What is the motivation for choosing Loehle's over all other global temperature reconstructions?

Only only 5 data points extend beyond 1970?

To claim that 5 "proxy" data points represent global temperatures... surely the only motivation could be outright fraud.

Loehle's own comment on the data is "It must be emphasized, of course, that this result is based on limited data."

The author's actual conclusion, corrected in 2008 with the help of skeptic poster child Steve McIntyre (an energy exploration industry insider who apparently claims he is not involved in the oil industry) is:

"The main significance of the results here is not the details of every wiggle, which are probably not reliable, but the overall picture of the 2000 year pattern showing the MWP and LIA timing and curve shapes."

In other words, according to the author thegeneral shape of a Medieval Warm Period and a Little Ice Age do seem to show up in the types of records he looked at. Did we really need a scientific study to tell us that? Probably not.

He also clarifies that the rise in 29-year-smoothed global data from NASA GISS from 1935-1992 (with data from 1978 to 2006) is 0.34°C. Even if we overlook his point that "instrumental data are not strictly comparable" with pollen records form ice cores, who cares about 1992? What about the additional warming from 1992-2008?

Loehle had to issue a correction to his paper in 2008, concluding "Future studies need to acquire more and better data to refine this picture." Apparently Roy Spencer and other skeptics have no intention to wait for "more and better data" before they jump to conclusions? As a skeptic everything that comes out on the subject, I had higher hopes for Roy's credibility as he investigates PDO influences. It's very disappointing to discover that Roy may have a very low standard for what he accepts as evidence.

Unfortunately there is nothing offered by Loehle (or anyone else that I'm aware of) to explain the MWP or disprove anything related to anthropogenic global warming because of it. In fact, one of the author's previous papers is:

"Geologic Methane as a Source for Post-Glacial CO2 Increases: The Hydrocarbon Pump Hypothesis," C. Loehle (Environ. Res. Div., Argonne Nat. Lab., Argonne IL 60439), Geophys. Res. Lett., 20(14), 1415-1418, July 23, 1993.

"Using a simple dynamic model, the hydrocarbon pump, evaluates the hypothesis that historical CO2 levels could have been governed by releases of methane from clathrates and as natural gas. This is likely; confirming evidence is presented."

So his interest in confirming past temperatures appears to be related to his hypothesis that these sorts of warmings in the past may be related to natural methane releases... which could be caused by initial warming of some kind... and could lead to subsequent greenhouse gas warming. That's one of the tipping poitns that scientists are concerned about today.

Add man's greenhouse gasses to trigger and amplify methane releases and warming, as we have for the past 150 years, and we're simply reinforcing the earth's demonstrated tendency to warm in response to increased greenhouse gasses.

Here is the actual Loehle paper

http://www.ncasi.org/publications/Detail.aspx?id=3...

You say “However, among other flaws, of the 18 original records used in the Loehle reconstruction, only 5 extend beyond 1970...

Here is the data used in the paper.

http://www.ncasi.org/programs/areas/climate/Loehle...

All 18 records extend beyond 1970.

Here is another paper that reached the same conclusion

“Cambridge, MA - A review of more than 200 climate studies led by researchers at the Harvard-Smithsonian Center for Astrophysics has determined that the 20th century is neither the warmest century nor the century with the most extreme weather of the past 1000 years. The review also confirmed that the Medieval Warm Period of 800 to 1300 A.D. and the Little Ice Age of 1300 to 1900 A.D. were worldwide phenomena not limited to the European and North American continents. While 20th century temperatures are much higher than in the Little Ice Age period, many parts of the world show the medieval warmth to be greater than that of the 20th century."

http://www.cfa.harvard.edu/press/archive...

Here’s the actual paper. (Published in Climate Research)

http://www.int-res.com/articles/cr2003/2...

“Overall, the 20th century does not contain the warmest anomaly of the past millennium in most of the proxy records, which have been sampled world-wide. Past researchers implied that unusual 20th century warming means a global human impact. However, the proxies show that the 20th century is not unusually warm or extreme”

Because the statistical methods used by Mann 2008, are just as bad as the those used by him during the original hockey stick graph.

http://www.climateaudit.org/?cat=71

It is only when you use bad statistics can you eliminate the MWP. As you can see the MWP has been documented in many studies.

http://www.co2science.org/data/mwp/mwpp.php

Bucket: I knew someone would say that. Very typical. Are you saying that all of those studies that were mentioned are also funded by big oil. These studies compose of 670 individual scientists from 391 separate research institutions in 40 different countries ... and counting!

I am still waiting for some hippie to say McKintyre can't also be trusted because he work for a mineral company.

Edit: The ones that say that the MWP was warmer are the one that CO2 science classifies as level one.

If you want to talk about spin, spinning is when there was a universal acceptance of the MWP, the elimination of the MWP for political reasons ( http://epw.senate.gov/hearing_statements.cfm?id=26... ). When historical records showed that the MWP was real, then claiming it was only limited to a certain period. These collections of studies shows that there was a climate shift in all part of the world, in a period coinciding with the MWP. As for your source of wikipedia, there is a reason why no one here uses that as a source, since eco fanatics monitor the site day and night and do not allow any changes.

http://www.cbsnews.com/stories/2008/07/08/opinion/...

There's no good reason to cite the Loehle reconstruction, unless one is pushing an agenda. It's no surprise it couldn't pass an independent peer review in any one of dozens of scientific journals, given the fact that it has comically fatal flaws (documented well above). Citing Loehle precludes anyone from criticizing any published temperature reconstruction to date. It's like someone believing the Earth was created in 6,000 years criticizing evolution theory. The fact that Roy Spencer promotes this is very revealing of his agenda. Ironically, he believes in intelligent design.

http://www.tcsdaily.com/article.aspx?id=080805I

In contrast, in additional to excellent spatial coverage, as mentioned, the recent Mann et al study published in PNAS used multiple proxy types.

http://www.realclimate.org/index.php/archives/2008...

Side note: c02science.org:

Be wary of industry-funded "think tanks".

"ExxonMobil has contributed $90,000 to The Center for the Study of Carbon Dioxide and Global Change since 1998"

http://en.wikipedia.org/wiki/Center_for_the_Study_...

EDIT:

Eric C: "Are you saying that all of those studies that were mentioned are also funded by big oil. These studies compose of 670 individual scientists from 391 separate research institutions in 40 different countries ... and counting!"

Which studies would those be? Feel free to cite a peer-reviewed study that claims the MWP was globally warmer than the current period (or even in the ballpark). If you examine what co2science.org is doing, you'll note that their conclusions don't follow from the studies they are citing. I'll give you one example to get you started. Here is one study they claims shows warmer temperatures during the MWP than today.

http://sandhills-biocomplexity.unl.edu/sridharetal...

Now, can you find anything within this study that backs this claim?

Alternatively, you can ask one of the authors of the study, rather than relying on spin from industry-funded think tanks.

"I do this by evaluating and understanding land surface-atmosphere interactions, with particular applications to climate prediction (especially precipitation) on seasonal and longer scales. Other broad-based research interests include the effects of changes in land use patterns (especially due to agriculture practices) on climate, sensitivity of climate to global changes in carbon dioxide and other greenhouse gases and the effects of tropical deforestation on climate, all of which have potentially profound implications for society."

http://snr.unl.edu/people/faculty/oglesby-robert.a...

I wonder if the list of scientists they cite would approve of their claims. Another example:

http://en.wikipedia.org/wiki/Raymond_S._Bradley

So yeah, co2science.org is a propaganda outlet, nothing more.

EDIT2

"As for your source of wikipedia, there is a reason why no one here uses that as a source"

Someone quoting from a goofy politician (Senator Inhofe) and an industry-funded think tank isn't in a good position to criticize sources. It would be the equivalent of quoting Al Gore (who by any measure has represented the science much better than Inhofe) and some environmental groups. Reliable sources are taken more seriously.

MWP is a period about 1000 years ago where global temperatures were warmer than the few hundred years before and after. The mere existence of a MWP does not mean the MWP was warmer than today. That's the folly c02science.org (and others) are deliberately making.

Yeah, Mann expected a hockey stick, so he created a scenario where no matter what data was entered into the model, it would show a hockey stick shaped graph... that's why he did that.

The fraud al gore announced today that he has no scientific evidence what so ever to support GW, so guess you guys are left looking stupid on your own, while a. gore laughs all the way to the bank with your money.

Tree rings are not very good indicators of temperature. He explains it better than I.

http://www.climateaudit.org/?p=4475