I recently (re)read a post by fellow volcanologist Erik Klemetti, on WIRED about geoengineering (sulphate aerosol injection), first posted in 2012 (it resurfaced on twitter this week).
I should say that I like Erik, and his blog, a lot (full disclosure, we've never actually met) but felt much of this article was wrong. Also, as an aside and for some context, we recently had something of a polite disagreement on the terms of engaging with the media around this article:
Erik's response here:
I was tempted to write something back to this, but went on holiday instead. Short version: it's worth engaging with media, I made the article better, there's no simple way to get the article you want - your only option is simply not to engage. I proved this to myself when dealing with a different journalist, at the same paper, on a second story a week later (on Iceland).
In that case, I insisted on more editorial control, thinking most whilst people would appreciate that every volcano erupting at the same time was simply a thought experiment, taking about likelhood of eruptions in Iceland was pretty serious. I got short shrift from the editor. Fortunately, the piece was mostlysensible (except the headline) and they got volcanologists with much greater expertise than me to provide quotes.
So it's either engage at your own risk or don't (or write a hugely popular blog).
Anyway, now that's out of the way, let's get onto the 2012 article. Here it, is - as always my comments in red:
I’VE SEEN A number of articles in the news recently touting [subtly implies 'for gain' which is not at all fair, maybe I'm overly sensitive!] the idea that man-made volcanoes could help mitigate against heat waves on a local scale. On the surface, that seems like a great idea … and I know, with Ohio gripped in what seems like an endless parade of >90ºF degree days this summer, even the suggestion that there might be a way to cool the region when the heat hits seems too good to be true. Well, you know how the saying goes, and sure enough, building an artificial volcano is not going to solve the ever-increasing problems with a warming planet. How do you know that, so little research has been done? An unqualified sweeping statement.
Here is the idea – when a volcanic eruption occurs, thousands [at least] of tonnes of material are thrown into the atmosphere. This material comes in a number of flavors. A lot of it is water vapor, usually from water that was dissolved in the magma and is now being released when the bubbles in the magma pop, causing an explosive eruption. Another large component of the material is ash fragments – these fragments are volcanic glass, mineral grains and fragments of pulverized rocks from previous eruptions that get caught in the action. The water vapor and ash can cause changes in the atmosphere, especially near the volcano where light can be totally blocked when the eruption is in full swing and the ash clogs the air. However, when we’re looking at the impact a volcanic eruption can have on weather and climate, the components that are most important are the aerosols (when in droplet form) – carbon dioxide (usually a gas), sulfur dioxide, hydrogen sulfide, fluorine, chlorine and more. The first three are the biggies as they can promote both heating and cooling of the atmosphere, with CO2 mostly driving warming (via greenhouse) and SO2/H2S driving cooling by dispersing the energy of the sun before it reaches the surface. [This is pretty confusing. All of the species listed are gases. Better to talk about them (as gases) being disolved in water (which dropped off the list?) or, in the case of sulphates, the solid phase too. This matters as CO2 (gas) has a warming effect but gases in solution (most notably SO2 of course) are the climate coolers. The emitted gases are precursors to the aerosol].
The big, sulfur-rich eruptions are the ones that seem to have the biggest effect on the global climate. You think of eruptions like Pinatubo (1991), El Chichon (1982), Laki (1783), Tambora (1815) and more – these really made a mark on global climate, usually causing cooling across hemisphere and potentially causing increased rain or droughts as regional rain patterns changed. Some, however, did also cause increasing temperature, as the dry fogs associated with Laki seem to coincident with a very hot summer across Europe. So, although most of the effect is cooling, it isn’t the only effect. [Warming was also measured in Northern Europe during NH winters after Pinatubo].
Geoengineers submitted to Atmospheric Chemistry and Physics that producing a small artificial volcano that spits aerosolized sulfur compounds into the atmosphere, we can decrease the amount of solar radiation reaching the Earthon a localized level, thus cooling that area. Sure, in theory, that is exactly what should happen. A number of problems exist: (1) the cost of the technology to do this is very high, [no it isn't. In fact, it's frighteningly cheap. I suspect it's > 1000 x cheaper than mitigation or adaptation. That gearing could be much higher, and might make geoengineering 'tempting'. The real cost of geoengineering would be around impacts, the technology itself is very, very cheap. So cheap individual rogue actors could (in principle, not saying it's particularly likely) deploy the technology] (2) some of the technology doesn’t exist yet [yes it does, we could do this in only a few years (or quicker on a Manhattan project-like footing)] and (3) we don’t know what we’re doing [yet you've just provided a detailed description of what happened after Laki (and we know far more about the response from Pinatubo). Do we know everything? No. Can we predict first order effects, for 'peak shaving' (argument is more complicated, see below), yes]. Sure, #1 and 2 can be overcome, but #3 is the most troubling – although we might be able to engineer this artificial volcano, we surely don’t understand the greater effects and long-term consequences of action like this. This is why more research is needed, particulary around the next VEI6 eruption.
This next section sounds compelling but is a total red herring. It's comparing uncontrolled release into the lower troposphere with controlled stratospheric injection. This is exactly the same mistake George Monbiot made when criticising geoengineering. Did Pinatubo affect the Midwest? Nope. Are people seriously proposing pumping the amount of material that industry did in the 70's and 80's. Nope. Most researchers are looking at slow ramping up of injection, starting at as little as 50,000 tonnes a year, to slow down the rate of warming in a controlled manner (called peak shaving).
Let’s still back and think back to the 1970’s and 80’s. What was a big problem across much of the Midwest and the eastern U.S.? Acid rain! How is acid rain formed? By pumping a whole bunch of aerosolized sulfur (and other goodies) into the atmosphere. At that time, it was not to cool the climate, but rather from the thousands of factories across middle America. As those factory exhaust fumes spread into the atmosphere, the jet stream carried the material east, mixed with rain water and produced acidic rains. This idea of an artificial volcano is really creating the same thing with the sole purpose of emitting these aerosols. So, you might get a cooler summer, but downwind they might get a healthy dose of acid rain.
These are local effects, seen when pumping acids (in hugely high concentrations) into the lower troposphere (i.e. < 100 m, the height of a chimney, above the surface). The key points are that the aerosols in the stratosphere (> 20 km in the case of aerosol injection) do not behave this way and that (for the example below) anthropogenic emissions into the troposphere vastly exceed (by a factor of 1000) our hypothetical release. There are lots of reasons to dislike this form of geoengineering. Acid rain is the least of them. I'm much more worried about how little material is requried to have a climatological signature.
Here's a quick calculation. Let's say we release 0.1 Mt (100, 000 tonnes) a year into the stratosphere and it distributes globally through atmospheric circulation. If it then fell out from a homogeneous distribution (clearly not correct, but for a well-mixed atmosphere not as poor an assumption as you might think) we can simply divide by the area of the Earth to roughly estimate fallout rates. 100, 000, 000, 000 grams (g) / 510, 000, 000, 000, 000 per square metre. (i.e 0.1 g for about a football pitch sized piece of the Earth per year).
Secondly, we can look at this a lot like the phenomenon of the global use of air conditioners. As more and more people worldwide take an air conditioned environment as a right, air conditioning increases without a thought to what the ramifications of all those air conditioners might be. If you’re one person buying an air conditioner, then it might not seem to be a big deal (see also: your car), but add up those AC’s, and the problem gets bigger. Now, picture community after community getting its own artificial volcano. Who is to stop every town in India or Kansas from getting one and running it all summer to keep the summer heat down? Now, we’re no longer talking after micro-volcanoes, but rather likely the equivalent to several VEI 6+ eruptions from a single country (or state) each year. What is that going to do to the global climate? We don’t know (other than, you know, bad things). There is a reasonable point here, under the ridiculous strawman (effects are not local (c/f above discussion and where did several VEI6+ eruptions from every country (i.e 50 Mt / yr) come from???). Who has control, and how it is agreed (or not) what the 'desired' climate looks like is an incredible political challenge. Given we know what the right answer is (reducing carbon use) and we're not getting far with that, what chance do we have of implementing what is obviously a sub-optimal solution? (credit to Peter Irvine for that question).
Humans have solved many of their problems throughout history through technology – we’re good at it. We’re also good at overlooking the long term ramifications of those technologies – and that is one of the key aspects most ideas like this overlook: human nature and behavior. This point is both annoying and patronising. No-one, even the most positive about geoengineering never, I say it again, NEVER, considers these problem without thinking about 'human nature and behaviour' (we'd call it the socio-political context). In fact, that's all we do. We talk about justice, we talk about governance, we talk about responsibility.
That is how we got ourselves to where we are now. Even geoengineers who [are almost always passionate environmentalists and often distinguised climate scientists] proposed these artificial volcanoes [therefore unsuprisingly] say that the best solution to cooling the climate is limiting anthropogenic CO2 emissions to help slow the increasing concentration of greenhouse gases in the atmosphere. We all know that volcanoes aren’t the cause of global warming, but we should also be aware that building our own volcanoes won’t be the solution either – at least not without ramifications we can’t anticipate, at least some of which will be social/political.
That is not to say there won't be physical ramifications (most notably, I believe, around rainfall patterns) but these must be considered in the context of future climate change. There is a range of future scenarios where it would be immoral not to intervene. We are therefore beholden to undertake research, on the understanding of a simple premise. Very few serious researchers are strongly in favour of deployment. Most, like me, would see it as tragedy; nothing less than a total abdication of our responsibility of planetary stewardship, were we to actually get to the point where deployment of global climate-altering technology was deemed necessary.