Arnold Kling  

Global Warming vs. the Outside Temperature

Mankiw Defends his Tall Tale... Basic Decision Theory...

Today, the high school where I teach had an "environmental awareness" seminar. I walked in during the middle, so I did not catch the woman's name. The kids said that she had worked with Al Gore, and that many of her slides were similar to those in the movie. I tried to keep quiet, but when she started saying that the seas were going to rise by 20 feet (she even said that 40 feet was a possibility), I said that the consensus was 20 centimeters. She also explained away all the scientists who disagree with her on global warming by saying they were paid for by energy companies, just as the tobacco companies paid scientists to deny a link between smoking and cancer.

The kids did not like her very much. I think she went over the way the movie "Reefer Madness" went over when it was shown in the 1950's. When you're over-the-top with teenagers, they tend to resist.

But maybe her problem was that it's so bloody cold outside. I looked up the history of heating-degree days for our area, and this page says that normal for 1961-1990 is 4046 per year. According to today's Washington Post, we are at 3839 for the winter so far (their "normal" is 3874), and the forecast for the next ten days suggests to me that we have a good chance of topping 4046 for the winter before we hit May.

Using the heating-degree-day metric, it looks like this winter is going to turn out to be close to normal relative to 1961-1990. I know that this is only one part of the world, and this is just one season of one year. But in economics, if we were looking at a recent trend and a number came in way off that trend, that would be considered an interesting data point. If, say, the consumer price index or personal income per capita in the DC area were to come in at the average levels seen in 1961-1990, the economics profession would have some 'splainin' to do. We'd wonder what we have to do to our models to make the point fit.

And economics isn't even a science.

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COMMENTS (18 to date)
John Thacker writes:

By this NOAA data, seems like most all places in the US are still warmer than the 1961-1990 normal, but it certainly is significantly colder than last winter.

Bruce K. Britton writes:

Perhaps they were not impressed because she was using nothing but an ad hominem arguement against the scientists: their claims could be true if they were working for the energy companies, or they could be true if they were not working for the energy companies; and they could be false if they were working for... etc.

People can discount ad hominem arguements if there is any other evidence, like your quite true 20 cm claim from the IPCC report.

TGGP writes:

Nice to see you admit economics isn't a science. It especially bugs me that Austrians seem to have a hang-up about insisting that economics is a science when they go farther than most in asserting how unlike the natural (I would say "real") sciences like physics.

Brad Hutchings writes:

We just need a way to hold them accountable. I had an undergrad course back in 1991 where a portion was taught by Sherwood Rowland and Ralph Cicerone, both Nobel laureates, the latter now president of the National Academy of Sciences. Rowland laid out the chemistry of CFCs and ozone depletion. Cicerone whipped the sorority girls into a frenzy with descriptions of terrible skin cancers they and their future kids would surely have and it was already too late to prevent that, but maybe The Montreal Protocol would make things better for future generations a century out. I don't mean to sound sexist about it, but you know, college guys don't spend all their free time working on their tans. Bringing this all back to Bryan's recent post on humility, I haven't heard Cicerone cop to being an alarmist 20 years ago, so I don't take him too seriously when he sits in front of Congress now and warns about global warming. Perhaps most people have forgotten the fable of the scientist who cried wolf, but I haven't.

Jim writes:

"I said that the consensus was 20 centimeters."

And you were wrong. Maybe you need to apologise to the kids for misleading them and tell them what the IPCC report actually says.

Bruce K. Britton writes:

I am looking at the 2007 IPCC Summary for Policymakers of Working Group I Table SPM-3 ( page 13 of the report): 'Projected...sea level rise...'
For the six scenarios, the bottoms of the ranges are 18-26 cm and the tops of the ranges are 38-59 cm.

But the most important item in the report has been widely ignored, it is, on page 16 " It is very unlikely that the MOC [the ocean circulation pattern] will undergo a large abrupt transition during the 21st century." This removes the keystone of the catastrophist arguement, which is the only one which justifies emergency action. We are left with adaptation mixed with prevention of slowly occuring changes.

Stefano writes:

Climate models predict an average warming of a few degree. That doesn't mean that it would be warmer everywhere or always. Some places may become colder.

As for sea level increases, perhaps it's because I live on the Alps, but it never seemed to me the worst outcome of climate change. Most concerning in my view are:

- the loss of glaciers and snow caps, causing a sortage of water in many high-populated areas as Western Europe, California(, not to mention India or China

- the possible disruption of the Gulf Stream

- the possibility of positive feedback, with higher temperatures triggering the release of more hothouse gases from the tundra or from ocean bottoms, worsening the problems even more.

Bruce K. Britton writes:

In the IPCC 2007 Summary for Policymakers ( Wkng.Gp 1), 28 cm is the midpoint of the B1 scenario in Table SPM-3. This seems the most likely source for the 22 cm claim, with a little error. The B1 Scenario seems a quite likely one (see p. 18 of the Report).

FBC3 writes:

"She also explained away all the scientists who disagree with her on global warming by saying they were paid for by energy companies, just as the tobacco companies paid scientists to deny a link between smoking and cancer."

As if there isn't a host of rent-seekers that don't have a stake in promoting anthopogenic global warming.

reason writes:

If, say, the consumer price index or personal income per capita in the DC area were to come in at the average levels seen in 1961-1990, the economics profession would have some 'splainin' to do.

You should look at the data this year for Germany. It might just change your mind. (Not to mention that your comparison is for data with a secular trend, which is what climate here is not supposed to have under the null hypothesis. Really, really lousy example!)

Jim writes:

Those trying to justify a 'consensus' figure of 20cm for sea level rise by 2100 should probably have a read of this post at RealClimate. I'd also be interested to hear whether the woman Arnold criticised had specified the period in which she thought the sea could rise 20ft. If you look past 2100, that becomes more likely and 20cm becomes even less likely.

Matt G writes:

After enduring a bitter cold spell here on the East Coast for the past few weeks, it yet again seems impossible to agree with the idea of global warming. However, one must look at the facts about this world issue:

a) Global Warming is a natural cycle that has occurred in the past (leads up to an ice age)

b) Over the last 100 years, through air samples taken from glaciers, it has been proven that our modern economy's greenshouse gases have rendered the effects of global warming more potent.

c) Finally, one must recognize that although it is called global warming, it causes extreme climate shifts, possibly rendering typically warm areas under sudden bitterly cold weather.

James A. Donald writes:

"" is using a false email address - is in fact using MY email address, to post false and absurd alarmist nonsense about global warming.

As it says at

I am the real, and I never post under that handle.

So if you see someone posting as, he is lying about his name, and therefore probably lying about everything else also.

Jim writes:

James, you need to calm down. I would never try to impersonate you. Now, would you like to explain exactly what I said qualifies as "false and absurd alarmist nonsense about global warming", or don't you have anything useful to say?

Bruce Britton writes:

Jim, James and Arnold: The IPCC report's range ( Table SPM-3) is between about 20 cm (actually 18 cm) and about 2 feet (actually 59 cm, which is about 23 inches). However, mentioned elsewhere in the two summaries released so far are statements interpretable as suggesting the remote possibility of 5-7 meters (about 15-22 feet).
Rather than referring to the secondary sources ( the statements of Arnold and the unnamed woman) I advise reading the summaries, which are the closest we can get just now to the primary sources, each of which is only about 18 pages, and quite clear, and then discussing the implications, which are not clear at all.

JKB writes:

I am beginning to think that the earth is messing the with climate gloom and doomers. Every time, they have a meeting down swoops some arctic air to freeze out their PR. Maybe they should have their meetings in New Orleans in August. Every one believes in global warming in August. Especially in the deep south were the heat walks around with you like a clingy girlfriend.

Not much science in the global warming arguments, it's all about the statistics which you seem to have down. The science doesn't support the extreme views of global warming and don't every look at their methodology or your really be disappointed.

Michael E Sullivan writes:

If, say, the consumer price index or personal income per capita in the DC area were to come in at the average levels seen in 1961-1990, the economics profession would have some 'splainin' to do. We'd wonder what we have to do to our models to make the point fit.

That's because the economic models don't expect the same amount of variance as climate models, and the amount of built-in expansion of the economy from 1961-1990 was *far* greater than the amount of global warming experienced betweeen 1961 and 1990. This is pure FUD, Arnold, and you should know better. Using the same logic as you just did, I could argue that the fact that the economy in buffalo was horrible for most of the 1990s was "an interesting data point that needs some explainin'" to all the economists who tell us that we were in a boom over that time.

No climatologist working on global warming I'm aware of has ever made any prediction that this winter in Washington DC would be any particular coldness, only that the chance it would be warmer than, say an average of the last twenty, was probably greater than the chance it would be colder. But those chances might have been 55% and 45%. Or 60/40, 70/30. I couldn't really say, but certainly not more than 90/10. Find me a single economist who will say that there is even a 10% chance that next year US GDP will be roughly average for the 1961-1990 period, and I'll take this argument seriously.

You're right to castigate people who talk as if 5-7m sea level rises are a certainty under business as usual in the next 100 odd years, when most climatologists would consider that the very outside range and one with a very small chance of occurence.

That said, in the indefinite time frame, if business as usual continues, sea level rises of 7m or even greater become not only possible but likely. It might take 500 years, and we all hope that the next 50-200 years will be enough time to figure out how to either sequester carbon, or replace fossil fuels as the primary source of energy in the world, making worries about what will happen 300 years moot. That said, keeping the long-term doomsday scenario in mind is one thing that can spur enough investment to actually avoid it, instead of sticking our thumbs up our bottoms for the next 200 years and then getting hit with IPCC reports that say "expected sea level rise by 2450: 7-10m".

The fact is that there is a long term planetary cost to putting greenhouse gases in the air. That cost appears to be very small for a given ton of CO2 (and our best estimates of the cost have a large error bar), but it is almost certainly >zero, and unless the markets are pricing it into their transactions, there is no guarantee that we will have the investment necessary to solve the problem before it becomes serious.

The fact that climatologists largely agree that the problem is very unlikely to be catastrophic (or even all that serious) within the next 100 years, does not mean they believe it will *never* become serious or catastrophic. If enough people pretend that global warming is a non-problem, that's how it *becomes* serious in 2300.

Bruce K. Britton writes:

I take it back: the most important unreported statement from IPCC report ( p. 16 of Woring Group 2 report) is

"For increases in global mean temperature of less than 1-3 degrees C above 1990 levels, some impacts [of warming] are projected to produce benefits in some places and some sectors, and produce costs in other places and other sectors....It is very likely that all regions will experience either declines in net benefits [of warming] or increases in net costs for increases in temperature greater than about 2-3 degrees C." Combine that with the "best estimate" of temperature change for the six scenarios considered of 1.8C, 2.4, 2.4, 2.8, 3.4, and 4.0.

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