Thinking about climate change

Wednesday 23rd November 2011

Climate change is a significant topic that affects the lives of pretty much every living human. As such, discussions about the subject can often get quite heated, with two distinct camps. One side says that climate change is caused by carbon dioxide emissions, and that the consequences for humanity will be absolutely dire. The other side seems to claim that the climate isn’t changing, or that the other side are making things up. To stoke up their claims both sides resort to bad science, misrepresentation of good science, and lots of good old ad hominem attacks. Here are a few things which we know to be true, at least as far as we can be sure about these things:

  1. Climate is changing. It always has, it always will.
  2. Global temperatures have risen.
  3. CO2 levels in the atmosphere have risen in the last circa 200 years, driven by industrialisation.
  4. CO2 is a greenhouse gas. Its presence in the atmosphere does have a warming effect (we’re dependant upon this for our survival!)

Sensible discussion of the topic has to start from at least these facts, as they represent the state of our current knowledge. It is ridiculous to claim that any of these 4 are untrue, because as far as we know all the evidence suggests that they’re not. But equally, sensible discussion of this topic cannot simply stop here. Because these facts raise some questions which need to be answered before we can devise any meaningful response to this issue:

  1. To what extent does CO2 cause changes in temperature? If there is x amount of CO2 added to the atmosphere, what is the corresponding change in temperature?
  2. To what extent is this a problem? What is the cost of doing nothing to stop climate change?
  3. If we can find ways to reduce/stop CO2 emission, what are the costs of doing so?

To think about those three questions, I’ll break them down into the appropriate subject areas. Question 1 is about the science, about working out what’s happening with the climate. Question 2 is about how we can deal with the effects of climate change and the cost of doing so, and so is really about engineering. And the heart of the third question is about reducing the reliance on energy sources which cause CO2 to be emitted (as energy use is the principal cause of CO2 emissions).


When we’re talking about climate, we’re talking about a huge, chaotic system. To start to understand how it works, we’re talking about modelling the flow of fluids (namely water and air) across the entirety of the Earth’s surface, taking into account countless different variables and the way they interact with each other. This is really hard to do, at least with any accuracy. And it’s really hard to look at such a system and to derive the effect that one particular variable has (namely CO2 concentration). So to come back to the first question I posed. Do we know the extent to which CO2 causes warming? No, we don’t. We can run all kinds of models to find some sort of estimate, yes, but finding out whether that model is accurate is not a trivial problem.

There’s lots of confusion about this, it seems. One side of the climate debate tries to make out that climate change is caused by anything but the activities of mankind, whilst the other is pretty set on the idea that it’s all down to CO2. Both sides vilify the other, and that doesn’t really make any sense. We can’t yet say – with any certainty – what effect the CO2 generated by our activities is having on the environment; but CO2 is a greenhouse gas, so it really isn’t a leap to say it’s having some effect.

A good example of this problem can be found when we examine the temperature change over the last decade, and compare it with the change in CO2 concentration in the atmosphere:

Temperature data are global averages from the HadCRUT3 dataset of temperature records. CO2 concentrations recorded at Mauna Loa Observatory, Hawaii.

The basic theory is that CO2 is causing mean temperatures to increase, and yet looking at the above graph, it’s rather hard to find such a relationship. HadCRUT and BEST both show that there has been no warming in the last decade (in fact, the HadCRUT data used here show that mean temperatures have decreased very slightly), even though CO2 concentration has steadily increased. More than likely, we can’t draw too many conclusions from this; 10 years is quite a small period of time when discussing climatic events which take place over a significantly longer amount of time. But at the very least, it causes us to question the claims about the significance of CO2. Because if CO2 really is as dangerous as we’re told, has such a dominant effect that we need to make drastic steps to reduce the amount we emit, we really should have seen accelerated warming in this period.

Now, for the sake of clarity, I am most definitely not saying that CO2 does not cause warming at all; simply that we haven’t properly quantified the warming effect that’s caused by our CO2 emissions. And that, whilst the temperature rose during the 20th century, we probably don’t know the whole story of why that happened; most likely it’s been caused by a number of things, and human activity could be a large or a small component (for instance, we know that solar activity has increased during the last few decades). Climate is variable, it always has been and it always will be, and so there isn’t a steady baseline to make comparisons from. We can’t say that CO2 and temperature have both risen, therefore increased CO2 has caused the temperature rise; it simply isn’t that straightforward. And it’s rather foolish to dedicate lots of resources to the cessation of CO2 emission, when we don’t know whether that really is causing unnatural climate change.


So. For the sake of argument, let’s ignore everything I’ve just said. Let’s make the assumption that CO2 is driving climate change, and that if we continue to pump it into the atmosphere it’ll cause a global temperature rise that will cause the environment to change. How could we deal with that?

Fundamentally, this is a problem about the maintenance of the natural and built environment. That’s not a new issue, we’ve been doing this for millennia, and engineers have been doing it using a scientifically rigorous approach for centuries. It’s what Civil Engineering is all about, and we’ve gotten pretty good at it by now. So, let’s look at one particular issue that is likely to be a problem, should global temperatures continue to rise: higher sea levels.

The first step in solving an engineering problem is to work out what exactly the problem is, so we’ve got to find out how much the sea is likely to rise. At the moment, the consensus seems to be that the sea level will rise between 75cm and 2m in the next 100 years. It’s quite hard to visualise what that looks like, what that really means for us. Happily it’s quite easy to model this, to see which bits of land will be flooded after a given change in sea level:

Map of British Isles with 2m rise in sea levels. Areas of land which are below the increased sea level are shaded blue. Source:

Not a particularly significant change, actually. The worst-affected area is landlocked anyway, so I guess it might not be encroached by the sea, although flooding may become more likely. But if we really wanted to, these are problems which we can easily solve. If a place is under threat from a 2m sea level rise, then we can build a dyke (or similar) to stop it from being flooded. If flood risk in a region is increased, then there are lots of techniques we can use to deal with that too. Or, in some cases it might be best to simply move away from the areas which are likely to flood, as there’s still plenty of higher land left. None of these approaches should really be that costly, certainly in comparison to some of the alternatives.

These problems can be solved, and in many cases are already being solved. It’s also worth mentioning that on the global scale, climate change might actually cause positive effects in some locations, for example by moderating the climate of places which are currently very cold. And so when we examine these issues to try to think about how to deal with the possible effects of climate change, it quickly becomes apparent that this is something that we know how to do, and that climate change really isn’t the end of the world.


Now let’s go even further with our assumptions by saying that we’ve decided that we should try to reduce the amount of CO2 we emit. The largest cause of anthropogenic CO2 emission is the burning of fossil fuels for energy. Therefore to make a meaningful reduction in emissions, we must use alternative sources of energy as much as possible.

Several countries have agreed to targets to reduce their CO2 emissions, and there are several policies which are in place to try to achieve this. Firstly, there are high taxes on CO2 emission, in order to discourage activities which cause pollution. There are also subsidies available for the production of certain (supposedly) sustainable sources of energy – wind power, solar power, etc. – to encourage people to install these facilities. And to try to make current fuels “greener”, a certain amount of bio-ethanol is blended with petrol and diesel used for transport.

There are problems with this: it’s expensive, and often grossly unfair. Taxes on energy affect everyone; directly in the price we pay for transportation, heating and electricity, and indirectly in the price we pay for goods. You might argue that, well, we’re wealthy, and we can afford it. And we probably can. If we think it’s an acceptable trade-off, then we can probably afford to sacrifice some luxuries, or lose a certain amount of investment – and jobs – even with the current state of the economy. It makes life difficult for ourselves, but not impossible.

Subsidies are less excusable. It’s the classic argument that subsidies distort the market and make it less efficient. Which is a good argument; we want to use alternative sources of energy when it’s actually efficient to do so, not just because we think we should, as that simply makes energy more expensive than it needs to be. This is also deeply unfair, as it benefits those who can afford to invest in “green” energy, at the expense of those who cannot. Frankly, I think it’s inexcusable to drive up energy prices for the majority with a scheme to provide cheap energy to the minority who are wealthy enough to buy into the scheme.

On the subject of unfairness, there’s also a broader point to be made. Firstly, we’re telling poorer parts of the world that they need to not emit CO2, but often the only affordable sources of energy available in such parts of the world are those which cause lots of CO2 to be emitted. So in a way, we’re asking less developed parts of the world to stay undeveloped, to stay poor. Which limits access to things like healthcare and education in those parts of the world, and so undoubtedly causes a huge amount of damage (or rather, it would if they all listened to us).

On top of this, we impose “green” policies which directly cause actual damage. For example, the requirement that fuels be blended with bio-ethanol has had the effect of raising the price of some foods. This increased price has meant that some people simply haven’t been able to afford to eat, which is thought to have caused at least 192,000 extra deaths last year. Some of the poorest people in the world are being starved because we want to burn their food to reduce our CO2 emissions. Whatever your views on climate change, that should make you mad.

What should we do?

The point that I’m trying to make is that our approach to climate change needs to be more intelligent. The science is very complicated, and probably not well-understood enough to be the basis of policy decisions which can have profound effects. We cannot say with confidence that we are the cause of the changes in climate that we observe.

Given this, it seems sensible to have a different approach to dealing with climate change: to analyse the costs and the benefits of the situation, to work out what really is the best course of action.

The cost of doing something about the possible threat of anthropogenic climate change is massive, as it calls for a fundamental change in the way we do things. It calls for us to abandon the sources of energy which allow us to access many of the resources we need to maintain our standard of living, and it calls for us to deny poorer parts of the world the opportunity to grow and develop and improve their basic standard of living. That is a massive cost. Given that the modest things we’ve already done have resulted in hundreds of thousands of deaths, it’s scary to consider the possible cost of doing more.

Additionally, the potential benefits of reducing CO2 to combat climate change are comparatively small. All we’d do is avoid a certain amount of engineering work which would be required to adapt to the changing environment. It’s not clear that we’d save all that much; the built environment will need to be maintained in the coming years regardless of climate change, and so all we’d do is change the parameters of problems that need to be solved anyway. But solving those problems becomes infinitely easier if we maintain our access to cheap, abundant energy.

Fundamentally, it seems to me that our response to the possible threat of anthropogenic climate change is wholly disproportionate. We’re causing more harm than we could ever hope to stop; we’re spending lots of money (and causing lots of deaths) for solutions that might not work, for a problem that probably isn’t that severe. Whatever way you slice it, that isn’t an intelligent trade-off.

Posted at 5:51 am | Posted In: EngineeringPolitics Tagged:



Friday 25th November 2011, 12:44 am

I was actually wondering whether to start commenting on this, because I disagree with you so thoroughly on most of the points here that I actually don’t know where to start.

The thing about people commenting on climate change is that there’s a undertone in a lot of it that climate scientists don’t really know what they’re doing. I can’t really think of another branch of science in which the competence of the people in that field is so regularly brought into question.

Yes, admittedly climate science is tremendously complex. I’ve not studied it myself, so I can’t claim to be anything even approaching an expert, but they have taken an enormous number of effects into account, both positive and negative feedback loops. For instance an increase in global temperatures will lead to an ice melt; so the overall albedo of the planet goes down, and we absorb more radiation. On the other hand, the ocean temperature increasing will cause it to dissolve more CO2 from the atmosphere, and thereby become more acidic. And so on, and so forth ad infinitum.

The only difference I can see between climate science and other branches of science is that the stochastic behaviour of the climate is treated as if it’s some sort of insurmountable barrier which makes their projections nigh-on worthless. This is, naturally, bollocks.

And then, after making the point that climate is complicated, you say:

“if CO2 really is as dangerous as we’re told, has such a dominant effect that we need to make drastic steps to reduce the amount we emit, we really should have seen accelerated warming in this period”

Because naturally, when you change a variable in a complex stochastic system, you expect to see a perfectly linear relationship with some other variable!

The bit about Solar activity is amusing because we actually have really good historical data for that; it’s thought for instance that the Maunder minimum is what caused the Little Ice Age. The Sun also has the wonderful property that on relatively short timescales it behaves incredibly predictably, having approximately 11 year cycles. I’m going to say that it’s reasonable to assume that they’ve corrected for Solar activity.

Coming on to your economic points: I have been wondering of late if you’ve swallowed either a textbook or propaganda, wasn’t really expecting it to be both. Can’t really say I’m a fan of the Austrian school.

Anyway. The point of taxes and subsidies is explicitly to distort the market. That’s what they’re for! It’s not an unintended consequence, it’s the point. The way that you help bootstrap a new set of technologies against something entrenched like the burning of fossil fuels which are already mature and have the benefits of pre-existing infrastructure and economies of scale, is that you artificially make the alternative more competitive. This is the point.

The justification here is twofold.

a) Assuming climate change is going to be a problem (which it probably will be, more frequent extreme weather events, it’s going to be terrible to be Dutch or Bangladeshi…) then the burning of fossil fuels represents an enormous negative externality. It imposes a cost on the rest of society, not just in climate change terms but also air quality. Taxing fossil fuels represents a way of putting a price on that cost.

Will it put people out of work? Yeh, probably, for contorted definitions of “putting people out of work”. Arresting people who smash windows puts glaziers out of work, too.

b) We’re heading straight for a cliff; if anything, we’re jamming our foot down on the accelerator. Even if we assume that the effects of climate change can be mitigated, we still have the problem of the finite nature of fossil fuels. They’re going to run out. I suppose you could argue that the market will come to the rescue; constant demand and dwindling supply will drive up prices, so alternatives will become economic, and the world will be saved! It might also cause an unimaginably severe economic contraction which will make the energy crisises in the 70’s look like a 24/7 party, but at least we’ll be kept warm at night knowing that at least we did right in the eyes of the Austrian school.

Here’s the thing: it’s quite possible that the age of ridiculously high growth on the back of being able to dig up a high-energy-density fluid from the ground is running out. If you’re concerned about growth in the developing world, I’d say the scarier thing is the notion that they’re going to have a hell of a time developing a non-fossil-fuel economy from scratch when oil becomes too expensive for them to buy.

And yeh, the biofuels thing was a fuck-up on an epic scale. We can only hope that doesn’t happen again.

Honestly, all I see in posts like this is an enormous amount of wishful thinking. All the data I’ve seen suggests that we have a really, really big problem; the last projections I saw show that a 2 degree rise in mean global temperatures is essentially inevitable. Any climate change action now is merely a mitigation of that. And then there’s the energy usage curves…


Friday 25th November 2011, 4:07 am

Yeah, I did briefly wonder whether to leave comments off on this one. Glad I left them on.

Here are some thoughts.

1) There is a lot of bad climate science (I’ve read papers where the analysis can be summed up as cum hoc ergo propter hoc, which is pretty shabby). A lot of the use of models is also pretty horrendous (e.g. I’ve heard tales of models being used which haven’t been validated in any way, which is grossly irresponsible). There is good climate science of course, but sadly because it’s less confident than the doom and gloom stuff, it doesn’t have as high a profile (I think a lot of the problem is actually the way science is generally reported, not necessarily the science that is done).

Note that my opinion is not that anthropogenic climate change isn’t a thing; my opinion is that the science is not yet sufficiently advanced for us to be sure enough. But I’m not an expert (although I have at least studied things which are relevant), and so I don’t have a definitive opinion on the subject, because I don’t know enough.

Because of that, I stated quite clearly in the post that my argument rests on the assumption that the science is correct, that climate change is man-made. The focus then is on what we should do about it.

By the way, after making the point that climate is complicated, I used an example to show that climate is complicated. Really, not sure what your point was with that quote… Thought it was quite amusing.

2) “I have been wondering of late if you’ve swallowed either a textbook or propaganda, wasn’t really expecting it to be both. Can’t really say I’m a fan of the Austrian school. Anyway. The point of taxes and subsidies is explicitly to distort the market.”

Several books actually, no propaganda. I think it’s important to learn about something before forming an opinion on it… (I also know what I don’t know; recently I’ve been trying to get my head around monetary policy – in light of the Euro crisis – as I realise that I know close to nothing about it. I digress).

Anyway, I think you’ve missed the point that I was trying to make. The economics I’ve referred to here (and generally when I’ve blogged on the subject) is also pretty uncontroversial, so I’m a bit surprised at the “propaganda” remark from you, although it is quite illuminating.

The point about subsidies distorting the market is that it stops us from properly finding out which technologies are best, from seeing what really works in the real world. Subsidising one form of technology might steal money away from other forms of technology which could work better. Look at how much money is poured into wind power; a technology which probably isn’t actually that useful on any large scale. Money is spent on that technology because of the subsidy, and so diverts investment away from other types of energy technology which might be more useful. We really don’t need a subsidy; distorting the market in this case is a bad idea.

The idea that we need subsidies to move away from entrenched technologies is laughable. History is full of examples of large businesses which ended up failing because the technology they specialised in became obsolete entirely without the help of subsidies (just look at the relative fates of IBM, Microsoft and Apple over the last 30-odd years, as different innovations have shaped the way technology is used). I saw a chart the other day which showed that the average lifespan of companies in one of the stock indices has been steadily dropping over the last few decades. Which suggests that the amount of time that technologies remain dominant is generally reducing as innovation occurs. Not entirely relevant to climate change, but an interesting aside nonetheless.

I note that you didn’t respond to the point that subsidies also drive up the cost of energy up for people who can’t afford to benefit from the subsidy. If we ignore the costs of something, then yeah, that something might superficially look pretty good. Sadly, that’s a poor strategy to follow in the real world.

Taxes are more complicated than subsidies. The role of taxes is not just to distort the market; irrespective of that they are also needed to raise money for the government (duh), and to charge for externalities, which I suppose is actually a method of correcting for a market distortion… That’s all fine, and as it should be. I don’t have a problem with taxes on pollution (and burning fossil fuels should be taxed irrespective of the possible climate change problem), the problem is that energy taxes are currently higher than they need to be to correct for the externalities (according to the IPCC’s calculation of the cost of CO2 emissions). And we can see it’s having an effect, in an economy which is already in dire straits.

The important thing about economics is that the effect of a policy might not be immediately obvious. But it’s critical to look at the bigger picture, to see whether what you’re doing is good or bad. Policy decisions that are fuelled by good intentions, but that only look at supposed benefits and that are ignorant of costs, are not beneficial in the long term.

3) “we still have the problem of the finite nature of fossil fuels[…] I suppose you could argue that the market will come to the rescue; constant demand and dwindling supply will drive up prices, so alternatives will become economic, and the world will be saved!”

Those of us who pay attention to the engineering industry will have noticed that alternatives are becoming economic, as developments in geotechnical engineering and the like mean that we can access more of the fossil fuel that was previously beyond our reach. A great example of this is the development of hydraulic fracturing of rock (which is a remarkably clever process) to allow for the extraction of shale gas. Shale gas is much more abundant than “normal” gas; even with what we’ve already found as a result of previous surveys (when we weren’t actually looking for shale), we’ve got enough in the UK alone for the next 100 years at least.

There have been similar developments in the extraction of deep oil, and there’s also some amazing work being done to bioengineer oil, a process which is obviously CO2-neutral. Point is: we’re probably not gonna run out of energy any time soon, although it might become a little more expensive. There’s been 25 years’ worth of oil left for the last 30 or 40 years…

Finally, and this is the crucial point:

“All the data I’ve seen suggests that we have a really, really big problem; the last projections I saw show that a 2 degree rise in mean global temperatures is essentially inevitable”

Adapting to climate change is fundamentally an engineering problem. Irrespective of my knowledge of climate science or economics, I do know about engineering. And as an engineering issue, dealing with the effects of a 2 degree rise in global temperatures really isn’t a massive problem. In fact compared with the notion of abandoning fossil fuels to stop a possible rise in temperature, it’s almost trivial. It also has the benefit of not killing people and of allowing people to improve their lives, which I’d count as a very good thing indeed (we have a record global population; I really doubt that could be maintained without use of fossil fuels).

My goal in writing this post was to emphasise the point that to think about climate change, as with any complicated issue we need look at the whole picture, to try to recognise the costs and benefits of all the possible courses of action, and to not oversimplify the issue. We need to be pragmatic, and to try to do the thing which best balances costs and benefits to affect the best outcome. So it’s a bit annoying – and a little puzzling – that your comment pretty much completely ignores that argument. Even if you disagree with my conclusion about what I think we should do, then at the very least you could engage with the substance of my argument and think about the whole problem, rather than cherrypicking bits out of context to make a partial argument.

I know about subsidies and taxes and the general justifications for them. My argument is that the justifications ignore the negative effects, and that these outweigh the benefits. If you disagree, then explain why the negative outcomes aren’t important.

I know that, fundamentally, burning fossil fuels for energy is undesirable because it causes pollution and possibly climate change. My argument is that at present, its one of the cheapest forms of energy we have, and that we can use that energy to do good things (like providing food and water; the latter is remarkably energy-intensive) and to combat the possible environmental results of using it. If you disagree, then explain what costs or benefits I’ve missed, that changes the cost-benefit analysis. Explain why mitigation is better than adaptation.

And I also know that there’s loads of research to find better forms of energy, and new technologies which mean we can access more of the sources of energy we presently use, for the foreseeable future. So explain why we need to make drastic changes with massive (probably unprecedented) costs, when that resource is there and available to use. I’d also be interested to hear what you think the most workable alternative is if we’re to stop using fossil fuels; as far as I can see, there isn’t one yet.

TL;DR: Swings and roundabouts. You’ve only looked at the roundabouts :-P

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