More about the CERN CLOUD experiment from Jasper Kirkby

Posted: June 12, 2011 by tallbloke in Astrophysics, climate



While ALPHA and antimatter have been hitting the headlines, Kirkby’s experiment – Cosmic Leaving Outdoor Droplets, or CLOUD – is no less intriguing. It is very different, focused on explaining not our existence but our climate. “We are trying to understand what the connection is – if any – between a cosmic ray going through the atmosphere and a change in clouds,” Kirkby explains. A cosmic ray is a sub-atomic particle created by supernovae explosions somewhere in the Milky Way. He adds, perhaps stating the obvious, that “it is clearly not as simple as that”. There is no doubt that CLOUD could have important ramifications. If some of the theories Kirkby and his team are testing are proven, they could suggest that the natural, rather than man-made, component of current climate change is greater than previously thought.

Outlining the background to the experiment, Kirkby says: “If we ignore the twentieth century when it was complicated by all the greenhouse gases and so on – when all climate changes were of course natural – there were these changes on hundred year or so timescales that do often seem to be associated with the sun. The amount of change in the climate is comparable to current warming and there is not a single known mechanism to explain them. So the cosmic ray connection with clouds is a candidate mechanism, and there are very few other possibilities.”

Clouds have a cooling effect because they reflect some of the sun’s radiation, so any long-term change in cloud cover would have a considerable impact on earth’s climate. And there is disputed evidence that cloud cover has reduced in recent decades as global temperatures have risen. Meanwhile galactic cosmic rays create a weak charge in the atmosphere. The theory runs that these charged molecules, called ions, may play a role in the creation of aerosols – tiny particles in the air which cluster and seed cloud droplets. At the moment, Kirkby explains, aerosols are poorly understood, but without them there would be no clouds in the sky. They are also responsible for the light scattering which creates the haze we see when looking at distant mountains.

Satellite measurements show a correlation between the intensity of cosmic rays, which varies with the sunspot cycle, and the amount of cloud cover. It is complex science but the aim of CLOUD is to gain an understanding of this apparent connection. “As far as I’m concerned,” Kirkby continues, “until this natural contribution to climate change is well understood there will be a big uncertainty as to what is going on with mankind’s contribution.”

The experiment itself is the first time a high-energy physics accelerator has been used to study atmospheric and climate science. “We are using a CERN beam as an adjustable source of cosmic rays,” says Kirkby. “We have a chamber, three metres, in which we put minute amounts of these gases and ultra-pure air humidified with ultra-pure water. We go to extreme lengths to work on the purity of the chamber. The air we use is made synthetically from liquid nitrogen and liquid oxygen and we are building a synthetic water system to make the water even purer. That is one of the big reasons why it has been important to do the experiment at CERN. There is a lot of know-how in the technology.”

One of the things that makes CLOUD exciting for Kirkby is that it feels like “a beautiful step back to an old style experiment where your results are right there in your notebook as you do your shift”. The first findings, which Kirkby claims will reveal four or five important discoveries – will be published in the next two months. CLOUD is also small by CERN standards – “we don’t have 2,000 physicists we have 50”. What it does have common with other CERN projects is that it is an international effort. There are 15 institutes involved, each contributing financially through their national research councils. Most are European but there are groups from the US and Russia. There are also some graduate students funded by the European Union. “It is a top-notch team,” according to Kirkby. “They are mostly aerosol and atmospheric scientists. There are also cosmic ray physicists and I’m a particle physicist. So it is an interdisciplinary team.”

His enthusiasm for both the experiment and his place of work shines through. “I have been here more than 25 years,” he says, “and I’ve yet to meet somebody who said they didn’t like working at CERN. It has very much a campus atmosphere and people are genuinely excited about what they are doing. CERN is a network – once you need an expert in a particular area there will be somebody available. There is a lot of sharing and a tremendously supportive spirit among everybody.

“As regards CLOUD, it is a strange experiment for CERN. The people who work on it, including the technical people and engineers, really like it. One of the reasons for that is everyone can understand and relate to it. It is very important for current understanding of climate change to understand natural solar variability and to understand clouds better. One of the very attractive things about basic research is that it has intrinsic value – it is new knowledge that you pass on. Most of particle physics is fundamental knowledge and it may not have an immediate consequence for society. But CLOUD is directly trying to clarify some important uncertainties in current climate change thinking. I have had more than one engineer tell me – ‘this is the first experiment I have ever worked on at CERN where I’ve told my wife or husband what I’m doing and they actually understand it.'”

The costs of the experiment stand at around €3m. “It is a significant amount of money,” Kirkby accepts. “If you compare it with a typical atmospheric experiment it’s definitely reasonably expensive. If you compare it with the LHC experiments then it’s less than 1 per cent – though you should compare them with putting a man on the moon or something.”

He goes on to explain some of the difficulties he faced winning the funding. “Although interdisciplinary experiments are very politically correct these days, in a world where there are limited resources – which is definitely the world we live in – the funding agencies are not at all used to funding across boundaries. Atmospheric funding agencies are not accustomed to paying for CERN experiments. By the same token CERN is not used to funding atmospheric experiments. When there are limited resources, and first class proposals are being turned down in your own subject it is very easy to put a line through the strange-looking proposal that doesn’t fit in anywhere. That to some extent was a problem but finally the experiment is up and running.” It is a notable personal achievement for Kirkby, then, that CLOUD has got so far. But how long will it go on?

In the future the chamber will be modified to create cloud droplets and ice particles themselves in order to study the direct effects on them of cosmic rays. One of Kirkby’s colleagues on a previous project was asked how long that experiment would last and he always replied: “Five years unless somebody has a good idea.” Kirkby is taking a similar line, but says: “I think it is going to take 10 years. We really want to settle this question. It could be that we find there are effects but they are not climatically significant. Or it could be that we find the whole thing is very important. But we want to settle it.”

  1. vukcevic says:

    It could be that we find there are effects but they are not climatically significant. Or it could be that we find the whole thing is very important.

    If it proves to be important, I think it is far more likely to be connected to the variation in the geomagnetic than the solar one; solar is in terms of nanoTesla, while equivalent GMF is in terms of microTesla.
    Recently I came across something even Dr. Svalgaard denied it exists, i.e. the gmf variation highly synchronised with solar. There was a protracted debate, so I will reproduce two sentences from Dr.S, opening and closing.
    June 9, 2011 at 1:42 pm :….This has nothing to do with the Sun.
    June 11, 2011 at 10:38 am: ….So there is a solar cycle variation of the external current that is comparable to the secular variation.
    Finally he was proven wrong, and put forward his more human face.

    Now back to GMF-GCR link
    Geomagnetic field across northern Hemisphere is a combination of what is happening between two varying magnetic extremity, one located at the Hadson Bay area (on decline) and the other central Siberia(on rise)
    ‘Hudson bay effect’ is by an order of magnitude stronger then the Siberian.
    Siberia , the weaker one, came to prominence around 1890’s and tracks the solar field with positive correlation and no delay.
    In contrast Hudson Bay has been there (in data file) from thee Maunder min, it has negative correlation to the solar, but to complicate the matter, it lags by about 35 years and to be even more puzzling it flipped to positive correlation in late 1970.
    At this point two fields, if there is a GMF-GCR link, started acting in the same direction rather then working against each other, and so reinforcing the solar effect that takes place at the far reaches of heliosphere.
    Anything to do with sudden rise in the NH temperatures?
    Difficult to tell.

  2. vukcevic says:

    p.s. to compare ‘Hudson Bay’ decline against ‘Siberia’ rise toggle between two links:
    or simply type in1910 in the link. Zoom in and compare numbers.

  3. tallbloke says:

    Vuk, thanks, very interesting observations. Regarding the “the solar effect that takes place at the far reaches of heliosphere” I found this snippet today:

  4. vukcevic says:

    re. link:
    Not entirely surprised, remember the discussion of protons hitting heliopose (aka garden hose jet hitting brick wall), these protons are not energetic enough to break through, but energetic enough to resist solar gravitation pull, and congregate in areas where galactic field is weakest. I would assume they may be source of these magnetic bubbles, in which case the GCR distribution along the edges of heliosphere is not as uniform as LS would have us believe.

  5. Murray says:

    Vuk, Landscheidt has a phase reversal (phase catastrophe??) about 1976. I have never understood his phase reversals. Could be related to your Hudson Bay magnetic reversal?

  6. vukcevic says:

    Hi Murray
    If you look at my web page
    The top graph, you can see that the ‘Hudson Bay’ magnetic pole (blue line) suddenly changed direction (note it is declining scale to the right). Why would this happen I have no idea.

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  8. Stephen DuVal says:

    Kirby Cloud Experiment Update
    Kirby will reveal very important discoveries in 2-3 months

    In a Jan. 5, 2014 interview, Kirby said that he will be able to discuss recent results from the CLOUD experiment at CERN in 2-3 months. The CLOUD experiment has made “several very important discoveries”. These include “very large enhancement” in the quantity of Cloud Condensation Nuclei and the chemical precursors of CCN.

    Start at minute 6:20 of this video:

  9. tallbloke says:

    Thanks Stephen. Please repost your comment on the new ozone thread.