Hi John and Greg‹So responding to both messages (and I pasted John¹s into the thread)
I would think the terrestrial biosphere time constant is a decade or two, but for the ocean, I¹d suggest that it is much shorter. My understanding is that the time constant of the wind-stirred ocean mixed layer is a year or two‹not a decade or two. Changing the net flux rate to the deep ocean would be pretty slow, but that net flux is pretty small. And so, how would it work. Well, in terms of the net flux to the ocean, the CO2 is driven into the upper ocean by the gradient between the atmosphere and the upper ocean, so once one stabilizes the atmospheric concentration and the ocean mixed layer concentration catches, up, there will be no gradient to drive the flux. Well, this is not quite correct as the net flux to the deep ocean would continue, so there could be a net flux from the atmosphere to the upper ocean to make up that difference. However, the ocean surface layer would also continue to warm as there is a lag in the thermal term‹and so the warmer the mixed layer, the higher the CO2 partial pressure would be and this would tend to resist uptake of CO2. In terms of gross fluxes, the carbon rich upwelling waters would end up giving off a bit more CO2 with CO2 stabilization as opposed to the situation were the CO2 higher, and the uptake in high latitudes where water is cold would not be going up because the atmosphere-upper ocean gradient would be less, so again, one would lose the ocean sink, and that would mean that a greater share of any emissions that did occur (so in reducing the CO2 emissions from 37 Gt CO2/yr, one does not get to assume the ocean sink would continue as it has‹and I suspect that would be a pretty fast adjustment. For the biosphere, John suggests that he is quite concerned about the continuance of the terrestrial sink (basically, it seems, whether or not one stabilizes the CO2 concentration). So, as I indicated initially, it seems to me that one would pretty quickly need to be taking up 90% of the 37 GtCO2/yr by your proposed approach‹and that is a lot of carbon to be taking up. Hence, I¹ll stand by my earlier statement that it will be hard for CDR/atmospheric and oceanic scrubbing to make much of a difference with respect to slowing the rate of climate change until emissions drop a lot. Mike Msg from John Harte‹combined into this thread. Mike, I think the truth is flanked by your's and Greg's statements. If we were to reduce emissions starting immediately so that each year from here on out we emit only about half current emissions, then for a decade or two, at least, the current carbon sink would roughly equal emissions and the CO2 level would be roughly constant, as Greg suggests. The concentration gradient between air and sea would slowly shrink however and so in the longer run the sink strength would diminish and emissions would have to be reduced further. At a steady annual flow from air to sea of 15 - 20 Gt(CO2)/y, however, it would take decades before there was an appreciable diminishment of that sink flow. The real shorter-term danger I think is that soil warming and forest dieback leading to terrestrial sources of CO2, along with possible CH4 releases, all because of the warming associated with trying to keep a steady 400 ppm of CO2, would necessitate much greater emissions reduction and the sooner we achieve that the better. John Harte Professor of Ecosystem Sciences ERG/ESPM 310 Barrows Hall University of California Berkeley, CA 94720 USA [email protected] On 1/25/15, 3:23 PM, "Greg Rau" <[email protected]> wrote: > I'm not necessarily advocating lowering air pCO2, but stabilizing pCO2 say at > the present 400 uatms. If this is stable, how does additional ocean degassing > ensue? Exactly how much CDR would be needed to achieve this, the resulting > response of natural CDR and natural emissions, and the required time course of > this I will leave to the modelers. Ditto for achieving stability via pure > anthro emissions reduction. Obviously, some combination of these will, in my > opinion, be needed to stabilize pCO2. Anthro emissions reduction would appear > to have significant technological and policy awareness lead relative to CDR. > I'm suggesting this needs to change, in case emissions reduction alone > continues to fail to achieve its promise. > > As for reducing air pCO2, this already happens on an intra-annual basis thanks > to natural CDR and in spite of ocean degassing: > https://scripps.ucsd.edu/programs/keelingcurve/2013/10/23/the-annual-rise-in-c > o2-levels-has-begun/#more-940 Is it unthinkable that this decline couldn't > be increased to some degree via human intervention? Wouldn't it be > desirable/necessary to investigate this in the now likely event that current > policies and actions have us blowing by the pCO2 "safety threshold" for > decades if not centuries, or beyond if permafrost/clathrate degassing ensues? > Greg > >> >> >> >> >> >> From: Mike MacCracken <[email protected]> >> To: Greg Rau <[email protected]>; Geoengineering >> <[email protected]> >> Sent: Sunday, January 25, 2015 11:10 AM >> Subject: Re: [geo] Energy Planning and Decarbonization Technology | The >> Energy Collective >> >> >> >> Re: [geo] Energy Planning and Decarbonization Technology | The Energy >> Collective >> Hi Greg--The problem with your calculation is that if you were to take CO2 >> out of the atmosphere, the ocean and biosphere would readjust to the lower >> atmospheric concentration and return to the atmosphere that they have taken >> up earlier when the original amount of CO2 was emitted. Thus, you really have >> to figure out how to sequester 90+% of the 37 Gt CO2/yr that is emitted‹you >> don¹t get to keep counting the 20 Gt CO2 taken up by the ocean and the >> biosphere. >> >> Mike >> >> >> On 1/25/15, 1:25 PM, "Greg Rau" <[email protected]> wrote: >> >>> Just to be clear, we currently emit 37.0 GT CO2/yr, yet in the short term >>> only 17.5 Gt/yr remain in the atmosphere, the rest being removed by natural >>> CDR (reviewed here: >>> http://www.nature.com/nclimate/journal/v4/n10/full/nclimate2392.html ). So >>> our net emissions is 17.5 Gt/yr. Cutting this by 90% via enhanced CDR alone >>> would mean removing an additional 15.8 GT CO2/yr over and above the 19.5 >>> Gt/yr already removed, a 81% increase in CDR. Is this sufficient to >>> stabilize air pCO2 or lower pCO2? If the latter then we'd also have to >>> contend with legacy CO2 degassing from the ocean. It should be easier to >>> reduce emissions than increase CDR, but then how is that going? I'd say >>> it's time to find out just how easy or hard additional CDR is, relative to >>> the technical, economic and political difficulties of emissions reduction, >>> and relative to the consequences if the latter strategy continues to >>> seriously underperform. >>> Greg >>> >>>> >>>> >>>> >>>> >>>> >>>> From: Mike MacCracken <[email protected]> >>>> To: Greg Rau <[email protected]>; Geoengineering >>>> <[email protected]> >>>> Sent: Sunday, January 25, 2015 8:27 AM >>>> Subject: Re: [geo] Energy Planning and Decarbonization Technology | The >>>> Energy Collective >>>> >>>> >>>> >>> Re: [geo] Energy Planning and Decarbonization Technology | The Energy >>> Collective >>> Let me expand my quick description to be 90% cut in human-induced emissions >>> (on top of all the natural sinks), so natural CDR does not count. >>> >>> And on the proposed removal industry, for $100 per ton of CO2, an awful lot >>> could be done to replace fossil fuels with other sources of energy, or even >>> better efficiency, a huge amount of which could be done for much less, if >>> we¹d try. So, nice that there is a CO2 removal approach as a backstop to >>> what the cost of changing energy would be‹basically, you are suggesting it >>> should cost less than $100 per ton of CO2 to address the problem. With the >>> new paper in Nature (lead author is a former intern that worked with me at >>> the Climate Institute) that the social cost of CO2 is more than twice the >>> cost of, then it makes huge economic sense to be addressing the problem. So, >>> indeed, let¹s get on with it‹research plus actually dealing with the issue. >>> >>> Mike >>> >>> >>> >>> >>> On 1/24/15, 1:40 PM, "Greg Rau" <[email protected]> wrote: >>> >>>> Mike, >>>> If it takes "a 90% cut in CO2 to stop the rise in atmospheric >>>> concentration", we are already more than half way there thanks to natural >>>> CDR. About 55% of our CO2 emissions are mercifully removed from air via >>>> biotic and abiotic processes. So just 35% to go? >>>> As for "CDR replacing the fossil fuel industry", here's one way to do that: >>>> http://www.pnas.org/content/110/25/10095.full , but low fossil energy >>>> prices (or lack of sufficient C emissions surcharge) are unlikely to make >>>> this happen. Certainly agree that we need all hands and ideas on deck in >>>> order to stabilize air CO2. But for reasons that continue to baffle me, >>>> that is not happening at the policy, decision making, and R&D levels it >>>> needs to. >>>> Greg >>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> From: Mike MacCracken <[email protected]> >>>>> To: Geoengineering <[email protected]> >>>>> Sent: Saturday, January 24, 2015 9:06 AM >>>>> Subject: Re: [geo] Energy Planning and Decarbonization Technology | The >>>>> Energy Collective >>>>> >>>>> >>>>> >>>>> Re: [geo] Energy Planning and Decarbonization Technology | The Energy >>>>> Collective >>>>> In terms of an overall strategy, it takes of order a 90% cut in CO2 >>>>> emissions to stop the rise in the atmospheric concentration, and that has >>>>> to happen to ultimately stabilize the climate (and it would be better to >>>>> have the CO2 concentration headed down so we don¹t get to the equilibrium >>>>> warming for the peak concentration we reach (recalling we will be losing >>>>> sulfate cooling). >>>>> >>>>> Thus, to really stop the warming, CDR in its many forms has to be at least >>>>> as large as 90% of CO2 emissions (from fossil fuels and biospheric >>>>> losses). That is a lot of carbon to be taking out of the system by putting >>>>> olivine into the ocean, biochar, etc. at current global emissions levels >>>>> (that are still growing). The greater the mitigation (reduction in fossil >>>>> fuel emissions), the more effective CDR can be‹what would really be nice >>>>> is CDR replacing the fossil fuel industry so ultimately it is as large. >>>>> I¹d suggest this is why it is really important to always be mentioning the >>>>> importance of all the other ways, in addition to CDR, to be cutting >>>>> emissions‹that is really critical. >>>>> >>>>> Mike >>>>> >>>>> >>>>> On 1/24/15, 10:19 AM, "Stephen Salter" <[email protected]> wrote: >>>>> >>>>>> >>>>>> Hi All >>>>>> >>>>>> Paragraph 2 mentions 'carbon negative' nuclear energy. The carbon >>>>>> emissions from a complete, working nuclear power station are mainly >>>>>> people driving to work. But digging, crushing and processing uranium ore >>>>>> needs energy and releases carbon in inverse proportion to the ore grade. >>>>>> There were some amazingly high grade ores, some once even at the critical >>>>>> point for reaction, but these have been used. Analysis by van Leeuwen >>>>>> concludes that the carbon advantage of present nuclear technology over >>>>>> gas is about three but that the break-even point comes when the ore grade >>>>>> drops to around 100 ppm. This could happen within the life of plant >>>>>> planned now. >>>>>> >>>>>> As we do not know how to do waste disposal we cannot estimate its carbon >>>>>> emissions. But just because we cannot calculate them does not mean that >>>>>> they are zero. >>>>>> >>>>>> Stephen >>>>>> >>>>>> >>>>>> >>>>>> Emeritus Professor of Engineering Design. School of Engineering. >>>>>> University of Edinburgh. Mayfield Road. Edinburgh EH9 3JL. Scotland >>>>>> [email protected] Tel +44 (0)131 650 5704 Cell 07795 203 195 >>>>>> WWW.see.ed.ac.uk/~shs <http://WWW.see.ed.ac.uk/~shs> YouTube Jamie >>>>>> Taylor Power for Change >>>>>> >>>>>> On 24/01/2015 14:56, Andrew Lockley wrote: >>>>>> >>>>>> >>>>>>> >>>>>>> >>>>>>> Poster's note : none of this explains why there's any need for >>>>>>> integration. Chucking olivine in the sea seems easier and cheaper than >>>>>>> all. >>>>>>> >>>>>>> >>>>>>> http://theenergycollective.com/noahdeich/2183871/3-ways-carbon-removal-c >>>>>>> an-help-unlock-promise-all-above-energy-strategy >>>>>>> >>>>>>> >>>>>>> 3 Ways Carbon Removal can Help Unlock the Promise of an All-of-the-Above >>>>>>> Energy Strategy >>>>>>> >>>>>>> >>>>>>> January 24, 2015 >>>>>>> >>>>>>> >>>>>>> >>>>>>> ³We can¹t have an energy strategy for the last century that traps us in >>>>>>> the past. We need an energy strategy for the future an >>>>>>> all-of-the-above strategy for the 21st century that develops every >>>>>>> source of American-made energy.² President Barack Obama, March 15, 2012 >>>>>>> >>>>>>> >>>>>>> An all-of-the-above energy strategy holds great potential to make our >>>>>>> energy system more secure, inexpensive, and environmentally-friendly. >>>>>>> Today¹s approach to all-of-the-above, however, is missing a key piece: >>>>>>> carbon dioxide removal (³CDR²). Here¹s three reasons why CDR is critical >>>>>>> for the success of an all-of-the-above energy strategy: >>>>>>> >>>>>>> >>>>>>> 1. CDR helps unite renewable energy and fossil fuel proponents to >>>>>>> advance carbon capture and storage (³CCS²) projects. Many renewable >>>>>>> energy advocates view CCS as an expensive excuse to enable >>>>>>> business-as-usual fossil fuel emissions. But biomass energy with CCS >>>>>>> (bio-CCS) projects are essentially ³renewable CCS² (previously viewed as >>>>>>> an oxymoron), and could be critical for drawing down atmospheric carbon >>>>>>> levels in the future. As a result, fossil CCS projects could provide a >>>>>>> pathway to ³renewable CCS² projects in the future. Because of the >>>>>>> similarities in the carbon capture technology for fossil and bioenergy >>>>>>> power plants, installing capture technology on fossil power plants today >>>>>>> could help reduce technology and regulatory risk for bio-CCS projects in >>>>>>> the future. What¹s more, bio-CCS projects can share the infrastructure >>>>>>> for transporting and storing CO2 with fossil CCS installations. Creating >>>>>>> such a pathway to bio-CCS should be feasible through regulations that >>>>>>> increase carbon prices and/or biomass co-firing mandates slowly over >>>>>>> time, and could help unite renewable energy and CCS proponents to >>>>>>> develop policies that enable the development of cost-effective CCS >>>>>>> technology. >>>>>>> >>>>>>> >>>>>>> 2. CDR bolsters the environmental case for nuclear power by enabling it >>>>>>> to be carbon ³negative²: Many environmental advocates say that >>>>>>> low-carbon benefits of nuclear power are outweighed by the other >>>>>>> environmental and safety concerns of nuclear projects. The development >>>>>>> of advanced nuclear projects paired with direct air capture (³DAC²) >>>>>>> devices, however, could tip the scales in nuclear¹s favor. DAC systems >>>>>>> that utilize the heat produced from nuclear power plants can benefit >>>>>>> from this ³free² source of energy to potentially sequester CO2 directly >>>>>>> from the atmosphere cost-effectively. The ability for nuclear + DAC to >>>>>>> provide competitively-priced, carbon-negative energy could help convince >>>>>>> nuclear power¹s skeptics to support further investigation into >>>>>>> developing safe and environmentally-friendly advanced nuclear systems. >>>>>>> >>>>>>> >>>>>>> 3. CDR helps enable a cost-effective transition to a decarbonized >>>>>>> economy: Today, environmental advocates claim that prolonged use of >>>>>>> fossil fuels is mutually exclusive with preventing climate change, and >>>>>>> fossil fuel advocates bash renewables as not ready for ³prime time² ‹ >>>>>>> i.e. unable to deliver the economic/development benefits of inexpensive >>>>>>> fossil energy. To resolve this logjam, indirect methods of >>>>>>> decarbonization ‹ such as a portfolio of low-cost CDR solutions ‹ could >>>>>>> enable fossil companies both to meet steep emission reduction targets >>>>>>> and provide low-cost fossil energy until direct decarbonization through >>>>>>> renewable energy systems become more cost-competitive (especially in >>>>>>> difficult to decarbonize areas such as long-haul trucking and aviation). >>>>>>> >>>>>>> >>>>>>> Of course, discussion about the potential for CDR to enable an >>>>>>> all-of-the-above energy strategy is moot unless we invest in developing >>>>>>> a portfolio of CDR approaches. But if we do make this investment in CDR, >>>>>>> an all-of-the-above energy strategy that delivers a diversified, >>>>>>> low-cost, and low-carbon energy system stands a greater chance of >>>>>>> becoming a reality. >>>>>>> >>>>>>> >>>>>>> Noah Deich >>>>>>> >>>>>>> >>>>>>> Noah Deich is a professional in the carbon removal field with six years >>>>>>> of clean energy and sustainability consulting experience. Noah currently >>>>>>> works part-time as a consultant for the Virgin Earth Challenge, is >>>>>>> pursuing his MBA from the Haas School of Business at UC Berkeley, and >>>>>>> writes a blog dedicated to carbon removal (carbonremoval.wordpress.com >>>>>>> <http://carbonremoval.wordpress.com >>>>>>> <http://carbonremoval.wordpress.com/> >>>>>>> <http://carbonremoval.wordpress.com/> >>>>>>> <http://carbonremoval.wordpress.com/> > ) >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> 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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