In response to my previous twitter conversation, and analysis of the poor ‘H&M’ graph here, Paul Carfoot responded.
So I went to look. The conversation with ‘sceptics’ revolves around AGW being ‘nothing new’ as it has been warmer in the past. So despite the graphs I refereed to previously clearly showing a 2004 temperature much higher than the MWP or other ‘peaks’, that point in my commets is assiduously ignored. So I looked at Paul’s blog to see his evidence for wny he thinks the H&M graph is OK as a reference.
The argument around current temperatures looks at this graph (linked by Carfoot to WUWT but actually from Alley)
Carfoot says “As you can clearly see it has been much colder in the past and much warmer too. ”
But the Alley graph & Easterbrook graph are for Greenland, not global, and the dates are to 1855, not present.
The second graph links to Ice Age Now, but the original is by Easterbrook.
Ice Age Now say “Created by Cuffy and Clow in 1997, and based on Greenland ice core records, this chart shows global temperatures for the past 15,000 years.” Carfoot says of these graphs “so why are we being told that it is warmer today than ever before in history? I will leave that question unanswered and for you to decide.”
The graph is Easterbrook graph is based on GISP2. However, the GISP2 “present” follows a common paleoclimate convention and is actually 1950. So the most recent temperature in the GISP2 series is therefore 1855. (more here and another critique here)
Here is the Cuffey (sp) & Clow paper from 1997. Carfoots graph is probably via WUWT here. Here is a version of the same, generated from the original data, plus the average temperature at the summit for the decade 2001-2010 – from here.
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.
So, finally, it doesn’t show global and it doesn’t show todays temperature, so that argument is disproved. You cannot rely on temperatures at the top of the Greenland ice sheet as a proxy for global temperatures. Easterbrook’s claim that “most of the past 10,000 [years] have been warmer than the present” is not true for central Greenland, let alone the global record.
There is another detailed analysis here, this graph is pertinent.