Thread: Chopping Up The Hockey Stick

Originally Posted by Taxcutter

Wanna know why ‘science’ gets no respect these days. Read this tale of manipulated data.

http://pjmedia.com/blog/the-death-of-the-hockey-stick/

LOLOLOL.......oh my, denier cultists and their mindless myths are soooooo funny.... and sooooo full of it.....

Climate myths: The 'hockey stick' graph has been proven wrong
In fact, later studies support the key conclusion: the world is warmer now than it has been for at least 1000 years.
New Scientist
Michael Le Page04 September 2009
(excerpts)

The "hockey stick" graph was the result of the first comprehensive attempt to reconstruct the average northern hemisphere temperature over the past 1000 years, based on numerous indicators of past temperatures, such as tree rings. It shows temperatures holding fairly steady until the last part of the 20th century and then suddenly shooting up. It provided yet more evidence that the rise in greenhouse gases due human activity is causing warming, although the case for this was already very strong. The conclusion that we are making the world warmer certainly does not depend on reconstructions of temperature prior to direct records.

2006 report of the US National Academy of Science (pdf). The academy was asked by Congress to assess the validity of temperature reconstructions, including the hockey stick. The report states: "The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1000 years. This conclusion has subsequently been supported by an array of evidence that includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators, such as melting on ice caps and the retreat of glaciers around the world".

Update: as suggested by the academy in its 2006 report, Michael Mann and his colleagues have reconstructed northern hemisphere temperatures for the past 2000 years using a broader set of proxies than was available for the original study and updated measurements from the recent past. The new reconstruction has been generated using two statistical methods, both different to that used in the original study. Like other temperature reconstructions done since 2001 (see graph), it shows greater variability than the original hockey stick. Yet again, though, the key conclusion is the same: it's hotter now than it has been for at least 1000 years. In fact, independent evidence, from ice cores and sea sediments for instance, suggest the last time the planet approached this degree of warmth was during the interglacial period preceding the last ice age over 100,000 years ago. It might even be hotter now than it has been for at least a million years.





(In accordance with Title 17 U.S.C. Section 107, this material is distributed without profit to those who have expressed a prior interest in receiving the included information for research and educational purposes.)

Appeal to numbers is a logical fallacy livefree. You have no reason to believe that they aren't making the same mistakes. And since they all work together and collaborate by e-mail we know that is a fact.

Originally Posted by Windigo

Appeal to numbers is a logical fallacy livefree. You have no reason to believe that they aren't making the same mistakes. And since they all work together and collaborate by e-mail we know that is a fact.

Nice to see that an open mind

Originally Posted by Taxcutter

Name-calling is not going to change the fact that Mann got caught falsifying data to make a flawed model work.

Liar.

Not one datum in Mann was falsified. Unlike your false statement above. Which I flatly predict you don't have the honesty to retract.

Originally Posted by Windigo

" I first generated 1000 random time-series in Excel – I did not try and approximate the persistence structure in tree-ring data. The autocorrelation therefore of the time-series was close to zero, although it did vary between each time-series.

Playing around therefore with the AR persistent structure of these time-series would make a difference. However, as these series are generally random white noise processes, I thought this would be a conservative test of any potential bias.

…
The reconstructions clearly show a ‘hockey-stick’ trend. I guess this is precisely the phenomenon that Macintyre has been going on about.

Hmmmm. What's inside that ellipsis, one wonders? Did Windigo even check it out? Might it be important? Or did Windigo just lift that directly from WUWT, where the same quote contains the exact same ellipsis in the exact same place?

Reading what's inside that ellipsis proves enlightening. So how did Rob Wilson actually generate hockey sticks? Just randomly? Nope. Not even close!

Here's what Anthony Watts hid from his readers, and what Windigo hid from you:

I then screened the time-series against NH mean annual temperatures and retained those series that correlated at the 90% C.L.

48 series passed this screening process.

In other words, out of 1000 random series, Wilson selected that less-than-5% that just happened to look like hockey sticks. And in fact, since his selection CL was only 90%, the fact that he only got 48 (rather than the expected 100) indicates that the actual NH signal is pretty darn non-random.

Nice job lying, Windigo.

Originally Posted by Poor Debater

In other words, out of 1000 random series, Wilson selected that less-than-5% that just happened to look like hockey sticks. And in fact, since his selection CL was only 90%, the fact that he only got 48 (rather than the expected 100) indicates that the actual NH signal is pretty darn non-random.

Nice job lying, Windigo.

You again don't understand what the hell you are talking about. It will be very hard to explain to you exactly how proxy reconstructions work because you are obviously clueless.

First your mistake is assuming that all the series included in a reconstruction actually make it into the reconstruction. This isn't true. Most of the series will be filtered out because they do not correlate well to temperature. Then either through PC eigen weighting or weighting on the correlation to temperature or both even more will be thrown out as their weights will be insignificant. Eventually you end up with only a handful of proxies accounting for the bulk of the final reconstruction. In the case of MBH98 its final shape was dependent on only one series and that series was not a temperature proxy. It was a CO2 proxy so all Dr. Mann showed was that CO2 has climbed in the 20th century.

Originally Posted by Poor Debater

Liar.

Not one datum in Mann was falsified. Unlike your false statement above. Which I flatly predict you don't have the honesty to retract.

You might want to check MBH98 Mann makes the fraudulent claim that his method had passed R and R2 verification. It didn't. He lied.

Repetition does not exonerate Mann.

Mann needs no exoneration. He was right and has been confirmed as such.

Is anyone denying the earth is getting warmer?

I mean really.
Why spend so much time trying to pick apart one persons data when the whole scientific world knows the earth is getting warmer?

For you people from countries other than the U.S, this is called "The bait and switch"