There’s no doubt about it: I’m creating the most boring climate blog around! Mostly, I’m just posting snippets of information as I find them, often with no particular interpretation. In comments at Real Climate, someone suggested people read “Internally and Externally Caused Climate Change” by Robock (1978). This paper describes the results of simulations using a a simple energy balance model and compares the to measurements of the earth’s climate. It’s quite interesting on a number of points, which I will discuss in no particular order. (Note, the points that interest me today are not necessarily the major points of the paper, which is available at here.)
Effect of Volcanic Eruptions on Climate
I recently wanted to see volcano eruption data, and obtained data back to 1889. So naturally, I found the curve showing veiling by volcanos eruptions back to 1600 interesting. Here it is:
It’s interesting to notice there were regularly occurring volcanic eruptions since the 1600s with a sudden drop in the rate of eruptions around the 20’s. Note that the absence of eruptions from 1978-2000 on the chart is illusory: the paper was written in 1978, and Robock must have simply drawn the axes out as is conventional. We know Pinatubo erupted more recently.
If I understand correctly, the figure show below is Robock’s comparison of one of his model post-dictions for the average 0-80 degree northern hemispherical average temperature to measured data. (This model post-diction included the effect of Mitchell’s estimates for aerosols.)
Because I want to eyeball these together, I’ve placed the post-dictions of my semi-empirical model immediately below Robock’s figure.
Discussion of Effect of Aerosols
The impact of industrial aerosols on climate seems to be hotly debated in the climate blog wars. Aerosols are known to have effects, but the magnitude appears somewhat uncertain.
Because there is so much rhetoric about aerosols, I think it’s useful to at least note when modelers began considering the effect of industrial aerosols. It turns out that Robock included their effects, while also discussing the uncertainty in the magnitude of the effect. So, at least this can be said: the importance of aerosols was recognized and discussed as early as 1978, which is fairly early in the whole “climate wars” debate.
The importance of aerosols was recognized and discussed as early as 1971:
http://www.sciencemag.org/cgi/content/abstract/173/3992/138
Schneider S. & Rasool S., “Atmospheric Carbon Dioxide and Aerosols – Effects of Large Increases on Global Climate”, Science, vol.173, 9 July 1971, p.138-141
Thanks Hans!
Fascinating. Good work, lucia.
Did you know we may get to test the Pinatubo experiment again? link, at least that’s what one of my meteorologist friends says.
Terry–Wow!
I’m kind of rooting for a big blow off!
If Pinatubo goes off violently, Carnac predicts that will lead to hellashious amounts of rhetoric 2 years afterwards!
The reason is that if the theory of AGW is true, there is every reason to believe there is heating “in the pipeline”. But, if there is heating “in the pipeline”, the eruption will do nothing more than offset the heating. So….. the GMST may not dip– it may only fail to rise for two or three years!
(In contrast if AGW is false, or there is no heating in the pipeline, a dip after the next blow will be as large or larger than the last Pinatubo blow!)
So, my thinking is, if the volcano blows about the same amount as last time:
* A dip in temperature of the same magnitude as the last time would mean AGW is probably wrong.
* A noticably smaller dip in temperature than last time, or no dip means AGW is probably right!
lucia, i agree. i’m rooting for a big blow off too—for 1. the climate experiment and 2. the highly hyperbolic and entertaining rhetoric.
your graphs are telling too, I find it hard to believe the earth hasn’t given up anything really big since Krakatoa, Pinatubo (and Mt. Hudson in the Southern Hemisphere that same year) being the only major ones since. I’d say we’re probably about due, but that’s up to the Earth.
We already have 10 years of next to zero warming – if we get another 5 we can safely declare AGW dead (or at least grossly exaggerated). A major eruption would be very bad because it would just give AGW advocates another 10 years to claim that the warming is ‘just around the corner’.
If we have no volcanic eruption in 5 years, and no warming, then yes AGW, must be exaggerated. Well… unless we find someone threw one heck of a lot of aerosols in the sky.
But, yes, at a certain point, the idea that 0.1C/ decade is coming is going to look weak if the temperature trend for 15 years doesn’t look distinctly up by 2013.
Comment 684: Thanks for posting the 1971 paper co-authored by Stephen Schneider, Hans. But note that Rasool was the first-named author, not Schneider.
wen waz the last earthquake