You wrote \Carbon dioxide levels at present are humanly speaking at a historical high. And political decisions are made at human time scales, not geological ones. The current climate change, too, is occurring at a time scale that’s much smaller than your typical geological process.\

The rate of climate change is, unlike often claimed, within the range of past occurrences historically speaking (and not geologically speaking this time). Look at the GISS global temperature graph for the 20th century. http://data.giss.nasa.gov/gistemp/graphs/

You will note that the slope of the warming trend from 1910 to 1945 is virtually identical to the slope of the claimed \man made\ trend from 1975 to 2005. It is quite conceivable that we have reached the inflection point of current warming since global temperatures have culminated in 1998 and have plateaued for some 5 years and are now possibly going down if the influence of La Ninas remains. We don’t need humans to cause these rates of temperature changes, nature can do that for us. Besides global temperature fluctuations are more likely to be caused by strengths and frequencies of ocean oscillations like the El Nino Southern Oscillation( ENSO), Pacific Decadal Oscillations (PDO), Atlantic Multidecadal Oscillations (AMO). If a period of say 30 years is dominated by El Ninos and positive PDO’s global temperatures will rise. If La Ninas are dominant then global temperature trends will fall. The oceans are vast repositories of heat and they will control climate more than has been given credit for by the IPCC. A very enlightening and elegant short paper was written recently by Prof. Pielke on this subject in Physics Today: http://www.climatesci.org/publications/pdf/R-334.pdf

Civilizations are (like climate) always subject to change and survive accordingly, like you explained in your second post. I understand that the cumulative costs of all the adaptations to a changed climate could be substantial. You forgot to mention, however, how to account for the cumulative benefits of a warmer climate. But let’s not exaggerate the catastrophic effects of, say a 2 degree, warming in a century. It effectively means in many instances only a zonal shift of average temperature of 200 km in northerly direction in the northern hemisphere. For example, the average temperature in Lille would become the average temperature in Paris at present. Or, Copenhagen would become as warm as Frankfurt. Essentially, the agricultural areas will expand in northerly direction. Agriculture exists over a temperature range of from maximum +40 C to minimum -20 C, or there about. And civilizations adapt to these temperature ranges by choosing the most optimal crops. It is odd that we focus so much on the risk of extinction of polar bears as a consequence of warming, yet the enormous benefits of an ice free arctic sea for humanity should outweigh perceived negative effects on the survival of the polar bears. By the way, they did survive the Holocene, Roman and Medieval warm periods.

As I have alluded to in an earlier post, precaution as a argument for action is the most misused and potentially disastrous principle (e.g. the invasion of Iraq because of the feared presence of weapons of mass destruction). The precautionary action must always be proportional to the severity of the potential danger and conditional to the likelihood of it occurring. However, that’s where the argument becomes victim of subjectivity, since there are always differences of opinion as to what and how big the potential danger is and the likelihood of it occurring. The pros (there are are many) and cons of global warming have never been mapped out and weighed against each other

Hence the precautionary principle is just a hollow term that only serves as a convenient obfuscation through which a subjective opinion obtains a fake aura of legitimacy. The AGW proponents and the majority of environmentalists (I belong to the minority of environmentalists who believe that anthropogenic CO2 happens to be (unintentionally) beneficial for our biosphere) love to use the precautionary principle: it gives them this (unwarranted) pretentious moral superiority over the evil deniers, skeptics, flat-earthers and Big Oil capitalists, to mention a few common ad homs that AGW’ers love to use.

That’s not how I see it. What I’m saying is that if you can not estimate a minimum likeliness, it might as well be 0.000001% and it would be completely irresponsible to waste billions of dollars on it. The only responsible action would be to spend some money on research to get an estimate of the odds.

Yes, a deadly heat wave in Scotland or sudden cold spell in India would be bad, but if you can’t tell me what the (minimum) odds are, it is irresponsible to invest billions of dollars in preventing it.

If you don’t follow such logic, you end up investing trillions of dollars building rocket shield to protect every single village on earth from accidental nuclear strike, alien invasion, etc.

You can’t just pick one unlikely disaster and ignore all other unlikely disasters to justify your budget choices.

> It annoys me how climate skeptics often confuse
> “survival of life on earth” with “survival of
> homo sapiens”, which they also confuse with
> “survival of our civilization”. What’s optimal
> or usual for the earth, may be very bad for us.

Completely agree, and I’m not confusing these as far as I know.

> There are many, many such small costs that
> occur when people are confronted with a
> climate that they are not used to. None of
> those costs is dramatical in their own right.
> But together they may well add up to a huge
> sum.

Now this is a really interesting point. What if the total cost of all adaptation is more expensive than the cost of mitigation? Lomborg has only done this sum for a limited set of problems and in that case the sum of adaptation is astronomically cheaper.

He’s only dealt with the worlds biggest problems, but perhaps the “long tail” of small problems changes the equation?

The only way to know for sure is to expand his selection and consider everything that is impacted by climate change, to see if that changes the conclusion.

Personally, I doubt it. Current carbon reduction schemes are astronomically ineffective. Even if a climate Armageddon in 2050 was a certainty, they would still be a waste of money; they would delay Armageddon by a few months. We might as well make the best of our last 40 years on earth and actually spend that money making it a better place.

Either way, no one has attempted such a calculation thus far.

There are many, many such small costs that occur when people are confronted with a climate that they are not used to. None of those costs is dramatical in their own right. But together they may well add up to a huge sum.

Changing the concrete on the roads in Sweden from a kind that resists spike tyres and ice to a type that resists tropical heat, is cheaper than cutting emissions.

Changing hunting policies to save polar bears is cheaper than cutting emissions.

Installing and operating air conditioners in every home in The Netherlands is cheaper than cutting emissions.

But is the sum of all these adaptations, which in their own are many orders of magnitude cheaper than cutting emissions, cheaper than cutting emissions? Many and many of those adaptations will have to be made all around the world.

One could say \well, if we don’t know the effects, they might just as well be good as they might be bad\. That seems to be a paraphrase of your treatment of the uncertainty principle. I disagree: I think I know the effects of change will be bad. Because weather that strays from the usual climate for a particular place always cause trouble. Even if the weather isn’t that extreme on a global scale.

If temperature ever gets close to around zero in mid India, it causes lots of deaths and makes it to the Dutch television channels’ news items. Someone from Montreal would consider such weather warm in January.

If, however, it were to be 40 degrees in summer in Scotland, people would die en masse. 40 degrees in summer in Bahrein would be business as usual. Change in climate is bad. That’s not a dogma, that’s easily observable.

“CO2 levels at present are geologically speaking at a historical low, except for a similar period of low CO2 levels in the Late Carboniferous and early Permian.”

So? Carbon dioxide levels at present are humanly speaking at a historical high. And political decisions are made at human time scales, not geological ones. The current climate change, too, is occurring at a time scale that’s much smaller than your typical geological process.

It annoys me how climate skeptics often confuse “survival of life on earth” with “survival of homo sapiens”, which they also confuse with “survival of our civilization”. What’s optimal or usual for the earth, may be very bad for us.

I agree with most if not all you just argued in response to my post. Indeed adaptation is for me the right approach to any change, be it natural or man induced, basically Lomborg’s perspective. Nevertheless one could safely make the case that change to a cooler climate, eventually culminating in a next ice age, is definitely less good for civilisation. That a next ice age is upon us is not a hypothesis but a geologically established certainty. The only question is when. And if humans could delay the onset of an ice age (which I doubt) through CO2 emissions all the better.

Also we could make the case that higher CO2 levels in the atmosphere are beneficial for food production in a world with its ever increasing population. CO2 levels at present are geologically speaking at a historical low, except for a similar period of low CO2 levels in the Late Carboniferous and early Permian. But in all other geological periods levels of CO2 generally varied between 1000 and 7000 ppm.

My main objection to the common application of the precautionary principle in the climate change debate is therefore the blatant lack of geological considerations and the closing of the eyes to the many benefits of a warmer world.

@chris : I don’t think the debate is (or should be) between warming and cooling. Both would result in equal fear and they have over the last decades as Lomborg points out. What people are really afraid of is change. Change is bad, unless it is blatantly obvious why it is good. Losing your job is always bad, unless you already have a better offer. Even if there is a fair chance that your next job will be better, many people prefer certainty (and culture plays a huge role in that too).

Human civilization, in it’s current state, is optimized for the present, including present temperatures. The same goes for polar bears. It is not fair to say that because the earth has known different temperatures and our temperature is random, any temperature change is irrelevant. We’re optimized for it and change, up or down, will take us out of that optimum.

Any analysis should not so much be about which temperature is best for us, but about whether it is better to stop the change or adapt to it.

As long as we can’t find a really really cheap way to stop the change, adapting just turns out to be cheaper.

As a side note, I’m optimistic that within the next decade or so we will find a really really cheap way to get atmospheric carbon levels to whatever level we like. It has only been a couple of years that enough smart people are trying to do this sort of thing. Listen to this talk for example:

http://ecorner.stanford.edu/authorMaterialInfo.html?mid=2051

The discussion about change and adaptation is often confused with the discussion about the optimum temperature. They are both interesting topics, but the first one has priority at the moment. That said, I would be interested to see someone calculate what CO2 level would actually be perfect for a population of 10 billion with tools like air conditioning and warm cloths. Should we optimize for agricultural area? Sea level? Or for energy conservation?

But such discussion will be largely academic. We can’t predict changes in society beyond a couple of years, so we can only calculate what’s good for us at this point in time. We would therefore have to make the adjustments in carbon *really* quickly (as in e.g. 10 degrees in 5 years), which would then lead to huge adaptation costs and probably the kind of global disaster nobody would be skeptic about.

The use of the precautionary principle in the climate change debate is misguided because the scientific community is heavily biased in its focus on the negative effects (see: http://www.numberwatch.co.uk/warmlist.htm ), ignoring the many benefits.

After all, there is no reason why today’s climate is the optimum for life on earth. There will be as many pros as cons, one would expect. See my provocative (and therefore somewhat simplistic) essay on the similarity between the belief in a religion and the belief in climate change catastrophe: http://web.me.com/chrisschoneveld

By ignoring the benefits of a warmer climate a cost/benefit analysis pertaining to efforts of mitigating CO2 emissions would be flawed from the outset and even more so in the absence of sound probabilistics. The fallacy of the precautionary principle is elegantly described here:

http://www.caerdroia.org/blog/archives/2007/02/the_problems_wi.html