After a short interlude of tedious boring, WUWT is back to normal. I last wrote about Anthony Watts and his blog: "Is this a lull before his next "big announcement" or dogwhistle to his lynch mob?" Turns out it was both.
The dog whistle
The "dogwhistle to the lynch mob" was, predictably, another article about Michael Mann (archived here), which was rehashing old denier speculation about Professor Mann's law suit against the National Review, Mark Steyn, the Competitive Enterprise Institute, and Rand Simberg.
The big announcement: The ITCZ in the western Pacific
The "big announcement" (archived here) if you can call it that, was that Willie Soon and his mate Bob Carter managed to get their names on a paper published in Nature Geoscience (pdf here). The paper was by a team of scientists who were looking at how the Intertropical Convergence Zone (ITCZ) shifted over the western Pacific during the Little Ice Age. The team used climate models (yes, really) and "a synthesis of palaeo-hydrology records from the Asian–Australian monsoon area" - yes - proxies for rainfall.
The ITCZ is described as a belt of deep convective clouds in the tropics. It shifts north and south over a year with the seasons - and it's not evenly situated around the world, with varying positions over different oceans. (It can also shift differently with different ENSO events.) Here's a diagram from another recent paper on the ITCZ:
|Figure 1 | Annual-mean precipitation, surface winds, and atmospheric energy balance. a, Precipitation (colour scale) is maximal at the ITCZ, and surface winds (vectors) converge there. The ITCZ over oceans (precipitation maxima) is marked by red lines. The right panel shows the zonal-mean precipitation. b, Atmospheric moist static energy fluxes F (vectors) are weak near the ITCZ, but their divergence div F (colour scale) is generally positive there. (The ITCZ over oceans is marked by the same red lines as in a.) The right panel shows the zonal-mean divergence of the moist static energy flux. Source: Schneider15|
In the new paper in Nature Geoscience, what these scientists found was that, contrary to expectations, the mean position of the ITCZ in the western Pacific didn't shift south during the Little Ice Age, it narrowed into the tropics. They explained in the paper and the supplement that some of the data is still a bit "iffy" (ie some regions have sparse data and there is some conflicting data), but they seem fairly confident of their overall findings.
From the abstract, it was previously expected that the ITCZ over the western Pacific would have shifted south in the Little Ice Age:
The mean position of the intertropical convergence zone over the western Pacific has been proposed to have shifted southwards during this interval, which would lead to relatively dry Little Ice Age conditions in the northern extent of the intertropical convergence zone and wet conditions around its southern limit.
Instead of the ITCZ in the western Pacific shifting south, what this study found was that it contracted to the tropics:
Our synthesis instead documents a synchronous retreat of the East Asian Summer Monsoon and the Australian Summer Monsoon into the tropics during the Little Ice Age, a pattern supported by the results of our climate model simulation of tropical precipitation over the past millennium.
In other words, this work found that in the western Pacific, the precipitation band/ITCZ moved towards the tropics at both the north and south extremities. The range got narrower. The extremes contracted. The abstract indicates their conclusion as a contraction of the seasonal latitude range of the ITCZ in the western Pacific:
We suggest that this pattern over the western Pacific is best explained by a contraction in the latitudinal range over which the intertropical convergence zone seasonally migrates during the Little Ice Age. We therefore propose that rather than a strict north–south migration, the intertropical convergence zone in this region may instead expand and contract over decadal to centennial timescales in response to external forcing.
(A few days ago I started to do a bit of reading about the ITCZ, which was prompted by papers discussing how energy is shifted from the southern hemisphere to the northern hemisphere via the Atlantic. I'm not sufficiently familiar with the subject yet to write about it at length, but am enjoying learning.)
About the authors
The paper lists the contributions of the team members. The study was done by Hong Yan from the Institute of Earth Environment in China, with Wei Wei (of The Alfred Wegener Institute) writing the section on climate model results. Willie Soon "contributed significantly to improvements in the manuscript", while all Bob Carter seems to have done is contribute to "improving the English".
Oh, and the authors declare no competing financial interests.
From the WUWT comments
Peter Miller questions the supposed consensus:
March 11, 2015 at 11:09 am
I do not understand the logic behind the supposed consensus opinion to which they refer – why should tropical rain belts in the southern hemisphere’s western Pacific migrate southwards in response to lower global temperatures?
Surely the tropical rain belts contract in size and intensity when it cools – weren’t the tropical rain forests a tiny fraction of their current size during the last ice ace, which peaked a mere 20,000 years ago?
Anyhow, their discovery seems to make complete sense to me – i.e. northern Australia became drier during the LIA – but it sounds like the establishment’s understanding of the ITCZ is yet another reason the climate models have got wrong.
Paul Westhaver confuses the Little Ice Age with the current greenhouse warming. He didn't see past the mention of the sun:
March 11, 2015 at 11:32 amKit Carruthers used sarcasm:
It’s the sun stupid!
“in response to external forcings such as solar irradiance variation”
For those of you who would like to eat some crow, you know who you are… yeah the AGW alarmists, yeah thats the ticket.
March 11, 2015 at 12:35 pm
The authors used climate models ergo this study is worthless.
MCourtney figures that now the whole world is in on the climate hoax (deniers like Willie Soon and Bob Carter included)
March 11, 2015 at 12:53 pm
But it is interesting to note the new “consensus” forming in Asia.
It’s not related to the truth (anymore than the Western “consensus” is).
But it is interesting.
Willis Eschenbach tries to sound clever while writing a completely irrelevant and meaningless comment and admitting he hasn't "given a detailed read to the paper":
March 11, 2015 at 12:43 pm
I must admit, I always get nervous when someone claims to see the “fingerprints” of the sun in something that happened four hundred years ago … my first question is, have they tested the technique with modern data? I mean, why would you see such putative fingerprints in four hundred year old sediments but not in the modern records?
Haven’t given a detailed read to the paper, but I have a rule of thumb—the further back in time someone has to look for support for a climate claim, the less likely it is to be true. Seriously, folks … if you can’t establish your claim with modern data, why should we believe paleo data shows it?
Gary Pearse figures the scientists should have left TSI out of their research and should have just looked at "rocks and sediments". In fact the scientists looked not just at records of lake sediments, but other records such as speleothems, stalagmites and coral luminescence:
March 11, 2015 at 1:05 pm
Certainly you can use rocks and sediments to identify major things like deserts vs wet places (and their alternations), ocean basins that are now on mountain tops and the like. However, they should have left out the sun and maybe just had a question mark at to the cause.
Rud Istvan sends his regards to no-one in particular (deniers make a habit of doing that when they are feeling narky), and disputes the TSI estimates. Is he saying he prefers sunspot counts to other estimates? The scientists didn't use sunspots. In the supplementary paper it suggests they used TSI as estimated by Bard et al (2000), based on 14C and 10Be analysis.):
March 11, 2015 at 4:41 pm
Especially when related to solar output that could not be accurately measured then, and for which proxy you have shown is worse than dodgy over the early ‘sunspot record’. Regards.
Pamela Gray is not impressed and thinks they should have looked at "other Earthly parameters" and "volcanic veils" or "land bridges coming and going", before pointing to the sun. The paper does mention volcanic forcing - but not much. It does seem to prefer the solar forcing:
March 11, 2015 at 7:20 pm
One must rule out the first encountered pathology. If we do not have records of the teleconnected oceanic/atmospheric conditions present during the period of time under question, to point to solar connections is premature. Due to internal fluid dynamics and other Earthly parameters present at the time under study, it makes sense that internal oscillations, prodded to extend or contract by internal events such as volcanic veils or land bridges coming or going, should be ruled out first. The study seems too willing to look outside a complicated internal system. Not impressed.
Hong Yan, Wei Wei, Willie Soon, Zhisheng An, Weijian Zhou, Zhonghui Liu, Yuhong Wang & Robert M. Carter. "Dynamics of the intertropical convergence zone over the western Pacific during the Little Ice Age." Nature Geoscience (2015) doi:10.1038/ngeo2375 (pdf here)
Schneider, Tapio, Tobias Bischoff, and Gerald H. Haug. "Migrations and dynamics of the intertropical convergence zone." Nature 513, no. 7516 (2014): 45-53. doi:10.1038/nature13636 (pdf here)
Haug, Gerald H., Konrad A. Hughen, Daniel M. Sigman, Larry C. Peterson, and Ursula Röhl. "Southward migration of the intertropical convergence zone through the Holocene." Science 293, no. 5533 (2001): 1304-1308. DOI: 10.1126/science.1059725 (pdf here)