Mitigating the risk of geoengineering
news.harvard.edu
news.harvard.edu
The attractive thing about sulfate aerosols is that they could be formed from sulfur dioxide, which is cheap to form via sulfur combustion and disperses excellently because it's a gas. Delayed oxidation reactions cause SO2 to form nuclei for aerosols. Even though calcium carbonate is also inexpensive, I don't think there is a comparably cheap/easy way to deliver a fluid precursor for it to the upper atmosphere. The closest I can think of is aerosolizing a calcium hydroxide solution that would carbonate in situ via reaction with atmospheric CO2... but calcium hydroxide is only slightly soluble in water. You'd need to lift a lot of extra water mass.
So, it just a matter of throwing tons of "dry sulfuric acid" on the atmosphere?
It would somewhat increase the surface precipitation acid burden, similar to the acid rain that was a byproduct of 20th century industrialization, but most sulfur oxides that come from power plants or metal refining are flushed out of the lower atmosphere by precipitation. By directly or indirectly adding SO2 to the stratosphere instead of the troposphere, the ratio of reflection:acid content would be higher than that of incidentally produced waste-product SO2. (That's why we can't start cooling the planet just by removing sulfur controls from existing coal plants; most of that SO2 would produce acid rain accompanied by little additional sunlight reflection.)
Isn't that 2C supposed to have come from "just give me a damn number" rather than any analysis of likely impacts?
I'm going to be very amused if we somehow stop any warming without reducing co2, and die off when all the shellfish keep dissolving.
I don't think that "amused" would exactly be my reaction if we kill off all the wild shellfish :-/
Pretty straightforward for direct photovoltaic generation, but the wider consequences on the (very complicated) Earth system are hard to say. Would it affect wind patterns (and wind power generation as a result)? What about plants/animals/agriculture?
On the other hand, anthropogenic climate change is already going to screw all those things up, so it's not like avoiding geoengineering is necessarily the right choice either. Just need to understand the potential risks and benefits as well as possible before considering it.
Edit: I probably should have found a way to use "hubris" in that sentence...
Caution is certainly warranted, and there is some danger of hubris, but running screaming from the room is not a productive response either.
Do you think that climate change is somewhere between "unbounded costs ranging in the hundreds of trillions of dollars over the course of 2050-2150," and "the death of humanity and/or all multicellular life on Earth"?
Because if so, the side effects of geoengineering probably aren't that bad, and even if they are, they're apparently only as bad as what you think the costs of doing nothing are.
On the other hand, do you think that climate change is either non-existent or some kind of relatively mild thing that will cause $100 Trillion dollars or less over the course of a century? Then probably geoengineering is not for you -- but that also means that you're somewhere outside the orthodoxy on climate change.
If you believe that climate change is a real big problem (ie, hundreds of trillions of dollars or much more in damages over a century timeline) AND that it is stoppable by being really persistent in asking people to use solar and wind power, then I don't think that you're being very realistic.
> I don't think that you're being very realistic.
> you're somewhere outside the orthodoxy on climate change.
> the side effects of geoengineering probably aren't that bad
Hubris.
So, look, if you don't believe that climate change will be disastrous, then you're perfectly within reason to say that geoengineering is a really bad idea. The beef that people have with you will not be that you're wrong to be opposed to geoengineering, their beef will be that you're wrong to think that climate change is no big deal. I'm not here to fight that fight. If that's your position, fine.
If you DO think that climate change is a big deal (and by big deal, I mean you think it's somewhere between "likely to stall all economic growth worldwide for centuries" and "likely to kill all of humanity"), then it's kind of hard to imagine what worse consequences geoengineering could possibly have.
And particularly, if you do think that climate change is a big deal (as described above), there aren't a lot of very realistic options besides geoengineering. It may be that even if we stopped ALL carbon emissions RIGHT NOW, we'd still have really bad climate change. And obviously, realistically, we just won't stop all carbon emissions now. We won't stop all carbon emissions in a decade, or two decades, or three. I am prepared to argue with you if you imagine that we can stop all carbon emissions now.
The only fourth way I can imagine is that someone might somewhat reasonably believe that in the near future, technological advance will get us out of this. That we'll discover some way to do massive carbon-less power generation at very low cost and/or that we'll discover an obviously unproblematic way to do carbon sequestration on enormous scale. I will say that if you assign a high probability of disastrous climate change, I don't see how you'd assign a similarly high probability of those exact technological advances. In fact, I might call such precise foresight... hubris.
And I'll grant that if you truly believe that climate change is "likely to kill all of humanity", that easily leads to a "damn the consequences" attitude toward fighting it.
However, your expression of the alternatives eliminates a lot of nuance. For example, suppose that climate change is "likely to stall all economic growth worldwide for centuries", meeting your definition of "a big deal". Is it really hard to imagine what worse consequences geoengineering could possibly have? What if geoengineering is "likely to kill all of humanity"?
So, yes, I'll remain at least as concerned about geoengineering (and "damn the consequences" thinking) as I am about climate change.
1. I think that you're probably underselling "stall all economic growth for centuries." It's not that different from "kill all humans" (for example: it would be hugely globally destabilizing. The odds of nuclear war would go way, way, way up. For another example: it might well either restart exponential population growth like we had in the late 19th/early 20th centuries, or else cause a demographic death spiral).
2. It's pretty hard to believe that climate change is very likely to go right up to the edge of "stall economic growth" and not have a very significant chance of tipping over to worse scenarios. You already implicitly believe in some positive feedback cycles here.
3. It is actually pretty hard to imagine that specifically aerosolizing sulfur dioxide is going to cause really catastrophic consequences that global warming won't already. As other commenters have pointed out, volcanic eruptions cause massive sulfur releases already. If you believe that the environment is so, so, so sensitive to any changes that any change you might make is likely to cause spiraling destruction of the ecosystem, well, then doesn't it seem likely that our many existing changes have already sent us past the point of no return? Like, if we're making 100 changes on the scale of sulfur release (which we are), and one change much, much, much larger than sulfur release (carbon release), it seems a little unlikely that sulfur release is the straw that breaks the camel's back.
There are some possibilities for nuance here! You can reasonably believe that, for example, ocean acidification is the bigger problem than temperature change per se, and sulfur release doesn't solve ocean acidification, and indeed may slightly (very, very, very slightly) contribute to it and more importantly may encourage people to regard carbon release as unproblematic and thus encourage more carbon use and thus more ocean acidification.
But I don't usually see people making targeted critiques like the one above, the kind of critique that only applies to one specific proposal. It's usually just sort of a general reaction to anything other than reduction targets. And, honestly, reduction targets aren't going to work, guys. Not alone.
Nature does this experiment for us every so often: large volcanic eruptions, such as the 1991 Mount Pinatubo eruption, put massive amounts of sulfur into the stratosphere, much larger than the amount we'd need to use. So it's pretty likely we would have noticed the negative effects if there were any (beyond the fact that we got much more cooling than we wanted for a couple of years).
There are other forms of climate engineering that would address C02 directly. One that's received a fair amount of press is "iron fertilization"[1]. I don't know, but my guess is that most people who talk about "solar geoengineering" (of any sort) probably think we're going to be doing solar geoengineering, iron fertilization, and probably multiple other forms of climate engineering at the same time. But not every article that discusses iron fertilization mentions sulfur dioxide, and not every article that talks about stratospheric sulfur dioxide mentions iron fertilization.