A year or two ago I decided to become a global warming agnostic, because I realized I wasn't able to separate the facts from what I wanted to believe, which was and still is that the science isn't in so don't worry. Since then I've tried to have no strong opinions myself, but instead listen to what people on both sides have to say, note what makes sense, and what doesn't. It's amazing how easier it is to think clearly when you have no ideological commitments to consider. Like listening to music without ear plugs.
I've decided it's time to come down off the fence now.
Are we humans the cause of global warming? Before I try to answer that, let's get a few distractions out of the way. They occupy the attention of some otherwise very bright people, but are not relevant to the question of man-made global warming.
It's irrelevant that some environmentalists, celebrities and other people who believe that we're warming the planet are hypocrites, evil, or in some way behave short of the carbon-neutral ideal. For instance, when scientists travel by plane to a climate science conference, that does not mean that they don't believe their own theories. When celebrities with private jet planes take part in climate awareness events, that does not make the message they're supporting wrong. I wish I didn't have to say this, because it should be obvious, but to a lot of people there's no difference between flaws in a theory, and flaws in the people who believe in it.
It is irrelevant that you think capitalism is evil, that you see a beauty and a harmony in nature that is superior to anything humans can create, and that you think technology takes us away from who we are. It is just irrelevant that you think capitalism is good, that you see beauty and harmony in an unregulated economy, and that you think technology gives us the freedom to be ourselves. And it is irrelevant that some people who disagree with you believe some of these things. It has nothing to do with climate science.
It is irrelevant that many people who talk about global warming misunderstand it, or distort it, or lie about it. It is irrelevant that many people who believe it is a problem, or that it isn't, do this for entirely the wrong reasons.
There's only one thing that matters, and that is the science of global warming. Not the people who debate it, not your beliefs or esthetics, just the science. That science has a life seperate from the public sphere. Imagine a wall: on one side you have real scientists doing real science, on the other you have amateurs, pundits, activists and politicians. Ignore that side. That's where you go to make things happen, but not to learn how things are.
Back on the side of science, we have to think carefully about what it is we're after, so we don't trick ourselves. The global warming debate has inspired a lot of amateur skepticism. People who normally believe firmly in the authority of science, now find themselves propelled by ideology to experiment with skepticism. Being new to it, they clumsily stumble over the ancient question "can we really know anything for certain at all?" Of course we can't. The closer you look at any advanced field of science, the more holes and uncertainties you find. You'll find dissenters, technical shortcomings, all kinds of excuses that, selectively applied, lets you reject theories you don't like, and believe in the ones you do like.
You can't use skepticism selectively, you have to be consistent, apply the same criteria to ideas you like as to ideas you don't like. There are three ways to do this. One is to not be skeptical at all, and believe unquestioningly in Science. If scientists say it, it is true, and if sometimes they contradict each other you just listen to whoever shouts loudest, or has the whitest labcoat or whatever. That's actually a good strategy. It's better than being a selective skeptic, (or believing unquestioningly in a religious authority). It's a cheap, low-risk bet, with a moderate payoff.
Another way is to dedicate your life to becoming an expert on some particular issue, so that you can think entirely for yourself. This is a bet with low risks and a very high payoff, but is so expensive that you can only do it for a couple of issues. Typically you do it only with your work.
Then there are those of us who want to form an intelligent opinion, but don't have the time or ability to become an expert. We know that scientists often get things wrong, but we also know that we have to take many things on trust. To do this well we need to be cost-efficient skeptics, who rely more on rules of thumb and general principles than on in-depth understanding. We learn the basics, but only to test the waters, we don't have time to go swimming.
It's from this point of view that I'm considering climate science. Not as someone who thoroughly understands it, but as someone who knows a few things about what a real science ought to be like, and can compare climatology to that standard.
I've concluded that climate scientists - not the activists and celebrities, not governments and organizations, but the scientists - have built a good theory, one that acknowledges the complexity of the subject. I don't think they're any better or worse than scientists in any other field, which means there's bound to be disagreement and corruption and mistakes and petty behavior. I wouldn't be surprised if they've missed something important. But yeah, it's real science, it's smart people "doing one's damnedest with one's mind, no holds barred". That probably applies to many skeptics as well, but the fact that they're a minority tells me something, it tells me that as a layman my best bet is on the majority.
Again, I'm not saying that I understand climate theory, I'm not qualified to. I'm saying that A) it is a real science, and B) that there is a majority view. Therefore we laypeople should accept it. If climate science is a pseudo-science dictated by politicians and activists, or if there is significant disagreement within the field, we shouldn't. But from what I can see that's not the case. Some argue that climatology can't be real science, because the only experiments it does are in computer models. I don't agree with that. Done carefully, science may also be the study of a non-resettable, uncontrolled complex system in real time. Far more difficult, yes, but still science. Or, by any other label, still valuable.
I didn't fully make up my mind on global warming until I saw the Channel 4 skeptical documentary The Great Global Warming Swindle, and followed the debate about it. Watching it gave me a hope that my old skeptic view might be right after all, (I really want to believe this). That hope was quickly snuffed out. The contrast between the two sides made me embarassed on behalf of the skeptics. Compare the slick style and clever editing of Martin Durkin's documentary with this dull and pedantic rebuttal from Chris Merchant at Edinburg University. It illustrates everything I hate about polemical documentaries, and everything I love about science. Cautious, boring, smart, glorious science.
At one point in the documentary, Durkin shows a clip from An Inconvenient Truth where Al Gore displays the correlation between CO2 and temperature over several hundred thousand years. What Gore doesn't tell you is that temperature actually begins to rise before CO2 levels do. Durkin uses this to prove that CO2 doesn't cause the temperature to rise. But nobody claims that there is a simple relationship here, there is a feedback loop involved. Higher temperatures causes more CO2 to be released, which causes higher temperatures. If you look at the theory, you see there's no problem here. That theory may incorrect, but Durkin isn't saying that, he merely misrepresents it, not unlike a creationist saying that evolution is purely random so it can't be a creative force.
Durkin claims that solar activity is a better explanation for global warming than CO2. In the graph he shows there seems to be a correlation, but only because his dataset ends around 1980. Durkin also points out that humans contribute only a small portion of the world's carbon emissions, which is true, but our contribution is cumulative, disrupting an existing balance. Again, misrepresentation, not scientific counterarguments. Why would he do these things? Listen to his explanation, judge for yourself. Data distortion, cherry-picked evidence, and, oh, quotes out of context. Is this beginning to sound familiar?
I actually first saw An Inconvenient Truth after writing most of this post, and I didn't particularly like it. Too emotional, too little science. I want technical details. I don't want to have something fascinating like a CO2-temperature feedback loop covered up with an "it's actually very complicated", as Al Gore does, I want to hear the juicy details. The details that go over my head still give me an idea of the nature of what I don't understand, the approach scientists use and the level of uncertainty involved. This allows me to apply those rules of thumb and general principles I mentioned. I described some of these principles earlier in a post about conspiracy-like worldviews, and now that I've had time to watch climate skeptics from an agnostic point of view for a while, I detect some of the warning smells I wrote about then. When something like The Great Global Warming Swindle manages to fall so flat on its face, and is still held up as a definitive refutation of climatology throughout the climate-skeptical punditsphere, that's a very bad smell.
For an example of good smells, the kind I'm looking for, listen to this technical and unemotional lecture series on climate change by Richard Wolfson at Middlebury College. Or read the Real Climate blog. Compare this with this. Maybe there are better cases to be made for the skeptic point of view, (let me know!), but to me the whole field looks pretty pathetic, with a purely ideological appeal. I share that appeal, I instinctively distrust environmentalists, but it just doesn't stand up to scrutiny.
So if global warming is man-made, and we can expect the warming to continue, where does that take us? It doesn't automatically follow that we have to do anything. Figuring out that we're warming the earth is a lot easier than predicting what effect this will have on the overall climate. And even if we conclude that global warming will cause damage, that doesn't mean the price of stopping it is worth paying. There might be other, more important problems we should focus on today. Unpredictable technological advances over the next century might do more to solve the problem than any government intervention.
This is where I go from having a strong opinion to a weak one. I'm not sure what we should do about global warming. On that question, I remain an agnostic. We should do something, but I don't know what. I want to hear your ideas, I'm not ready to form my own. But in looking for the answer, there are a few things I think we should keep in mind.
First, there is no safety net. I touched a bit on this when I wrote about black swans. The story we've created about ourselves and our place on this planet - as its highest achievement and natural rulers - is a comfortable lie. The idea of major catastrophes or hardships caused by climate change seems strange and remote only because we, in the mere heartbeat of Earth's history we can remember, haven't experienced any. But there is no justice in the universe. You screw up, then you die.
At the same time, the idea of a planetary doomsday also seems in a way comfortable and familiar to us, precisely because it's a good story. The climate predictions that are most likely to reach you, the news consumer, after having passed through filter after filter after filter, are the predictions that make the best stories. Usually horror ones. Take that as another reason not to listen to non-scientists. Reality ignores all our stories, and plays by its own rules. That's why we need science.
Third, even though we shouldn't trust specific climate projections too much, particularly the ones that make it through the media filters, it seems reasonable to me to be very concerned. When you mess with a system you don't understand, one that involves enormous forces and intertwines with the basis of life for every single one of us, the resulting change is probably for the worse. Maybe not catastrophically worse, but enough so that unpredictable climate change is not something you want to happen. You want things to stay the same, because you're very small and the earth is very big and what you already have is something you've learned to live with. It's not just that the phase space of possible climates is vastly bigger than that of comfortable ones. Even change within the comfort zone requires costly adaptation, can cause loss of life, political instability, etc. Climate change is inherently undesirable.
It also seems to me that, while it is impossible to predict the climate of 2050, you can still establish a relationship between, say, higher temperatures and stronger hurricanes, or other weather extremities, and use that to say something about what we may expect. All predictions are not equally speculative.
At a minimum, we should embrace any cheap optimizations we can find. If there is a way for us individually, or society as a whole, to reduce carbon emissions at little cost or annoyance, we should take it. One such cheap optimization might be nuclear power. We have it, it works, and it's both safer than its reputation, and cleaner than the current alternatives. Another might be to simply not waste electricity in your home. Or use more energy efficient technologies. While it may be somewhat expensive to invent or invest in those technologies, that efficiency might soon pay for itself. Cheap optimizations like these are no-brainers, and I'm sure there must be many of them.
Expensive measures, for instance ones that reduce emissions at the cost of less fuel efficiency, or that require massive regulation, are harder to justify, (by which I mean precisely that, and not that I'm against them.) Any effort spent reducing carbon emissions is effort not spent elsewhere. Is carbon offsets really the worthiest cause for you to spend money on? Does the cost of regulation justify the effect on the climate? We should be careful of the Lollilove factor, the tendency of well-off people to to embrace charitable causes that make them feel good about themselves, but do little good for anyone else. We who live in the world's wealthiest countries live in bubbles of dream reality, where the scale and nature of the world's problems are reflected only by accident. The fact that global warming has penetrated these bubbles does not mean that it is more important than the problems we don't notice.
On the other hand, ranking problems objectively in this way leaves out an important factor: The ability of people to care. If problems #1-7 are too remote or boring to capture our sympathy, and #8 is the greatest tearjerker since Titanic, that doesn't mean we should discourage people from caring about #8 - it might be that or nothing at all. Also, while environmentalism shouldn't be about guilt reduction, feeling good about something you've done for the environment doesn't make it misguided. So, no, I'm not against expensive measures, I just want to thoroughly understand them and their consequences first.
I'll remain undecided on what to do for a while longer, and very much open for sane ideas. But as for global warming, it is happening, it is caused by human activity, it is a serious problem, and we should do something to slow it down.