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Guest essay by Eric Worrall
A US study has suggested hurling crushed limestone into the stratosphere to halt global warming, on the grounds that it would do less damage than sulphates, and might help repair the ozone layer.
Atmospheric limestone dust injection could halt global warming
Geoengineering using limestone aerosols would also help to stop ozone layer depletion
Distributing limestone particles into the upper atmosphere could apply the brake to global warming while simultaneously repairing the ozone layer, scientists in the US propose. A solid aerosol of limestone or the mineral calcite dispersed 20km up would reflect and scatter incoming solar radiation, slowing greenhouse gas warming, and neutralise three important halide-bearing acids responsible for ozone destruction.
Up until now, atmospheric geoengineering research had focused on injecting sulfates into the stratosphere, but this would generate sulfuric acid and damage the ozone layer. Conversely, calcite or limestone would neutralise the acids HNO2, HCl and HBr, which provide the nitrogen, chlorine and bromine radicals that destroy ozone. ‘This would restore the ozone layer, though not perfectly,’ says senior author David Keith at Harvard University. ‘A base would react with those main acids in the stratosphere, which are dominant in the catalytic cycles that manage ozone.’
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‘We are not suggesting that we go ahead and manipulate the whole planet, but a flight experiment from a stratosphere balloon could make a small cloud of aerosol, with a few hundred grams of material and allow us to make real in situ measurements of stratospheric chemistry,’ says Keith. There are lots of uncertainties about reaction rates at present, he adds.
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The abstract of the study;
Stratospheric solar geoengineering without ozone loss
Injecting sulfate aerosol into the stratosphere, the most frequently analyzed proposal for solar geoengineering, may reduce some climate risks, but it would also entail new risks, including ozone loss and heating of the lower tropical stratosphere, which, in turn, would increase water vapor concentration causing additional ozone loss and surface warming. We propose a method for stratospheric aerosol climate modification that uses a solid aerosol composed of alkaline metal salts that will convert hydrogen halides and nitric and sulfuric acids into stable salts to enable stratospheric geoengineering while reducing or reversing ozone depletion. Rather than minimizing reactive effects by reducing surface area using high refractive index materials, this method tailors the chemical reactivity. Specifically, we calculate that injection of calcite (CaCO3) aerosol particles might reduce net radiative forcing while simultaneously increasing column ozone toward its preanthropogenic baseline. A radiative forcing of −1 W⋅m−2, for example, might be achieved with a simultaneous 3.8% increase in column ozone using 2.1 Tg⋅y−1 of 275-nm radius calcite aerosol. Moreover, the radiative heating of the lower stratosphere would be roughly 10-fold less than if that same radiative forcing had been produced using sulfate aerosol. Although solar geoengineering cannot substitute for emissions cuts, it may supplement them by reducing some of the risks of climate change. Further research on this and similar methods could lead to reductions in risks and improved efficacy of solar geoengineering methods.
Read more: http://www.pnas.org/content/early/2016/12/07/1615572113
Its nice that the geoengineering crowd seem to have moved onto less toxic options than sulphates.
Limestone is quite dense, around three times denser than water, so it would be interesting to see how long the particles stayed aloft. But the full text of the study seems to suggest fluffing the particles up a bit, making them porous, to increase surface area available for neutralising ozone destroying acids. This would likely create a pumice like consistency, which could help the particles persist longer in the stratosphere.
The study also sounds a cautious note about the possible impact of their limestone particles on bioavailability of nitrates, and other potential environmental impacts. So maybe limestone might be as damaging as sulphates after all.
Who are the geniuses going to blame when their scheme triggers the next ice age?
There is a very simple solution to CO2 “pollution” that nobody seems to be mentioning. It involves injecting something into the atmosphere that has zero mass — it’s called “intelligence” (periodic-chart abbreviation, IQ), a rare element that scientists give far too little importance in the human-caused CO2 global warming debate.
No self respecting engineer would participate in such a scheme, not even as a test. If there truly was a global warming problem (which isn’t the case so why is this even being discussed), engineers know that to fix problems you always go after the ROOT CAUSE of the problem. You don’t put bandaids on problems or non problems that may cause even bigger unforseen problems. The whole premise of this scheme is obviously faulty from the start unless one is of a mindset (usually political) where the term “root cause” never enters the discussion.
Scott,
The enlightened intelligentsia of this rarefied blog are aware that there isn’t a problem, but much of the rest of the world has yet to see the light.
There are comments saying “don’t screw with the climate”, yet that would imply that human beings CAN control the climate. Interesting.
@Reality check: either humans are not able to manage energies and materials on a large enough scale to substantially affect the climate, in which case “screwing with the climate” would be a huge waste of effort and resources, or they are, in which case the odds of catastrophe are unpleasantly high.
The plain fact of the matter is that human beings do not understand complex systems, not even systems they themselves have created, with all the working parts visible. If we could, the USA would never have repealed the Glass-Steagall Act https://en.wikipedia.org/wiki/Glass%E2%80%93Steagall_legislation. (OK, so some people DID see the gun being loaded and the trigger being pulled, but top people at Bear Stearns, Lehman Brothers, Citibank, and so on, who were morally obliged by their position to understand the financial system, clearly didn’t. Suicide by legislation and hubris.)
I think it’s fair to same that *some* people who post here think that humans can’t affect the climate, but that *many* people who post here think that humans *can* affect the climate, and indeed through things like land use change demonstrably *have* affected climate, just not very much.
Although I copied the interview I heard, I can’t find it now. Three or four years I listened to a forestry guy or federal agricultural expert give a fascinating description of how with their research they were able to determine that the Dust Bowl was not the effect of heat, although that contributed, but land use management. Which he said they didn’t understand in the 30s.
Who set the standards for the ozone layer?
God.
Which means these guys will royally louse it up.
God is a fictional entity just like GW.
You are welcome to your opinion. Free speech ‘n all that 😀
David Keith thinks he did. The arrogant pr**k described geoengineering he was doing over New Mexico during a panel in 2010 without permission of the people. Someone in the audience really went after him, and forced him to admit they were doing it without knowing the consequences.
could apply the brake to global warming while simultaneously repairing the ozone layer,
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the operative word is ‘COULD”.
dog turds sprayed in the air “could” do the same. Or nerve gas. Or a plague of frogs.
Imagine for one minute that when we built bridges, or buildings, or aircraft the engineers involved said “that could be strong enough” or “that could work”.
The big problem with having scientists propose ANY solution is that they have NO PROFESSIONAL LIABILITY. In contrast, when engineers say something will work they have a legal liability to make sure it will work.
It is high time that the government took the issue of climate change out of the hands of the scientists and gave it to the engineers. We are repeatedly told that the science is settled, so where is the justification for further scientific study?
Settled science is not a scientific problem, it is an engineering problem. It is high time the problem was given to professional engineers to MAKE IT WORK. With full financial liability if it doesn’t.
How did these clowns get university degrees? Limestone clouds, deaf fish, heat disappearing and lurking in the ocean depths, lulling us into a false sense of security until it pops out and starts warming the atmosphere.
Utter drivel!
What about the amount of energy that is required to hurl the dust into the stratosphere. Won’t this create more carbon dioxide that is absorbed. Sounds absolutely ridiculous.
Just halt all funding from wherever.
We are in the midst of madness on a grand scale, and I am an ordinary human being who accepts facts, or tries to!
The problem with all those “scientists” looking for money is the idiots who consider doing so against the interests of science and mankind.
How do we halt this madness? It equals waste on a grand scale, of money and constructive intelligence.
Politicians are at the root of this.
They feed on ignorance of ordinary folk who are not sucessfuly informed, because those people for many reasons, take in “bites” of misleading information.
We need a site, for all people, that gives facts relating to their lives.
How do we do,this?
I wish I knew. Someone out there does. Do not do it for profit, do it because it is in your interest and for all of usi, long term.
Here’s hoping.
Is this supposed to be real – or a plot for a Bond movie? Do we send in 007 with a scantily clad Asian girl and bunches of ninjas dangling from ropes into the villain’s labs?
“No Mr. Bond, I expect you to die, and reduce the surplus population.”
This scheme would fit a Bond Villain. At least a couple were eco-fanatics with plans to exterminate much of humanity and start over with a group of their followers.
Uh, limestone dust isn’t reflective to the energy that needs to be reflected and the problem is is if Global Climate Destruction Warming Change Greenhouse is right, putting up an aerosol would slam us into a Glaciation event in less than 52 hours.
I’ve seen a lot of the 3 and 4 year old _debunked by the IPCC themselves_ claims showing up in news again.
What utter drivel. How much limestone has to be injected at 20 km above the surface to achieve -1Wm(2)? Thousands, tens of thousands of tonnes annually? And as Eric observed in his opening note, what’s the mean suspension time?
I like the idea of using limestone but to make more cement and emit more life-giving CO2 and maybe someday even get some nice warming. Perhaps pass a law that we all live in durable concrete housing.
Not a “greenwash”, a whitewash solution?
By which he means that he already knows they will be too slow, but they would like the money to pretend to do it anyway. That’s the beauty of modeling: You don’t waste time modeling the things you already know will probably fail. Choosing the deliberately wrong thing to model is an essential part of developing “skill in the art”.
That should keep the innards of turbo jets well polished.
How is it that any ludicrous scheme proposed by these idiots is treated as tenable?
No details of the practicality of such a scheme?
Actually, geoengineering has the advantage of not locking in to a solution that cannot be
easily reversed or heavilly modified, which is where our green beanies are heading with their
potentially catastrophic idea of ridding the planet of its carbon emitting apparati. The
green sprouts often use catastrophic to describe totally non-catstrophic situations, but their
tunnel vision plans truly are potentially catastrophic. Heaven help the world if they succeed.
Paper on limestone dust toxicity
http://www.irjes.com/Papers/vol3-issue8/Vesion%201/J386672.pdf
Sounds like this dust would be fun to have impinging the fan blades of your airliner at 25000 feet.
If it wasn’t for the defeat of hillary we would be going ahead on these types of projects… full speed. Thankfully there is now a chance that we may be spared. Whew! GK
This idea is as useful to the Earth as digging holes and immediately filling them in again is. This is a non-solution to a non-problem.
Where does limestone come from?
Wow lucky I kept my grandfathers old cannon that he used to shoot dry ice into the air to make rain maybe I can volunteer to help out!? Are these ” scientists” for real must have gone to Harvard or Yale only their could they become such idiots! Man is very arrogant to think he can affect the atmosphere of this world or any other for that matter!?
Clearly Dr Evil has to be frozen and put into orbit along with bigglesworth the cat or at least his cash should be cut off. With a new Sherriff in town, you’d think hairbrained schemes like this would self edit. Calcium carbonate fillers and extenders cost, what? $100/t on the ground to make and the stuff they are talking about is very fine precipitated product (200-300$?) and then the cost to put it into the stratosphere! We then end up with alkaline rain, yeah that sounds exciting for the biosphere etc.
Probably, the best sceptic comment of all time was that of Steve McIntyre, musing that most climate scientists today would be lucky to have highschool science teaching jobs in an earlier generation. And Mac is one of the kindest, nicest, fairest-minded guys you’d ever hope to meet.
I wasn’t aware that the ozone layer needed repairing.
It doesn’t, just another way to bilk the tax payers to keep some group of fuax scientists in jobs,I guess it’s the new welfare more educated more sophisticated,but a social program no less!!?