Thanks, David. I agree. Failure to appreciate long term effects and ocean acidification impacts, together with questionable/opaque discounting schemes has I believe resulted in CO2 mitigation being greatly undervalued by the economists and this is significantly undermining policy and political will. Regards, Greg
>Greg > >GWP's by design ignore all climate impacts beyond 100 years. > >This has real consequences as it makes methane look relatively more >important that it should be, and it also overweight's the beneficial >impacts of biomass sequestration in some calculations. > >While some traditional economists may assume that discounting allows >them to ignore any impact beyond 100 years, this GWP formula has >long been a point of contention as most of us do value the future of >the planet beyond 100 years. > >Adopting a 100 year analysis horizon, as the IPCC generally does, >takes our eye off the long term consequences of dumping fossil >carbon in the atmosphere. The risk of sea level rise look much less >serious if one only looks a century out. > >Scientific understanding about the long term impacts of fossil >emissions is decades old (see Jim Kasting's old papers for example), >popular realization of these facts is long overdue. > >Cheers, >David > > > >From: Greg Rau [mailto:[email protected]] >Sent: November 16, 2009 1:23 PM >To: [email protected]; [email protected] >Subject: Re: [geo] Re: Rejected - a simple argument for SRM geoengineering > >In light of recent modeling results on the lifetime of CO2 in the >atmosphere, I am concerned that the current time-integrated (not >instantaneous) GWP estimate for CO2 has been underestimated and >hence GWP's of other gases (esp short-lived gases) relative to CO2 >have been overestimated. E.g., Eby et al., 2009: >http://*ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2F2008JCLI2554.1 >show that 20-30% of excess emissions of CO2 and 60-70% of the >subsequent CO2-caused surface air temp anomally exists 10,000 years >after emission. Isn't this (or is this?) a far larger total >time-integrated GW effect than a mass equivalent emission of CH4? >Experts please set me straight. >Thanks, >Greg > > >>Agreed, one has to consider a time period, so assume one takes a >>day that when injected there is no decay over this period-so it >>might as well be a second of time one takes-so virtually >>instantaneous. And I'll assume linearity on methane absorption and >>logarithmic for CO2. >> >>So, for methane, humans have caused an increase of roughly 1000 ppb >>which converts to about 3 GtCH4, and this causes a forcing of about >>0.5 W/m**2 (at the tropopause) per IPCC. >> >>For CO2, we know that a doubling (so we'll say from 300 to 600 ppm >>so we are in the range of interest) causes a forcing of about 3.6 >>W/m**2 (at the tropopause). So, 300 ppm of CO2 in the atmosphere is >>roughly 600 GtC or 2200 GtCO2 (and global warming potential is done >>for CO2, I believe. >> >>So, if we take the ratio of forcing to mass for CH4 divided by the >>ratio of forcing to mass for CO2, we get a rough estimate of the >>instantaneous GWP, so >> >>[0.5/3]/[3.6/2200] equals roughly 100 >> >>for the ratio at t=0 (so allowing for no decay) of the radiative >>forcing caused by a unit mass of CH4 added to the atmosphere to a >>unit mass of CO2 added to the atmosphere. >> >>Not exact, but plausible. >> >>Mike >> >> >> >> >>On 11/16/09 3:42 AM, "Peter Read" <[email protected]> wrote: >>John, Andrew >>Re "BTW, does anybody know the _immediate_ warming potential of methane?" >>Someone will correct me no doubt but my understanding is that >>warming is a rate process measured in W/m^2 >>So "instantaneous" [[== "immediate"?]] warming is an incorrect concept >>Unless it continues for a second, a week, a year, 25 years, for >>whatever, no warming takes place. >>So it is necessary to multiply by a duration to get joules/m^2 >>It's how many joules get into the low albedo meltwater on top of >>Greenland's ice that decides how much gets melted each year to fall >>down crevasses and lubricate the eventual collapse of large areas >>of ice into the oceans. >>Meaning that the integral [[roughly]] under the CO2 level curve is >>what matters [multiplied by the warming potential over that period] >> when it comes to measuring threats of Greenland's collapse >>So the key issue is duration - how long elevated greenhouse gas >>levels last and how to get them down. >>Think that's right >>Peter >> >>----- Original Message ----- >> >>From: John Nissen >><<mailto:[email protected]>mailto:[email protected]> >> >>To: [email protected] >> >> >>Cc: geoengineering >><<mailto:[email protected]>mailto:[email protected]> >> >> >> >>Sent: Monday, November 16, 2009 6:18 PM >> >>Subject: Re: [geo] Re: Rejected - a simple argument for SRM geoengineering >> >> >> >>Hi Andrew, >> >>You say: "I don't oppose John's argument, but the evidence on the >>severity of the problem is far from conclusive." I disagree. >> >>The methane presents a very real risk - because of the uncertainty >>on timing combined with the potential size of methane discharge - >>perhaps even enough to cause thermal runaway due to positive >>feedback, as is thought to have happened in the past [1]. Risk >>management involves identifying events and assessing them in terms >>of their likelihood and magnitude of impact [2]. Thus something >> with a small likelihood (such as rapid massive methane excursion) >>can have a high risk, if the magnitude of impact is sufficiently >>large (and you can't get much larger than thermal runaway). >> >> >>It is possible that much or most of the methane trapped in frozen >>structures has built up over hundreds of thousands of years. >> There is little sign of massive methane discharge in the ice >>record. In fact methane seems to track the temperature even better >> than CO2 [3]. >> >>But of course methane discharge is not the only high risk event - >>there is also the Greenland ice sheet disintegration. >> >>BTW, does anybody know the _immediate_ warming potential of >>methane, as opposed to the 20 year value (72), 100 years (25) or >>500 years (7.6)? The lifetime is only 12 +/- 3 years. See [4]. >> >>Cheers, >> >>John >> >>[1] >><http://**en.wikipedia.org/wiki/Clathrate_gun_hypothesis>http://**en.wikipedia.org/wiki/Clathrate_gun_hypothesis >> >>[2] >> <http://**en.wikipedia.org/wiki/Enterprise_risk_management>http://**en.wikipedia.org/wiki/Enterprise_risk_management >> >> >> >>[3] >><http://**answers.yahoo.com/question/index?qid=20090329215018AAxqYFk>http://**answers.yahoo.com/question/index?qid=20090329215018AAxqYFk >> >> >> >>[4] >><http://**en.wikipedia.org/wiki/Greenhouse_gas>http://**en.wikipedia.org/wiki/Greenhouse_gas >> >> >> >>--- >> >>Andrew Lockley wrote: >>At present the likely methane excursion is far from clear. >> Further, it is also unclear how quickly the total excursion will >> occur. The excursion rate is highly significant due to the short >>life of methane in the atmosphere. The methane ends up as CO2, in >>itself a major issue. However, the CO2's likely effect is nothing >>compared to the devastating temperature spike which may result >>from a sudden methane excursion. >> >> >>I don't oppose John's argument, but the evidence on the severity of >>the problem is far from conclusive. We need much more research >>into: >> >>1) The methane reservoir in clathrates and permafrost >> >>2) The size of potential methane sources currently frozen as >>organic detritus >> >>3) The likely changes to the GWP of methane in future atmospheres, >>as the levels of hydroxyl radicals etc. shift over time and as a >>direct result of methane excursion. Recent research on this asks >>more questions than it answers. >> >> >> >>My personal feeling is that the range of likely outcomes is from a >> significant amplification of AGW, right up to a 'Great Dying' >>sized mass-extinction event when we come within a sneeze of >>sterilising the entire planet. I'd be tempted to bet on the >>latter, but I wouldn't be around to collect the winnings, so I'll >>keep my wallet in my pocket. >> >> >> >>My suggestions is that geoengineers look at ways to clean up the >> methane from the atmosphere, and then lock down the resulting >>carbon. My guess is we've got about 50 years to do this, but >>virtually no time at all if the methane can't be dealt with once >>it's in the atmosphere. Therefore, I'd support John out of >>precautionary principle-based reasoning. >> >> >> >>A >> >> >>2009/11/15 jim woolridge <[email protected]> >> >>Nice one, John; the train of argument is clear (of limpid clarity, in >>fact!) The problem is that the people and institutions addressed are >>in the business of politics, the art of the possible, rather than in >>the business of logical evaluation. They hear what you are saying and >>must see the validity of it. But politically what is true and what is >>doable do not always coincide, as we all know from as many examples as >>one cares to ennumerate. >> >>We have to keep hammering away at the arguments, to the point at which >>they are generally understood and accepted, and also keep on >>politicking in the sure and certain hope that eventually the >>acceptance of the arguments and the cowardice/caution/horse sense/ >>opportunistic careerism of the politicos will achieve the right kind >>of intersection. In the next year or so (& wouldn't it be a great >>help to have the environmental NGOs on board.) >> >> >> >>On Nov 12, 10:51 pm, John Nissen <[email protected]> wrote: >>> It is incredible. It is so obvious. >>> >>> 1. Global warming is driven largely by atmospheric CO2 according to the >>> concentration above its pre-industrial level; and >>> >>> 2. After emissions are stopped it could take millenia for the >>> concentration to fall back to that level, because the effective lifetime >> >> > of some of that excess CO2 is many thousands of years. >>> >>> Therefore: >>> 3. Drastic emissions reduction, even to zero overnight, cannot and will >>> not stop the Arctic continuing to warm for decades. >>> >>> Therefore: >>> 4. The Arctic sea ice will continue to retreat, accelerating the warming >>> due to the albedo effect. >>> >>> Therefore: >>> 5. The permafrost will continue to thaw releasing increasing quantities >>> of methane, a potent greenhouse gas, potentially adding many degrees to >>> global warming; and >>> >>> 6. The Greenland ice sheet will become increasingly unstable, >>> potentially contributing to an eventual sea level rise of 7 metres. >>> >>> Therefore: >>> 7. To avoid these two catastrophes, we need to cool the Arctic quickly >>> enough to save the Arctic sea ice; and >>> >>> 8. Probably the only feasible way to do this is through solar radiation >>> management (SRM) geoengineering. >>> >>> 9. SRM is not a last resort, it is needed now to cool the Arctic. >>> >>> It is incredible that people do not seem to follow this train of logic - >>> it is so obvious. >>> >>> Yet when I challenged a panel of geoengineering experts to refute this >>> argument, the response was that geoengineering (even just to cool the >>> Arctic) was too dangerous - not that the argument was false! [1] >>> >>> So we continue to hear politicians and their advisers claiming that >>> emissions reduction alone can be sufficient to keep the planet safe. [2] >>> >>> And we continue to hear geoengineering experts saying that >>> geoengineering should only be used as a last resort. [3] >>> >>> How can this mindset be changed quickly, to avoid leaving geoengineering >>> too late? >>> >>> John >>> >>> P.S. Apologies to those who have heard this all before and accept the >>> logic as self-evident. >>> >>> [1] This challenge was put to the panel at the launch of the Royal >>> Society geoengineering report, on September 1st, with response from the >>> team leader and panel chairman, Professor John Shepherd. >>> >>> [2] For example at the geoengineering hearing at the House of Commons, >>> November 2008. >>> >>> [3] For example at the congressional hearing on geoengineering, November >>> 2009. >> >>-- >> >>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] >><<mailto:geoengineering%[email protected]>mailto:geoengineering%[email protected]> >> >>. >>For more options, visit this group at >><http://**groups.google.com/group/geoengineering?hl=>http://**groups.google.com/group/geoengineering?hl=. >> >> >> >> >>-- >>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=>http://**groups.google.com/group/geoengineering?hl=. >> >> >> >> >> >>-- >>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=>http://**groups.google.com/group/geoengineering?hl=. >> >> >> >> >> >> >> >> >>No virus found in this incoming message. >>Checked by AVG - www.**avg.com >>Version: 8.5.425 / Virus Database: 270.14.67/2505 - Release Date: >>11/15/09 19:50:00 >> >>-- >>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=>http://**groups.google.com/group/geoengineering?hl=. >> >>-- >> >>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=. >> > >-- >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=. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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