A new proxy reconstruction of the last two thousand years of temperature shows that there has been a decline of 0.3 degrees per millennium over the that period.
Published in Nature Climate Change the paper finds that orbital forcings (essentially how close the sun and the earth are) are around four times as significant as CO2 emissions.
The reconstruction uses Maximum Latewood Density (MXD) rather than Tree Ring Width (TRW), the method used by the notorious Michael Mann Hockey Stick.
The authors are obviously painfully aware of the fraud practiced by Mann where he substituted instrumental records for proxies when the proxies didn’t show what he wanted (otherwise known as “Mike’s Nature trick”) as above their most significant graph they show how their records correlate with the temperature record up to the end of the reconstruction.
The tree rings are only from Sweden, which means that they aren’t global, but then neither was the Hockey Stick. Significantly for global warming models the Arctic regions are supposed to warm faster than the equator, so if there was unusual 20th Century warming it should show up here before many other places.
It also has implications for recent events in Queensland where the 12th International Coral Reef Symposium has been hearing how accelerating global warming is already affecting the Great Barrier Reef. On the basis of this they’re not facing anything they haven’t faced in recent geological time.
Dear Graham,
I thought Mann’s graph was replicated independently by the National Center for Atmospheric Research (Wahl 2007) and they basically replicated the curve.
I’m wondering how you know the author’s “are obviously painfully aware of the fraud practiced by Mann where he substituted instrumental records for proxies”? Did you talk to them?
I’m not sure what you think the paper does for the GW argument but from my admittedly cursory reading nothing. I thought it was universally accepted that the earth was in a cooling trend prior to the 20th century.
That orbital fluctuations have a greater effect on climate than CO2 is also indisputable otherwise we would never have experienced ice ages after the first warming period in a plant rich world.
I don’t see any implications for the fears currently held about the Great Barrier reef.
Comment by csteele — July 17, 2012 @ 11:55 pm
Hi Cameron, the alarmist position, aided and abetted by Mann’s creation, has been that current temperatures are records and that CO2 controls the temperature. You seem to disagree with both those positions, which means that not only are you and I in accord, but you’ve missed some of the more ridiculous pronouncements by Tim Flannery, Ian Lowe, Peter Garrett, Julia Gillard, Rachendra Pachauri, Al Gore, James Hansen and so on.
Comment by Graham — July 21, 2012 @ 12:09 pm
Dear Graham,
You may have misunderstood my position.
Of course CO2 is one of the things controlling the temperature. It is our second most influential GHG after water vapour and without it our average global temperature would be 32C cooler without the Green house effect of which CO2 contributes roughly 20%.
Doubling our CO2 levels, even given bandwidth constraints, will obviously impact on global temperatures and that is what the data shows.
I would like to know what pronouncements by James Hansen, the only climate scientist in the bunch, you have found objectionable?
Comment by csteele — July 21, 2012 @ 3:55 pm
Cameron, doubling CO2 will theoretically have a very small effect on temperature on its own – somewhere between 1 and 2 degrees, which will be quite pleasant or tolerable in most places. In fact barely noticed. Doubling CO2 doesn’t double temperature, or anything like, at the concentrations it occurs in the atmosphere, because as it grows in concentration it absorbs proportionately much smaller amounts of infra-red radiation, until it absorbs virtually none at all.
But the data doesn’t show that CO2 actually has the theoretical effect in the real world. It’s got to be having some effect, but no-one can be sure how much. And other factors in the past appear to have had a larger effect than CO2.
That’s why the IPCC decided to promote Mann’s Hockey Stick, even though it bore little relationship to what everyone understood the case to be at that stage. They promoted it because it appeared to show that CO2 was controlling the atmosphere.
Proper reconstructions, like the one I’ve cited show how bad a job Mann did, and as I pointed out, because of his dishonesty in splicing two different types of datasets together when one of the datasets didn’t show what he wanted it to, other researchers are now being very explicit about the integrity of their data.
As for Hansen, the goose recently predicted that earth’s seas could “boil” as a result of CO2 emissions http://youtu.be/1uxfiuKB_R8. I’m not sure why you would single him out from the others. They are all mostly scientists who say they know about global warming, or Nobel laureates because of their work on global warming, with the exception of Gillard – she just happens to run a policy which seeks to cripple an economy to limit CO2 emissions because of what she “knows” about the science.
Comment by Graham — July 24, 2012 @ 10:16 pm
Dear Graham,
Sorry for a late return to this and apologies too for the clumsy wording in my previous post.
You said; “Doubling CO2 doesn’t double temperature, or anything like, at the concentrations it occurs in the atmosphere,”
Why did you feel the need to put this statement up? I never claimed CO2 doubled temperature but your post, with respect, leaves the impression I did. I had also acknowledged the bandwidth constraint of the impact of CO2 increases earlier.
And as you say the temperature effect of increased CO2 alone does not account for all the predicted rise, other forcing factors come into play. Hansen accurately predicted the global temperature will rise ‘above the noise’. The debate is now primarily about how much it will continue to grow.
As to Mann’s graph one only has to look at the thing to see he clearly labelled what was reconstructed historical data and what was instrumental data.
http://en.wikipedia.org/wiki/File:Hockey_stick_chart_ipcc_large.jpg
Subsequent studies including the one you cite replicate his work even after substantial improvements in technique.
Yet Mann has been subjected to vicious attacks from your side of the debate, recently being compared to “Jerry Sandusky, a convicted serial child molester”.
http://www.skepticalscience.com/mann-fights-back.html
By all reputable accounts he is a good scientist who has contributed to our understanding of climate change and whose work has been refined, built upon, and strengthened by subsequent studies.
Perhaps, on reflection, labelling him a ‘fraud’ is an injudicious act, especially given the fact he has had about enough of the libels and might just be prepared to bite back. Rare indeed for a climate scientist but probably timely.
Comment by csteele — July 30, 2012 @ 1:58 pm
Cameron, anyone who says that the Hockey Stick has been vindicated is not in touch with the literature. Did you read my post? The whole point was that it is a rebuttal of Mann’s work. To assert otherwise is to suggest you didn’t read the post.
Just because some of Mann’s colleagues managed to replicate his fallacious analysis does not make it right.
You are missing the point of his fraud (and I’d be happy for him to sue me, but he wouldn’t because truth is a complete defence). He may have labelled his data, although most missed the labelling, but he didn’t flag that the reason he changed the method of measurement was because the method that he was relying on didn’t show the increase that he wanted – in fact it declined over the period.
That is fraudulent and not something a “good scientist” would do. There are too many such in the catastrophist clique, and you might want to read this analysis of Hansen’s latest paper http://cliffmass.blogspot.co.uk/2012/08/climate-distortion.html.
It concludes:
Unfortunately, a very limited, but highly visible, group of scientists like Hansen are choosing to tell a story that is not supported by the facts, with a media that is happy to amplify such claims. Global warming due to greenhouse gas emissions of mankind is a very serious issue…one which our civilization is not dealing with in an effective way. But scientists must give society the straight facts and not shade or exaggerate the facts based on our personal views on what should be done.
Comment by Graham — August 11, 2012 @ 7:59 am