You will recall that we recently had a look at work done by Dr Jasper Kirkby and others in the CERN/CLOUD project.
The possible story in my words from cosmic rays to temperature change is this.
The earth is constantly being bombarded with galactic cosmic rays (GCR), high-energy particles from exploding stars. These act on tiny particles (aerosols) of sulphuric acid and ammonia molecules which cluster together to forms “seeds” called cloud condensation nuclei (CCN) from which clouds grow. Clouds are assumed to have a net cooling effect on surface temperature.
An active sun protects the Earth from GCRs to some extent. Conversely with a less active sun more cosmic rays get through. More cosmic rays mean more clouds and the cooler global temperatures.
It’s important to understand that CCNs can and do form without the assistance of GCRs, and that it is the change in GCRs operating at the margin which may or may not cause a significant change in temperature.
Every step of the way must be scientifically examined and proven. The mechanism must work, and in quantities large enough to make a difference.
A BBC article which I hadn’t seen when I wrote the earlier post, explains what the CERN/CLOUD project did and didn’t do. The CLOUD project did show that cosmic rays cause a ten-fold increase in the formation rate of nanometre-sized aerosol particles. But these particles are far too small to form droplets. Professor Mike Lockwood of Reading University said that the particles only grew to 2 nanometres whereas to influence incoming or outgoing radiation:
droplets must be of the order of 100 nanometres (nm). The growth rates would be really slow from 2 to 100nm because there simply is not enough sulphuric acid in the atmosphere.
Kirkby told BBC News:
“We’ve shown sulphuric acid and ammonia can’t account for nucleation (the very early stages of cloud seed formation) observed in the lower atmosphere.
“We’ve found that this can only account for a tenth to a thousandth of the rate that’s observed.”
On another thread Jess linked to an an ars technica article reporting on other studies. These studies are not helpful to the Svensmark hypothesis that cosmic rays “have more effect on the climate than manmade CO2”.
These studies have indicated that the number of cloud condensation nuclei is not very sensitive to the nucleation of aerosols by cosmic rays. There are a few reasons for this. First, there are many other sources of aerosols (including particles in sea spray and anthropogenic emissions), so the total change in aerosols due to fluctuations in cosmic-ray-induced nucleation is not as significant as it might otherwise be. Second, the aerosols are competing with each other to condense a limited supply of vapor, meaning that any increase in the total cloud condensation nuclei is limited.
In addition, most aerosols collide and combine with other particles long before reaching the size of a cloud condensation nucleus—a process called “coagulation.” Increasing the number of aerosols increases the frequency of these collisions, again dampening the effect on the number of condensation nuclei.
In model simulations, a 15 percent increase in cosmic rays (which is about the variation in one 11-year solar cycle) leads to an increase in condensation nuclei of less than 0.2 percent. Even assuming that cosmic rays could have a significant effect on cloud condensation nuclei, it remains to be shown that this would, in fact, account for the observed fluctuations in global low cloud cover. (Emphasis added)
Moreover while the relationship between cosmic ray intensity and solar activty seems to work quite well, in the following graph cloud cover (grey) seems to have decisively parted company with cosmic rays (solid) from 2004:
Jeffrey Pierce at RealClimate has a guest post which goes into the mechanisms in some detail. He is left looking for one or more amplification factors which at present are simply not there. His final thoughts:
While reported observed correlations between cosmic rays and clouds are suggestive of effects of cosmic rays on clouds, cosmic rays rarely change without other inputs to the Earth system also changing (e.g. total solar irradiance or solar energetic particle events, both also driven by changes in the sun, but distinct from cosmic rays). Thus, we must understand the physical basis of how cosmic rays may affect clouds. However, it is clear that substantially more work needs to be done before we adequately understand these physical connections, and that no broad conclusions regarding the effect of cosmic rays on clouds and climate can (or should) be drawn from the first round of CLOUD results. Finally, there has been no significant trend in the cosmic ray flux over the 50 years, so while we cannot rule out cosmic-ray/cloud mechanisms being relevant for historical climate changes, they certainly have not been an important factor in recent climate change.
Pierce looks at this and can find no trend:
If the shape of the above approached that of the graph below for the last 50 years the prospects for Svensmark’s thesis would no doubt improve:
It’s perhaps worth repeating here that establishing a significant GCR/cloud/climate link would require demonstrating the following:
- … that increased nucleation gives rise to increased numbers of (much larger) cloud condensation nuclei (CCN)
- … and that even in the presence of other CCN, ionisation changes can make a noticeable difference to total CCN
- … and even if there were more CCN, you would need to show that this actually changed cloud properties significantly
- … and that given that change in cloud properties, you would need to show that it had a significant effect on radiative forcing.
Eric Steig says none of these are yet anywhere close to being shown. But if you really want to get into the topic, read the whole RealClimate thread on Pierce’s post.
19 thoughts on “More on cosmic rays and clouds”
OK, Brian, I will bite quickly, say my piece and depart.
While your links are interesting (and appreciated), they get us no further forward than the information available for discussion on the last thread. So forgive me if I repeat a little.
GCRs are not the point, or at least are only a small part of it. The fundamental point is that the IPCC-licensed climate models are crap when it comes to clouds, both their formation and their deformation (precipitation). There is still debate, for Heaven’s sake, about the basic question of whether clouds are a feedback or a forcing ie the direction of causation.
And it isn’t denialism to point this out. The IPPC admit that it is the largest source of uncertainty in the modelling, albeit playing its significance down. Nor is it slagging off climate scientists. Clouds are very complex.
GCRs are one small area of uncertainty bearing on cloud formation, and only one. If Svensmark was totally wrong, and I rather agree with you that preliminary signs are not good for him, this would still leave enormous gaps in the knowledge and modelling of climate impact of clouds.
In other words the wider issue is clouds generally and their bearing on the reliability of climate modelling: reliable enough to bet trillions and the future direction of human civilisation on or not?
There are conspiracy theorists (who, moi? never) who will say that it is in the interests of those who do wish to make the bet, for whatever reason, to play up the cloud issue as merely the narrow one of GCRs and Svensmark, to divert attention from the many bigger uncertainties surrounding modelling in relation to clouds, and their potential implications .
No we haven’t got very far.
Wozza, why do you highlight only the costs and uncertainties associated with trying to abate future climate change? Why do you not acknowledge that BAU is a massively risky strategy?
Even allowing for the uncertainties associated with clouds (and aerosols) the best science suggests that the probability of future warming is very high with a considerable chance of causing very significant ecological and economic harm.
Wozza: You say:
Most of us buy housing insurance because we would prefer to lose a small amount each year than risk losing a much much larger at some indeterminate time.
Climate action at this stage is much the same. There are a number of low cost things the world can do in the next 20 yrs that will slow down emissions enough to make a significant difference. There are also low cost things we can do to help us survive the effects of global warming.
Sure, we may reach a point at some time in the future where we have to choose between doing little or really suffering significant damage to avoid further global warming – but we are a long way away from this point right now.
Every step of the way must be scientifically examined and proven. The mechanism must work, and in quantities large enough to make a difference.
And then explained to someone who reads the funnies in the Hun (sometimes).
Maybe it is a false correlation but to me the really scary thing about that measurements of global temperature graph is the way it tracks our history over the past 100 years or so. I guess there have been other comment on this but it probably bears repeating.
First we have a rapid temperature rise from the first world war to the second world war, where the pace of industrial development slowed and the temperature dropped. Then we have a small recovery and a flat tenperature profile until the end of the 1970’s where the so called “third world” started to industrialise
If there really is any real correlation with human industrial activity
(I include power generation, and all manufacturing here) we are in trouble.
Maybe we need a third world war to bring the temperature down?
Huggybunny, the flatness of global temps from the 40s to the 70s was due to the production of sulphates. In the 70s we realized they were causing acid rain, so we drastically reduced their production. After that, global temps started to increase rapidly.
Huggy, check out the Pew Centre graph I used in the previous post. My understanding is that before WW2 the graph wobbled a bit due to natural variability. After WW2 we started forcing things hard. As Silkworm said there was a masking effect from pollution initially.
Wozza, I for one understand a little more as a result of the RealClimate post in particular. And if anything the prospects for Svensmark’s thesis look a bit worse, if anything.
On clouds, they would have to be short-term in their effect. I had another look at Section 2 of this paper by Hansen et al. They put climate sensitivity with short-term feed-backs at 3C, plus or minus 0.5C, leaving aside aerosols, which are his major concern in relation to uncertainty. They do point out that changes in cloud cover generated by aerosols may be an important factor.
But all that pales when they consider long-term feedbacks as well.
It should be noted that they are working from paleoclimate evidence rather than models. It seems to me that the case for taking action on climate mitigation is absolutely compelling.
Thanks – yes I had not considered them, in the late 60’s early 70’s they started to fit electrostatic precipitators to smoke stacks to ameliorate emissions as well as to go to low sulphur coal.
The Conversation has a pretty good new piece by Karl Braganza & Justin Peter (some climate dudes from BOM) on the cosmic ray hypothesis. Specifically they note the expected effect in much the same way as Brian above:
Their conclusions about the kerfuffle:
John D @3
The insurance analogy as has frequently been pointed out simply doesn’t hold up. People don’t take out house insurance to prevent a fire, but to compensate them if one occurs.
If the proposals were to spend the trillions by creating a fund that would be tapped in the future, when (if) damage actually happens, to rectify it, you might have a point. That is, if the object were adaptation; adaptation strategies are far more important than mitigation in my view, especially since much of the mitigation proposed is simply fanciful.
Mind you, you’d have to keep the ALP out of power for a century or so, if you want the insurance future fund unraided for various boondoggles and Nannyisms till needed.
Actually, Wozza, I think you’ll find that some, at least, of your insurance premium helps pay for the fire brigade, so it’s not quite such a bad analogy as you’d have us believe.
The fire brigade doesn’t prevent fires though does it DI(NR)? It deals with a post-fire situation, with a view to reducing impact and restricting damage. Looks more like adaptation, not mitigation, to me.
Elements of subjective judgment in that of course, but the point is that one cannot usefully argue an issue as complex as climate change by a simplistic analogy like insurance – I should probably have just said that rather than drag adaptation vs mitigation into the analogy – though Combet does keep trying.
Wozza, adaptation simply isn’t practical against relentless changes such as sea level rise, ocean acidification, impact on biosphere and biological extinctions, food production etc.
The reason you take out insurance is to spread the risk. I’ll accept that the analogy has limitations, but looking at risks, if there is a 1% chance the warmists are right we are taking an unacceptable risk if we do nothing. The denialists have to be 100% sure they are right, which is a higher standard than you usually get in science.
Let’s hope that today’s vote on the Carbon Price is the beginning of the end for Moany Abbott and his rain of economic doom. Looking at the faces of Coalition Members in Parliament yesterday I personally think that he is now a spent force and Malcolm Turnbull will soon move to a higher profile as Coalition Caucus members redevelop their moral spinal strength once soon removed from their prolonged period floating in factual weightlessness to face the full gravity of our real world Changing Climate situation.
i’ll second that. i’m looking forward to the price on carbon getting passed today. going forward it gives everyone something actual to debate on merits.
Brian, I actually think that is two steps because the assessment of the science and the resulting risk is not the same thing (this is a central part of my recent paper on uncertainty in Climatic Change).
So – there’s the probability of the hypothesis of a change in radiative forcing due to GHGs causing climate change? P is so close to 1, it’s not worth trying to think of a number.
There’s the probability of climate sensitivity being a positive feedback. Has evidence from models, palaeo and obs. What’s the chance of that being wrong? 1 in a thousand? I wouldn’t go more than 1 in 100 and even then, it’s a hugely generous concession. What about sensitivity being <1.5C? IPCC last time said that it was very unlikely; i.e. <10% and this is a generous concession, too.
At such low sensitivity, it requires extra-ordinary changes in Earth's albedo and atmospheric aerosol (dust) to produce the low temps of the last ice age. The same goes for producing the high temps and sea level (+25m) of the pre ice-age climate. Now with all the money spent on lobbying against climate change, couldn't there have been some investment in the science to show how Earth works under those assumptions? No – because everyone knows it's more efficient to create doubt in the media and to invest in political opposition to the science.
So there's risk. Several ways to manage it, as you say. Mitigate by reducing the cause, adapt by reducing the anticipated response, get compensated for damages when they occur by paying a premium to a central pool or taking it on the chin (bear the risk).
There is, or should be, no relationship between p(Hypothesis) and the degree of action required, though many people insist (intuitively) this is the case. It's like being half pregnant. This is where we get the all-or-nothing response embedded in current political debates. It's not about the science because there is no credible alternative hypothesis for how the climate works. The adapt or mitigate one-or-the-other construct is likewise untenable. We already know that the limits of adaptation fall way below the levels of climate change likely to be reached under no or limited mitigation. And there are adaptation limits for some sensitive areas below the current target of 2C, so the picture is one of net loss for those activities.
Insurance pools are being considered and set up for least developed countries (in response to Wozza). The World Bank is on it. The Australian Government has already decided it does not want to be the insurer of last resort for future climate damages. Take it up with Treasury.
How well the models predict the risk is an issue, but it's a different form of uncertainty, not the same as confidence in a hypothesis. John D's example is one of a small ongoing payment to avoid serious harm, in that it relates to insurance. It's actually better than insurance because it mitigates the risk through re-directing industry instead of disappearing into the insurer's investment pool. There are transaction costs but they are way under, IMO, the transaction costs one requires to adjust to a rapidly changing climate.
Thanks, Roger. As a climate risk specialist we need to give careful consideration to your comments.
Ta Brian – and thanks for the impetus – this idea has been bugging me for a bit. Drew out a few things I hadn’t thought of, too, about all or nothing politics and progressive policy that l’ll ponder.
Related to the post, there’s a really good article in September 6 Eos but it’s behind a paywall.
EOS, TRANSACTIONS AMERICAN GEOPHYSICAL UNION, VOL. 92, NO. 36, P. 297, 2011 doi:10.1029/2011EO360001
Does the space environment affect the ecosphere?
Nathan A. Schwadron, Harlan E. Spence and Rosemarie Came
It basically says that the links between cosmic rays and solar irradiance and the atmosphere are unknown. And cannot yet be used to predict what may happen (although they suggest something will!)
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