AGU presentation backs up McIntyre's findings that there is no late 20th century hockey stick in Yamal

If you are just joining us, the story is this. After 10 years of data being withheld that would allow true scientific replication, and after dozens of requests for that data, Steve McIntyre of Climate Audit finally was given access to the data from Yamal Peninsula, Russia. He discovered that only 12 trees had been used out of a much larger dataset of tree ring data. When the larger data set was plotted, there is no “hockey stick” of temperature, in fact it goes in the opposite direction. Get your primer here.

Now there’s independent confirmation from a study presented at the American Geophysical Union Conference in 2008 that there is no “hockey stick of warming” at Yamal.

The presentation is” Cumulative effects of rapid climate and land-use changes on the

Yamal Peninsula, Russia by D.A. Walker, M.O. Leibman, B.C. Forbes, H.E. Epstein. (click link for PDF)

In the hallway poster for their AGU presentation, they have this graph, with the caption saying a “nearly flat temperature trend” for Yamal, especially for the late 20th century period where the “hockey stick” from those 12 trees emerges:

See the AGU poster here (warning, big 18 MB PDF file)

Here is how they summarize the graph above in the AGU presentation:

• Sea ice: -25%
• Summer surface temperature: +4%
• Maximum NDVI: +3%
• None of the trends are significant at p =0.05 because of high interannual variability.

NDVI is the vegetation index.

There’s also an interesting polar sea ice, temperature, and vegetation index trend map that is similar to what Lucy Skywalker recently plotted.

I’m sure we’ll see an explosion from “Tamino” any minute now to refute this, oh wait, he’s gone on record as saying:

As for Steve McIntyre’s latest: I’m really not that interested. He just doesn’t have the credibility to merit attention. I have way better things to do.

OK then, one less angry, sciency, rant by an anonymous coward who won’t put his name to his own work to worry about. Talk about credibility. Sheesh.

Here is the conclusion Walker et al makes in their AGU presentation

• Satellite data suggest that there has been only modest summer land-surface warming and

  only slight greening changes across the Yamal during the past 24 years. (Trend is much

  stronger in other parts of the Arctic, e.g. Beaufort Sea.)

• Kara-Yamal: negative sea ice, positive summer warmth and positive NDVI are correlated

  with positive phases of the North Atlantic Oscillation and Arctic Oscillation.

So it seems sea ice extent, the NAO, and the AO are the bigger factors for temperature in Yamal. It also appears that the Arctic is getting slightly more green.

If anyone has access links to the full paper, feel free to post it here.