Quote:
Originally Posted by andyc
Thanks Mike! It's the price of a climate research training that you have to deal with vocally uninformed (or sadly misinformed) people claiming that you, and every single relevant national science academy, and virtually every one of tens of thousands of relevant academics on the planet is wrong. All repeating tired old talking points that have been debunked a hundred times over, and who have collective blindspots to such things as the last 15 years being the time of the fastest accumulation of heat in the part of the world that collects >90% of global warming (Levitus et al 2012). No, the 2% of surface temperatures which have slowed (not stopped), despite every natural forcing going negative, is somehow much more important  . That even in surface temperatures, La Ninas in the late 2000s are warmer than every El Nino pre-1998, is apparently no problem. That if you extend the 1975-1998 trendline through the 2000s, there is no significant change - there is simply a positive trend in La Ninas, El Ninos and neutral years. I wonder if the 'hiatus' will be so popular among the blog skeptics after the next significant El Nino (absent a big equatorial volcanic eruption)?
I can't really be bothered dealing with each point of your latest Gish Gallop Renato, in which there is another worn list of long-debunked talking points, but I will address just one:
Mike Mann published one of the most talked-about papers in climate science in 1999, showing that average temperatures across the Northern Hemisphere had gradually trended slightly cooler over the past 1000 years, before very sharply warming in the past century. On a hemispheric (and subsequently a global) scale, the European historical periods known as the Medieval Warm Period and the Little Ice Age were not at all apparent. To cut a long story short, the MWP and LIA were found to be neither global in extent or in timing (as questioned by Hughes and Diaz in a seminal paper in 1994), and so while it was warm in Europe, other regions were cooler, and vice versa. This fits very well with the understanding that climate forcings were not changing too much over these periods except for the continuation long, slow cooling from a Northern Hemisphere precessional insolation peak which culminated in peak warmth in the mid-Holocene. Modern forcing from increased greenhouse gases is enormous by comparison. Mann's paper has been replicated something like a dozen or more times, many of which are shown in the relevant figure from the IPCC AR5 WG1 report. More recently than that, it was replicated by the massive PAGES 2k project, which you can read a summary of here, and yes, you can even go and read the actual sources too.
This area is of particular interest to me, as my PhD and postdoc were on studying Holocene palaeoclimate and glacier changes in the North Atlantic region (and where even the undergrads can see the scale of recent glacier retreat  ). Now a couple of statisticians claimed to find errors in Mann's methods. Strangely, they didn't try and replicate the work (just throw mud at it), and when others examined the statisticians' work, it was found to have numerous serious errors of its own, including a chronic case of cherry picking, where the program they used pre-selected the results they wanted. But nowadays, that's all ancient history, as there are so many replications of the original study, with widely differing methods and proxy sources, that Mann's work has been verified beyond any reasonable doubt. That's the scientific process.
But still some would try and throw mud at Mike Mann. Including those who think an undergraduate essay mark is supposed to impress me  |
Hi Andy,
I must say you have me a tad confused. You give a link to all the major studies which you say confirm Mann and the Hockey Stick (i.e. WGI_AR5_Fig5-7.jpg) - and I see, for example, one solid-lined light blue graph, and a dark-blue broken line graph which give higher temperatures in the Medieval Warm Period than in 2000, and which give very low temperatures during the Little Ice Age. The dark green solid graph also gives a similar result, except that it goes a tiny bit higher by 2000. And there is a similar shape for the solid-lined dark blue graph
Thus how exactly do these graphs confirm Mann and his Hockey Stick graph, rather than disprove it?
Thanks for that graph - I think it actually proves my point. In 3rd Assessment Report the Hockey Stick was the centre piece. In 5th Assessment report, it is shoved in with a bunch of others that contradict it.
You praise Mann profusely, and claim there is no controversy. Even the Wikipedia article on the Hockey Stick Controversy (whose writers appear to be Mann supporters) wind up citing the Hans Storch review, which states at,
http://en.wikipedia.org/wiki/Hockey_stick_controversy
"
Hans von Storch review
In May 2007, Hans von Storch reviewed the changes in thought caused by the hockey stick controversy writing:
In October 2004 we were lucky to publish in Science our critique of the ‘hockey-stick’ reconstruction of the temperature of the last 1000 years. Now, two and half years later, it may be worth reviewing what has happened since then.
At the EGU General Assembly a few weeks ago there were no less than three papers from groups in Copenhagen and Bern assessing critically the merits of methods used to reconstruct historical climate variable from proxies; Bürger’s papers in 2005; Moberg’s paper in Nature in 2005; various papers on borehole temperature; The National Academy of Science Report from 2006 – all of which have helped to clarify that the hockey-stick methodologies lead indeed to questionable historical reconstructions. The 4th Assessment Report of the IPCC now presents a whole range of historical reconstructions instead of favoring prematurely just one hypothesis as reliable."
More interesting is the testimony by fellow a Lead Author to Michael Mann at the time of the 3rd Assessment report to a US House of Representatives Committee about what happened, where he says Mann amputated Briffa's data, and shoved to never-never land Dahl-Jensen's ice bore reconstruction which showed warmer temperatures in the Medieval Warm Period than now.
https://science.house.gov/sites/repu...110331_all.pdf
Oh - and I noticed that you didn't want to debate what I raised, that after over 20 years and four assessment reports of hysterical alarmism over extreme weather events, they have finally been put to bed in this report. I wouldn't want to debate it either if I were you.
Cheers,
Renato