Friday, June 27, 2014

Another Good Article by Dan Kahan

The source of the public conflict over climate change is not too little rationality but in a sense too much. Ordinary members of the public are too good at extracting from information the significance it has in their everyday lives. What an ordinary person does—as consumer, voter, or participant in public discussions—is too inconsequential to affect either the climate or climate-change policymaking. Accordingly, if her actions in one of those capacities reflects a misunderstanding of the basic facts on global warming, neither she nor anyone she cares about will face any greater risk. But because positions on climate change have become such a readily identifiable indicator of ones’ cultural commitments, adopting a stance toward climate change that deviates from the one that prevails among her closest associates could have devastating consequences, psychic and material. Thus, it is perfectly rational—perfectly in line with using information appropriately to achieve an important personal end—for that individual to attend to information on in a manner that more reliably connects her beliefs about climate change to the ones that predominate among her peers than to the best available scientific evidence.
His empirical claim is that disbelief in global warming, or in evolution, is not evidence of scientific ignorance. If you separate groups on roughly a left/right basis, belief in warming increases with increasing scientific intelligence (measured in other ways) in the group predisposed to believe in it (left), decreases with increasing scientific intelligence in the group predisposed not to believe in it (right). Similarly with evolution if you divide the groups into more or less religious. His explanation ...:
If that person happens to enjoy greater proficiency in the skills and dispositions necessary to make sense of such evidence, then she can simply use those capacities to do an even better job at forming identity-protective beliefs.
The article is too long and starts with an irrelevant analogy to observer effects in quantum mechanics, but it has lots of interesting stuff in it. Among other things, if you test people to see how much they understand about the theory of evolution, those who believe in it do no better than those who don't. Similarly for global warming.

Monday, June 23, 2014

Interesting Post About the Climate Argument

I came across a recent piece discussing evidence about beliefs on climate issues. It finds  that Democrats mostly believe temperatures are warming due to human action and something must be done about it, Republicans mostly don't, but that the difference is not due to differing perceptions about what climate scientists believe. If the question is not what is true but what most climate scientists believe, Republicans and Democrats give roughly similar answers—correct in some cases, incorrect in others.

The author's conclusion is that the debate has become a status conflict, with each side taking the position that it is wise and good, the other side the opposite. One implication he draws is that the campaign to persuade people that 97% of climate scientists agree is based on the mistaken assumption that the reason people are not persuaded is that they don't know what climate scientists believe.

It struck me that his description fits my observations of the online debate. Most participants appear confident that their side is right, the other side stupid or evil. Most of the posts and comments are attempts by one side to put down the other. Substantive arguments occasionally appear, but they are largely cut and paste from popular web sites on the side of whoever is posting them.

I should add that I do not think it is clear what climate scientists believe. As best I can tell by my involvement in the argument, most such scientists think global temperature has been trending up and humans are at least partly responsible, many, perhaps a majority, think humans are mainly responsible. I have seen no evidence of what percentage take the next two steps, the conclusion that if nothing is done the results will be terrible and the further conclusion that there is something that can be done that is worth doing. But those steps are essential for the policy argument that one side of the dispute is pushing and the other side opposing.

As of 5:50 EST 6/23/14 the piece described in this post appears to have vanished. I have not yet figured out why or where, if anywhere, I can find it again.

After an exchange of emails with the author, who turned out to be someone I knew from my time at U of C Law school, the link is now fixed.

Friday, June 20, 2014

The Purpose of Commencement Addresses

I don't usually make posts that are links to webcomics, but this one is both good economics and good commentary.

I deduce from further research that the strip in question is aimed at readers with a background in physics and economics and side interests in philosophy and probability theory. Funny that.

Thursday, June 19, 2014

Is the Ocean Still Warming?

The latest data seem to show a very considerable slowdown in ocean warming, starting a few years after the slowdown in atmospheric warming.

That raises an obvious puzzle. As I understand the situation—readers are welcome to correct me if I am wrong—there are satellite measurements of incoming and outgoing radiant energy, and they show a substantial net inflow. If atmosphere, surface, and ocean are all warming much more slowly than they were twenty years ago, where is that energy going?

The two obvious alternatives are that we are missing something, that warming is happening somewhere we cannot readily measure it such as the deep ocean, or that there is something wrong with the measurements that show a net inflow. I do not know enough to offer an educated guess as to which is the case and no other alternatives occur to me.

Heat Content, Temperature, Oceans, and the Pause

Surface and atmospheric temperature appears to have been roughly constant for about the past twelve years, perhaps a little longer, a pattern not predicted by the IPCC models. One response has been that the "missing heat" is going into the ocean. This raises a number of questions, but I want to start with one that only occurred to me recently. Data on the surface and atmosphere is routinely reported in the form of average temperature. Data on the ocean is routinely reported in the form of total heat content. Why?

What is measured, in both cases, is temperature. Presumably the heat content numbers are produced either by multiplying average temperature  by the heat capacity of the ocean or perhaps by doing it for different parts of the oceans and adding. To reverse the process, one divides the increase in heat content of the ocean by the heat capacity of the ocean. The result should be the increase in average ocean temperature. I have not been able to find any exact statement of what the heat capacity of the oceans, so calculated it, using the following figures found online:

Heat capacity of ocean water:   3993J/Kg/K

Volume of the oceans: 1.3 billion cubic kilometers

A cubic kilometer is 10^9 cubic meters and a cubic meter of water is 10^3 kg. Multiplying it out, I get a heat capacity of the ocean of about 5x10^24 Joules/°K. Readers are invited to check the calculation.

Consider the following graph:

It shows an increase in ocean heat content from 1960 to the present of a little less than 2x10^23 Joules. Dividing that by the heat capacity of the ocean gives us an increase in average ocean temperature over fifty years of .04°C. That looks a lot less scary than the graph of heat content, which may explain why it is not the form in which the data is usually presented.

And it matters. Assuming the IPCC calculations of net heat content increase are correct, the effect of heat going into places other than the ocean is significant. The effect of heat going into the ocean is not.

Friday, June 13, 2014

The Tangled Web of Foreign Policy

Has anyone commented on the fact that the recent events in Iraq make the U.S. and Iran de facto allies, both opposing a Sunni uprising? Or that the U.S. and the militants we oppose in Iraq are de facto allies against Assad's regime in Syria, a semi sort of maybe Shia regime supported by Iran?

When the militants steal military equipment the U.S. provided to the Iraqis to use it against the Iraqi government, that's just terrible. If, on the other hand, they steal it to use against Assad, ...  .

Monday, June 09, 2014

A Hockey Stick Question

There is an interesting argument I have seen with regard to Mann's hockey stick reconstruction of past temperatures. I am not sure if it is correct. The hockey stick has been the subject of a lot of heated controversy pro and con and I am not in a mood at the moment to try to wade through it, so I thought I would sketch the argument and see if anyone here can give me a good reason to believe that it is either true or false. 

It goes as follows:

Most of the reconstruction is based on proxies for temperature such as tree rings, since nobody was producing reliable instrumental data in 1500 A.D. The recent part, on the other hand, is based on instrumental data. The claim I have seen is that Mann's graph shows proxies up to one date, proxies and instrumental up to another date, instrumental only starting sometime around 1960-80. That fits what sense I can make of the graph in his paper, the exact date at which the proxies disappear being hard to make out. The further claim, and the critical part, is that if you run the proxies up all the way to the present they do not show as sharp a rise as the instrumental data.

The instrumental data is a more reliable source of information than the proxies for the period when we have it, so if the only objective is reconstructing what has happened to global temperatures over the past six hundred years or so it makes sense to use it where available. But part of the point of Mann's paper is that the recent temperature rise is unprecedented. To show that he needs an apples to apples comparison, a comparison between the proxy record for the past and the proxy record for the recent period of rising temperature or a comparison between the instrumental record for the past and the instrumental record for the recent period. The latter is impossible, since there is no instrumental record for most of the period he is looking at, but the former is not. 

If the proxy record for the past century fails to show the rapid temperature rise in the instrumental record, that is evidence that the proxy record is an unreliable source of information, in particular unreliable as a way of detecting rapid rises. And it is probably more unreliable the farther back we go, since the farther back we go the less relevant data is available. If so, the fact that the proxy record shows no rapid rises in the past may not mean that they did not happen.

Can anyone tell me if this argument is correct? Does the proxy record for the second half of the 20th century show a substantially milder rise in global temperature than the instrumental record?

Global Warming and Wishful Thinking

Political beliefs affect what one wants to be true. People are pretty good at persuading themselves that what they want to be true is true.

That works in both directions in the context of arguments about climate change. People who share my political views are suspicious of government regulation, CAGW (Catastrophic Anthropogenic Global Warming) provides an argument in favor of more government regulation and is used as such an argument at present, so we naturally want to look for arguments against CAGW.

On the other side, it's my experience that people who think global warming is a terrible problem that must be dealt with are also, by some odd coincidence, people who think the things that need to be done to deal with it are things most of which ought to be done anyway, that the real cost is low or negative. They are likely to put that point in terms of creating a cleaner, more sustainable world. From their standpoint, CAGW provides arguments to persuade people to do things they want done, so they naturally want to look for arguments in favor of CAGW.

There is no logical reason why there could not be people out there who believe that a forced shift away from fossil fuels has very large human costs, that by raising the cost of energy it will slow or stop the process by which several billion people are finally escaping from poverty, but think the cost of not doing it is even worse. But despite participating in quite a lot of online climate arguments, I do not think I have encountered a single person  who takes that position.

[I specify CAGW rather than AGW because the argument for action to hold down CO2 emissions requires not only that the globe is warming because of human action but that the net effect of that warming will be negative and large. Also because my own view is that global temperatures have trended up over the past century, that at least part of the reason is probably CO2 produced  by human action, but that there is no good reason to expect the consequences to be negative and large—for details see my old post on the subject and related posts. Hence I believe in AGW but not in CAGW.]