flacaltenn
Diamond Member
http://www.nature.com/nature/journal/v484/n7392/full/nature10915.html
and
A Reconstruction of Regional and Global Temperature for the Past 11,300 Years
[[Apologies, initially pasted the first link in twice]]
Just a few points about your display of proxy data.
Those graphs are the temperature reconstructions from proxies located in different places all over the world. Note the vertical scale. When attempting to calculate the average temperature of the entire planet, it will be necessary to combine temperatures from the hollows of the Antarctica mountains to the sand dunes of the Gobi desert. Right? Such datasets will subtend a relatively large vertical expanse of your workspace. Thus your first plot.
Second, the conversion ratios between proxy parameters and temperature is frequently neither linear nor constant over time (thus "the decline").
This data presentation is disingenuous; intended to make the process look faulty in a manner you should know it was not.
hahahaha! look faulty?
I am trying to show people how uncertain proxy data is. not only is the data uncertain but the methodology for choosing the proxies and then standardizing them also adds more uncertainty.
the OP actually starts off questioning why Shakun truncates CO2 at the beginning of the interglacial. the reason, of course, is that temps start going down while CO2 continues to rise. that dilutes the message somewhat doesnt it?
proxy reconstructions are a good and necessary thing. so are climate models. the problem arises when they are presented to an unsuspecting public as 'a sure thing', and the conclusions drawn from them as solid evidence. Shakun had very little evidence about the CO2 levels yet made pronouncements as if he did, to the press. Marcott made a reasonable paleoreconstruction for his PhD thesis but then added a hockeystick at the end incorrectly and went out on a press release tour.
I have just flipped through this entire thread. I find nothing from you concerning Shakun truncating CO2 data at the beginning of the interglacial. So you will have to explain that charge if you want to talk about it.
As to running down Marcott because he put a 20th century proxy on the end of his data: that charge has always appeared to me to be a ridiculous stretch. You described the rapid temperature rise of the 20th century as a "preconceived conclusion". Sorry, Ian, but that boat has sailed.
Try again.
Ive posted interviews with Marcott concerning proxy accuracy.. Hes very honest about not having either time resolution or temp resolution left after the averaging process.. Resolutions of 100s of years ARE NOT GOOD enough for Abe to rely on them to show that either the current temp or THE RATE OF CHANGE of that temp is exceptional for the modern era..
INDIVIDUALLY those regional proxies might be meaningful. But there is not adequate spatial sampling to ever give credibility to a "GLOBAL AVERAGE.
Replacing proxy data with modern data is not a crime.. But you SHOULD BE OBLIGED to show how well the proxy average APPROXIMATES the modern record.. if u dont do that you are misrepresenting the credibility of the study.. No temp rez or time rez for the modern record out of the proxies by themselves? Then dont make outrageous claims in the headlines comparing modern temps and rates to millenia ago... Simple academic honesty.
And Marcott has attempted to quell the proxy hype...