Green Myth-Busting: Cosmic Ray Flux
Myth: Our current global warming is due primarily to a decrease in cosmic ray intensity.
Fact: The fact is that this theory is extremely new, and has only recently been considered possible. There are still many questions left to be answered and more work to be done on quantifying its effect before such a statement could have any validity. Before we get into the details of why this is, I’d like to explain the theory itself a little better.
Basically, this theory, researched by a scientist named Henrick Svensmark, claims that the Sun indirectly affects our climate. The first thing to understand is that clouds generally have a cooling effect on the planet, through an effect called albedo: they reflect sunlight back into space. Next, we have cosmic rays, which are "energetic particles originating from space that impinge on Earth’s atmosphere". Cosmic rays primarily consist of protons, and they originate from outside our solar system. The Sun also emits rays, called solar cosmic rays, which have much lower energy than cosmic rays. When there is an increase in solar activity, the increased solar cosmic ray intensity causes a decrease in the other cosmic rays, called the Forbush decrease.
According to the cosmic ray flux theory, cosmic rays, upon entering our atmosphere, produce small particles called aerosols, which aid in cloud formation. So, more cosmic rays means more clouds and a greater cooling effect. However, this theory’s proponents claim that we are currently in a period of increased solar activity, which is causing less cosmic rays to enter our atmosphere. This means less clouds and therefore, a warming effect.
From the outset, Svensmark’s research has been met with criticism. His problems started when he claimed a correlation between cosmic ray intensity and global cloud cover based on limited data:
One of the biggest criticisms levied against Svensmark was that he had used data from a satellite that did not measure total global cloud cover. When other researchers plugged in a more comprehensive data set, the correlations Svensmark found between cosmic radiation and the Earth’s global cloud cover broke down.
So Svensmark tweaked his theory: Though clouds at middle and high levels are unaffected by cosmic rays, he said, low-level cloud formation was still highly correlated.
Criticism lingered.
Criticism has lingered because, while he’s found a correlation with low-level clouds, his experiments do not reflect real-world conditions. In his experiments, he has taken a mixture of water, sulphur dioxide, ozone, and air, and bombarded it with high energy UV light. According to Eli Rabett, this experiment contained about "5000 times more SO2 than in places where clouds actually form" and "more ozone than in the ozone layer". There is also concern over the use of high energy UV, which according to Gavin Schmidt at RealClimate, "never penetrates the lower troposphere." This is quite a problem, considering Svensmark’s supposed correlation is with low-level cloud formation. Schmidt also listed several additional questions that still need to be answered:
First, the particles observed in these experiments are orders of magnitude too small to be Cloud Condensation Nuclei (CCN). In the press release, this is why they talk about the ‘building blocks’ of CCN, however, aggrandisation of these small particles is in no sense guaranteed (Missing step #1). Secondly, the focus is on low clouds over the ocean. However, over the ocean, there are huge numbers of condensation nuclei related to sea salt particles. Thus to show that the cosmic ray
mechanism is important, you need to show that it increases CCN even in the presence of lots of other CCN (Missing step #2). Next, even if more CCN were made, you would need to show that this actually changed cloud cover (or optical thickness etc.) (Missing step #3). And given that change in cloud properties, you would need to show that it had a significant effect on radiative forcing - which despite their hand waving, is not at all well quantified (even the sign!) (Missing step #4). Finally, to show that cosmic rays were actually responsible for some part of the recent warming you would need to show that there was actually a decreasing trend in cosmic rays over recent decades - which is tricky, because there hasn’t been (see the figure) (Missing step #5).
I’d like to clarify here that the purpose of this article is not to discredit Svensmark’s research. The study is peer-reviewed, and is for that reason, at least feasible. For all we know these questions could be answered in the future, with additional research. The point I want to make is that this is a very new theory. Many skeptics have latched onto this theory, claiming that it explains 20th century warming, and therefore debunks anthropogenic global warming. On the contrary, Svensmark’s work has created more questions than it has answered, and is therefore nowhere near solid enough to warrant such bold claims.
Tags: Climate Change, cosmic ray flux, global warming, Green Myth-Busting, Science and Tech
- Uncategorized
July 27th, 2007 at 8:38 pm
I realize that the theory was first hypothesized about ten years ago, but it has only recently been published. So, maybe "new" isn’t the best choice to describe it, but I’m simply intending to point to the numerous uncertainties surrounding cosmic ray flux theory.
August 1st, 2007 at 7:43 am
Jason,
The response which you wrote seems to be somewhat at an odds with the essay you wrote - or perhaps you were responding to someone somewhere else?
August 8th, 2007 at 2:24 pm
Yeah, I was responding to a comment that might’ve gotten lost in a spam queue or something. The person was claiming that the cosmic ray flux theory is not new, but has rather been around for quite some time. I meant to clear this up by explaining that I meant "new" as far as how much research has been put into it.
August 20th, 2007 at 11:33 am
Consider the following, so well put:
“Fact: The fact is that this theory is extremely new, and has only recently been considered possible. There are still many questions left to be answered and more work to be done on quantifying its effect before such a statement could have any validity.”
That is extremely reasonable. It doesn’t reflect one iota on the merits of the theory, of course (newness doesn’t mean wrongness), but the fact that it’s “…new, and only recently been considered possible…” - why, come to think of it, those exact same words could be used to describe the theory of catastrophic anthropogenic (CO2) contributions to climate change…doncha ya think?
I love hearing anti-skeptics wax skeptical. You finally get to hear it stated in ways that they themselves are wont to bristle in defense over, when it’s coming at them (in equally reasonable tones, no less).
August 27th, 2007 at 4:24 am
The 2007 Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) Ch 6: Palaeoclimate at
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Pub_Ch06.pdf
shows high temperatures now and about 800 - 1000 years ago (page 467), high solar forcing now and in the same period (Page 477), high greenhouse gases now, but NOT 800 - 1000 years ago (Page 448).
October 13th, 2007 at 11:13 am
Hmmmm!
No replies to the above rather powerful observation anyone?
March 22nd, 2008 at 12:35 am
Every theory undergoes modification after testing. Svensmark is simply doing what all scientists do. There is no criticism in that. It is the right thing to do.
I think your criticisms of Svensmark are generally ridiculous. I can equally produce similar problems for the IPCC theory on CO2. First all, the ground data and shipping data is inaccurate (e.g. ships going in different directions record different temperatures due to heat from their funnels; urban heat sources; growths around weather stations, the list is endless). Secondly, we can see that from historical records CO2 appears to lag behind climate changes - this would indicate that CO2 is not the driving mechanism at all; methane is a better candidate. Then there is my chief problem: how to explain using the CO2 model the fact that when Greenland is warm, Antartica is cold and visa versa - you cannot do that with a gas: it should all be the same. On the other hand Svensmark’s theory and the evidence he has produced using REAL experiments, point to cloud formation due to cosmic ray flux as being key to explaining ALL climate changes over history, at all times. Nowhere does the IPCC show an experiment that can provide similar experiments that can show or at the very least explain climate change is CAUSED by CO2 by MANKIND. It is all correlation and a bit of chemistry! All they show is correlation data, which as we know can be very suspect, since it is quite easy to misinterpret or find correlations between things that don’t exist. I bet I could for example find a correlation between geography teachers going to the toilet to urinate and their stress levels, but this clearly is not the cause of them going to the toilet!
I work within the field of saving energy (and as it happens reducing human emissions) and I do so as a scientist who doesn’t bury his head in the sand and reject any theory that might affect funding! We should embrace new research, new theories; science should be about discovery. It should not be about people making a living from a theory that has taken over the political debate and become enshrined as the only solution; that makes scientific enquiry into a cash-cow religion. It becomes then a matter not of science but a shouting match; fear of losing funding becomes all important. I think this is why Svensmark has had so many opponents.
As a scientist qualified to talk about climate change I must also point out that Svensmark’s idea is based on lots of experimental data; it is very wrong to call this a ‘new’ theory; or to say that somehow it cannot show the whole atmosphere. Show me an IPCC piece of research that considers the WHOLE of the atmosphere, top to bottom, everywhere, and can clearly explain what causes global warming/cooling! You will not find one anywhere that comes up to Svensmark’s level of experimental data. All you have is correlations, correlations, and correlations. And these of course prove absolutely nothing because it is very likely you are looking in the wrong place. You are studying the geography teachers stress levels, rather than his water intake!
Your first criticism means you haven’t really understood what the theory is suggesting. It doesn’t have to be guaranteed, because it works on the overall global picture, it MUST work! It all a matter of the volume of air and the chemicals present at the LOW altitudes involved.
Your second point: No you don’t! You don’t have to show this because as long as you get cloud cover from one source that all you need. Those other chemicals can be ruled out: build yourself a cloud chamber and try it if you don’t get the point!
(It is pure balderdash to suggest try to suggest that you need to build an entire new planet, fill it with sensors and then do the experiment, in full, with all chemicals available. I’d like to see the IPCC doing that with CO2!)
It has to produce optical thickness as you call it because as you can see it is like a domino effect, and thickness MUST build up from what is available in the atmosphere. You don’t really need to show this since it has already been observed over the Pacific by US aircraft. Check the data if you don’t believe me.
It has already been shown that clouds contribute to significant radiative forcing. You can go to the NASA website and download it. Without doubt, more cloud at low level, means more reflections of energy that otherwise would help to warm the planet. It must be significant since we also know that supervolcanoes create clouds that have very similar affects. And in any case water vapour is the key greenhouse gas, but also the key component to reflecting energy from the tops of clouds.
There is a very famous piece of work done by N Marsh and Svensmark that shows that as cosmic rays and cloud formation ‘correspond’ to each other all the way up to 1995 from 1980. It would be very unusual for this not to continue in the current period of 1995 to 2008, and forever! When is your ‘recent’ global warming supposed to have taken place? Well, everyone I know says 1950s onwards. Thus 1980 to 1995 is as representative as any other period.
The fact is this. If this theory gets to a state where it is proven, then will we no longer have to worry about preventing emissions? It appears that many scientists believe that would be the case. They are completely WRONG!
CO2 is known driving force of global warming. We cannot therefore just ignore it. However, we must note that its effects are much less than we previously consided to be the case. In fact the IPCC knows this and puts minus signs to show its levels of uncertainty. Clouds are its major problem in all of its computer models.
However, to reduce CO2 is also to reduce acid rain, CO, NO, NO2, and a range of toxic gases that are being pumped into our environment. THere is lots of medical research showing that toxic pollution - from cars say - can alter brain function, cause long-term lung damage, heart and circulatory damage, and a host of problems including leukaemia (unburnt fuel - benzene is thought to be responsible) etc etc.
ALso, it would be much better for the USA and Europe to do away with oil so we don’t have to rely on oil producing states for our only true source of wealth: energy. We should do everything we can to save energy, and use renewable energy. We should also invest in using ocean algae to produce energy and use its fertilizer to re-fertilize the deserts.
See http://www.enactenergy.com news - newsletter March 2008 for example on c-green solutions.
April 3rd, 2008 at 3:43 pm
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