Comments on: Millar et al: The Sierra Nevada MWP

By: Medieval Treeline in Finland « Climate Audit

Medieval Treeline in Finland « Climate Audit — Thu, 28 Oct 2010 16:41:43 +0000

[...] results from treelines are not limited to the north Atlantic and Greenland, but extend to the Sierra Nevadas (117 W), Sweden, Finland, Polar Urals (65 E) and a Siberian transect (90-100E). I’ll add a [...]

By: Steve Rodriguez

Steve Rodriguez — Wed, 12 Apr 2006 00:23:36 +0000

RE 16: Well yes, I have been paying attention to the amazing weather here in CA this year. But I also know that if you check the recent record you will find that the trend in late season precip (Apr and May)here has been steadily positive over the last 35 years or so. An interesting change with a relatively observation period.

By: Steve Sadlov

Steve Sadlov — Wed, 12 Apr 2006 00:03:02 +0000

Steve, sounds like you are fairly familiar with the Sierra Nevada! Interesting that the exact scenario you’ve described seems to be happening right now. We’ve had this persistent Siberia Express in place in California and certain, the snow pack is amazing. I checked a location at the Sierra crest on Sunday and one of the basalt fortress formations I am familiar with, which normally juts at least 10 – 15 feet out of the snow at this time of year, was nearly buried.

By: Steve Rodriguez

Steve Rodriguez — Tue, 11 Apr 2006 23:56:28 +0000

WHOOPS- continue that thought- How the distribution of precipitation regionally and independent of seasonal temperature cycles may affect montane glaciaers and ecosystem characteristics. for instance, consider what would be the net effect of no net increase in precip or temperature but rather an increase of precipitation in the months of April and May that was accompanied by a slight decline in temperature in those months. Extend the scenario by considering the persistent albedo and atmospheric cooling effects due to the lingering snow pack at high elevation. Such seasonal distribution hypotheses are almost never mentioned-only the periodic(in discreet annual units) net changes in temp and precip. The inter-annual interaction of temperature and precipitation, especially in higher elevations, is dynamic and likely has produced some of teh anomalous ecosystem responses mentioned in the studies and above comments. Any thoughts? hope I am not too late to get a response.

By: Steve Rodriguez

Steve Rodriguez — Tue, 11 Apr 2006 23:44:52 +0000

stumbled onto this blog looking for record of past climate flux may provide clues on how global change may manifest in CA and PNW. Something that bothers me about the models predicting sea level rise and catastrophic melt scenarios, which is related to the lack of data points at a regional scale, is how the DISTRIBUTION

By: Steve Sadlov

Steve Sadlov — Wed, 29 Mar 2006 19:48:42 +0000

RE: 12. And the converse, Swamp Cypress, which are thought to be excellent moisture proxies. Now here’s an idea. Examine Bristlecones solely for possible correlation to other indicators of paleo moisture and see what you get. Hmmmmmm ….

By: jae

jae — Fri, 17 Mar 2006 21:45:15 +0000

Below is a photograph of the drought (drouth) record (1276-1299) on display in the mesa verde museum, I was there last september.
http://home.casema.nl/errenwijlens/co2/mesaverde_drought.jpg

By 1300 Mesa Verde was deserted, the Ancestral Puebloans “moved on” south into New Mexico and Arizona.

Now THERE is a good use for tree ring measurements. I still can’t figure out how climatologists can tell the difference between drought and temperature by “reading the tree rings,” unless the trees grew in an area where drought is very unlikely (a rain forest?)

By: Hans Erren

Hans Erren — Thu, 16 Mar 2006 20:32:13 +0000

Ancestral Puebloans lived on Mesa verde between 550 and 1300.

Most of the cliff dwellings were built from the late 1190′s to the late 1270′s.
http://www.mesa.verde.national-park.com/info.htm#his

Below is a photograph of the drought (drouth) record (1276-1299) on display in the mesa verde museum, I was there last september.
http://home.casema.nl/errenwijlens/co2/mesaverde_drought.jpg

By 1300 Mesa Verde was deserted, the Ancestral Puebloans “moved on” south into New Mexico and Arizona.

By: JerryB

JerryB — Thu, 16 Mar 2006 17:46:07 +0000

Re #3,

Armand,

The Millar et al paper does not mention a mean annual mean temperature difference; it does mention the following:

“Medieval mean annual minimum temperature was warmer than current by 3.2 C, with large differences in winter (+3.5 C, January) and summer (+4.0 C, July). Mean annual maximum temperature was also greater in the Medieval period (+2.3 C), with greater differences in winter (+3.2 C, January) than summer (+2.6 C, July).”

Depending on how the “mean annual (minimum/maximum)” were calculated, it may, or may not, be plausible to infer a mean annual mean difference of about 2.75 C.

By: Steve McIntyre

Steve McIntyre — Thu, 16 Mar 2006 12:39:13 +0000

#8. I’m not fully conversant with the archaeological evidence, but my impression was that the Mesa Verde culture flourished in the MWP – the end of the 13th century is after the medieval period, which had more rather than less settlement. I’ve also seen some specialists distinguish between warm-wet, warm-dry, cold-wet and cold-dry scenarios. Woodhouse has written about the “20th century pluvial” in the American Southwest. Intuitively it seems to me that societies built at desert margins will be relatively vulnerable to climate change.