Turning aside from the moment from the strange world of Monkers we come to something that at least touches on science: to what extent did the atmospheric nuclear tests of the 50’s and 60’s affect the climate? It turns out that the answer is “hardly at all” and that the question isn’t interesting; but I haven’t seen the answer written down properly anywhere, or even considered properly, so I’ll present what I’ve gleaned here (I’m almost certain this came up in sci.env in the Olde Dayes but I can’t find it).
The latest folk to resurrect the idea that “all those bomb tests must have done something” are JN (Jo Nova) / DE (David Evans) in their BIG NEWS series. They’re currently bogged down fighting off LS over TSI, but when that’s beaten to death or quietly forgotten, they’ll need to return to the question of “attribution”. In their part VII their model – curve-fitting in my view, though they insist its a “physical” model though I don’t think they know what that means – produces a stonking forcing from bomb tests (which in itself tells you their model is non-physical, even if you don’t know any details). I’ll inline their picture below.
Notice how the bomb-tests line in black is massively bigger than the volcanoes line, by a factor of something like 10. They’ve done that because they want their model to match the observed temperature changes; and they’ve decided to “model” the 50’s-70’s dip (which most folks ascribe to aerosol-from-fossil-fuel-use cooling) as being due to bomb tests. I’ve no idea why they thought this would be a good idea, and even they have realised that its just a touch problematic: While this is only an answer found by numerically piecing together the test yield data with the output of the solar model and the observed temperatures, it fits. Maybe the nuclear winter hypothesis is partly correct. We feel it is likely to overestimate the effect. Alternative causes for a cooling influence during the 1950s to 1990s could be pollutant aerosols and/or whatever caused global dimming, or even the Pacific Decadal Oscillation (PDO). With no data that quantifies their effects, the total climate model only had the nuclear bomb yield data to work with, but it is remarkable that the piece that fits the puzzle quite well is the atmospheric nuclear bomb test data.
JN attempts some kind of defence of the bomb idea: You’ve [that’s not me, BTW – W] called the contribution of the atmospheric bomb tests a fudge factor but you haven’t actually provided any reasons why 440Mt of explosions wouldn’t have some cooling impact. The question then is how much of an impact is reasonable. We provided two papers with estimates in the same ballpark.
So there are two defences in there: the first is “oh it must have had some effect” which is just squid ink. The second is refs to some papers – this is better. The papers JN is referring to here are Fujii, Y. (2011). The role of atmospheric nuclear explosions on the stagnation of global warming in the mid 20th century. Journal of Atmospheric and Solar-Terrestrial Physics, Volume 73, Issues 5-6, April 2011, Pages 643-652 and Edwards (2012) Entangled histories: Climate science and nuclear weapons research, The Bulletin of Atomic Scientists. The statement that “We provided two papers with estimates in the same ballpark” is rather hard to understand if you read the papers. The Edwards one can be neglected; it says nothing really to the point. The title of the Fujii one is thoroughly to the point, and if we had nothing but the title it would prop up the JN / DE theory wonderfully. But the paper is either ignorant or dishonest, I don’t know which, since it says The stagnation in global warming in the mid 20th century has not been simulated well even by the most advanced climate models. But as the graph I’ve inlined shows (from IPCC AR4 WGI) that’s not true (and note that the paper was written well after AR4. But the main problem with the Fujii paper is that it makes no attempt to deal with actual observations of stratospheric aerosol loading. Its full of arm-waving, and it attempts to compare the 440 MT yield with the traditional “nuclear winter” papers; and it even manages to notice that the comparison makes no sense because the nuclear winter scenario is based on soot from city fires being lofted; but goes on to make the comparison anyway.
And so we return to the pic I inlined at the top, and will include again here slightly cut for convenience:
(this stuff is also available somewhat updated and in glorious techicolour from http://data.giss.nasa.gov/modelforce/strataer/).
If you care about the details, you need to be aware that the data here is non uniform, and fairly crude in the early days. As they say:
We divide our discussion of stratospheric aerosol data sources into four periods (Figure 1), which have successively improved data quality. In period 1 (1850-1882) we have only very crude estimates of aerosol optical thickness based on the volume of ejecta from major known volcanoes, supported by qualitative reports of atmospheric optical phenomena. Period 2 (1883-1959) has measurements of solar extinction, but during the time of principal volcanic activity (1883-1915) the data are confined to middle-latitude northern hemisphere observatories. Period 3 (1960-1978) has more widespread measurements of solar and stellar extinction, lunar eclipses, and some in situ sampling of aerosol properties. Period 4 (1979-1990) adds precise widespread data from satellite measurements.
Incidentally, I’m not entirely sure what the “?” above the peak over Pinatubo is; probably its the caveat about post-1990 data at the end of their section 2.
And, errm, well: there you have it. The stratospheric aerosol loading looks like volcanoes, and looks nothing at all like the line DE’s model produces. Attempting, in a genuine physical model, to use a bomb-test forcing that peaks at more than 10 times the volcano forcing and whose time-integral is even larger would produce massive cooling. In DE’s toy curve-fitting model you can mash the curves together, but it means nothing.
This ties into “Dr” Roy Spencer is sad and lonely and wrong (and part 2, where I diss Curry as well). And by that I mean the overall theme, not the details: that JN / DE don’t have anyone serious they can discuss this stuff with, so they’re forced to do all their “science” in isolation. Which is, like, really hard maan. Which is why people don’t do it if they have a choice.
