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Thursday, June 19, 2014

A curious finding from WUWT in Korean speleothems

Sou | 5:53 PM One comment so far. Add a comment

Here's one for the shrinks out there. Anthony Watts isn't scoffing at a new scientific paper and the question is, why not? (Archived here).

There's a new paper in Nature about climate (hydrologic) patterns in the mid-latitudes and how there appear to be opposite swings in part of the northern and southern hemisphere mid-latitudes in relation to moisture. (Anthony has finally taken notice of the gripe that he doesn't link to sources, because this time he did link to the press release, though not to the paper itself.)

The researchers were studying climate patterns over the past 550,000 years. They analysed samples from limestone caves in Korea. In glacial periods when it is cold and dry the limestone growth stagnates and in interglacials when it is warm and moist they grow (I'd say it's a bit more complicated than that, but that's the gist of it). Having established climatic patterns in those locations they looked at a range of climate data from elsewhere - solar insolation, glaciers, and deep sea sediments, and found that the same climate change patterns for the same periods.

So then they examined other limestone formations in the southern and northern hemisphere and found a see-saw pattern for the hydrology of the mid-latitudes. More moisture meant a bit warmer and less moisture meant colder and the hemispheres had an opposite pattern, or a see-saw pattern during glacials and interglacials.  From the press release:
In particular, he and colleagues revealed the fact that climate changes in the Northern and Southern Hemispheres showed opposite tendencies by analyzing the fact that stalagmites and flowstones in the temperate zones of the Northern and Southern Hemispheres had opposite growth periods. This suggests for the first time that the so-called phenomenon of the interhemispheric hydrological seesaw that the precipitation changes in the tropical regions show opposing tendencies between Northern and Southern Hemispheres had been spread to the temperate region in which the Korean peninsula was located at least for the last 550,000 years.
Due to the interhemispheric hydrological seesaw, when it rains frequently in a region that belongs to the intertropical convergence zone (ITCZ), it accelerates the growth of plants and increases the temperature, whereas other areas exhibit cold dry weather. This theory has been applied only to the tropical region and had not been significance in global climate change. However, if it is expanded to the temperate regions by the study of Doctor Jo, the seesaw phenomenon may be regarded as another key factor besides the insolation change which has been regarded as the most powerful factor in the glacial and interglacial cycles.

Put simplistically, as I understand it, when it's warm and moist somewhere it's cold and dry somewhere else - and this has been observed as a see-saw hemispherical pattern in some areas of the tropics and now, with this research, in part of the mid-latitudes. The pattern is purported to be a climatic response to orbital forcing. So it looks as if we're talking about gross patterns over millenia on a geological time scale, not annual, decadal or even centennial patterns.

I found the abstract easier to follow than the press release, so here it is (my paras):
An interhemispheric hydrologic seesaw—in which latitudinal migrations of the Intertropical Convergence Zone (ITCZ) produce simultaneous wetting (increased precipitation) in one hemisphere and drying in the other—has been discovered in some tropical and subtropical regions1, 2, 3. For instance, Chinese and Brazilian subtropical speleothem (cave formations such as stalactites and stalagmites) records show opposite trends in time series of oxygen isotopes (a proxy for precipitation variability) at millennial to orbital timescales2, 3, suggesting that hydrologic cycles were antiphased in the northerly versus southerly subtropics.
This tropical to subtropical hydrologic phenomenon is likely to be an initial and important climatic response to orbital forcing3. The impacts of such an interhemispheric hydrologic seesaw on higher-latitude regions and the global climate system, however, are unknown. Here we show that the antiphasing seen in the tropical records is also present in both hemispheres of the mid-latitude western Pacific Ocean.
Our results are based on a new 550,000-year record of the growth frequency of speleothems from the Korean peninsula, which we compare to Southern Hemisphere equivalents4. The Korean data are discontinuous and derived from 24 separate speleothems, but still allow the identification of periods of peak speleothem growth and, thus, precipitation.
The clear hemispheric antiphasing indicates that the sphere of influence of the interhemispheric hydrologic seesaw over the past 550,000 years extended at least to the mid-latitudes, such as northeast Asia, and that orbital-timescale ITCZ shifts can have serious effects on temperate climate systems. Furthermore, our result implies that insolation-driven ITCZ dynamics may provoke water vapour and vegetation feedbacks in northern mid-latitude regions and could have regulated global climate conditions throughout the late Quaternary ice age cycles.

The curiosity at WUWT


The research is interesting in and of itself. What I also found interesting from a denier-watch perspective was that it was presented at WUWT without any "claim" in the headline and as if it were solid science, not something to be mocked. Anthony wrote the following headline and lead-in (archived here):
Study finds climate of the past behaved as hemispherical opposites
Posted on June 18, 2014 by Anthony Watts
This is from a press release from the Korean Institute of Geoscience and Mineral resources (KIGAM) The English in the PR is not the best, but is does have an interesting finding.

The question in my mind is:
  • Is this a new resolution of Anthony's in response to a small number of people requesting less scoffing at science and more of the "here it is, you decide" approach - or
  • Is it that Korean science is more acceptable to science deniers than science from the USA, Oceania and Europe? (Two of the authors are from the University of Minnesota, but Anthony probably doesn't know that.)

The research itself relies on fairly sparse data from few locations - "24 separate speleothems from 15 limestone caves" in Korea combined with what I understand to have been existing analyses from selected locations elsewhere in the world.  The southern hemisphere data is only from a few locations - described in the research as the western Pacific, though it includes caves in Naracoorte in South Australia.

The supplementary information includes the following images (click to enlarge):
Background image is from NASA Eclipse Web Site (http://eclipse.gsfc.nasa.gov/transit/TV2004.html). a, Peak interglacial periods are characterized by large geographic variations in the seasonal ITCZ and strong atmospheric meridional overturning circulations. b, Stadial periods show intermediate climatic conditions between those of peak interglacial and full glacial periods. c, Interstadial periods show intermediate climatic conditions between those of peak interglacial and full glacial periods. d, Full glacial periods are characterized by small geographic variations in the seasonal ITCZ and weak atmospheric meridional overturning circulations. Conceptual geographic ranges of estimated permafrost and ice sheets during stadial periods are shown by grey- and white-coloured areas, respectively48. Also shown are the cave locations of active speleothem growth during each time period (red dots)4, 15, 21, 42, 49, 52, 54, 55, 56, 57, 58, 59. See Methods for a detailed description of the scenario.

I'm not questioning the research itself.  It looks quite interesting and the scientists themselves as well as reviewers from Nature think so too.

What I'm curious about is why, when science deniers reject global temperature reconstructions of the past one or two millenia, which are based on many, many more proxies of many many more different types from many, many more locations all around the world - why they would embrace a study of climate patterns over five hundred and fifty millenia based on a very small number of proxies from a much smaller number of locations? (You may recall the vehement protests from the denialati at Marcott13.)


From the WUWT comments

Anthony Watts had better watch out. Some of his readers respond as if the paper has merit - heaven forbid! For example, a couple of people picked up on the orbital linkage (Milankovitch cycles), though they didn't seem aware that the research findings were that this was likely a "climatic response to orbital forcing". JimS says:
June 18, 2014 at 6:33 pm
Perhaps this phenomenon can be explained by the Milankovitch precession cycle?

Frank Lee responds to JimS and says:
June 18, 2014 at 7:58 pm
JimS suggested this may have something to do with Milankovitch’s precession cycle, but I believe it is the eccentricity of the elliptical orbit that would better explain the differences between the northern and southern hemispheres. As I understand them, both the tilt and precession cycles would move both hemispheres toward or away from a glaciation at the same time, but the eccentricity cycle would have opposite effects on the hemispheres. 

PeteP adds some information from a sciencedaily.com article about  a 2009 paper about oceanic patterns and says:
June 18, 2014 at 8:50 pm
Is this perhaps related to, and builds on, this study of the Atlantic Ocean currents?
Cardiff University. “Oceanic Seesaw Links Northern And Southern Hemisphere During Abrupt Climate Change During Last Ice Age.” ScienceDaily. ScienceDaily, 3 March 2009. .
The new study suggests that abrupt changes in the north were accompanied by equally abrupt but opposite changes in the south. It provides the first concrete evidence of an immediate seesaw connection between the North and South Atlantic. The data shows, for example, that an abrupt cooling in the north would be accompanied by a rapid southerly shift of ocean fronts in the Southern Ocean, followed by more gradual warming across the south.
Dr Barker explains: “The most intuitive way to explain these changes is by varying the strength of ocean circulation in the Atlantic. By weakening the circulation, the heat transported northwards would be retained in the south.” 

Greg Goodman starts off well but spoils it a bit at the end when he says (excerpts):
June 18, 2014 at 11:39 pm
There have been several lines of evidence that the hemispheres do not run in sync.
A lot of warmist claims that LIA was predominantly a NH phenomenon. Opposite tendancies of polar trends as we are currently seeing, often refered to as “polar see-saw” and differences of timing in the changes that marked the end of last glacial period.
...There are clearly large scale changes that produce opposing effects in each hemisphere. Since the NH has more land and thus less heat capacity at the surface it’s temperatures will vary more than SH. Thus the usual obsession with metrics like “global mean surface temperature” could suggest “global warming” even if the global heat content did not change. 

Then come the less knowledgeable WUWT-ers. Gunga Din confuses weather and climate and says:
June 18, 2014 at 6:56 pm
Perhaps I missed something (wouldn’t the first time), but might not the fact that the seasons are opposite in the NH and SH have something to do it?

Santa Baby says irrelevantly and wrongly (the sun has a polarity flip every 11 years or so):
June 18, 2014 at 8:31 pm
The Sun changes magnetic polarity after aprox 22 years and Earth does not? 

philjourdan says:
June 18, 2014 at 5:37 pm
That seems to jive with the fact that almost all the warming during the 90s was in the NH. And why Antarctica ice is growing.


Finally the hard core WUWT illiterati bash away at their keyboards, as they do with every science article. Eustace Cranch says:
June 18, 2014 at 6:14 pm
“…in relation to glacial and interglacial cycles which have been puzzled for the past 60 years.”
The cycles have been puzzled? Dang, climate science confuses everything :)

And illiterati member Aphan says:
June 18, 2014 at 7:30 pm
Wait..what? They are just now figuring out that they are opposites??? Woah

cnxtim says:
June 18, 2014 at 5:16 pm
So, I guess now the new “scare-em” headline will be CHAGW?


Kyoung-nam Jo, Kyung Sik Woo, Sangheon Yi, Dong Yoon Yang, Hyoun Soo Lim, Yongjin Wang, Hai Cheng, R. Lawrence Edwards. "Mid-latitude interhemispheric hydrologic seesaw over the past 550,000 years". Nature, 2014; 508 (7496): 378 DOI: 10.1038/nature13076

Barker, Stephen, Paula Diz, Maryline J. Vautravers, Jennifer Pike, Gregor Knorr, Ian R. Hall, and Wallace S. Broecker. "Interhemispheric Atlantic seesaw response during the last deglaciation." Nature 457, no. 7233 (2009): 1097-1102. doi:10.1038/nature07770

1 comment:

  1. Never was so much ignorance owed by so many to so few! Bert
    Apologies to Churchill.

    ReplyDelete

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