I believe that climate change is happening and that humans are mainly responsible because of greenhouse gases (GHGs) we're putting into the atmosphere. But the number of people who believe this has been going down, it seems - in the US, 20% less think the planet's warming than did so two years ago. (And that's before you've asked them whether they think it's natural variation.) Concern about climate change has, unsurprisingly, been affected by the economy, as the HSBC climate confidence monitor shows. (Opens PDF.) In this survey, people in the UK are the least concerned citizens anywhere in the world; we're second only to the US in thinking there are higher priorities for public spending - odd when you consider the level of state welfare we already have compared to other countries surveyed. There may be high scientific consensus - not so in public opinion.

Why the shifts in opinion? And does it matter? Yes, it really does. Copenhagen will come and go, and people will still be stuck in their respective bunkers arguing what they always argued, avoiding the issue altogether and hoping it will just go away - or still making up their minds. 20% change in two years: people's opinions on this are quite elastic, it seems.

Every one of us is going to play a role, however small, in how things look a hundred years from now. The one thing pretty much everyone agrees on is that governments cannot - or should not - be expected to attack the problem alone. We all have a part to play. But there seems to be a problem: what action or inaction one chooses could lead to two entirely opposing outcomes, depending on who you believe. If you argue that GHGs don't matter (or some variant, e.g. that they're relatively unimportant), you may be helping to make the Earth a much less hospitable place for humans to live in - so much so, that if left unchecked, societies might unravel. If you argue we need to reduce GHGs, some say you'll be contributing to 'measures so destructive that even if only half of them were implemented, they would take us back to the dark ages'. For either choice, catastrope is prophesied.

The run-up to Copenhagen is heating these arguments up. Here in York, the student branch of the Freedom Association hosted a 'climate week'. I only made it to the 'science' session, but it fitted with the Association's stated aim of 'challenging climate alarmism'. David Bellamy was there telling the story - first made popular by US energy and coal producers - that co2 is a natural fertiliser and putting less of it in the air will hurt poor farmers. Coal man Richard Courtney was there, doing that peculiar but common thing of arguing several different positions at the same time: global warming isn't happening, and it doesn't matter if it is, and if it's bad we can just put sulphur back into airplane fuel.

And on what basis can I argue with them? On the face of it, anyone who isn't a climate scientist must choose which scientist's opinion they will defer to. You can, in fact, make an appeal to authority to support whatever position you want, since the full range is available from scientists themselves. The fact that a vast majority support AGW (anthropogenic global warming) just underscores this point: majorities aren't always right. "If mankind minus one were of one opinion, then mankind is no more justified…" etc.

But I don't like this appeal to authority at all. I heard it again at the Freedom Association event: "I'm not a scientist, so I must defer..." Rubbish. It's absolutely true that no-one can grasp every facet of the science. This is, of course, just as true for climate scientists as anyone else, since the range of relevant fields is so vast. But we have more than just a binary choice between "being a scientist" or "appealing to scientists' authority." This really struck home listening to those putting the case for AGW last week - two undergraduates gamely talking about their own specific issue, and a barrister who's evidence mainly consisted of "I remember it being colder in London."

Bellamy had a graph. Well, he had many, many graphs - but one sticks in my mind: the IPCC projections pointing to a rise in global temperature, and Bellamy's trendline pointing at a jaunty angle down at the floor. I don't know if the lack of effective response in this session was due to the student FA failing to invite actual climate scientists, or whether climate scientists refused to speak. There were certainly some in the audience. What I do know is that all of the anti-AGW speakers used common arguments that anyone half-prepared should have been able to have a go at countering. A thirty second lesson in trends perhaps: on the day of the talk, it was unusually warm. Are we to conclude that Spring is coming? Would it be fine to have a graph with an arrow pointing to the sky to make this point?

Such arguments would be unlikely to sway the opinion of some of the most vocal anti-AGWers present that evening, who I saw clutching 'While the Earth Endures' ("God, not man, is in charge of the climate, he proves to his own satisfaction by appeal to scripture.") But for anyone unfamiliar with the arguments, they might see the BBC telling us we're cooling or the Mail questioning the basic science or, more recently, that climate change theory is 'starting to shatter'.

There are often appeals to scientific common sense: Christopher Brooker (the Telegraph 'dark ages' man) says: 'more than ever, it is a matter of the highest priority that we should know whether or not the assumptions on which the politicians base their proposals are founded on properly sound science.' Seemingly reasonable appeals to skepticism, reason, 'free enquiry' and falsification are heard. As York FA's chair says, 'it is vital that the science be liberal, objective and untainted by political pressure.'

I absolutely agree. It's why I'm writing about this at all. For any person equipped with some logic and an open mind, with a little perseverence and a willingness to make mistakes along the way, many of the ideas that make up the corpus of climate change science can be learned. Along the way, one can pick up enough about the scientific method itself to gain the ability to tell cuckoo science from the real thing.

Or so I'm hoping, because I have a lot to learn myself. As I said before, I believe climate change is happening and we're the primary cause. There are a lot of things I'm unsure about. The role of models, for example: what do we actually know about boundary conditions of the climate system? We know winter is coming because the system is bounded by the angle of the Earth to the sun as a year passes - so we know not to confuse today being warmer with the approach of Spring or a wet summer with global cooling. How does it work with the climate as a whole? I also don't know how I'd satisfy myself about something as fundamental as the relative role of co2 in radiative forcing. Despite that, I believe that if I want to find out, and talk to some scientists along the way, I'm not going to discover that climate change isn't happening, or isn't a problem, or doesn't matter anyway.

I could be proved wrong. But my forays thus far into the world of climate science 'skepticism' have not been very promising. Much anti-AGW stuff picks up one piece of the science, finds some reason it's questionable and then dismisses the entire theory. Here's a recent example, discussed at Devil's Kitchen, questioning the idea of the greenhouse effect itself, falsifying the whole thing with one equation they consider plausible. (Hat tip to Danny W.)

It's easy to see how one gets from this to the idea of a global warming ideology that silences its critics, as Stanley Trimble claims. (Opens PDF from the Cato Institute.) Here I am, doing the same: apparently claiming that opposing views are not real science. The Telegraph, the Freedom Association, CATO etc claim they're true defenders of scientific skepticism - dissenting voices cannot, should not be silenced. At the same time, such arguments often attack scientists themselves; just this morning, Tim Lambert writes of one such attack. They come in many forms: science is an ideology (Trimble) / 'just another special interest lobby group' (Monckton) / just a bunch of fraudsters / 'incestuous groupings of friends and associates' (Tom Fuller) / climate change is one MASSIVE lie (James Delingpole).

Quite a set of accusations. Of course, it could be true that the entire scientific establishment is some sort of masonic lodge, and the only people doing real science are on the outside. But I think science itself offers tools for answering that question. Philosophy of science 101 talks about the demarcation problem. It would be easy enough to step back from the issue itself and to spend as many years as one liked discussing the philosophical niceties of this, but right now, to steal a Zapatista phrase, we need to 'walk asking'. So there's another demarcation problem I want to talk about: sorting skeptics from deniers. This will help work out whether attacks on science itself are justified. The scientific method has skepticism built in. That's the point of it, its reason for being, its oxygen. I'll come back to that in a moment. Here's an example of a waverer at the 'Letters from a Tory' blog taken from the top ten of TotalPolitics top 100 conservative blogs, discussed at Next Left (where they wonder why all ten oppose AGW.) They emailed him/her to clarify what he thought and got this reply:

This might sound strange, given my opinionated blogging, but I honestly have no idea what the hell is going on with climate change. You get the official line of '50 days to save the world' or whatever, and then you get the 'we've now got global cooling, everything's fine, the evidence is all rubbish and full of lies' side of the debate - and I have no idea what to make of it all. There are just so many opinions, so many sources of evidence, so many accusations, so many claims, so many politicians with their own agendas, so many pressure groups with their own agendas, so many cynical bloggers, so many climate change 'deniers', so many critics on both sides that I just don't know what to make of this issue. I just feel that it's not worth having an opinion on climate change unless you spend months looking at this stuff and genuinely listening to both sides, and I just don't have the time or the resources to do that nor have I come across anyone who seems to have already achieved this.

(Hat tip: Ben Goldacre.)

If that's sincerely meant, I have a great deal of sympathy. Indeed, it takes us back to the central question of this post: how is the non-scientist supposed to come to any sort of conclusion? I'm arguing here that, even for a beginner, the scientific method offers a route to a place where we can actually say, beyond reasonable doubt, which things are pretty much certain, which things aren't, and by how much. It will also allow you to know when someone else has been using those methods.

But then how to demarcate the waverer from the denier? I've tried to find a better word - suggestions gratefully received - since it would be nice to be able to avoid the retort, 'so you're equating me with a holocaust denier?' No, if I'm going to argue you're a climate change denier, it's because I think you're doing two things: being unscientific, and being willfully, noisily unscientific in a way designed to make it harder for - say - the conservative blogger above to reach their own conclusions. In effect, I'm reserving 'denier' for anyone engaging in FUD. Obviously, the line must be pretty blurry - one might accuse Letters from a Tory of willfully avoiding engaging with the science. That isn't fair, though - since cases of blatant denier tactics are so prevalent, there's plenty of scope for giving other people the benefit of the doubt.

This demarcation is important. I've said that the scientific method has skepticism built in. Considering it for a moment as a social technology for producing knowledge, how does that work? In fact, does it work? At root, there must be an element of trust (otherwise why let a heart surgeon operate on you rather than a close friend with a scalpel, some boiling water and access to Google?) But that needn't be built on blind trust. There should be a transparent route to checking for yourself, and people who've been along that route you can talk to. Those who make accusations of fraud or ideological manipulation should not, conversely, go unchallenged if they cloak themselves in scientific skepticism, when what they're doing is merely attacking scientists.

It's a big ask. The chair of York's Freedom Association quotes Popper:

The history of science, like the history of all human ideas, is a history of irresponsible dreams, of obstinacy, and of error. But science is one of the very few human activities - perhaps the only one - in which errors are systematically criticized and fairly often, in time, corrected. This is why we can say that, in science, we often learn from our mistakes, and why we can speak clearly and sensibly about making progress there.

Nicely put: the sometimes messy, but nevertheless incremental, progress of science. Yet the Freedom Association et al wrongly use this to argue the science of climate change isn't certain enough. Well, I could be wrong - perhaps they've examined all the evidence and concluded the uncertainties are too strong. But how does the non-scientist sort the certainties from the uncertainties? In my ideal world, you'd be able to regularly wander into your local university or school, and check whether co2 does in fact have a radiative forcing effect. (Opens a school-kids dad-supported experiment.) There'd be simple examples to work through for understanding trends. Temperature data points would all have RSS feeds. There would be a clear learning path to help you understand why Monckton's arguments about chaos theory are red herrings. There would be accessible ways to learn how climate modellers use probability distributions. You'd learn when not to be beaten over the head with science, to step back and ask what issues are actually being examined, what hypotheses are being proposed.

I worry this is not an attitude we cultivate much. The apparent hounding out of Professor Michael Reiss last year for 'encouraging an analysis of the evidence' on creationism points to a rather hammer-like approach to scientific learning. Of course, he could have been doing what I'm implying many climate change opposers do - using scientific method as a back door for their own agenda. But it doesn't appear that's the case here; I have trouble understanding how it could have been 'in the best interests' of the Royal Society for him to step down. If you have no critical reason to decide between creationism or evolution, you have only your teacher's word for it. I think (entirely unscientifically!) that the lack of effective response to Bellamy, Courtney et al reflects this: believing the science because you're told to leaves you entirely exposed when anyone disagrees. You'll have only "I defer to scientists…" left. There may be good reasons for deferring to scientists, but maybe you need to have engaged with those reasons before the "I defer" argument really can really have any weight.

That Freedom Association climate piece above - whilst lauding Popper and falsification - also says:

By appointing a group of scientists to find evidence of something, the patron of this group will always receive reward; just as a different patron who demands his own scientists disprove this conclusion will similarly receive reward. Thus the danger of climate change science is that there is only one patron.

The cynical implication is that you pay for the answer you want; I'm not entirely sure how the writer squares this with their defence of the scientific method. If you can buy whatever conclusion you require, what do you need science for? It would not avail you, whether government-funded scientist or curious layperson. I suspect the 'one patron' they refer to is the state; it is a common right-of-centre view that the whole thing is a taxgrab, or possibly a plot to instigate a World Communist Government. On the other hand, am I claiming that science is somehow immune from the forces of hegemony? Well - I defer to Sokal quoting Alan Ryan:

The minority view was always that power could be undermined by truth ... Once you read Foucault as saying that truth is simply an effect of power, you've had it. ... But American departments of literature, history and sociology contain large numbers of self-described leftists who have confused radical doubts about objectivity with political radicalism, and are in a mess.

There seem to be a growing group of people doing the same with climate change. Often - as above - the scientific highground is claimed, while in the same breath scientists are derided as shills at best and lying conspirators at worst. I can happily put this sort of thing in the 'denier tactic' box - you cannot argue two contradictory things at the same time and still pretend you're making a sensible argument.

I'm not diving much into the science today, but I do want to ask: what to make of claims that 'there is too much uncertainty to warrant action?' Again, those using arguments about uncertainty often slip into attacks on scientists themselves, as with the 'hockey stick', despite it seeming to be a complete red herring. (That'll have to be a post to itself.) There is uncertainty. But generally - as with the Mail above - skeptic attacks fail to acknowledge that, as Brad Delong puts it, 'uncertainty usually has two tails, not just one.' Consider that, if this graphic is correct, that tail stretches way out past a lot of reporting and that the IPCC itself is conservative (despite claims of the opposite.) (Graphic via this yoof presentation.)

That means having to work out what's beyond reasonable doubt and what things we still don't know. The uncertainties themselves do not mean the entire AGW theory is falsified. For myself, I feel like I have a lot to learn yet before I can tell what that landscape looks like in detail. We won't get anywhere with this proben, though, if scientific attacks blur with attacks on scientists, or if we select those theories that suit us.

But does uncertainty blur the distinction between science and political action? A prominent climate change opposer, Pielke Jr, chose James Scott's Seeing Like a State as his must read for Copenhagen. He says:

The painful truth is that no one knows how to decarbonize the global economy. Unrealistic commitments to targets and timetables for emissions reductions under an ever more complex superstructure of international bureaucracy cannot succeed. This is more than common sense - it's a lesson of history.

Pielke is making argument (e) from RealClimate's list of (often simultaneously argued) 'contrarians convincing case' points: 'well, it might actually be really bad, but hey, its unstoppable anyway.' Seeing Like a State is sort of my PhD bible, so it's quite a thing it appearing on this list. If we take a stab at Hayek's view, one might imagine he'd say:

OK, so climate change is bad. Which would you rather live in - a rather more inhospitable world, where there's a risk of some damage to human institutions, some mass migration, some effect on wildlife, all with an element of uncertainty - or in a clement-weather fascist dictatorship?

I often wonder, as do others, why right-of-centre thinkers tend to opposed AGW. Easy answers abound, and must be true for some: cognitive dissonance, the occasional industry shill. But the above guess at Hayek's view suggests an answer: perhaps there's a weighing up of the risks, and right-wing thinkers give much more weight to Hayekian-type fears. The economist in me wants to believe this: it would mean people are implicitly being rational, and attempting to weigh probabilities. However, there are few such thinkers who seem to stick to their political guns. Attacks on science almost always follow close behind (supporting the cognitive dissonance theory.) Pielke does this: citing Scott whilst simultaneously fighting on the opposer's side in the hockey stick wars. Isn't his radical doubt about state action enough for him?

Thought experiment: a huge asteroid is hurtling towards Earth. Scientists have two models: 50% say it will hit us slap bang in the Atlantic Ocean. The other half gives us a near-miss. (Maybe 50% are die-hard Newtonians.) How do we decide what to do?

Hah - climate change is almost nothing like this. As with this recent synthesis in Nature (PDF) for example, the science is, pretty much, never so black and white. But it's a useful thought experiment: if we faced such a stark global choice, what criteria should inform our decision? How do those criteria change as risks become more probabilistic?

Scientists now tell us the asteroid has split into a hundred pieces. The question then becomes: are any pieces of a threatening size likely to hit us? How many, and how bad is the damage likely to be? For the two different theories, there's now a probability distribution made up of hurtling rocks. This is much closer to the problem we actually face, and it draws attention to the fact that, for each possible answer, there may be any number of possible actions that could be taken. It also illustrates that many theories may produce a range of uncertain futures.

It's a trivial truth that some scientific findings have no consequences for immediate action; the search for exoplanets springs to mind. What I've been arguing for here is this: it's possible to do exoplanet science in the same way as climate science. The fact that action may be implied should have no impact on that work. As Schneider points out, of course, in reality it's not quite that easy. Maybe I should rephrase: it is possible, but its hard work to make it so. This week's outcry over the sacking of David Nutt is comforting in that regard. A quick google for "david nutt" "climate change" reveals a few commenters concluding the opposite: the government should sack 'climate charlatans' as well. It would appear to imply the opposite: the scientific community is keen to see a boundary maintained. It may well be the government has a pick n mix attitude to scientific advice, but it hardly supports the argument that - for example - IPCC scientists are doing State Power's bidding.

(Update: didn't take the Daily Mail long to print the Nutt-AGW comparison - "Global warming may or may not be a certainty, but anyone who queries it has his sanity questioned." And look, comparisons to totalitarianism. Hat tip: Tom Stafford)

There has yet to be a settlement between science and politics akin to the separation of legislature and judiciary, but guarding that separation is incredibly important and entirely possible. This shouldn't require scientists be automatons: no-one would consider a career in medicine if they had to sign a contract declaring themselves uninterested in human welfare. In fact, quite the reverse: doctors sign a Hippocratic oath. That doesn't make them incapable of practicing good science.

But how to do that hard politics/science disentangling work? Take Galton's eugenics as an extreme example - there have been some horrendous overlaps of 'common sense' and scientific practice in the past, mostly when applied to human beings . Indeed, one of the original aims of my PhD was to call out theories that used science as a figleaf. One essay I wrote changed my views on all this. I wondered how David Icke's theory that the world is being run by 12 foot Annanuki lizards would stand up next to some other political theories. I was shocked to discover that, scientifically speaking, I had no more reason to believe a number of theories I'd had some sympathy with than the idea the world was controlled by shape-shifting alien reptiles. I don't think this means we should all only believe falsifiable political theories. But it did make me fully realise that any knowledge we have gained through scientific work is precious, and that it's an incredibly powerful tool for whittling down the extent of our ignorance about the world.

I'm aware I've been arguing fairly unreflectively for 'this thing called science.' In fact I've used the word so much I'm getting a bit of semantic satiety. Arguments about the philosophy of science are useful, but there's so much pseudoscientific low-hanging fruit to be harvested that too much chin-stroking is hardly necessary. There are very few people left in 'elite circles' who still question AGW - and it seems there are less all the time. But things may turn around - especially as people's pockets are further hit. If the state may only play a small role, it's imperative as many people as possible know that they can check on the science themselves - if they choose to.

I don't know if this faith in science is misplaced - Al Gore certainly seems to believe in appealing to people in other ways. I'm certainly not against other approaches - indeed I have a large place in my heart for other modes of knowledge and action. But science and scientists made us aware of this problem in the first place, and its still the only game in town for anyone genuinely wanting to find out if it's real, and how bad things are. I don't think that option is as open to people as it should be. Some would argue the science is certain enough - all this is backtracking, muddying the waters. We should just call deniers deniers and concentrate on the gargantuan problem we face. (Watch those percentages go!) I disagree. Skeptics and deniers alike should be taken up on their offer of a reasonable, open-minded look at the science, and it should be open to anyone who wants to take part. Everyone should know that - if they want to walk it - there's a clear route, and a set of tools to help them along the way.