re: #89 lostlakehiker

If you look up “hockey stick retraction” on Google, you will get lots of hits, including: ncpa.org

This flaw in methodology was also highlighted by Henry Pollack and Jason Smerdon (Journal of Geophysical Research, 2004) and led to a retraction by Mann (and Scott Rutherford) in the Journal of Geophysical Research (June 2004). In this article they admit to underestimating the temperature variations indicated by the proxy data since 1400 by more than one-third, which explains why their previous work failed to track the Little Ice Age. While admitting this error, Mann and Rutherford fail to recognize the extent to which it undermines their historical reconstruction and its relation to present temperature trends.

I didn’t have a research career tied to the MWP or the Little Ice Age, but I did have friends whose funding was hurt and who were pressured to retract papers. Oops! Losing your funding for “only” a couple years can be pretty painful. Again, this is about the handle of the hockey stick and not at all about recent climate. But I knew that there were going to be royal battles about this.

For example: “The MWP was the result of a minor Milancovitch cycle that affected the Earth by substantially less than deniers would like to imagine…”

I’m not a denier, but I can point you at papers on the MWP in North and South America and Asia. Hmmm…

“Major wet interval in white mountains medieval warm period evidenced in δ13C of bristlecone pine tree rings California”. Climatic Change 26 (2–3): 299–307. doi:10.1007/BF01092420

Li, H.; Ku, T. (2002). “Little Ice Age and Medieval Warm Periods in Eastern China as Read from the Speleothem Records”. American Geophysical Union 71: 09. Bibcode 2002AGUFMPP71C..09L

Keigwin, Lloyd D. (1996-11-29). “The Little Ice Age and Medieval Warm Period in the Sargasso Sea”. Science 274 (5292): 1503. doi:10.1126/science.274.5292.1503. PMID 8929406

And just for fun: sciencemag.org
Yes that is an article with Michael Mann as lead author describing the MWP and Little Ice Age—and trying to come up with a model where the warming and cooling were not global.

I think you mistake which side of your argument I am on. Neither. I think that whether CO2 levels cause heating or cooling depends on a complex interaction between water vapor, CO2, and the oceans. If I had global climate model that fit the data—I’d be planning a trip to Stockholm. As it is, I think we (the global research community) are about a decade or two from doing that.

But the one thing that has come out of existing models is that the current warming is at higher latitudes, with little or no warming at the equator.

In the meantime I feel like everyone is ignoring the extent to which CO2 levels that the human race has never had to cope with are killing people. Get that story out, and we can hope for correction of the problem. Natural gas releases more water vapor than CO2 during combustion, oil is somewhere in the middle, and coal results in say 95% CO2 with other noxious gasses. :-( So I am all in favor of shutting down all coal burning power plants as fast as possible—with B52s if necessary. That might be enough to start global CO2 levels declining.