Why do deniers focus on Mann's hockey graph and none of the other countless reconstructions that agree with it?

Because they haven't got a clue what they are talking about and most of the time they just repeat the BS they read over at WUWT and other deniers blogs. The recent question here on the use of proxy data instead of publishing the real temperatures is a good example of just how incredibly stupid some of them are.

Edit: read Pat's very recent answer to that same question. It's hilarious: http://answers.yahoo.com/question/index;_ylt=Agrej...

@ Ottawa Mike:

Your John Daly link features the very same schematic chart discussed here on YA only yesterday. Contrary to Daly's claim, the figure he displays at the top of his article was NOT presented by the IPCC in their 1990 report. You can check for yourself at page 202 at the link provided below. [1] The original chart published clearly noted that the time-scale used represented "Years Before Present" which in scientific terms mean "up until 1950". [2]

It therefor did not reflect the additional 40 years of warming up to 1990 as many, Daly included, wrongly assumed (and sadly many still do even when it clearly states "Years Before Present"). This minor misunderstanding is the whole basis of Daly's argument and that of a large part of the denial community who scream and shout that the hockey-stick is wrong and that IPCC suppressed the MWP in its next report (which did include the latest decades of warming). All because they do not comprehend a basic scientific term.

@Pat

Out of curiosity, why did you block me? You signed up to YA while I was virtually inactive here so it could not have been because of some encounter you and I have had.

It was a lie based on manipulated data, but this does NOT mean we should treat our planet with the contempt we do... however it does show that there is a VERY different agenda from the one we are being bullshitted with by the mainstream media, just underneath the surface. The J-curve hypothesis HAS been discredited, try the UK magazine New Scientist, which references sources from the Royal Society (a highly respected UK scientific body). The e-mails show that data is being suppressed, twisted and manipulated... WHY? The only thing we CAN all agree on is that our politicians have been lying through their teeth, THEY are responsible for the poor state of our planet, deforestation, species loss etc - and this proves they cannot be trusted as far as we can throw them!

Probably for much the same reason that a lot of them are still going on and on about Al Gore. If they can make it all about one old reconstruction, movie, et cetera that has subsequently been shown to have some flaws (like most science more than 10 years old... one of the cool things about science is that scientists keep going back and correcting past errors...), then they don't have to pay attention to all the *other* evidence saying the same thing.

And it is likely that the errors in the Mann reconstruction are the kind of minor errors (relative to current data) that you would *expect* of a graph that was using less data than is available today.

Denialists love to have a villain. They would rather pretend that the hypothesis of today being a period of rapid change after 1,000 years of climate stability is just something that Mann made up, rather than one which has been confirmed by many other studies.

OM

LOL! You use a link which shows an obsolete graph.

Don't worry Gringo, Pat has blocked me from answering their questions too ... would suggest that perhaps you got too many thumbs up, or didn't agree with his opinion.

What I love about the John Daly BLOG is that instead of publishing his results/critique of the graph in a respected scientific journal (which is the place for scientifically arguing such matters) he has gone to a blog post instead (where he has to face no scientific critique or credibility to defend). Could it be because he has no credenitals, experience or expertise in climatic sciences, mathematics, modelling or statistics?

Note most answers also haven't focused on the alternatives ... sort of says a lot doesn' it.

The meaning of the BEST data:

"Berkeley Earth has just released analysis of land-surface temperature records going back 250 years, about 100 years further than previous studies. The analysis shows that the rise in average world land temperature globe is approximately 1.5 degrees C in the past 250 years, and about 0.9 degrees in the past 50 years."

The statistical work was conducted by David Brillinger, PhD in math at Princeton and professor of statistics at Cal.

http://berkeleyearth.org/david-brillinger/

Some F students "deal" with their limitations by copying and pasting anti-science garbage here instead of trying to become less pitifully ignorant.

"Also, what exactly is incorrect, shoddy, scandalous about the Mann et al reconstruction?"

This was written a few years ago by the late John Daly but it summarizes the problems in an easy to understand way: http://www.john-daly.com/hockey/hockey.htm

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Edit@Gringo: "The original chart published clearly noted that the time-scale used represented "Years Before Present" which in scientific terms mean "up until 1950". [2]"

I'm not sure what point you are making with this but your wiki link clearly states that the 1950 "before present" definition was made specifically for radio carbon dating. Since the IPCC does not discuss the term in the surrounding their figure 7.1, your assumption that that graph ends in 1950 is a large stretch. As a matter of fact, two points would challenge that assumption. The first is that they must have had data after 1950 unless they extracted that chart from a mid 1950's study (couldn't find one referenced). As well, if you look closely that the physical length of the scale after 1900AD, it looks like more than half a century.

Regardless, I'm not sure how any of that invalidates Daly's entire analysis. Seems to be some cherry-picked nit-picking. I guess you are good at pointing that out to others since you have such a skill at doing it yourself.

Baccy Baby: If the greenies can merely discount whatever Spencer and Linz have to say without reason I can reasonably discount BEST with reason. The 'B' in BEST stands for Berkeley (or as they say at the Lawrence Livermore Labs, Bezerkly). They are a known Communistic or Liberal society. They are extremely agenda driven and are not to be trusted.

When any organization has to sink so low as to consider them an authoritative source, then you know they are in intellectual trouble.

Our government spent millions, if not billions, to credibly massage the data. Bezerkley is just trying to use a name of a University to enhance credibility. You are hard up if you have to use Bezerkley or Penn State.

Which reconstructions exactly are you referring to that "agree" with Mann's. Perhaps you are referring to other tree ring constructions used by the Hockey team? If you are interested, I think

Montford did a fair job of providing a history of Mann's reconstructions. You should give it a read even if the title sounds biased. It probably is but he goes out of his way to be fair IMO.

http://www.amazon.com/The-Hockey-Stick-Illusion-Cl...