Anthony Watts has put up another shonky chart of GISP2 temperatures (archived here). No-one's complained so far, but he's got the current temperature in central Greenland as being about as cold as the Little Ice Age or colder.
Here is GISP2 from the Richard Alley data (Cuffey and Clow). These data go from 95 years BP to almost 50,000 years ago. I've only included the past 20,000 years or so. 95 years before present is 95 years before 1950, which is 1855. I've put in the average temperature at the summit for the decade 2001-2010, which was 29.9°C, as indicated in Kobashi et al (2011), which I discuss a bit further down.
|Data source: Alley, R.B.. 2004. GISP2 Ice Core Temperature and Accumulation Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #2004-013. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.|
Here is the WUWT chart:
See how Anthony Watts reckons that it's as cold as the coldest period in the Little Ice Age? He's put the "present temperature" and "present global warming" the same as the temperature back in 1855.
Look more closely. You'd have thought Anthony and his merry band would have known when the denier's favourite periods, the Little Ice Age and the Medieval Warm Period took place. But he gets those wrong, too. [h/t a few people]
He's been told about this over and over and over again. But he won't take any notice. At WUWT it's whatever you can get away with to reject science.
Here are charts from the 2011 paper by Takuro Kobashi and colleagues, showing surface temperatures in Greenland over the past 4,000 years.
A cosmic event, but no certainty
Anthony's shonky chart was to illustrate a press release about a new paper in the Journal of Geology, which is about the distribution of nanodiamonds, which the authors say support the hypothesis that the Younger Dryas cooling was caused by a cosmic collision, perhaps a comet, crashing here on Earth.
You can read the press release here. If you've a subscription, you can read the paper here.
Neither the press release nor the paper makes the strong claim of Anthony's headline, which was: "Younger Dryas climate event solved via nanodiamonds – it was a planetary impact event". The press release and the paper talk about the evidence being consistent with the cooling 12,800 years ago being caused by a cosmic impact, and inconsistent with it being caused by "natural terrestrial processes".
I'm not making any comment on the paper. Feel free to talk about it if you want to. I was mainly writing this article to talk about the mislabelled chart that keeps resurfacing at WUWT in one guise or other.
From the WUWT comments
By the time I'd finished writing, I see that finally at least one person commented on Anthony's chart. Greg asked:
August 29, 2014 at 9:20 am
What’s the source of the Greenland temp graph in this article?
Showing current temperatures almost as low as LIA :?
gary gulrud would like to see other evidence of a cosmic impact. That's not an unreasonable request.
August 29, 2014 at 10:19 am
Not an expert but 13,000 years is like geologic yesterday. Point me to the crater, please?
There were various other comments and speculation. The deniers are playing sceptic (for a change).
Kobashi, Takuro, Kenji Kawamura, Jeffrey P. Severinghaus, Jean‐Marc Barnola, Toshiyuki Nakaegawa, Bo M. Vinther, Sigfús J. Johnsen, and Jason E. Box. "High variability of Greenland surface temperature over the past 4000 years estimated from trapped air in an ice core." Geophysical Research Letters 38, no. 21 (2011). DOI: 10.1029/2011GL049444
Charles R. Kinzie et al "Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP" The Journal of Geology. Article Stable URL: http://www.jstor.org/stable/10.1086/677046