There’s a new Lonnie Thompson article online at PNAS (thanks to Steve Bloom for reference). It has some "supporting data" – "supporting data to Thompson means only digital versions of the graphics, rather than detailed archives such as Majewski provided for the Everest ice core. Just to annoy anyone who was actually interested in the data and create a obstacle, Thompson archived this limited data as pdf rather than ascii. You can convert it to ascii, but it took me a couple of hours by the time that I’d sorted out different number of entries on each line.
Thompson mentions the 5000-year old plants. I’ll discuss this on another occasion. Here I only note that Thompson does not provide any detailed information on the exact location of the plant deposit or whether this was the only organics recovered.
Thompson takes note of the increasing doubt about whether is a temperature proxy, and, in his closing, argues that anomalous is evidence of anomalous climate, even if it’s not directly associated with temperature. However, for the most part, he directly equates levels and temperature. He discusses both Tibetan and Andean results. Here I’m just going to talk briefly about Andean results.
The graph that carries forward to his Tropical Summary is his Andean "summary" shown below:
From Thompson et al Figure 5D
The blue curve is accumulation; the red curve is . (The only contributor to the blue curve is Quelccaya as flows at the other sites appear to have prevented annual dating. I haven’t checked exactly what’s going on with dating at these other sites.
From the above graphic, it appears that the Andean levels are closing at a fairly loud two-sigma departure. Seemingly powerful evidence of anomalous climate. But this is the Hockey Team, so it never does any harm to check the individual series.
The underlying 5-year averages for Thompson’s three Andean sites are shown in Thompson’s Figure 5A, shown below. Now, I don’t know about you, I have trouble discerning a strong and robust common warming trend in the these three series. Squinting at the Huascaran series in particular, I’d say that, if is supposed to be a thermometer, it doesn’t show anything anomalous about the last half of the 20th century. Same with the Sajama series. No values are shown for Huascaran in the 1990s (I’m not sure why) and none for Sajama in the last part of the 1990s. Now Quelccaya was updated in 2003. It seems to be the active ingredient in the overall average, so I guess it must show a big 20th century trend. In this case, there have been 3 holes, 2 drilled in the mid 1980s (with archived results) and the 2003 update, so it must tell quite a story.
From Thompson et al Figure 5A
Thompson has archived annual from the 2003 hole from 1604 (but no earlier) to 2002 in connection with the PNAS publication. I’ve compared this data to previous results for two 1984 holes in the graph below, showing 20th century results. A small preliminary point before I discuss the obvious: the very elevated values: although the 2003 hole tracks the earlier holes fairly closely, for some reason the very elevated values associated with the 1983 El Nino are not shown in the 2003 results. Thompson does not discuss this. Possibly the values of adjacent years have blended together because of melting or diffusion or something, but the 2003 values are much smoother through the 1983 El Nino than the earlier results.
Quelccaya for 20th century. Compiled from previously archived data and from NAS archive. Black – 2003 core; blue, red 1984 cores.
Maybe it’s just me, but I have trouble discerning a strong 20th century trend in this data. If I didn’t know that this data seet was suppsoed to end two sigmas on the hot side, I’d also be inclined to say that the last few years of the record end up pretty close to the average value. Yes, there was a strong El Nino reflected in elevated 1997 values, but it looks like there was strong El Nino in 1941 or so as well.
Now the last few years of this record do not make a 5-year average and I’m sure that was the only reason why Thompson didn’t use them in his summary graphic. But don’t you wonder just a little a bit, if the up-to-date values had been off the chart, that Thompson might have figured out a way to get them into the graphic.
But there’s interesting data news: here we have an up-to-date proxy record, right up to 2002. On the multiproxy theory of the world, this proxy record should have been off the chart because of late 20th century warming. I have trouble discerning an increase above levels in the 1930s (as with Greenland). But maybe that’s just me.