All the talk since yesterday is about the new Jan Esper et al paper: Orbital forcing of tree-ring data published by Nature Climate Change. Press release here.
The main focus of the paper is the modest long-term 0.3°C cooling per thousand years that has taken place over the last 2000 years, likely due to Earth’s orbital factors. Unfortunately the authors did not go into the cause of the wide and obvious temperature variations occuring over the period. The press release quotes the authors:
We found that previous estimates of historical temperatures during the Roman era and the Middle Ages were too low,” says Esper. “Such findings are also significant with regard to climate policy, as they will influence the way today’s climate changes are seen in context of historical warm periods.”
That sure blows out of the water Al Gore’s AIT con-job claim that the Medieval Warm Period was a just minor negligible event, doesn’t it?
Yet, it’s a pity Esper et al did not go into why temperatures 1000 years ago were as high as today’s and why temperatures of the past varied so widely.
There are some fascinating points about the curve that others will surely look into:
1. 20th century rise is not unusual
The abrupt temperature rise near the end of the 20th century is not unusual. Similar or even greater rises occurred around 1500AD, 1150AD, 700AD, 300AD and 100BC.
2. No correlation with CO2
Recall that CO2 was more or less steady at 280 ppm before starting its sharp climb 150 years ago. Yet, the smoothed temperature curves over a range of almost 2°C and the annual measurements range over 6°C! This completely contradicts the old storyline that climate had been more or less stable before man started emitting CO2. Clearly an array of powerful natural factors are at play here.
3. Natural cycles are clearly visible
The 1000-year solar cycle is clearly visible, and strongly suggests that there’s much more to solar forcing than total solar irradiation. There has to be a solar amplification mechanism, such as the one put forth by Svensmark, which, by the way, is gaining support from a growing body of scientific evidence. Of course there are some quacks who may suggest cyclic volcansim.
4. IPCC under-estimated natural trends
The press release states: “Our results suggest that the large-scale climate reconstruction shown by the Intergovernmental Panel on Climate Change (IPCC) likely underestimate this long-term cooling trend over the past few millennia.” That also can be interpreted as: The IPCC likely over-estimates the short-term warming of CO2.
Looking at the 2000-year chart above, it certainly wouldn’t take a rocket climate scientist to reach that conclusion.
The CO2 global warming theory has just lost another leg.
Maybe “The Age of Science” is not dead after all. But, then again, “The Age of Reason” had a few such days after the French Revolution and it never recovered; I guess the smart thing to do is wait and see and hope for the best, which seems both reasonable and rather scientific these days, nicht wahr?
In Australia, re-enlightenment is gaining traction in, of all places, Academia.
http://contrary2belief.wordpress.com/2012/07/10/back-to-school-for-the-syllabusters/
In response to the sciences syllabus for school students:
————-
The view of science as outlined by the Queensland Studies Authority was utterly rejected by the Australian Council of Deans of Science, representing the heads of science faculties in the nation’s universities. The council’s executive director, John Rice from Sydney University, said it was a misleading view of science and misunderstood “the unique way in which science goes about understanding things”.
“That statement makes scientific knowledge sound as though it’s no more than the fantasies of a bunch of scientists,” he said.
“That’s quite wrong. It fails to understand the way in which science grounds itself in observation and testable hypotheses.“
…
Professor Rice said the national science curriculum made a similar error, oversimplifying the idea of scientists proving and disproving hypotheses to suggest that scientific knowledge was agreed by consensus among scientists.
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Pigeon. Cat. Pigeon.
Just checked the major German dailies, weeklies. Normally they pounce on every climate report out there. Not this time, though. So far not a peep about this new report.
Okay, let’s give them a couple more days.
Reporting about this is hard work for them, because they need to invent plausible smears about the authors.
Although this paper has not yet received wide critiquing to further affirm it, the whole tenor of the publication seems cautious and reasonable, consistent with sound scientific method.
As far as the news media goes (at least her in the U.S.), I strongly suspect that this news will be ignored or sppun in a manner to minimize the impact.
The collaboration of the scientists involved is just the “way things should be.”
Great post, Pierre!
Mr Gosselin, you say
“The abrupt temperature rise near the end of the 20th century is not unusual”
If you are referring to the upward wiggle of the thick black line on the main graph “the abrupt temperature rise” is actually at the BEGINNING of the 20th century, i.e. the period c.1900 to 1940. After that it levels off. The scale is rather smaller than we are used to and so a bit confusing.
But there is no late 20th century hockey stick blade. Hurrah!
The line actually becomes unreliable from 1912 to the present as it is done with a “100 year spline filter” the paper says. Don’t give to much on the shape of the final wiggle. Can’t find any more information but obviously the window for the filter shrinks near the end, how will it react? Dunno…
Hu McCulloch ain’t too impressed: (2009)
http://climateaudit.org/2009/08/23/spline-smoothing/
I’ve never used a spline filter myself. I prefer ordinary low pass filters, moving averages, exponentially weighted moving averages, they have nice predictable properties.
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