Skip to comments.The Marcott Hockey-stick: smoothing the past and getting a spike from almost no data? (AGW nonsense)
Posted on 03/15/2013 9:20:32 PM PDT by Ernest_at_the_Beach
It's Friday evening in the USA but Saturaday in Australia....
Just came across this....and it has a lot of Graphs...have not read thru it at all....but they are trying the Good ole Mann Hockey stick again....
Too much MONEY at stake for the leftie Politicians ....they just have to keep LYING!
The message to the world is unequivocal:
We are heading for somewhere that is far off from anything we have seen in the past 10,000 years its through the roof. In my mind, we are heading for a different planet to the one that we have been used to, said Jeremy Shakun of Harvard University, a co-author of the study.
There are two factors in the new Marcott paper that are major red flags. For one, there is hardly any data in the modern end of the graph. Ponder how researchers can find 5,000 year old foraminifera deposits, but not ones from 1940? Two: theyve smoothed the heck out of longer periods. Marcott et al clearly say there is essentially no variability preserved at periods shorter than 300 years So if there were, say, occurrences of a warming rise exactly like the last century, this graph wont show them.
Some of the data has a resolution as poor as 500 years and the median is 120 years. If current temperatures were averaged over 120 years (that would be 1890 to now), the last alarming spike would blend right in with the other data. Where would the average dot be for the last 500 years. It would be low, cold, and there would be no hockeystick at all in a 500 year averaged graph. But if there was a period of rapid warming sometime in the last 10,000 years, one which occurred over say, 50 years, it would disappear amongst the uncertainties.
Robert Rohde (of the BEST Project) points out that so much of the variance is lost that it is equivalent to smoothing the series with a 400 year running average, saying it will completely obscure any rapid fluctuations having durations less than a few hundred years.
It may be necessary to sacrifice the variance, and blend and blur those past peaks (given the uncertainties) but after doing so, how can Marcott et al say anything at all, even a squeak, about the rate of warming in the last 100 years?
In the end the hockey stick seems to come from a 20 year reconstruction of data that has a median of 120 year resolution. Would that have the effect of heavily weighting some proxies while smoothing out the others? Its all very well to trumpet that there are 73 proxies, but some of them obviously count for a lot more than others.
The new hockey-stick blends high and low resolution data from many proxies in the past with mixed resolution data (but few proxies) in recent times. Its a complex method which produces something not seemingly reflected in the actual proxy data. Where are the hockey-stick-proxies? It also doesnt help that ten percent of all 73 proxies fail their own criteria for inclusion. (Thanks to Willis for all those spectacular spaghetti graphs, and thanks to both Craig Loehle, and Roberto Soria for advice).
Am I reading this incorrectly? Note fig a and fig e here. See that dive to zero on the right hand edge just at the point that the hockey-stick appears in lower graphs? Are there virtually no proxy records during the time of the spike? Note that the lines in the other graphs here come from temperature reconstructions which are area weighted and Monte Carlo based graphs.
See also the next figure. Note in a and d, the ragged edges as the proxies run out of data on the right? See how the number of records plummets to zero? Note how this correlates with the spike (c and f). Steve McIntyre writes that the Alkenone proxies are the largest group of proxies (31 of 73) yet the uptick is mysteriously absent from the data. McIntyre does not believe that the uptick is due to splicing in of the instrumental data, but cannot explain it yet. Can Marcott explain it? You would think so, but his response left McIntyre baffled.
Notice in c, the hockey-stick spike is coming mostly from the ocean? Hmm.
Even Marcott admits the reconstruction of the modern spike is not robust in either the Northern or the Southern Hemisphere, and where else is there? (Thanks to Steve McIntyre for asking him).
Regarding the NH reconstructions, using the same reasoning as above, we do not think this increase in temperature in our Monte-Carlo analysis of the paleo proxies between 1920 − 1940 is robust given the resolution and number of datasets. In this particular case, the Agassiz-Renland reconstruction does in fact contribute the majority of the apparent increase.
Regarding the SH reconstruction: It is the same situation, and again we do not think the last 60 years of our Monte Carlo reconstruction are robust given the small number and resolution of the data in that interval.
So why all the newspaper headlines? The non-robust result turns into a PR message.
Did they mention this is the paper in paragraph four as Marcott says? Well, kind of not really. Heres a hint:
Without filling data gaps, our Standard5×5 reconstruction (Fig. 1A) exhibits 0.6°C greater warming over the past ~60 yr B.P. (1890 to 1950 CE) than our equivalent infilled 5° × 5° area-weighted mean stack (Fig. 1, C and D). However, considering the temporal resolution of our data set and the small number of records that cover this interval (Fig. 1G), this difference is probably not robust. Before this interval, the gap filled and unfilled methods of calculating the stacks are nearly identical (Fig. 1D).
Hes saying the difference between the two versions is not robust, but not that the main feature of the graph is fickle, flakey, or may disappear under analysis. (Thanks to McIntyre and Eschenbach for spotting that.)
Me, I wonder why Science published the paper in the first place?
Now look at the graphs of the actual proxies offered in the supplementary material. Note how the proxy data in red and blue lines shows no hockey-stick. But this is the tropics, so thats not unexpected.
Same with these northern hemisphere proxies. No hockey stick in this data either?
A lot of the data is from the ocean, which shouldnt rise and fall nearly as much as land based data, yet apparently caused the spike?
The spike below certainly looks spectacular on the 11,000 year scale. Great visual, nice optics but we struggle to point to many actual proxy data points from individual sites that shows this shape, let alone many widespread proxies which we ought to expect if this is a global temperature representation? Marcott averaged many non-spikes and got a spike tricky eh?
The supplementary material is extensive, which is commendable. It describes, at length, how they use simulations to reconstruct the global temperature. On top of that is a 20 year sampling done on the data in the last 1500 years. The hockey stick does not show in 100 year or 200 year samplings. (The blue line below is the 20 year sampling). It also did not show in the Marcott PhD thesis of 2011. The plot thickens?
In their methods (below), the bolded phrase in point 3 describes how they chose to compare to high-resolution reconstructions of the past 1000 years, in this case to Mann. Their graph wouldnt look as reliable if they compared it to Ljundqvist, or to Loehle
They talk of using the instrumental record to check to see that their locations are representative of global temperature (which it may well be, but if they dont have proxy data from recent times, they dont have proxy data ).
To examine whether 73 locations accurately represent the average global temperature 271 through time, we used the surface air temperature from the 1×1° grid boxes in the NCEP-NCAR 272 reanalysis (83) from 1948-2008 as well as the NCDC land-ocean dataset from 1880-2010 (84). [Page 20 supplementary materials]
Look at the downward slope, and uptick in b. Note how it doesnt mesh with the red model.
The authors describe how the North Atlantic has the largest disagreement with the model:
Comparing the temperature data and model simulations by region demonstrates that the largest data-model disagreement is in the mid-high latitude Northern Hemisphere sites while the data and model in the equatorial and mid-high latitude Southern Hemisphere sites are in agreement within the Monte Carlo based uncertainty after 9,000 yrs BP (Fig. S25b,c,d). When the North Atlantic proxy sites that show the largest temperature changes are removed, the data and model are within the Monte Carlo based uncertainty, both in the global stack and the mid-high latitude northern hemisphere stack (Fig. S26a,b). The data-model disagreement may suggest that the model could be missing a key climate component that is intrinsic to the North Atlantic basin. In particular, the AMOC may have slowed during the Holocene, resulting in an amplified cooling in the North Atlantic basin and a warming in the Southern Hemisphere that could have dampened any cooling effect expected from orbital tilt (87-89).
Here the northern Atlantic data is removed.
The Southern Hemisphere contains the fewest proxies. Food for thought?
There is much entertainment on skeptic blogs as this epic study gets unpacked. Tune in this weekend
Its just a shame that science authors are in such a rush to get their news headlines that they dont publish online first (or ask Steve McIntyre to review it), so they could iron out the details before hundreds of thousands of people were told a story that didnt stack up.
Lewis, S.E., et al., Post-glacial sea-level changes around the Australian margin: a review, Quaternary Science
Reviews (2012), http://dx.doi.org/10.1016/j.quascirev.2012.09.006 [abstract] (paywalled).
Ljungqvist, F. C., Krusic, P. J., Brattström, G., and Sundqvist, H. S (2012).: Northern Hemisphere temperature patterns in the last 12 centuries, Clim. Past, 8, 227-249, doi:10.5194/cp-8-227-2012, 2012. [abstract] [PDF] or try this [PDF] [CO2science discussion]
Svend Funder1, Hugues Goosse, Hans Jepsen, Eigil Kaas, Kurt H. Kjær, Niels J. Korsgaard, Nicolaj K. Larsen, Hans Linderson, Astrid Lyså, Per Möller, Jesper Olsen, Eske Willerslev, A 10,000-Year Record of Arctic Ocean Sea-Ice VariabilityView from the Beach, Science 5 August 2011:Vol. 333 no. 6043 pp. 747-750 DOI: 10.1126/science.1202760
Weekend reading....however the first few paragraphs pretty much give the story.
The hockey stick is a fraud and global warming is a fraud.
No hockey stick, just red card and penalty box.
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