Uncharted Territory

January 22, 2010

Interestingly, Volcanoes can Trigger El Ninos

Filed under: Agriculture, ENSO, Geoengineering, Global warming, Science, Volcanoes — Tim Joslin @ 6:24 pm

Once again, I’m starting this post as I’m halfway through another one that may or may not see the light of day. I was trying to put together a rant following the Royal Society’s (RS’s) panel discussion on geo-engineering (available on royalsociety.tv), which I attended on Tuesday evening. The meeting followed a report issued by the RS last September.

Rather than rule out most of the possibilities, the RS boffins recommend further research. A cynic might suggest this was self-serving; I couldn’t possibly comment.

There are numerous problems with many of the geo-engineering approaches. But I wanted to be original and see if I could find evidence to support my hypothesis (noted in a previous post) that trying to cool the planet by injecting sulphur dioxide (SO2) into the stratosphere where it would produce reflective particles would block a disproportionate amount of sunlight striking the atmosphere at a shallow angle (i.e. more tangentially). More sunlight would therefore be blocked at the ends of the day, high latitudes and in winter.

In fact, the boffins noted on Tuesday that a disproportionate effect in the Arctic could be “beneficial”. This doesn’t stop them apparently relying on a computer modelling study that simply plugs in “a reduction in global mean insolation of 1.84%”.

The RS study repeatedly discusses recent volcanic events in order to assess possible effects of the geo-engineering plan.

Having looked into the matter, I can say this is bordering on a waste of time.

Drs Strangelove want to fire enough SO2 into the sky to block out around 2% (on average) of the sunlight, their sums suggesting this would counterbalance a doubling of CO2 levels.

But this interesting graph (courtesy of WIkipedia) shows what volcanoes do:

Mauno Loa observations of atmospheric transmission of sunlight

Wow! They don’t block 2% of solar radiation, rather 10 to 20% on a regular basis, and presumably even more when a real biggie goes off.

And this is enough to cause real disruption.

First off, the boffins worry about affecting the monsoon and other aspects of the hydrological cycle, citing the effects of the Pinatubo eruption in 1991. But Pinatubo caused massive short-term cooling. Monsoons rely on the land becoming warmer than the oceans, leading to rising air, drawing moist air towards the landmass. Obviously, if you reduce sunlight by 10% or so, the land will warm much slower and could remain too cold, relative to the ocean (which is kept warm by stored heat), for a healthy monsoon.

Second, I noted in a comment on a previous post that El Chichon was followed by a strong El Nino. As can be seen from the graph I gave at the time, there was a weaker one after Pinatubo. “Could they possibly fit together?”, I found myself wondering. Yesterday, via Realclimate, I came across a paper suggesting that yes, indeed they could (pdf).

The point, of course, is that El Ninos occur when warm surface water flows (unusually) east across the Pacific (see also Wikipedia). The warm water builds up in the first place because the initial flow (ultimately due to the rotation of the Earth) creates, in turn, an atmospheric warm zone to the west (around Indonesia), and a cooler region near South America. Lower pressure maintains a significant difference in the surface level between the west and the east of the ocean (maybe 60cm!). But the feedback relies on maintenance of the temperature (and hence atmospheric pressure) differential and eventually breaks down, typically in December (when the sun is not overhead at the Equator) and the whole thing collapses like a lop-sided souffle in an unevenly heated oven. Warm waters temporarily flow east with significant effects on the global climate for a year or two.

Fairly obviously, a general cooling event, such as a volcanic eruption, is likely to trigger an El Nino.

As an aside, it might be worth noting that a warming period is likely to lead to a strong El Nino, as observed in 1997-8, for example. The warming will reinforce the feedback creating the original imbalance. 1982-3 was also a strong El Nino event:

El Chichon anomaly (1983-4 temperatures compared to 1980s)

Maybe the cooling caused by the 1982 eruption of El Chichon enhanced an El Nino that was anyway ready to take place. Or maybe it was always going to be a big one.

At the risk of trying to read too much into limited evidence, it might be possible to surmise that the 1997-8 El Nino was so strong because the global warming trend leading up to it was reinforced by recovery from the Pinatubo cooling event. Similarly, to stretch the point even further, 1972-3 is listed as a strong El Nino, and followed the recovery after the Agung eruption, though that was 10 years before and not so large as El Chichon and Pinatubo (though a graph over at SkepticalScience gives a different impression). Fascinating stuff – no wonder climate scientists can’t wait for another major eruption!

Incidentally, because we mainly measure the temperature at the surface of the planet, El Ninos show as spikes in the data, because warm surface water covers cooler layers over a large area of ocean (and in turn affects temperatures on land). When a volcano triggers an El Nino, the cooling caused by the volcano is therefore partially obscured by the El Nino. An eruption when we were already in an El Nino state would consequently likely appear to have a greater effect on global temperatures than one that triggered an El Nino.

The geo-engineering plan is entirely different to the case of intermittent volcanic forcings. The plan involves a semi-permanent sunscreen to block 2% of sunlight. The problems will be entirely different. Relying on the historical record of the effects of volcanic eruptions won’t allow us to predict all the effects of the geo-engineering proposal.

Logic tells me that an SO2 sunscreen will disproportionately affect high latitudes, where sunlight is a highly valued commodity. Politically, it would of course be next to impossible to achieve broad agreement to go ahead with the geo-engineering plan. Furthermore, in a warmer world, with increased tropical desertification, we may be relying on food production in more northerly areas. Blocking sunlight might not be a bright idea.

Nevertheless, I carried on surfing for a bit for evidence that volcanic forcings could affect high latitudes more. The best I could come up with was the Russian famine of 1601-3, likely triggered by an eruption in Peru.


October 12, 2009

Superfreakonomics, Oliver Burkeman, Hubris and Bounded Rationality

Oh dear, oh dear, oh dear! Hubris meets rationality…

I very much enjoyed Freakonomics. I see from the position of the bookmark in the copy on my shelf that I’ve read past halfway, so it must have been good. I recollect that I was particularly impressed by the discussion of the absence of ill-effects of a policy of random selection of pupils by over-subscribed schools in Chicago, clearly the fairest solution. In fact, I remembered the discussion of random selection in Freakonomics just last week when I read of a rant by a Mike Best, Headteacher, Beaminster school, Dorset:

“It was George III who said that the pathway to hell was paved with good intentions, and so it is with Labour initiatives. They have ranged from the mad (random allocation of school places)…”

Sir, George III was famously mad, and, if I recollect any history at all, died before the Labour party was even formed…

Unlike George III, the Freakonomics authors, Levitt and Dubner, urge policy to be made on the basis of dispassionate analysis of data. And not, perhaps, on the say so of so-called experts with a vested interest.

Considering myself an arch-rationalist, I eagerly read an article by Oliver Burkeman in today’s Guardian discussing the sequel to Freakonomics, Superfreakonomics. I didn’t know whether to laugh or cry.

The reviewer’s comments make interesting reading too. Burkeman writes, for example, that:

“Those arrested on charges of terrorism, [the authors] explain, are disproportionately likely to rent their home, have no savings account or life insurance, be a student, and have both Muslim first and last names. Superfreakonomics makes no mention of the possibility that the police might simply be targeting Muslims disproportionately, and Levitt seems genuinely baffled that anyone might object, on civil-liberties grounds, to targeting all those who fulfilled the relevant criteria.”

Burkeman seems to be implying that he believes behaviour likely to lead to arrest on charges of terrorism is evenly distributed throughout the population, and that Muslims are therefore being targeted unfairly. Maybe I’m missing something here, and I don’t want to offend anyone, but isn’t the main terrorist threat at present from Muslim extremists? Just as a while back the main threat in the UK was from Irish nationalists? Or are these social phenomena just a figment of my imagination? Maybe in WWII British soldiers took more Germans than Americans prisoner just because they were targeting them disproportionately.

But this is nothing compared to Burkeman’s discussion of Superfreakonomics’ espousal of the geo-engineering plan to block out sunlight by “pumping large quantities of sulphur dioxide into the Earth’s stratosphere through an 18-mile-long hose, held up by helium balloons…”. Apparently, Nathan Myhrvold is promoting the idea. He should know better as well.

Anthropogenic stratospheric SO2 injection is a complete and utter non-starter, for the simple fact that warming isn’t the only problem caused by CO2 emissions. This has been very well known for some time. Conferences have been held to discuss the problem. I’d have expected Burkeman to know this.

5 minutes thought might cause one to wonder as to the biological effects (the impact on ecosystems, crop yields…) of decreasing light reaching the Earth’s surface – at the same time as CO2 levels are increasing. And you’d still have time to realise that we’d have to keep squirting SO2 into the stratosphere indefinitely, because it only stays up there for a short while, whereas the warming CO2 will remain in the atmosphere until we stop emitting it and/or do something to get the level in the atmosphere back to pre-industrial levels. Any disruption of the SO2 hosing process for any reason (war, terrorism, economic dislocation, court injunctions…) would lead to rapid temperature increases, because the CO2 would no longer be masked. And before the egg-timer rang you’d realise that any hint of adverse side-effects would make the plan entirely impractical on political grounds.

Myhrvold and the Freakos (sounds like a 60s rock band, don’t it?) have, it seems, walked into the hubristic trap of believing they understand the whole problem. Messing with the biosphere and the climate system requires other forms of analysis than the correlation of data-sets and a good understanding of the importance of the role of incentives in explaining human behaviour. The authors have exceeded their intellectual authority – they are skilled at analysing “closed” economic problems (where the boundary can easily be defined), but don’t seem to appreciate that tackling global warming is an “open” problem. I’m particularly astonished at this given their background as behavioural economists – I can hardly believe they are not aware of the concept of “bounded rationality“.

All Burkeman does is lamely point out that:

“The primary objection to this plan, as with other ‘geoengineering’ schemes, is that there’s no predicting the unknown negative effects of meddling in such a complex natural system. And it’s strange, given how much is made in both Freakonomics books of the law of unintended consequences, that they don’t mention this in the context of Myhrvold’s plan.”

Quite. But Oliver, they can’t even deal with the known knowns, let alone even the known unknowns. You don’t need to fret about the unknown unknowns!

The geo-engineering twaddle is all a shame, as Superfreakonomics apparently argues that:

“The problem with trying to reduce carbon emissions … is that the incentives are all wrong. Too many of the benefits are ‘externalities’, from which the people making the sacrifices will never benefit – and the whole history of economics demonstrates that such completely unself-interested behaviour is impossible to implement on a large scale, especially when so many people suspect that their sacrifice would not, in fact, make a significant difference to the outcome.”

I wouldn’t underestimate the potential of peer-pressure – as Burkeman puts it, “our self-interest can include a desire for the warm glow of acting in a moral or charitable way” – but I doubt this will be enough. Surprisingly, Burkeman doesn’t press this argument against the economists – whose profession has been known to not fully understand that there IS such a thing as society – but tails off into incoherence after noting that:

“This, of course, is desperately tricky territory. My immediate personal response is that Levitt’s view is irresponsible defeatism, which I find repugnant.”

“Repugnant”???!!! I’m with Levitt here. We all need to grow up and face facts.

Don’t squirt SO2 into the sky because, if this is the level of intellectual debate on how to deal with global-warming, all I can say is that we need the heavens to help us! (If I may be permitted to pluralise in a cryptic nod to Battlestar Galactica – buy the box-set if you don’t know what the frak I’m on about!).

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