> rather dire circumstances I think that it is unwise to prematurely >> >>> limit >> >>> consideration of our CO2 management options in this way, and with >> >>> IPCC's >> >>> reach and influence, perhaps irreversibly (?) >> >>> >> >>> Greg >> >>> >> >>> ________________________________ >> >>> From: Knutti Reto <[email protected]> >> >>> To: Greg Rau <[email protected]>; Geoengineering >> >>> <[email protected]> >> >>> Sent: Friday, March 7, 2014 3:43 PM >> >>> Subject: RE: [geo] NAS-Royal Society report - recent new report >> >>> release >> >>> >> >>> Hi Greg, >> >>> >> >>> Thanks for your comments. >> >>> >> >>>> However, where I come from if something is declared irreversible >> >>>> there are >> >>>> no exceptions >> >>> >> >>> That is one way of looking at it, but AR5 chose a different definition >> >>> below. If you say "no exceptions", that implies you would even allow >> >>> for the >> >>> forcing to get negative temporarily to reverse it. Then of course most >> >>> things are reversible. >> >>> >> >>> Section 12.5.5.1: >> >>> "The term irreversibility is used in various ways in the literature. >> >>> The AR5 >> >>> report >> >>> defines a perturbed state as irreversible on a given time scale if the >> >>> recovery time scale from this state due to natural processes is >> >>> significantly >> >>> longer than the time it takes for the system to reach this >> >>> perturbed state (see Glossary). In that context, most aspects of the >> >>> climate >> >>> change resulting from CO2 emissions are irreversible, due to the >> >>> long residence time of the CO2 perturbation in the atmosphere and the >> >>> resulting warming (Solomon et al., 2009). These results are discussed >> >>> in Sections 12.5.2 to 12.5.4. Here, we also assess aspects of >> >>> irreversibility >> >>> in the context of abrupt change, multiple steady states and >> >>> hysteresis, >> >>> i.e., the question whether a change (abrupt or not) would be >> >>> reversible if the forcing was reversed or removed (e.g., Boucher et >> >>> al., >> >>> 2012). Irreversibility of ice sheets and sea level rise are also >> >>> assessed >> >>> in Chapter 13." >> >>> >> >>> >> >>> You proposed: >> >>>> "Anthropogenic climate change and ocean acidification resulting from >> >>>> CO2 >> >>>> emissions are completely reversible, though only on 100 kyr time >> >>>> scales via >> >>>> natural land and ocean CO2 removal processes" >> >>> >> >>> That is scientifically correct. But how relevant is it if it takes 100 >> >>> kyrs >> >>> to return to preindustrial? Given the developments (not just in >> >>> climate) in >> >>> the last century, I personally would be surprised if our civilization >> >>> still >> >>> exists even a thousand years from now (but of course I have no >> >>> scientific >> >>> arguments for that). I would argue that for most practical purposes a >> >>> thousand years is as irreversible as is a million. >> >>> >> >>>> "However, interventions to accelerate this CO2 removal by enhanced >> >>>> natural >> >>>> or by artificial means have been proposed (rather large citation >> >>>> list), and >> >>>> could potentially hasten the return to "safe" CO2, climate and ocean >> >>>> chemistry conditions." >> >>> >> >>> Chapter 6, executive summary (p. 469): >> >>> "Unconventional ways to remove CO2 from the atmosphere on >> >>> a large scale are termed Carbon Dioxide Removal (CDR) methods. >> >>> CDR could in theory be used to reduce CO2 atmospheric >> >>> concentrations but these methods have biogeochemical and >> >>> technological limitations to their potential. Uncertainties make it >> >>> difficult to quantify how much CO2 emissions could be offset by CDR >> >>> on a human time scale, although it is likely that CDR would have to be >> >>> deployed at large-scale for at least one century to be able to >> >>> significantly >> >>> reduce atmospheric CO2. In addition, it is virtually certain that >> >>> the removal of CO2 by CDR will be partially offset by outgassing of >> >>> CO2 >> >>> from the ocean and land ecosystems." >> >>> >> >>>> "Further research is needed to evaluate these possibilities, >> >>>> especially if >> >>>> we continue to fail to manage atmospheric CO2 concentrations by other >> >>>> means." >> >>> >> >>> Chapter 6, executive summary (p. 469): >> >>> "The level of confidence on the side effects of CDR methods >> >>> on carbon and other biogeochemical cycles is low. Some of the >> >>> climatic and environmental effects of CDR methods are associated >> >>> with altered surface albedo (for afforestation), de-oxygenation and >> >>> enhanced N2O emissions (for artificial ocean fertilisation)." >> >>> >> >>>> Care to share with us how the original IPCC wording was hammered out >> >>>> and by >> >>>> whom? >> >>> >> >>> I won't comment on IPCC internal things. This document is 1500 pages, >> >>> and >> >>> more than a million words, it should speak for itself. As you can see >> >>> above, >> >>> most things are actually discussed somewhere. >> >>> >> >>> But in terms of the process, authors write the chapters and the >> >>> executive >> >>> summaries for each chapter. Those chapter summaries are then used by a >> >>> drafting team to write a first version of the summary for >> >>> policymakers. Both >> >>> the chapters and the summary go through two rounds of reviews that are >> >>> essentially open to any scientist. 55,000 comments were submitted, we >> >>> responded to each of them, all comments and responses are public. >> >>> Anyone on >> >>> this list could have made comments, and maybe some did. What remains >> >>> is >> >>> hopefully a synthesis that is shared by most of the scientific >> >>> community, >> >>> and it's as transparent as possible. These summary are not statements >> >>> written over coffee by one or two people, but reached by discussions >> >>> in >> >>> large groups, and they evolve over years as the authors respond to >> >>> comments >> >>> and rewrite their chapters. >> >>> >> >>> Reto >> >>> >> >>> >> >>> From: Greg Rau [mailto:[email protected]] >> >>> Sent: Freitag, 7. März 2014 06:13 >> >>> To: Knutti Reto; Geoengineering >> >>> Subject: Re: [geo] NAS-Royal Society report - recent new report >> >>> release >> >>> >> >>> Thanks for clarification, Reto. However, where I come from if >> >>> something is >> >>> declared irreversible there are no exceptions. A more accurate >> >>> statement >> >>> (though perhaps less philosophically diplomatic given the likely >> >>> personalities involved) might have been "Anthropogenic climate change >> >>> and >> >>> ocean acidification resulting from CO2 emissions are completely >> >>> reversible, >> >>> though only on 100 kyr time scales via natural land and ocean CO2 >> >>> removal >> >>> processes (e.g., Archer et al. 2009). However, interventions to >> >>> accelerate >> >>> this CO2 removal by enhanced natural or by artificial means have been >> >>> proposed (rather large citation list), and could potentially hasten >> >>> the >> >>> return to "safe" CO2, climate and ocean chemistry conditions. Further >> >>> research is needed to evaluate these possibilities, especially if we >> >>> continue to fail to manage atmospheric CO2 concentrations by other >> >>> means." >> >>> >> >>> Care to share with us how the original IPCC wording was hammered out >> >>> and by >> >>> whom? >> >>> >> >>> Regards, >> >>> Greg >> >>> >> >>> >> >>> >> >>> >> >>> ________________________________ >> >>> From: Knutti Reto <[email protected]> >> >>> To: "[email protected]" <[email protected]>; >> >>> "[email protected]" >> >>> <[email protected]>; Geoengineering >> >>> <[email protected]> >> >>> Sent: Thursday, March 6, 2014 2:21 PM >> >>> Subject: RE: [geo] NAS-Royal Society report - recent new report >> >>> release >> >>> >> >>> From a perspective of climate change commitment, the warming resulting >> >>> from >> >>> past emissions (zero emission commitment) stays for centuries and does >> >>> not >> >>> go away, so in that sense is irreversible (unlike for methane for >> >>> example >> >>> where temperature would drop quickly after stopping emissions). Of >> >>> course it >> >>> is not truly irreversible. It is reversible to a large degree (as >> >>> shown in >> >>> various papers cited below) if we were to remove the CO2. I don't >> >>> think >> >>> anyone would disagree, and to me it's a question of how what we mean >> >>> by >> >>> irreversible (see for example IPCC WG1 section 12.5.5.1). >> >>> >> >>> In IPCC AR5 we even say this in the Summary for Policymakers: "A large >> >>> fraction of anthropogenic climate change resulting from CO2 emissions >> >>> is >> >>> irreversible on a multi-century to millennial time scale, except in >> >>> the case >> >>> of a large net removal of CO2 from the atmosphere over a sustained >> >>> period. >> >>> Surface temperatures will remain approximately constant at elevated >> >>> levels >> >>> for many centuries after a complete cessation of net anthropogenic CO2 >> >>> emissions." (my emphasis) (Section E.8, page 28) >> >>> >> >>> Whether net removal of CO2 is plausible, desirable, likely,... is a >> >>> separate >> >>> question. >> >>> >> >>> Reto >> >>> >> >>> ---------------------------------------------- >> >>> Reto Knutti >> >>> Institute for Atmospheric and Climate Science >> >>> ETH Zurich >> >>> Universitätstrasse 16 (CHN N 12.1) >> >>> CH-8092 Zurich, Switzerland >> >>> [email protected] >> >>> http://www.iac.ethz.ch/people/knuttir >> >>> Phone: +41 44 632 35 40 >> >>> Fax: +41 44 632 13 11 >> >>> ---------------------------------------------- >> >>> >> >>> >> >>> From: [email protected] >> >>> [mailto:[email protected]] On Behalf Of Greg Rau >> >>> Sent: Donnerstag, 6. März 2014 21:47 >> >>> To: [email protected]; Geoengineering >> >>> Subject: Re: [geo] NAS-Royal Society report - recent new report >> >>> release >> >>> >> >>> Thanks Ron. In fairness, this is a report on climate change evidence >> >>> and >> >>> causes, not solutions. Nevertheless, they couldn't resist some >> >>> leakage into >> >>> the prescriptions side: >> >>> "Citizens and governments can choose among several options (or a >> >>> mixture of >> >>> those options) in response to this information: they can change their >> >>> pattern of energy production and usage in order to limit emissions of >> >>> greenhouse gases and hence the magnitude of climate changes; they can >> >>> wait >> >>> for changes to occur and accept the losses, damage and suffering that >> >>> arise; >> >>> they can adapt to actual and expected changes as much as possible; or >> >>> they >> >>> can seek as yet unproven 'geoengineering' solutions to counteract some >> >>> of >> >>> the climate changes that would otherwise occur. Each of these options >> >>> has >> >>> risks, attractions and costs, and what is actually done may be a >> >>> mixture of >> >>> these different options. " pg. B9. >> >>> >> >>> And yes, the following statement has yet to be proven - "The current >> >>> CO2-induced warming of Earth is therefore essentially irreversible on >> >>> human >> >>> timescales. The amount and rate of further warming will depend almost >> >>> entirely on how much more CO2 humankind emits." >> >>> Not surprisingly echoing the Matthews and Solomon paper to which Klaus >> >>> and I >> >>> dared to offer a rebuttal: >> >>> http://www.sciencemag.org/content/340/6140/1522.2.full >> >>> >> >>> >> >>> I would be more concerned about the upcoming NAS report on >> >>> geoengineering >> >>> where the true colors and biases of those involved will be in full >> >>> view: >> >>> >> >>> http://nas-sites.org/americasclimatechoices/study-in-progress-geoengineering/ >> >>> Very unfortunately, SRM and CRD will be discussed in the same report, >> >>> and no >> >>> doubt by some in the same breath. As I noted on Feb 21, the >> >>> involvement of >> >>> the CIA with the NAS in a geoengineering study (part of this report?) >> >>> ought >> >>> to really bring out the chemtrailers: >> >>> >> >>> http://www.motherjones.com/politics/2013/07/cia-geoengineering-control-climate-change >> >>> >> >>> In any case, this report is likely to influence CRD policy, in >> >>> particular >> >>> critically needed, supportive R&D policy, for years if not decades. >> >>> One can >> >>> only hope that NAS will not feature the APS's 2011 DAC report as >> >>> conclusive >> >>> evidence that sucking CO2 out of the air is hopelessly expensive and >> >>> call it >> >>> a day, but I'm not holding my breath. Meantime, 55% of our CO2 >> >>> emissions are >> >>> annually removed from air for free. Is it inconceivable that we >> >>> couldn't >> >>> proactively, safely, and very cost effectively increase this fraction >> >>> by >> >>> some amount? We might never find out if certain very influential >> >>> forces have >> >>> their way. >> >>> Greg >> >>> >> >>> >> >>> ________________________________ >> >>> From: Ronal W. Larson <[email protected]> >> >>> To: Geoengineering <[email protected]> >> >>> Cc: Greg Rau <[email protected]>; Ken Caldeira >> >>> <[email protected]> >> >>> Sent: Thursday, March 6, 2014 11:08 AM >> >>> Subject: [geo] NAS-Royal Society report - recent new report release >> >>> >> >>> List: cc Drs. Caldeira and Rau >> >>> >> >>> 1. I hope we can have some comment on last week's release of the >> >>> NAS - >> >>> Royal Society report entitled: >> >>> A Discussion on Climate Change: Evidence and Causes >> >>> It can be downloaded for free at >> >>> >> >>> http://nas-sites.org/americasclimatechoices/events/a-discussion-on-climate-change-evidence-and-causes/ >> >>> I had been relatively happy with it until yesterday when a friend >> >>> noted it seemed to be arguing for irreversibility in the answer to the >> >>> last >> >>> question (#20) - which showed no hint of carbon dioxide removal as an >> >>> option. The entire text for Q20 reads (emphasis added): >> >>> >> >>> "If emissions of greenhouse gases were stopped, would the climate >> >>> return to >> >>> the conditions of 200 years ago? >> >>> >> >>> No. Even if emissions of greenhouse gases were to suddenly stop, >> >>> Earth's >> >>> surface temperature would not cool and return to the level in the >> >>> pre-industrial era for thousands of years. If emissions of CO2 >> >>> stopped >> >>> altogether, it would take many thousands of years for atmospheric CO2 >> >>> to >> >>> return to 'pre-industrial' levels due to its very slow transfer to the >> >>> deep >> >>> ocean and ultimate burial in ocean sediments. Surface temperatures >> >>> would >> >>> stay elevated for at least a thousand years, implying extremely >> >>> long-term commitment to a warmer planet due to past and current >> >>> emissions, >> >>> and sea level would likely continue to rise for many centuries even >> >>> after >> >>> temperature stopped increasing [Figure 9]. Significant cooling would >> >>> be >> >>> required to reverse melting of glaciers and the Greenland ice sheet, >> >>> which >> >>> formed during past cold climates. The current CO2-induced warming of >> >>> Earth >> >>> is therefore essentially irreversible on human timescales. The amount >> >>> and >> >>> rate of further warming will depend almost entirely on how much more >> >>> CO2 >> >>> humankind emits. " >> >>> >> >>> 2. There is also a figure associated with this taken from a >> >>> paper >> >>> by Zickfeld etal, found at: >> >>> >> >>> http://www.elic.ucl.ac.be/modx/users/thierry/articles/2013_Zickfeld_et_al_JClim.pdf >> >>> which does talk about negative emissions, albeit not very positively. >> >>> This >> >>> perhaps justifies the above term "essentially", but I still feel that >> >>> a >> >>> quite pessimistic and gloomy outlook is given, that should seem >> >>> unjustified >> >>> to anyone believing in CDR as a necessity and possibility (as I do). >> >>> >> >>> 3. The public release event last week of 1.5 hours can be >> >>> viewed >> >>> at https://vimeo.com/88282420 . Four of the principal authors (Brian >> >>> Hoskins, Eric Wolff, Benjamin Santer, Inez Fung) gave brief comments >> >>> on >> >>> the report and the process - in response to questions from a reporter >> >>> and >> >>> maybe 10 from an audience at NAS headquarters. They all responded >> >>> fine, but >> >>> see one question below. >> >>> >> >>> 4. Re Geoengineering being something to consider, Hoskins >> >>> and >> >>> Fung answered a question in the 63 - 68 minute timeframe using the >> >>> word, >> >>> saying it was the fourth of four actions that could be taken. The >> >>> report >> >>> says (last page): >> >>> "....or they can seek as yet unproven 'geoengineering' solutions to >> >>> counteract >> >>> some of the climate changes that would otherwise occur. " >> >>> They apparently wanted to be sure that the audience in the room knew >> >>> that >> >>> they intentionally did not talk about either SRM or CDR. They >> >>> emphasized >> >>> that the graph in Question 20 makes no mention of either SRM or CDR >> >>> because >> >>> they didn't want to get into those topics. But I now interpret (I >> >>> hope >> >>> correctly??) that irreversibility was being ruled out, as they >> >>> apparently >> >>> would include CDR as part of geoengineering. My preference is that >> >>> they had >> >>> said something about at least afforestation/reforestation (Jim >> >>> Hansen's >> >>> approach to CDR) - as nice credit was give about Hansen's early >> >>> warnings. >> >>> >> >>> 5. Other questions were on a major release arctic methane >> >>> release. Near the 69 minute mark there was question on costs - but no >> >>> specific answers >> >>> >> >>> 6. Dr. Fung said (my version, not from a transcript) just >> >>> before >> >>> the 96 minute mark (after a question suggesting 25%-40% CO2 removal): >> >>> " Because we have put this much heat into the system - removing >> >>> that >> >>> CO2, you still would have that heat in the system. It would take a >> >>> very >> >>> long time. And so we would still be warmer than in 1800." >> >>> This indicates to me that it could be that she truly believes in >> >>> irreversibility. That one can reduce CO2, but not temperatures - >> >>> which, if >> >>> true, would argue against CDR. But I don't believe such >> >>> irreversibility to >> >>> be true, and I am hoping she doesn't either. >> >>> a. One piece of counter-evidence is from Drs. Cao and >> >>> Caldeira in >> >>> http://iopscience.iop.org/1748-9326/5/2/024011/fulltext/, showing a >> >>> rapid >> >>> fall in surface temperature after a hypothetical complete removal of >> >>> CO2. >> >>> b. Another is similar by Dr. Andrew Lacis in >> >>> http://www.giss.nasa.gov/research/briefs/lacis_01/ >> >>> c. Another is in several analyses by Dr. Hansen. One, >> >>> showing >> >>> rapidly falling temperatures after afforestation in figure 9 (with CO2 >> >>> decline in Figure 5) in: >> >>> >> >>> >> >>> http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0081648 >> >>> >> >>> 7. I repeat that overall the report is helpful in providing >> >>> counter evidence to climate deniers. But this is to hope that others >> >>> can >> >>> comment on how else to interpret Dr. Fong's comment at the 96 minute >> >>> spot. >> >>> I am sure she knows several orders more in magnitude than myself about >> >>> almost any climate topic, but I fear that those arguing against CDR >> >>> will >> >>> find comfort in her words and the above answer to Q 20. Can anyone >> >>> offer a >> >>> good explanation of these "anti-CDR" (pro-irreversibility) remarks? >> >>> I note >> >>> for Dr. Rau (who has complained on this list about "irreversibility") >> >>> that >> >>> Dr. Susan Solomon is a co-author of this new report. >> >>> >> >>> Ron >> >>> >> >>> >> >>> >> >>> -- >> >>> 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 [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/groups/opt_out. >> >>> >> >>> >> >>> -- >> >>> 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 [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/groups/opt_out. >> >>> -- >> >>> 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 [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 [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 [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. >> >> -- >> 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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