Huang’s Inconvenient Paper
By Paul Homewood
I came across a paper, originally published in 1997, rather by accident. Called “Late Quaternary temperature changes seen in world-wide continental heat flow measurements”, and written by Shaopeng Huang, Henry N. Pollack and Po Yu Shen, it uses analysis of more than 6000 bore holes to construct a record of global temperature for the last 20,000 years.
Significantly, the paper was published just before Michael Mann’s infamous hockey stick came out.
Huang’s abstract succinctly sums up their findings.
ABSTRACT
Analysis of more than six thousand continental heat flow measurements as a function of depth has yielded a reconstruction of a global average ground surface temperature history over the last 20,000 years. The early to mid-Holocene appears as a relatively long warm interval some 0.2–0.6 K above present-day temperatures, the culmination of the warming that followed the end of the last glaciation. Temperatures were also warmer than present 500–1,000 years ago, but then cooled to a minimum some 0.2–0.7 K below present about 200 years ago. Although temperature variations in this type of reconstruction are highly smoothed, the results clearly resemble the broad outlines of late Quaternary climate changes suggested by proxies.
http://onlinelibrary.wiley.com/doi/10.1029/97GL01846/abstract
The paper itself offers a bit more detail:
So we learn that:
1) It was warmer than now for much of the Holocene, till around 2000 BC.
2) The colder interval during the Dark Ages, from 400 to 700 AD is identified.
3) Most importantly of all, the MWP is said to be up to 0.5K warmer than present, possibly more at the peak of warming 700-800 years ago.
4) The numbers imply that temperatures fell by up to 1.2K in the space of about 500 years.
The coverage of boreholes used was pretty comprehensive, albeit with a heavy NH concentration.
Boreholes, of course, are only one proxy for estimating past temperatures, and may well be far from perfect. But it does come to similar conclusions as evidence from ice cores, for instance, in Greenland.
But what really stand out is the fact that, when the IPCC report came out in 2001, it was Mann’s hockey stick that was put forward as if it was absolute fact, and the conclusions of the Huang paper were conveniently swept under the carpet.
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NOT A LOT OF PEOPLE KNOW THAT 
this is what we get from the greenland ice core
I don’t know about anyone else, but I find it hard to accept that temperatures measured in a borehole can tell us very much at all, even if it does fit with my view of climatic history.
Agreed!
I had a look through the pdf which is full of statistical stuff but short on details of how the measurements work. One can only presume that someone discovered that the relation of depth to temperature is not linear. They then discovered that the chart of deviations bore some resemblance to other charts of paleo temperature reconstructions. Unlike tree rings or ice cores where you can physically count the number of seasons gone by, with boreholes surely you have to do a fair bit of thumb-sucking.
Although it doesn’t sound very robust, if 6000 boreholes around the world show similar deviations then some common factor must be driving temperatures, and it could well be land surface temperature.
Unfortunately I couldn’t find the “method” part of the analysis on the web, but stoat has been busy and reported in wikipedia and elsewhere that the Huang Pollak Shen paper substantiates other reconstructions in showing that the past was cooler than today.
Geologically speaking, quite a lot. Provided the data is reliably obtained, meaning using a reproducible methodology, the rate of heat flow coming from or going into the earth is precisely the right data to understanding broad scale climate change history.
Paul, it might be helpful if we could at least the figure 2 from the paper in front of us?
sorry, that should read: Paul, it might be helpful if we could at least SEE the figure 2 from the paper in front of us?
It’s in the link if you download it. I left it out it’s highly confusing! (You’ll see what I mean)
Anyway, take some time today to watch this video:
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The whole paper may be downloaded from the page of the link to abstract at top.
Thermal capacity and thermal conductivity altogether provide a very long thermal time constant for earth crust. Permanent heat flow from Earth core being rather constant upon billion years scope (provided no tectonic event occurs): All this follow simple Physics Laws. Thence superficial temperature variations are religiously recorded in ground first kilometers of depth. The difficulty is to cope with local heat generated by drilling when measuring temperatures afterwards, but this is very trivial.
Is there any discussion on heat flow through rock in the paper? I ask because I once visited a gold mine in South Africa and it was VERY warm at the bottom. My guide said the temperature was constant during the years he worked there. I have also noted that rocks in the desert can feel cold at night but are quite warm inside if they get broken open. Nights in the desert got very cool at the surface but if you had to climb a few feet up a radio mast you noticed the air was warmer. So much for desert night time lapse rate.
isnt this the same Huang who contributed the truncated borehole in the spaghetti graph? and then returned to his 1997-like results a few years ago? no doubt after checking which way the wind was blowing ;>))
yup…..
from JoNova, http://joannenova.com.au/2012/11/the-message-from-boreholes/
@Ian
nice
here is the original graph that I checked
compared to this
the greenland ice core analysis shows a relatively stable temp. for the past 10000 years, ie. from -8000 to 2000AD.
Paul, the boreholes issue is interesting, and I spent quite a bit of time going through it.
http://joannenova.com.au/2012/11/the-message-from-boreholes/
I see Ian c posted the spaghetti graph I did of the various interpretations of huang et al over the years, all of which contradict the other versions. As far as I can tell, we need another 1000 years of data to definitively calibrate boreholes with surface temps. But boreholes are quite good at marking out “global swings”. I found the newer calibrations of Huang unconvincing. Many proxies estimate the peak of the MWP to be about 950-1000AD, and the bottom of the Little Ice Age to be about 1700AD. The newer Huang moved the little ice age forwards in time, and the MWP too. This presumably shrinks the size of the amplitude, and underestimates the temperature swings, which fits with the theme of the hockeystick, but the timing is shot.
Even the 1997 initial Huang paper estimates the peak of the MWP to be in 1350 and the LIA in 1800. If the heat took longer to flow through the rock and these peaks were really in 1000AD and 1700AD, the temperature swings would be even larger wouldn’t they?
Never forget that according to Ice core data the previous millennium 1000 – 2000 AD was the coldest of our current benign Holocene. i.e. more that 1.5degC colder than the climate “optimum”.
The Holocene at 10,000 years plus is long in the tooth and has been responsible for all the advancement of mankind. It should fall of the edge anytime this century, next century or within this millennium.