Mann tries to revive his dead hockey stick with a press release

Why don’t you post a link to a peer reviewed reconstruction ?

For the DIY data analysis junkies (like me) this portal is indispensable: http://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets
And the aforementioned Moberg, et al. (2005): http://www.ncdc.noaa.gov/paleo/pubs/moberg2005/moberg2005.html
Also available from KNMI:
http://climexp.knmi.nl/data/imoberg2005.png
Compare to Mann, et al. (2009):
http://climexp.knmi.nl/data/inh_mann.png

[trimmed]

dbstealey,

As we see posted right within most of the graphs, they are based on empirical evidence. They aren’t reconstructed past temperatures that are elucidated on their spatio-temporal pattern.

http://www.climatedata.info/Proxy/Proxy/icecores.html
Whilst ice cores allow direct measurement of atmospheric gases, like CO2 and Methane, some care is needed in interpreting the results. This is because of the fact that, while the snow is being compressed into ice, gas transfer may occur between the atmosphere and the layers of ice. Indeed, dating information is sometimes given for the “ice age” and “gas age”. Because the gases in the atmosphere are mixed and decay over time this adds another element of uncertainty. In effect, the data represent the average over a period of time, which can be several decades; a corollary of this is that data calculated from ice cores, for temperature of CO2 for example, will have less variation than the measured record.
Errors in the time of events identified in the ice core records can be in hundreds of years. The following graph shows ice ages estimated for the Vostok ice core by 4 different methods compared with “orbital tuning”. Orbital tuning refers to calibrating the times against the Milankovitch cycles and the associated changes in radiation (Figure 1).
In the case of temperature no direct measurement is possible. The temperature values are estimated from different isotopes of oxygen and hydrogen. The methodology is based on the assumption that different isotopes evaporate at different rates depending on the temperature. It is generally considered that the best estimate of temperature from ice cores is based on the use of both Oxygen-18 and Deuterium. Another complication is that ice is not stationary, which means that the ice collected at lower layers may not be the ice that was originally underneath the upper layers. Despite all of these limitations, it is generally accepted that ice cores give a good representation of temperature over very long periods. They are able to answer such questions as what drives the cycle of ice ages and warm periods and what is the role of CO2 in long-term climate change.
http://www.pnas.org/content/97/4/1331.full
Where annual layers are not observed because of depositional or postdepositional effects, by dating is conducted by correlation to other well-dated records, radiometric techniques in favorable circumstances, and by ice-flow modeling if needed.
…
The amount of ice between two time lines in a core, corrected for the layer thinning from ice flow, is the snow accumulation (9). The flow corrections range from trivial and highly accurate to difficult and uncertain, depending on the site and its history. Buried snow drifts introduce noise in the records, and sublimation may be important in especially low-accumulation zones, but accumulation typically provides a useful history of atmospheric delivery of snowfall to a site (9).
…
Paleothermometry.
Ice cores are local paleothermometers, telling past temperature where they are (or where the snow fell, if glacier flow has caused ice in a core to have come from a significant distance). The classic paleothermometer is the stable-isotopic composition of water in the ice core (10). Natural waters typically contain a fraction of a percent of isotopically heavy molecules (in which the hydrogen or oxygen contains one or two “extra” neutrons). The vapor pressure of this heavy water is less than for “normal” light water. As an air mass is cooled and precipitates, it preferentially loses heavy water and must increasingly precipitate light water. At very low temperatures, heavy water has been greatly depleted and precipitation is isotopically light. Empirically and theoretically, isotopic composition of precipitation and site temperature are strongly correlated in time and space (10, 11); colder places and colder times have isotopically lighter precipitation.
Repeated for emphasis: strongly correlated in time and space
Compare: elucidated on their spatio-temporal pattern

One more reminder for the learning impaired: there is still not one measurement of AGW.

So according to you, we know all about past climate change from indirect estimates via ice cores (sometimes using MODELS no less!!!), but are completely incapable of measuring it directly today with modern instrumentation. As well, ice core data are empirical evidence, everything else is “alarmist mumbo-jumbo” for some unknown though likely arbitrary reason. Yes, I see the superiority of your argument.

dbstealey,

Gates, I read the first sentence, which referred to “interpreting”. Intrepreting is not modeling; everyone interprets all the time.

Ahead of the curve I see. The expected stopping point was: Where annual layers are not observed because of depositional or postdepositional effects, by dating is conducted by correlation to other well-dated records, radiometric techniques in favorable circumstances, and by ice-flow modeling if needed.

I stopped reading your confirmation bias after that. I have better thing to do then to read your cherry-picked nonsense.

So sorry. I could go back to name calling instead of discussing science if that would make you more comfortable.

Global warming has stopped. That’s something you can’t handle. And all your pal-reviewes carp means nothing compoared with that fact.

Oh. Well, this plot …
http://jonova.s3.amazonaws.com/graphs/lappi/gisp-last-10000-new.png
… which you posted as “empirical evidence” supporting your argument is from same guy who wrote the “pal-reviewed carp” and “cherry-picked nonsense” which you see as evidence of my “confirmation bias”. In other words, you should probably stop using that plot, it’s all effectively the same “smoke and mirrors”. Pretty clever those warmists, they even manged to fool you.

(A wasted posting effort by a banned sockpuppet. Comment DELETED. -mod)

[snip. -mod.]

milodonharlani,

Brandon, you must be aware that Cowtan & Way reconstructed numbers, so their Frankenstein´s monster is not comparable to ice core observations, ie actual data.

ROFL! Tell you what, let’s just ditch modern thermometers altogether then and use only “actual” ice core data from now on!

Your graph is like the HS, with rotten apples grafted onto incomparable oranges.

You do realize that all proxy reconstructions are calibrated against instrumental records in the first place, don’t you? Yes, even ice cores. How do you think we mapped deuterium isotope ratios to temperature to begin with?

dbstealey,

So obviously Gates gets his talking points and misinformation from low-traffic alarmist blogs.

My comments to milodonharlani on ice cores are based on information I obtained from primary literature: http://wattsupwiththat.com/2015/02/15/mann-tries-to-revive-his-dead-hockey-stick-with-a-press-release/#comment-1860597
But you wouldn’t know it because your immediate reply to that post clearly spells out that you didn’t read it: Gates, I read the first sentence, which referred to “interpreting”. Intrepreting is not modeling; everyone interprets all the time. I stopped reading your confirmation bias after that. I have better thing to do then to read your cherry-picked nonsense.

On the other hand, milodonharlani has been around for a long time, and he knows what he’s talking about.

And there we have it. Citing literature written by domain experts and reviewed by their peers prior to publication is a fallacious appeal to authority, but vetting someone’s arguments on the basis of their relative history of blog commentary is not.
That is so fantastically bizarre.

milodonharlani,

If the difference between inferring past temperatures from ice cores & from the instruments & proxies used by Cowtan & Way escapes you, then there´s not much point in continuing.

Well since you continue on unabated regardless, it so happens that there’s a GHCN station on Greenland which covers nearly the entire period that HADCRUT4 product with the C&W interpolations:
ANGMAGSSALIK (GREENLAND (DENMARK))
coordinates: 65.60N, -37.63E, 52.0m (prob: 275m)
WMO station code: 4360 (get data)
Rural station
Terrain: mountain valley WATER
Station is located at 1km from coast
Found 119 years with data in 1895-2014
Being so near the coast, I wouldn’t expect it to show the same temperature variability as the interior of the island, but it compares nicely to the C&W dataset for both the 5-degree grid of the summit itself, better with the C&W dataset when I mask for the entire Greenland land mass. From 1700-present:
http://3.bp.blogspot.com/-F8_I4QkFDXo/VOPe1oM2IzI/AAAAAAAAAVk/H5_CFHCdxog/s1600/GISP2%2Bvs%2BHAD4CW%2Bvs%2BStations%2B1700%2BCE-Present.png
From 1600 BC to present:
http://1.bp.blogspot.com/-qSWF9WCGjIc/VOPe1umo10I/AAAAAAAAAVg/vytiUgcjmEc/s1600/GISP2%2Bvs%2BHAD4CW%2Bvs%2BStations%2B1600%2BBCE-Present.png
1300 BC is roughly tied for the highest Greenland Summit temperature in Holocene as estimated by Alley (2000).

In a comment to Bob Tisdale´s recent post, I asked Robert Way about the validity of your graph grafting Cowtan & Way onto Alley´s GRIP data. He was kind enough to reply that he preferred Kobashi´s approach & link to the relevant paper:
“In my view the Kobashi et al approach seems most appropriate:
see this study and the more recent ones
http://www.leif.org/EOS/2011GL049444.pdf”

Thank-you, I will review the comments and the linked paper.

The Eemian was also a lot hotter, without benefit of a Neanderthal industrial age. So were the prior super interglacials, again without fossil fuel burning by H. antecessor or H. heidelbergensis.

With benefit of higher insolation at high northern latitudes as estimated at the June equinox. And IIRC something on the order of 6-8 m higher mean sea level. Milankovitch partially explains timing and amplitude, but not fully. Varying insolation due to orbital parameters do NOT rule out CO2 and methane’s amplifying roles as a feedback to insolation changes. For the life of me I simply cannot understand why the insistence on such either-or arguments.