Thanks Doug. This discussion is relevant to geoengineering so copying to that group.
My conversations with Stephen Salter suggest brightening clouds over the Gulf Stream to cool the current would be an effective way to cool the Arctic. Two papers which imply the Gulf Stream would be a good location for Marine Cloud Brightening are https://www.hindawi.com/journals/isrn/2012/142872/ and https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.2014.0053 Robert Tulip From: Douglas MacMartin <[email protected]> Sent: Sunday, 7 March 2021 11:26 PM To: [email protected]; 'John Nissen' <[email protected]> Cc: 'Clive Elsworth' <[email protected]>; 'Gene Fry' <[email protected]>; 'Chris Reed' <[email protected]>; 'Douglas Grandt' <[email protected]>; 'Peter Wadhams' <[email protected]>; 'Stephen Salter' <[email protected]> Subject: RE: [CDR] The Enormous Risk of Atmospheric Hacking Well, unfortunately we don’t even know yet when/where/how much MCB works (and you should really really hope that it isn’t very effective, because that means that climate sensitivity is on the low end), so without understanding the right meteorology to influence, this isn’t ready to go deploy. And over the gulf stream is not likely one of the regions where it is effective, if I recall right. And if you do that at meaningful scale, I bet it would be controversial too, but of course no-one really knows. And we don’t know how to pump water onto sea ice at any relevant scale, or the extent to which the newly formed ice is more saline vs adequate brine rejection (and if it’s particularly saline then it melts first, decreasing albedo earlier in the melt season). These are all great things to research. So is SAI. Bottom line is, we do not have any options that we can simply go out and start doing tomorrow without a ton of research first. (And the closest to being able to do that – which doesn’t mean it’s the best in any other respect – is high-latitude SAI.) I think it’s a bit premature to start throwing out options. d (And once again removing the CDR google group from the addressees, since this doesn’t belong there.) From: [email protected] <mailto:[email protected]> <[email protected] <mailto:[email protected]> > Sent: Sunday, March 7, 2021 6:12 AM To: 'John Nissen' <[email protected] <mailto:[email protected]> >; Douglas MacMartin <[email protected] <mailto:[email protected]> > Cc: 'Clive Elsworth' <[email protected] <mailto:[email protected]> >; 'Gene Fry' <[email protected] <mailto:[email protected]> >; 'Carbon Dioxide Removal' <[email protected] <mailto:[email protected]> >; 'Chris Reed' <[email protected] <mailto:[email protected]> >; 'Douglas Grandt' <[email protected] <mailto:[email protected]> >; 'Peter Wadhams' <[email protected] <mailto:[email protected]> >; 'Stephen Salter' <[email protected] <mailto:[email protected]> > Subject: RE: [CDR] The Enormous Risk of Atmospheric Hacking Planetary brightening is essential to cool the temperature. My view is the best ways to brighten and cool the planet are Marine Cloud Brightening using sea salt in the air to cool the Gulf Stream flowing into the Arctic, and pumping ocean water onto the Arctic sea ice cap to freeze over winter and prevent melting. Stratospheric Aerosol Injection is too controversial. The immediate required cooling effects might be achieved just through sea ice and sea salt for the Arctic, creating time for the required slower progress on carbon removal and emission reduction. Robert Tulip From: John Nissen <[email protected] <mailto:[email protected]> > Sent: Saturday, 6 March 2021 10:27 AM To: Douglas MacMartin <[email protected] <mailto:[email protected]> > Cc: Clive Elsworth <[email protected] <mailto:[email protected]> >; Gene Fry <[email protected] <mailto:[email protected]> >; Carbon Dioxide Removal <[email protected] <mailto:[email protected]> >; Chris Reed <[email protected] <mailto:[email protected]> >; Douglas Grandt <[email protected] <mailto:[email protected]> >; Robert Tulip <[email protected] <mailto:[email protected]> >; Peter Wadhams <[email protected] <mailto:[email protected]> > Subject: Re: [CDR] The Enormous Risk of Atmospheric Hacking Thanks Doug, The ozone hole is the obvious downside to SRM, but not a show stopper. I am glad that under a realistic scenario of careful deployment the effect on the ozone might be quite small. But how could one possible say that SRM is more dangerous than not deploying SRM? There is extreme urgency to save the Arctic sea ice before the Arctic gets locked into a lower-albedo state. Because then the Greenland Ice Sheet melt could be unstoppable. There could be a major change in global atmospheric circulation due to the decreased pole-to-equator temperature gradient. And there's all that methane trapped in thawing permafrost. So we need Emergency SRM Now. There is no time to lose. IPCC has ignored the Arctic situation while it has been deteriorating in front of their very eyes. It would be totally irresponsible not to act to cool the Arctic when there is plenty of evidence for potential catastrophe if we don't. What will our children think of us if the worst happens and we could have stopped it so easily? Cheers, John On Fri, Mar 5, 2021 at 9:43 PM Douglas MacMartin <[email protected] <mailto:[email protected]> > wrote: Um… - Re Clive: I think there’s zero question that the impacts of things like SAI need to be more thoroughly investigated, but this sort of black-and-white absolutism about impacts isn’t helpful. We know the sign of the effect that sulfate aerosols would have on ozone, but depending on how much you do, and when you start, that will affect how much reduction in high-latitude ozone there is, and model analyses don’t support the conclusion that under realistic scenarios the resulting ozone loss would be so catastrophic. (Broadly in simulations where there is no mitigation and SAI is used to get back to roughly today’s temperatures, the worst-case SH ozone is going back to 1990 levels, and the impact on NH ozone is small. So yeah, ozone is a thing to take into account in assessments, it’s certainly not true that that alone makes SAI a bad idea.) - To Gene: when you make claims that run counter to something in an IPCC report (i.e., an assessment of the science that is authored by many climate scientists, and reviewed by many more), you might want to provide evidence. I think there are lots of fair criticisms of IPCC reports, and even more with regards to the media coverage of them, but the fact remains that in climate models, which DO include albedo changes such as sea ice, the residual warming after net-zero is reached is to first order balanced by the continued uptake of CO2 (and if you only consider the first and ignore that second factor then you’ve missed the entire reason why net-zero emissions may be close to stabilizing temperature). There’s lots of research on this, and an entire zero-emissions MIP. Absolutely fair to say there is uncertainty and we shouldn’t be planning for a 50% or 66% success rate. But you’re a bit over-confident in your own guess that there is 100% certainty that all the models are completely wrong and all climate scientists are wrong. If you have a scientific critique, fine; but ignoring the science isn’t the best position from which to argue against others such as McKibben. Nor is it at all necessary to make your claim in order to justify the need for CDR (as the IPCC has also made abundantly clear if anyone read the details – though they certainly bent over backwards in SR1.5 to pretend that there were viable emissions pathways to hit 1.5C without CDR, with IMHO really clearly conveying to the likes of McKibben what those scenarios imply about either societal transformation or the uncertainty in climate sensitivity). - Re McKibben, the blindingly obvious error he and others make would be that even if one started with his premise that we shouldn’t deploy CDR or SRM for the next 10 years (fair for sure on the latter, and hard to imagine how we could do CDR at meaningful scale in next 10 years no matter what), how can we possibly have options available then if we don’t invest today? Is it conceivable that we’ll dramatically alter our emissions profile AND be incredibly lucky in climate sensitivity, sure, that’s a possibility. But I think like everyone on this group I’m simply not as much of a reckless gambler as he is with the planet and all of those who live on it. From: [email protected] <mailto:[email protected]> <[email protected] <mailto:[email protected]> > On Behalf Of Clive Elsworth Sent: Friday, March 5, 2021 4:07 PM To: Gene Fry <[email protected] <mailto:[email protected]> >; Carbon Dioxide Removal <[email protected] <mailto:[email protected]> > Subject: Re: [CDR] The Enormous Risk of Atmospheric Hacking Gene A stratospheric SRM intervention using SAI would damage the ozone layer, which by damaging phytoplankton with increased UV would then affect the ocean's natural CDR capability. Also, darkened parts of the ocean and forests would turn from being CO2 sinks (or neutral) to sources. Iron(III) chloride aerosol forms naturally over the ocean from reaction with airborne dust and seawater spray. The aerosol acts as a photo-catalyst that produces chlorine radicals which deplete methane and other GHGs. We propose enhancing ocean CDR with a carefully managed and monitored dispersal of fine iron(III) chloride aerosol to iron poor areas of the ocean. Long-awaited paper on that coming soon. An SAI intervention would also alter the chemistry of the troposphere, rendering even naturally occurring iron(III) chloride aerosol ineffective. Clive On 05/03/2021 19:23 Gene Fry <[email protected] <mailto:[email protected]> > wrote: The author appears to be under the illusion that if we stop emitting, temperature stops rising. Maybe the author is from Earth B. But we know that there is no Planet B. The author's illusion is widely shared, most notably by the IPCC in the 1.5 vs 2.0°C report in 2018. However, Earth’s energy imbalance approaches 1 W / square meter, which is a lot. Legacy CO2, equal to about 40 years of annual CO2 emissions, will produce lots more warming as the (mostly albedo) feedbacks play out. CDR, supplemented by SRM (countering loss of Arctic albedo and sulfates), is required. My three cents. Gene Fry ==================== On Mar 5, 2021, at 2:06 PM, 'Greg Rau' via Carbon Dioxide Removal <[email protected] <mailto:[email protected]> > wrote: Aimed at SRM but applicable to CDR? https://www.newyorker.com/news/annals-of-a-warming-planet/the-enormous-risk-of-atmospheric-hacking "Engineers have provided us with cheap solar and wind power, and with affordable batteries to store that power. This means that, if we want to, as a civilization, we can devote the next decade to an all-out effort to transform our energy system. And the Intergovernmental Panel on Climate Change has said that, if we do—if we cut our emissions forty-five per cent from 2010 levels by 2030—then we have a shot at limiting the temperature rise to the 1.5-degrees-Celsius target set in the Paris accord. Our attention—all our attention—should be on that goal. If we don’t meet it by 2030, then we need to have a serious talk as a species and start assessing our options. That’s the moment for beginning these kinds of tests, not now, when they will become a rallying point for the people and the interests that want to slow the pace in this decade of transformation.” GR Not clear if this strategy also applies to CDR, but McKibben et al apparently view anything besides emissions reduction (until 2030) as a threat to the planet. Anyone else see this as dangerous? Let’s make sure we fail at emissions reduction before thinking about additional methods of climate/CO2 management? 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