Simply put, Nova thinks the data in the HP97 graph she uses dates to 2000, when in fact it only goes to 1900; it doesn’t include the last 100 years of warming. And although the original authors have explained this, and Nova is fully aware, she chooses to ignore any science which disagrees with her own agenda and political motives.
That’s no exception in Nova’s look at the Medieval Warm Period, although she takes it ups it a notch. Not only does she incorrectly use Huang & Pollack 97 (HP97), she goes on to ignore very clear statements by the authors which explain why Nova (and others) misinterpret their HP97 results.
Lewandowsky – we’ve more data for you!
It seems strange that Nova is presenting the work of Pollack since, for those that aren’t aware, Pollack shared the 2007 Nobel Peace Prize with Gore and has been quite outspoken about our need to act on AGW (see here, here and here). So how is it Nova uses his evidence in support of her argument?
Lets be kind and say that initially Nova saw a graph (probably via Monckton) with data that made it look like the MWP was warmer than today and immediately grabbed it for her blog. Whoops, she didn’t read the fine print and had now painted herself into the corner of a borehole. If you read the paper HP97 state …
We excluded data with representative depths less than 100 m . . . [because] . . .the uppermost 100 meters is the depth range most susceptible to non-climatic perturbations. . .; moreover, subsurface temperature measurements in this range yield information principally about the most recent century
The authors of the 97 paper then go on to provide another couple of papers and in the 2008 paper they again specifically go to lengths to explain why it is incorrect to use the HP97 as evidence of a warmer MWP.
So why does Nova not accept their work? Nova says “Huang published another in 2008 where he discounts the meaning of his earlier work” and that they only modified their work so as to be included in the IPCC report (huh? A 2008 paper in the 2007 IPPC report???).
But they don’t discard their work at all! In S. P. Huang H. N. Pollack and P.Y. Shen 2008, they clarify why the 1997 paper can’t be used as a comparison against today’s warming …
The fundamental difference between HPS97 and HPS00 is that they do not analyze the same data. Below we describe their respective datasets, and show why the results of HPS97 cannot be used for comparing MWP warmth to the 20th century. We then proceed to integrate the two datasets into a new reconstruction …
The consequence of excluding the upper 100 meters is that the 20,000 year reconstructions in HPS97 contain virtually no information about the 20th century. As the authors of HPS97 we can be criticized for not stating explicitly in the abstract and figure caption that the ‘present’ (the zero on the time axis) really represents something like the end of the 19th century, rather than the end of the 20th century.
They also say:
These reconstructions show the warming from the last glacial maximum, the occurrence of a mid-Holocene warm episode, a Medieval Warm Period (MWP), a Little Ice Age (LIA), and the rapid warming of the 20th century. The reconstructions show the temperatures of the mid-Holocene warm episode some 1–2 K above the reference level, the maximum of the MWP at or slightly below the reference level, the minimum of the LIA about 1 K below the reference level, and end-of-20th century temperatures about 0.5 K above the reference level.
Despite being fully aware that the authors of the papers that Nova is listing do not agree with her, Nova goes ahead and deliberately misleads her readers. Another disgraceful and pathetically deceptive act!
Thanks to “Nice One” for pointing this out and doing the research into Nova’s deception.