Saturday, August 8, 2009

Climate Consensus? Maybe, But About What?

(This is a slightly edited version of a post I made to the WTA-Talk email list on July 31, 2009.)

James Hughes posted [on the WTA-Talk email list] the results of one particular survey that reported apparently strong agreement on something or other. James especially highlights the figure of 97% agreement. That does indeed sound very impressive. I do think that such a tight consensus among a group of scientists would be something to give considerable epistemic weight to -- at least in the absence of major objections, say from a neighboring discipline. I’m perfectly willing to be persuaded that a consensus on some clear point exists that I currently disagree with. So far, however, I haven’t been given sufficient reason to do so. Let's look at little more closely at this particular survey and my reasons for doubt.

>Two questions were key: Have mean global temperatures risen compared
>to pre-1800s levels, and has human activity been a significant
>factor in changing mean global temperatures?
>
>About 90 percent of the scientists agreed with the first question and 82 percent the second.

These numbers are lower than the most impressive one of 97%, but still high.

>The strongest consensus on the causes of global warming came from
>climatologists who are active in climate research, with 97 percent
>agreeing humans play a role.

Agreement was lower in certain groups:

>Petroleum geologists and meteorologists were among the biggest
>doubters, with only 47 percent and 64 percent, respectively,
>believing in human involvement.

Why would agreement be higher among the climatologists than among other scientists, including meteorologists and physicists? One plausible answer is that it's because the climatologists can make better judgments. (Although evidence-based forecasting shows that expert forecasts of future changes cannot be trusted with this kind of problem.) Another plausible answer is that groupthink is at work, as it is in so many areas of human activity. This is hardly an arbitrary suggestion, given all the accusations of "denial" and "planetary traitors" and the strong pressures being exerted against skeptics.

Of course there are other surveys, which produce different results. Climatologists are only one group qualified to answer these questions. But l'll set that aside here.

One question that comes to mind is; How were the people to be questioned selected? What percentage of the total does the 3,100 or so represent? From what I've seen, some 10,200 earth scientists were contacted. Only 3,100 replied. Now, these may be representative, or they may not be. Anyone with an academic background in the social sciences, or statistics knows that samples can and often do misrepresent the whole. Given the thousands of scientists who have signed dissenting opinions, I'm not terribly confident that the percentages of respondents in this survey accurately represent the whole group. It seems, for instance, that earth scientists working in private industry were ignored. Given that government-funded scientists may have an incentive (above and beyond the obviously heavy peer-pressure) to agree, the results may not give an accurate picture of all relevant scientists.

These questions come to mind especially because of the highly politicized nature of this discussion. Also, specifically, because of misrepresentations such as seen with the IPCC report, where a small group of people claim to speak for a much larger group. (Compare the summary of the IPCC report to the actual details of the report...)

Other surveys have yielded different percentages. You can see that just from the Wikipedia article.

But, set aside these concerns.

Much more troubling are the questions and the conclusions so quickly drawn from them. Consider the questions. What exactly were those surveyed being asked?

1. "Have mean global temperatures risen compared to pre-1800s levels?"
1800 was around the time that we began to recover more quickly from the Little Ice Age. So what does this tell us? Not much about today or about human activity. It does show that climate scientists agree that the global temperature changes over time. Who is going to disagree with that?

2. Has human activity been a significant factor in changing mean global temperatures?
So, 82% said yes to this. Is this anything to get excited about? Should it impress those of us who are a bit skeptical about warming catastrophe stories? Suppose you are entirely certain that carbon dioxide released by humans is not the cause of global warming. You would still easily grant that global mean temperatures has risen due to the urban heat island effect.

In addition, the question is very vague, certainly if "significant" is taken in the sense of statistical significance (as it presumably is by these scientists). If those climate scientists believed that only 2% or 5% of observed warming could be attributed to human activity, they would still agree with that statement.

How many would still agree if the question was:
-- Do you agree that warming was almost certainly primarily due to human activity? (Not just "significant".)
-- Is global warming principally or quantifiably due to human activity?
-- Are you certain or almost certain that human activity would cause a degree of future warming that constituted a catastrophe?
-- Do you believe that large cuts in carbon dioxide would be effective or cost-effective?
-- Do you believe that the Kyoto Protocol is a sensible solution?

Claiming consensus -- even if entirely justified -- on such vague questions that few skeptics would disagree with is an easy victory that gets us nowhere with any discussion that matters. Once again, dumbing down the issue to a "consensus" of some vague kind isn't useful.

Aside from the foregoing points, I have to say that given the inaccuracy of climate models (as shown comparing them to the past), being impressed by a supposed (or even real) consensus of climate scientists doesn't look too different from relying on a consensus of astronomers. (I would have equally harsh things to say about economists, when they model whole economies...) Granted, that's overstating it. But not by a whole hell of a lot. Again, see my previous post pointing to an audit of the forecasting methodology of the IPCC report, which is considered the gold standard.

I just can't see climate modeling as having attained the status of a hard science at this stage. Even if there was a rock solid consensus on some point of interest (rather than on statements that I have no problem with at all), I would not feel rationally compelled to assent to it as I would, for instance, in the case of a consensus among particle physicists who tell me not to worry about strangelets as they start up the Large Hadron Collider.

8 comments:

Mark Plus said...

I suspect the climate issue has become politicized for arbitrary reasons. If the scientists had framed the effects of fossil fuels burning on the atmosphere as "climate control technology" (CCT), we'd probably see the political alignments around it reversed. Conservatives, libertarians and other advocates of nature-domination would latch onto CCT as new tool to increase man's mastery over the forces of nature; while leftists and progressives would hold CCT in deep suspicion, if not dispute the validity of its underlying science.

After all, what self-respecting advanced global civilization wouldn't want the ability to control its planet's climate? The climate scientists have done us a favor not unlike the scientists in the 20th Century whose work led to electronics, nuclear technology, genetic engineering and so forth. Nothing about climate science per se supports the agenda of the limits-to-growth people, so we should take it back from them and get it to work in our favor.

Cosmic said...

I agree with some of your points Max. I have yet to see any study of the climatologist opinion "after" correcting for political bias. My guess off hand is that the field would be dominated by leftist/progressives with an "axe to grind" against the free market. Until I see a study showing actual evidence to the contrary, I have to go with my gut on this one and think the field is highly biased and therefor worth discounting for the most part.

al fin said...

Politicians and journalists have made a hash of what more responsible climate scientists are doing and saying.

Climate catastrophe is unlikely, although benign global warming is just as likely as benign global cooling -- and is thus "plausible."

Journalists, politicians and the environmental lobby use the language of "climate catastrophe" to boost ad revenue, to support draconian legislation, and to solicit donations and acquire ever greater political influence.

Climate models are garbage, simply put. Too many climate studies departments have abandoned scientific observation in favour of climate computer games without predictive validity. It is a massive step backward for science when that happens.

Giulio Prisco said...

I don't think climate models are "garbage", but they are extremely hard to get right. Having done some work on this topic I know that including every possible relevant factor into a model would bring any existing or planned supercomputer to its knees.

Climate research is heavily politicized, and researchers know they have to say the PC thing to get their grants.

I think the possibility of climate change must be taken seriously, but I consider it as a possibility supported by some suggestive evidence, and not as a certainty.

So I agree with Max' balances assessment, which does not justify the recent hysterical attacks against him.

zeev said...

Asides from the predicted catastrophic rise in sea levels (due to arrive in thousands of years), the predicted imminent effects global warming upon changing weather patterns are quite nebulous: rain patterns will change, hurricanees of greater intensity, etc.....

the problem of the politicization of the 'science' is that no imminent claimed consequences of global warming are specific enough to incur widespread concern, thus their zinger; the big lie constructed by global warming policy makers :
Manmade global warming is IRREVERSABLE and thus we must act now.

the same logic spewed from the mouth of leaders and politcians was used...and lies were spun in order to obtain the 'public consensus' (read panic, fear, and hatred) that led americans into the wars in vietname and iraq-afghanistan.

It is more than clear that the social observations of the global warming movement have very real implications for any views that one should take towards 'authorities' claiming to have developed consensus on the 'science.' You can bet that the hype is being intentionally overblown to manipulate the public into supporting a 'solution' which will not only enrich the few insiders and the expense of the general public, but that, analogous to manner in which the wars in iraq-istan were 'sold' in hopes of stabilize the world and reducing terrorism but have yielded the opposite affects, will actually make the problem of global warming worse.

Jim Lippard said...

I see the politicization as largely on the climate skeptic side--the George C. Marshall Institute, the Heartland Institute, the Cato Institute, the Science and Energy Policy Project, the Science and Public Policy Institute, the Oregon Institute for Science and Medicine--these are the main forces pushing criticism of anthropogenic global warming in the U.S., and it's the same few names associated with all of them. There are climate skeptics with legitimate credentials in climate science, but very few. And these organizations tend to make arguments that those skeptics don't--many climate skeptics are skeptical about the degree of earth's climate sensitivity, but not that there is a warming trend that has human contributions to greenhouse gases as a significant source of the forcing. These organizations, by contrast, cheer the recent Pew poll that shows American belief that there's warming at all has declined.

Jim Prall's site of citation counts is a good resource:

http://www.eecg.utoronto.ca/~prall/climate/

Max More said...

Jim: What bothers me about your comment is that it seems to contribute to the persistent and insistent polarization on this issue. You make it sound like there are only two positions. (It's as if you didn't read my post that you're commenting on...)

The "skeptics" are not a single position. There are extreme skeptics who reject the idea that there has been any warming over the past century or so. I completely agree that this position seems completely unsustainable. There are those who question exactly how much warming there has been. This seems somewhat plausible around the edges, but too much time (in my view) is being wasted on minor points here when the trend and magnitude seem pretty well established. There are those who argue that we have no reason to believe that any of the warming anthropogenic. Then there are those who question the extent to which the warming is human-related. This seems perfectly reasonable to me at this point. The models simply are not reliable enough to demonstrate with any confidence the degree to which warming is anthropogenic in origin. Then there is a distinct discussion about the reliability of long-term projections. This is one that especially interests me. I think the "standard view" is weakest here -- and the views of alarmists like Gore are especially doubtful. The final issue, distinct from some of the others, is that of what actions to take. It's crucial to distinguish between these.

Max

rkm said...

I'm impressed. This is the first forum I've seen that includes people from different sides of the issue, and yet has rational dialog.

I've done a bit of research, and the most relevant thing I've seen is the ice-core data, which shows we are in relatively cool period historically. It also shows that an ice age is long overdue. Even before the industrial age, this was already the longest inter-glacial period on record.

The IPCC models are the least persuasive thing I've seen. The models begin with the assumption that warming is a problem and that Co2 is the cause. The models do not include an adequate treatment of clouds, which makes them rather irrelevant. After all, water vapor is by far the most important greenhouse gas, and reflection from clouds can trump all greenhouse gases.

ciao,
richard