I do have that book somewhere‹thanks for the reminder about it. Mike
On 1/26/15, 4:12 PM, "John Harte" <[email protected]> wrote: > Hi Mike, I sympathize with your wish to understand carbonate chemistry and > it's relation to the carbon cycle in the oceans. 30 years ago I found I > couldn't understand what was in the literature so I just worked it all out for > myself. Its described on pages 128 to 149 in my book: consider a spherical > cow. Maybe you will find that useful. > > Sent from my iPhone > John Harte > > > On Jan 25, 2015, at 7:11 PM, Mike MacCracken <[email protected]> wrote: > >> Re: [geo] Energy Planning and Decarbonization Technology | The Energy >> Collective Hi John‹Good question‹and we need Greg or Ken to weigh in. >> >> My guess is that the numbers for ocean carbon on the diagram include all of >> the active forms of C, and so only a small amount is really in the form of >> CO2 and so affecting the atmosphere-ocean gradient that is calculated. I have >> always wished that I had more solidly come to understand ocean C chemistry. >> >> Mike >> >> >> >> >> On 1/25/15, 9:38 PM, "John Harte" <[email protected]> wrote: >> >>> Hi Mike, >>> >>> The figure is useful: If 597 (atm) had been in equilibrium with 900 (mixed >>> layer) pre-industrial, how can 597+165 be within a few Gt(C) of equilibrium >>> with 900 + 18? If the atm. and the mixed layer of the sea are that far out >>> of equilibrium, seems to me the sink will operate for a while (decades) even >>> if future emissions = current sink over that period. In other words, what >>> I am questioning is whether there would, within a year, be a hugely reduced >>> gradient. Am I misinterpreting the numbers in the figure??? >>> >>> It will be nice to sort this out!! >>> >>> John >>> >>> >>> John Harte >>> Professor of Ecosystem Sciences >>> ERG/ESPM >>> 310 Barrows Hall >>> University of California >>> Berkeley, CA 94720 USA >>> [email protected] >>> >>> >>> >>> On Jan 25, 2015, at 6:16 PM, Mike MacCracken <[email protected]> wrote: >>> >>>> Re: [geo] Energy Planning and Decarbonization Technology | The Energy >>>> Collective >>>> Hi John‹So I have attached a diagram of the carbon cycle from IPCC AR4WG1 >>>> Figure 7.3 that shows natural flows (in black) and then the augmentations >>>> as a result of human activities (in red) >>>> >>>> There is a time constant for uptake of particular molecules of CO2 into the >>>> mixed layer, so mass in mixed layer divided by atmospheric flux, and that >>>> is 10 years (what I think you are referring to). I don¹t think, however, >>>> that this is what determines the lag time for the net flux and so what >>>> counts in what we have been talking about‹basically, if there were suddenly >>>> no gradient, there would immediately be no net flux and it does not matter >>>> which molecule is where. So, in my view, what matters is the gradient that >>>> is created by each year¹s emissions, and as that goes down, the gradient >>>> will be less, and if the atmospheric concentration were suddenly held >>>> stable, the driving gradient would pretty quickly go to zero (there would >>>> still be the gradient with the deep ocean as its cycle time is of order >>>> 1000 years, so the flux to the deep ocean would continue. >>>> >>>> And I don¹t think there is anywhere near a 10-year lag in the concentration >>>> gradient between the atmosphere and the concentration at the top of the >>>> mixed layer‹nor do I think that the vertical mixing time down of order >>>> 100-200 meters in the upper ocean layer is anything like a decade given >>>> wave and isopychnal mixing and wind driven flows‹I¹d suggest less than a >>>> year, but that is a guess. [WE NEED AN AUTHORITATIVE COMMENT FROM KEN C]. >>>> >>>> Best, Mike >>>> >>>> >>>> >>>> >>>> On 1/25/15, 6:10 PM, "John Harte" <[email protected] >>>> <x-msg://4924/[email protected]> > wrote: >>>> >>>>> Mike, I could be wrong but i was under the impression that the relevant >>>>> time constant (inverse rate const.) characterizing the gradient-driven >>>>> gross flow of CO2 from air to sea is on the order of a decade or two. A >>>>> result I thought obtained from C14 tracer studies. I am also under the >>>>> impression that the year to year variation in the sink strength does not >>>>> track annual emissions very closely, suggesting that there are longer time >>>>> constants in the system (as well as "noise" from variations in wind etc. >>>>> and inter annual variability in the terrestrial sink). >>>>> >>>>> It's been a while since I looked at this so maybe my understanding is out >>>>> of date. >>>>> >>>>> >>>>> Cheers, >>>>> >>>>> John >>>>> >>>>> John Harte >>>>> Professor of Ecosystem Sciences >>>>> ERG/ESPM >>>>> 310 Barrows Hall >>>>> University of California >>>>> Berkeley, CA 94720 USA >>>>> [email protected] <x-msg://4924/[email protected]> >>>>> >>>>> >>>>> >>>>> On Jan 25, 2015, at 1:27 PM, Mike MacCracken <[email protected] >>>>> <x-msg://4924/[email protected]> > wrote: >>>>> >>>>>> Re: [geo] Energy Planning and Decarbonization Technology | The Energy >>>>>> Collective >>>>>> 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] <x-msg://4924/[email protected]> >>>>>> <x-msg://4873/[email protected] <x-msg://4873/[email protected]> > >>>>>> >>>>>> >>>>>> On 1/25/15, 3:23 PM, "Greg Rau" <[email protected] >>>>>> <x-msg://4924/[email protected]> <x-msg://4873/[email protected] >>>>>> <x-msg://4873/[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-ris >>>>>>> e-in-co2-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] <x-msg://4924/[email protected]> <x-msg://4873/[email protected] <x-msg://4873/[email protected]> > > To: Greg Rau <[email protected] <x-msg://4924/[email protected]> <x-msg://4873/[email protected] <x-msg://4873/[email protected]> > >; Geoengineering <[email protected] <x-msg://4924/[email protected]> <x-msg://4873/[email protected] <x-msg://4873/[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] <x-msg://4924/[email protected]> <x-msg://4873/[email protected] <x-msg://4873/[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] >> <x-msg://4924/[email protected]> <x-msg://4873/[email protected] >> <x-msg://4873/[email protected]> > > >> To: Greg Rau <[email protected] <x-msg://4924/[email protected]> >> <x-msg://4873/[email protected] <x-msg://4873/[email protected]> > >; >> Geoengineering <[email protected] >> <x-msg://4924/[email protected]> >> <x-msg://4873/[email protected] >> <x-msg://4873/[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] <x-msg://4924/[email protected]> <x-msg://4873/[email protected] <x-msg://4873/[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] >> <x-msg://4924/[email protected]> <x-msg://4873/[email protected] >> <x-msg://4873/[email protected]> > > >> To: Geoengineering <[email protected] >> <x-msg://4924/[email protected]> >> <x-msg://4873/[email protected] >> <x-msg://4873/[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] >> <x-msg://4924/[email protected]> <x-msg://4873/[email protected] >> <x-msg://4873/[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] >>>> <x-msg://4924/[email protected]> <x-msg://4873/[email protected] >>>> <x-msg://4873/[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> >>>> <http://WWW.see.ed.ac.uk/~shs> <http://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-can- >>>> 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/> >>>> > <http://carbonremoval.wordpress.com >>>> <http://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] >>>> <x-msg://4924/[email protected]> >>>> <x-msg://4873/[email protected] >>>> <x-msg://4873/[email protected]> > . >>>> To post to this group, send email to [email protected] >>>> <x-msg://4924/[email protected]> >>>> <x-msg://4873/[email protected] >>>> <x-msg://4873/[email protected]> > . >>>> Visit this group at http://groups.google.com/group/geoengineering. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>>> >>>> >>>>>>> >>>>>>> >>>> <Anthropogenic_carbon_cycle.png> >>> >>> > -- 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.
