Geologist Dr. Sebastian Lüning and Prof. Fritz Vahrenholt have been busy mapping the Medieval Warm Period using Google as a tool.
Lately their focus has been on a number of studies examining temperature reconstructions from the Baffin Island and Western Greenland. This focus has been in part in response to a recent paper by Nicolás Young, a glacial geologist at Columbia University’s Lamont-Doherty Earth Observatory, which claimed with “great clarity of evidence” that the Medieval Warm Period did not exist globally and that it was a “patchy” phenomenon at best.
First Lüning finds that the paper’s emotional tone peculiar – one that seemed to be fishing for media attention at any price. Lüning notes, “One has to wonder that Columbia University would allow such an emotional and combative press release to go through.” Lüning and Vahrenholt added: “The paper also failed to get any attention from the German press. Did they sense that something could be rotten about it?”
Lüning’s and Vahrenholt’s spent three weeks examining Young’s paper and many others from the region. Their conclusion: Young’s paper is ripe for the dustbin.
In all the two German scientists looked at more than two dozen papers from the region inquestion, covering some 20 locations, see plot below:
Figure 1: Chart of studies with results of the Medieval Warm Period (MWP). The numbers refer to the sequence of the discussion in the text. Red points indicate MWP was warm, blue points show it was cold. See the interactive Google Maps map here.
Because time is short, I’ve translated only the summaries. All the abstracts of the more than 2 dozen papers presented are in English at Lüning’s and Vahrenholt’s post, which I’ve linked to above.
Summary of results for Canada
In the North Canadian Arctic, the situation certainly appears to be clear: The MWP is described in numerous studies. Only 2 of 16 glacier studies (among them the one from (Young et al. 2015) show MWP glacier advances, which likely was a local phenomenon, e.g. caused by heavy local snowfall.
Lüning and Vahrenholt also looked at studies examining western Greenland, see following chart:
Figure 2: Chart of studies with results of the Medieval Warm Period (MWP) – Close-up of Greenland’s west coast. The red markers indicate a warm MWP, the blue ones indicate it was cold. See the interactive Google Maps here.
In Western Greenland all studies show that the Medieval Warm Period was in fact warm. Moreover not only does Lüning’s and Vahrenholt’s comprehensive Google Maps-based survey show that the Medieval Warm Period was real in the Arctic, but that it was clearly a global phenomenon as well.
Lüning and Vahrenholt summarize:
The detailed analysis of all the literature concerning the MWP in the Northeast Canadian Arctic as well as western Greenland shows that the claims made Young et al. 2015 are untenable. The MWP in the region is well-documented. Suddenly all these studies are supposed to be wrong? Young and his colleagues obviously failed to put the other local studies in the necessary regional context. Because of the failure to do so, they arrived at misleading and faulty conclusions, which they actively promoted to the broad public in a provocative and scientifically unbalanced press release. It remains unclear as to why the peer-reviewers of the journal Science Advances did not detect these deficiencies and did not request corrections. Will the many authors of the papers presented here discuss the results with Young et al. in order to resolve the deviating results, or do they risk being publicly ostracized as climate skeptical lobbyists? The scientific climate discussion is in a political choke hold. The Young et al. paper and its inappropriate alarmist marketing (“coup de grâce for the MWP”) is an example of the questionable and emotionally-charged condition of today’s climate research.”
The valuable Google Maps resource was put together by Lüning and Vahrenholt, and is still in progress as much remains to be mapped. It has involved considerable work and has been crowd-funded so far by less than €12,000 in support from private donors. You can also help:
Donations by bank transfer:
Account : Prof. Dr. Fritz Vahrenholt
Account No.. 1280579069
Routing No.: 20050550
Please remark: MWP-Projekt
Donations by PayPal: