Stratospheric Controlled Perturbation Experiment

I have predicted for a while that as the issue of climate change becomes ever more urgent, the public attitude regarding geoengineering will at some point undergo a phase transition. For a long time it seems the general attitude has been that deliberately interfering with the Earth’s climate on a large scale is “unthinkable”: beyond the pale. I predict that at some point this will flip and the general attitude will become: “how soon can we do it?”

The danger then is that we rush headlong into something untested that we’ll regret.

For a while I’ve been advocating research in geoengineering, to prevent a big mistake like this. Those who consider it “unthinkable” often object to such research, but I think preventing research is not a good long-term policy. I think it actually makes it more likely that at some point, when enough people become really desperate about climate change, we will do something rash without enough information about the possible effects.

Anyway, one can argue about this all day: I can see the arguments for both sides. But here is some news: scientists will soon study how calcium carbonate disperses when you dump a little into the atmosphere:

First sun-dimming experiment will test a way to cool Earth, Nature, 27 November 2018.

It’s a good article—read it! Here’s the key idea:

If all goes as planned, the Harvard team will be the first in the world to move solar geoengineering out of the lab and into the stratosphere, with a project called the Stratospheric Controlled Perturbation Experiment (SCoPEx). The first phase — a US$3-million test involving two flights of a steerable balloon 20 kilometres above the southwest United States — could launch as early as the first half of 2019. Once in place, the experiment would release small plumes of calcium carbonate, each of around 100 grams, roughly equivalent to the amount found in an average bottle of off-the-shelf antacid. The balloon would then turn around to observe how the particles disperse.

The test itself is extremely modest. Dai, whose doctoral work over the past four years has involved building a tabletop device to simulate and measure chemical reactions in the stratosphere in advance of the experiment, does not stress about concerns over such research. “I’m studying a chemical substance,” she says. “It’s not like it’s a nuclear bomb.”

Nevertheless, the experiment will be the first to fly under the banner of solar geoengineering. And so it is under intense scrutiny, including from some environmental groups, who say such efforts are a dangerous distraction from addressing the only permanent solution to climate change: reducing greenhouse-gas emissions. The scientific outcome of SCoPEx doesn’t really matter, says Jim Thomas, co-executive director of the ETC Group, an environmental advocacy organization in Val-David, near Montreal, Canada, that opposes geoengineering: “This is as much an experiment in changing social norms and crossing a line as it is a science experiment.”

Aware of this attention, the team is moving slowly and is working to set up clear oversight for the experiment, in the form of an external advisory committee to review the project. Some say that such a framework, which could pave the way for future experiments, is even more important than the results of this one test. “SCoPEx is the first out of the gate, and it is triggering an important conversation about what independent guidance, advice and oversight should look like,” says Peter Frumhoff, chief climate scientist at the Union of Concerned Scientists in Cambridge, Massachusetts, and a member of an independent panel that has been charged with selecting the head of the advisory committee. “Getting it done right is far more important than getting it done quickly.”

For more on SCoPEx, including a FAQ, go here:

Stratospheric Controlled Perturbation Experiment (SCoPEx), Keutsch Group, Harvard.

21 Responses to Stratospheric Controlled Perturbation Experiment

  1. Rogier Brussee says:

    Aerosols in the stratosphere take many years to wash out but they still within a few decades. I.M.O the main problem with such an approach is that it will require constant effort to keep the aerosols up there. If people neglect doing it because of war, politics, money, …, civilisation collapses as extremely rapid warming sets in in an atmosphere containing too much CO2. In fact the atmosphere is likely to contain far too much CO2 as pressure to stop emissions has dropped.

    I.M.O. a more promising low tech approach is too scrub the atmosphere of CO2 with artificially accelerated weathering, i.e. the “green beaches” approach. In this low tech approach a few km^3 worth of the common green mineral olivine is mined, ground into sand and dumbed on tropical beaches or used as coastal defense. Olivine (Fosterite) reacts exothermally with CO2 and the enormously increased surface area, contact with warm water and constant movement ensure that the sand is weathered in a few years.
    As an added bonus, it will decrease the acidity of the oceans (if you are careful about using Fe poor olivine).

    On the other hand one approach does not exclude the other.

  2. David Winsemius says:

    We already had a large-scale geo-engineering event. In the days following 9/11, the commercial airline fleet was grounded for 3 days. Hence greatly reduced injection of water vapor into the stratosphere.I seem to remember that the reported temperature change was in the negative direction. (Hazy memories of a PBS Nova program.) I expect that calcium carbonate should be more reflective of incident energy in the visible and UV spectrum than water vapor.

  3. ishicrew says:

    I was up in the mountains in eastern WV on 9-11 –but i had a radio.
    So i listened to the news. I didn’t know what this was about–planes hitting buildings, etc. . And then i took my walk up on North Mountain–i didn’t see a plane for 3 days . It was a no fly zone. very quiet. I liked that. no noise.

    There is a 2011 article in Naitonal Geographic magazine that says a small nuclear war could stop anthropogenic global warming (AGW) for a few years.

  4. Bob says:

    1) Why not do the big climate experiments on Mars? We don’t need to know if there is/was ever life there at the expense of life here.
    There’s a whole big universe out there for answering such questions, later, if we survive.. Maybe Venus would be a better choice for large-scale climate experiments: we may want to colonize Mars later. I’ll guess the overpopulation problem (which presumably is or will inevitably become the cause of climate change, economic cannibalism, soiled nest, &c.) also can’t be controlled in a confined location like a planet any more easily than on a isolated island in the Pacific. Experiments on genetic engineering are not justified by excuses like He Jiankui’s: If we don’t do it, someone else will (If we don’t destroy the planet someone else will?).

    2) Why do more people than ever toggle like Schmitt triggers these days? Everyone’s so polarized, like magnets? All or nothing? Abortion, or no abortion? Capital punishment, or no captial punishment? Spin up or spin down? Whatever happened to ‘having an exit plan’, ramping things up slowly, inching forward, backing off when there’s non-linear behavior, and- never painting yourself into a corner? Science seems to be largely about distinguishing this from that, zooming in, repeat, … But it seems to degenerate sometimes into binary polarization. Are there mathematical systems that start-off with a continuum but inevitably degenerate into binary states? Don’t they always have some kind of imperfection that prevents a complete —–?

    3) More money for education.

    4) The dust from Africa falling on the Amazon is another big atmospheric event. Volcanic activity. Clathrate deposits. …
    Wouldn’t you rather experiment on Mars or one of the simpler moons before the most complicated planet in the solar system,
    if not in this whole backwater, comparatively unscenic property in the galaxy? The aliens are calling us cannibals, inbred hillbillies, …unworldly. They’re laughing at us and our self-inflicted plight?

    Beware of hydrogen hydroxide, dihydrogen monoxide, and hydroxic acid in your drinking water!

    • John Baez says:

      Why not do the big climate experiments on Mars?

      Because people want to know how to prevent global warming on Earth. Mars is very different; experiments there would be of little use for this purpose. Plus, they’d be about 1,000,000 times as expensive.

      • Bob says:

        I thought the whole idea was to prevent the Earth’s atmosphere from degenerating into something like either Venus’ or Mars’. Surely there’s much to be learned by carefully studying exactly what we are trying to avoid? I am surprised to read that much about the solar ‘atmosphere’ is also not well understood.

        True, that is a lot more money, but much U.S. economic expansion came from massive spending on “global cascading, avalanche climate catastrophe early-warning and avoidance”. (Ever since we dropped the Keynesian gold standard, and the emergence of the econophysical Hayekian Austrian School of Economics, I really don’t understand what money ‘is’, nor how to measure it correctly.)

        Repairing the ozone hole was apparently a big success. Hopefully smarter people than moi will continue to be in positions of respected authority and be allowed to act responsibly as needed.

  5. ecoquant says:

    I think it’s important to do these experiments in order to find out what cannot be achieved using these techniques as much as what can be achieved. There were experiments done do check iron fertilization of oceans in the South Atlantic, and they showed the technique was basically useless for creating the desired plankton bloom, because of unanticipated complications from oceanic flows and the biosphere.

    And, too, people need to understand what we already know these technologies cannot do, such as limiting ocean acidification. In addition the impacts that will have on oceanic protein, it’s possible it might harm ocean plankton. If that were the case, the oceans after an extended period of sun scattering would not be the same as those before it began. Of course, if emissions continued during that interval, with or without the sun scattering, the oceans would be in the same peril. Presumably, however, heat effects and such would be greater in the absence of scattering.

  6. ecoquant says:

    By the way, readers here may be interested in one of the Grand Challenge topic areas created by the U.S. National Academy of Engineering: Develop Carbon Sequestration Methods.

    • John Baez says:

      My friend James Salsman claims it should be much easier to suck CO2 out of solution in water than out of the air, both because there’s more CO2 per volume in water than in air, and also because aqueous reactions work more efficiently. Does anyone know if this is widely accepted?

      In the methods where people grind up rocks like serpentine and let them react with CO2, I guess it’s important to keep those rocks wet?

  7. We don’t understand the dynamics of the stratosphere as of yet, so does it make any sense to fiddle with it by adding aerosols?

    • ecoquant says:


      While I agree the albedo hacking seems utter folly, since it solves little of the full problem and has the potential for many unintended consequences, both physical and social, I think its champions would argue that it is no more foolish than our current unimpeded path, even after more than 50 years of scientific advice.

      That doesn’t justify it, though.

      • Agree completely. The jet-stream patterns are complex and who knows what would happen to regional climate if that gets thrown for a loop. The consensus can’t even seem to agree what causes the equatorial stratospheric wind cycling (the QBO), so I can’t imagine they can understand what happens in the upper latitudes with any certainty.

        See further a long-running discussion over in the Azimuth Project Forum on the QBO and ENSO thread.

  8. Joe Moeller says:

    Maybe something that could be used to help sell people on the idea of doing this research would be to compare it to something similar that happened in the past. Autopsies used to be taboo and I think illegal, depending on the place and time period. Obviously today most people think autopsies are something that should be done, but done with care and respect.

    • John Baez says:

      The problem with this particular research is that people quite correctly see it as a possible prelude to deliberate interventions that will affect the whole Earth’s atmosphere. If we aren’t careful this could be disastrous.

      But the research could also show these interventions are likely to be dangerous, so it might also serve to prevent these interventions.

      • Joe Moeller says:

        Right, I think that’s why the “with care and respect” part is so important in the analogy.

        • John Baez says:

          Okay. The analogy seems a bit funny because messing with one person seems like so much less of a big deal than messing with the planet. But I guess it helps to remember that back then many Christians believed in the literal resurrection of the body on Judgement Day, and thought that messing with dead bodies would impair their ability to be properly resurrected. (At least that’s what I’ve heard.) So autopsies would be sort of like murders.

        • ecoquant says:

          … many Christians believed in the literal resurrection of the body on Judgement Day, and thought that messing with dead bodies would impair …

          Yes, this was inherited, acknowledged or not, from their Jewish forebears. Even though they’ve lost of bunch of these opinions, there remain many Jewish practices which hark back to a more primitive relationship with the universe. For example, unlike Christian cemeteries, Jewish ones have much wider spaces between rows, so people do not need to walk on top of graves. Similarly, returning from the graveyard, the pitcher of water outside and towel is intended to wash “death” off the hands. Ditto covering of mirrors with clothes, based upon the thought that, at moments of transition between life and death, the living are more susceptible to having their souls stolen. Finally, the accompanying of a dead body from the moment of death until burial.

          We might laugh at these — I’m not saying anyone here would — but these all come from a perspective of the universe which is much more haunting than now. Indeed, part of Sagan’s Demon Haunted World is how, with the loss of appreciation for Science and Mathematics, we might be returning to that spooky time.

          Let me give a modern example. Many progressive environmentalists eschew plastic in all its forms, championing, for instance, unconditional plastic bag bans. No doubt, use of disposable bags, plastic and paper, is a bad thing, as long as reusable bags are used some large minimum of times. But, then, despite efforts to convince people quantitatively of the harm of paper bags and their manufacture, which includes upstream wastes and chemistry in many forms, as well as sourcing original paper, in most instances (not, for the latter, at Whole Foods), and the relative cheapness of hauling a million plastic bags in one trip to a store, paper bags are embraced because they are intrinsically “more natural”. It’s as if plastic were a demon spirit and people want to exorcise it.

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