Source: The Guardian
URL: http://www.guardian.co.uk/science/audio/2011/aug/29/science-weekly-podcast-space-sounds
Date: 26/08/2011
Event: Alok Jha and Ian Sample discuss the CLOUD experiment at CERN
People:
Alok Jha: We're going to take a look at this week's science news now. With me is the Guardian's Science Correspondent Ian Sample, and the Observer's Science and tech editor Robin McKie. Ian, let's start with you. This is some latest results from CERN, but, weirdly, it's to do with climate change.
Ian Sample: Right. So this is a project that's called CLOUD. Now, essentially what the project is doing is, it's an extremely clean chamber, which you can use to simulate how clouds form in the atmosphere. Now, the reason that the project was set up was specifically to answer this question as to whether, if at all, cosmic rays from deep space - basically these come from exploding stars in the Milky Way - whether those rays can influence how little particles called aerosols are created and grow in the atmosphere. And we know that these aerosol particles ultimately can seed clouds - they become substrates for cloud droplets to grow on and that's how clouds form.
Now the results that came out were really interesting. I mean, actually the main result was not so much to do with the cosmic rays, and I'll talk about why they're interesting and why they're contentious a bit in a moment - but the main result that came out was that if you look at what's called the boundary layer of the atmosphere - this is a fairly low down altitude of the atmosphere - all - a lot of climate models that model the sort of creation of these aerosols assume that these little particles form when sulphuric acid and water and ammonia get together, and you end up with these particles forming, now, you can get aerosols forming in the atmophere, you can also get them just kicked up from the planet, so you can get them as dust and sand and water spray from the sea.
Alok Jha: Just to be clear before anyone thinks aerosols are things that come out of cans that destroy the ozone layer, aerosols are simply very, very, very tiny particles.
Ian Sample: Sure, yes it's the generic word for small liquid or solid particles that are just suspended in the atmosphere. Now, that original - sorry I was talking about the main result from the paper, and what it found was that, people thought as I say these three components made aerosols naturally - water, sulphuric acid and ammonia - but when you do that in this experiment, you get something like between a tenth and a thousandth of the amount of aerosol you would expect. So what they're saying is that there are some other - and in this case it has to be organic gases - a gas or gases - that are playing into this process.
Now, that might seem incredibly sort of esoteric, but what it means is that there are vapours coming off that are going into the atmosphere - whether they're from human activity or just from natural processes - like being animals or plants - that are crucial for the formation of these particles that do lead to cloud formation. And it's interesting to find that out, because if it's something that humans are producing through their activity, it means that there is another thing that we are doing that is influencing the climate.
Alok Jha: And the implication is of course then that if we can't account for all the cloud formation, then we'd have to change the models we use for predicting climate change.
Ian Sample: That's right, because there are some models that build into them the nucleation and the growth of these particles, and when they get to a certain size, about 100 nanometres, they can start to seed clouds.
Now let's just talk very quickly about how these aerosols and the clouds affect climate. The aerosols themselves - they're just tiny particles - they can affect how radiation from the Sun is reflected back out to space, so they can kind of themselves reflect light back out. Also by forming clouds, clouds can, you know, reflect light out as well, and so they can influence climate. They can work different ways, but they can influence climate as well.
Alok Jha: And so is this news exciting if you're a climate sceptic?
Ian Sample: Well the reason the climate sceptics have jumped on this was really the second part of the study which looked at what happened when you simulate cosmic rays going through different parts of the atmosphere, and with this cloud chamber you can simulate really high up and cold and rarefied parts of the atmosphere, and the lower down ones where there's higher temperatures and there's also far more gases to play with.
Now, what the study found was, at the higher altitudes and the cold rarefied parts of the atmosphere, cosmic rays were increasing the nucleation of very small aerosols between two - and tenfold. Now that can be - what the experiment doesn't go on to say is - didn't look at - was whether those particles grew big enough to seed clouds. And they're also in a kind of a part of the atmosphere where you don't really get cloud formation - they're too high up, so you'd normally expect these things to happen lower down, but the climate sceptics have jumped on it and said: "Aha! So cosmic rays cause clouds to form, basically", which is a longstanding argument from climate sceptics, and if it does, then you can tie this back into how the Sun's activity affects cloud cover, and so affects climate change.
Alok Jha: So climate change is not anthropogenic, proved by CERN.
Ian Sample: Yeah, and so there are people out there who say this is entirely, you know that climate change and warming is entirely down to fluctuations in the Sun's activity, which affects how many cosmic rays basically reach Earth.