What do you get when you mashup a boomerang with a hockey stick? Probably a game that even drunk Australians wouldn’t play.* Yet that is the latest new wrinkle in climate change this week.
Science magazine has just published a new article that purports to be the latest “smoking gun” of human caused global warming. The article, “A Reconstruction of Regional and Global Temperature for the past 11,300 Years,” uses the usual “proxy” methods to estimate a global temperature history for this whole time frame. Whereas the infamous Michael Mann “hockey stick” graph (see Figure A) purported to demonstrate that the late 20th century was the hottest in the last 2000 years, the new boomerang-hockey stick (see Figure B immediately below) shows that the recent spike in temperatures is way out of line with the long, smooth temperature curve of the last 11,300 years that by itself looks like a boomerang. You can expect the Total Freakout treatment from the climate campaign over this in the coming weeks. Mother Jones magazine offers the opening bid with, “The Scariest Climate Graph Just Got Scarier.” I always thought that the superlative form of any modifier (“scariest”) meant “that which could not possibly be more scary,” but silly me. Of course environmentalists can always be more frightened of something.
The authors note that current temperatures have not yet risen above levels seen during the last 11,000 years, but the suddenness of the increase over the last 100 years is thought to indicate the decisive human influence, i.e., that this increase can’t be natural or largely natural. I have no idea whether the proxy reconstruction of the last 11,000 years will hold up under closer scrutiny (the discussion of the methodology in the complete article is very technical), though I’ll mention in passing that for a long while a lot of the climateers tried to dismiss the medieval warm period with the claim that the warmth was just regional to northern Europe, because, you know, we simply don’t have enough proxy sources from the southern hemisphere (true) to get a complete global picture. Subsequently there has been some southern hemisphere evidence that the medieval warm period was indeed global, though because there is so little land mass in the southern hemisphere the basic objection that we lack a lot of data is correct. So . . . why wouldn’t the same problem affect this new reconstruction? I expect we’ll hear a lot from the skeptic camp about the strengths and weakness of this study shortly.
But there is one simpler way of getting at why this finding represents an overstatement. One of the things I’ve long noted about the basic chart the climateers use to shock us with “soaring” levels of CO2 in the atmosphere depends upon the oldest trick in the book—compressing the vertical axis. When you display the rising trend of CO2 levels, and include benchmarks for the pre-industrial level and the level at which CO2 will have doubled, the phenomenon looks much less ominous. (See my Figure C.) For one thing, you can grasp how far we have to go to a doubling of CO2; the climate campaign always sounds like we’re going to get there the day after tomorrow unless we start cutting off our noses today. Likewise, note in Figure B how compressed is the temperature range—the complete swing is within about 1 degree C. If you extend the scale of the axis to represent a wider temperature range that includes temperature range that is perfectly compatible with human flourishing (humans live close to the North Pole, and in the middle of the hot desert)—I’ve done 10 degrees in my Figure D below—the whole thing looks rather less dramatic. But what fun is that if you live off panic?
The other thing this chart—or any chart—can’t do, even if correct, is predict the future. To repeat a central point: the basic relationship between greenhouse gases and temperature is non-linear, that is, there is diminishing warming from each additional molecule of GHG in the air. That’s why a doubling of CO2 alone will only get you about a 1.1 degree C increase in temperature. Which is not much to write home about; in fact, that amount of temperature increase likely has net benefits for the planet, as the IPCC itself has grudgingly acknowledged if you know how to read between the lines in their phonebook-sized reports. All of the action in the catastrophic scenarios depend on uniformly positive amplifications of the “feedback” effects, which this chart cannot help demonstrate.
By the way, another way of looking at Figure B is that if humans are driving the recent temperature rise, we took up the cause just in the nick of time to stave off a downward temperature trend toward a new ice age. (There have been a few heterodox climate skeptics that have been saying this from the beginning.) Could be interesting to see how we look back on our treatment of this whole subject 100 years from now. Is there any panic claim from 100 years ago that bore out in the extreme way the doomsters predicted?
Another question is whether this graph will show up prominently in the next assessment report of the Inter-governmental Panel on Climate Change (IPCC), which is thought to have been completed by now? Mann’s hockey stick graph was added at the last minute to the 2001 IPCC assessment, without the knowledge or approval of many of the scientists involved in the writing of the formal report that year.
The abstract of the Science magazine article can be found here; the complete article requires a subscription. Green Weenies all around.
*Apologies, by the way, to all beer swilling Australians everywhere. No offense actually intended. I rather like a country whose beer comes in a can whose very size screams, “Pints are for pussies.”