Hockey stick graph?

Question

http://whyfiles.org/211warm_arctic/images/1000yr_change.jpg

hey weres the medieval warming period and the post war economic boom drop in tempreture!

Answer 1

The hockey stick graph was great for environmental alarmists because it shows exactly what they are trying to prove.  Al Gore couldn't resist including it in his movie, even though it's quite well know to have no scientific basis.  

He had to chose his words very carefully though, it's hard to use a graph based on ficticious numbers to prove anything even if it does look as good as the hockey stick.

(edit)

Bob, the graph was not smoothed, but every data set was given a weighting based on how the twentieth century average compared to the overall average, in other words how much it looked like a hockey stick.  Some trees data sets were given weightings of 350 times the average because they happened to look more like hockey sticks.  

Nobody else has been able to find hockey sticks in Micheal Mann's raw data and his algorithm can produce hockey sticks from random data.

Answer 2

Even the AGW crowd has abandoned the hockey stick for something that looks more like those snow shovels for people with bad backs.

They now accept an MWP but insist that we started to exceed MWP temps in the 1990s.

Of course, that still leaves them with two hundred years of uninterrupted temps at early 1990s levels, and no catastrophe, no runaway warming, etc....    So it's kind of irrelevant whether it was warmer than peak 1990s levels or the approximately 0.2 degrees C cooler that they now appear to concede - - - that would make the MWP about even with today's temps - - for two centuries straight.     Without any of the global catastrophe that they tell us will result at the present temperatures.

But that doesn't change the fact that it most certainly WAS warmer, based upon events that occurred that cannot occur now because it is not warm enough, and that since they occurred have been attributed to warmer temperatures, and many of which were attributed at the time to warmer temperatures.

The Hockey Stick controversy has always been a significant issue for me.    They can't prove their case outright - it relies upon their being given a certain benefit of the doubt.   I'd be a lot more open to giving them that benefit of the doubt if they had more credibility, which was destroyed when they re-wrote the climate history.    

The record of what grew when and where, what land and sea passages were iced over for what period of the year, etc... - the tangible evidence - supports a warmer MWP.    And that is why the MWP was the accepted climate history from the time it happened until the climate had become a political issue and the skeptics were gaining a lot of headway in the debate by citing recent non-CO2-driven warm periods such as the warmer MWP, the almost-as-warm Roman period and the warmer HM.

The physical evidence is from around the world - from the Sierra Nevadas to the Alps, from the American Southwest to Greenland to England to Germany to China, from the arctic to New Zealand.    Not all of the events happened at exactly the same time - but then, we're repeatedly told that non-synchronous warming today is actually supportive of global warming today.

Indeed not only is there the physical evidence from around the world, but during the MWP and the ensuing LIA there were written accounts of climate change - in literature such as Chaucer's Canterbury Tales and in correspondence, such as when the Pope wrote that he could not send ships to Greenland because of the increased sea ice.

Human behavior changed - the economy changed.   People planted crops at higher elevations and colder latitudes.    Keep in mind the state of the economy at the time, with its lack of credit - - it was a very expensive endeavor to begin planting a new crop on your land, a crop that hadn't been grown on your land before.    You risked your fortune to plant a new vineyard in lower England or go to Greenland to start a dairy farm - - this wouldn't have been done after only a couple of warm years, rather it would have to have been warm on a sustained basis for a generation to justify such an investment.    

How can the physical, tangible and indeed written record be overturned on the basis of scant proxy reconstructions?

But it's more than that.

The basis for overturning the MWP is NOT "reconstructions" generally - - - the sedimentary records show the MWP as do the ice core records taken together.    

The basis for overturning the MWP, for re-writing it out of the climate history, is reconstructions that rely on tree ring proxies - - either tree rings only or a blend of evidence in which tree rings form the only cool medieval signal.

Except that the cool medieval signal from the tree ring data is based on the assumption that tree rings keep getting wider with temperature, no matter how warm it gets.    

Most of the tree ring samples used in the studies that purport to override the MWP were taken in 1980.    

We know it warmed from 1980-2000.

So, it would be a good idea then to validate the tree ring methodology by updating the samples and comparing the model to the measured temperature record for 1980-2000.

Dr. Mann argued that this would be too expensive - - but it's been done with a half dozen samples so far - - and surprise surprise, the tree rings do not get wider from 1980-2000.....

Not that tree rings are good proxies for temperature anyway - - there are several other factors related to growth, such as rainfall, other plants competing for sunlight and soil nutrients, pests, the roots extending to a layer of soil that is less nutrient-rich, etc.....     This alone would have been enough to throw out the tree ring data, since in many cases entire centuries for entire continents are reconstructed based upon one or two individual trees.

So to put it bluntly:  the best you can say for those who think or thought that the MWP didn't actually happen, that "new science de-bunks it," is that they want to believe that.    Nobody who doesn't already want to come to that conclusion can look at the evidence and come to that conclusion.

Now - do prior, non-CO2-driven warm periods prove that the 20th century warming wasn't man-made?

No.

But they do mean that we can't just infer that the 20th century warming was man-made, and they also prove that we can't just automatically assign validity to the "runaway warming from methane release" theory, since it's been warmer than it is today, for centuries at a time, and no such massive methane release occurred.    What it means for the polar bears is unclear, since their population is now recovering from overhunting, which wasn't the case hundreds or thousands of years ago.

But to bring the discussion full-circle, the MWP denial (ironically, by those who call everyone else "denialists") is a severe blow to the credibility of the AGW proponents.

They still do not seem to realize this - that most objective, open-minded people are likely to become MORE skeptical, are LESS likely to believe in AGW, as a result of this historical revision.

As for their explanation of the mid-20th century cooling (and it was a cooling), it does make sense that dark particulates would refract some sunlight back into space.    Though, with the development of the third world, we'll probably see more dark particulates in the atmosphere than we had in the 1950s.  But making intuitive sense does not prove that that theory is correct - - based on lab experiments we concluded that CFCs were the cause of the ozone hole.   We banned CFCs 20 years ago, most countries comply, CFC levels are down precipitously, yet the ozone hole is bigger now than it was then.

EDIT - the MWP was NOT a "regional event in Europe."    For example, tree lines were higher in the Sierra Nevadas, the Anasazi suffered through droughts much more severe than the droughts now seen in the American Southwest and had to abandon their homes, and Lake Naivasha dried up for 200 years.   Lake Naivasha is in Kenya, which is not in Europe......     Lake Naivasha is lower than it was a century ago but still exists in the 21st century despite much greater water drainage for irrigation and other uses than was the case during the MWP.    

This is what I mean - - the statement below about "limited to Europe" is palpably untrue.    It's just factually false.   There's no open debate on this issue - it's like saying the Diamond Backs beat the Red Sox last night.   It's just a flat out untruth.   Yet they run with it.   Why do they think this will cause more people to believe them?    Why don't they think that so obviously lying about one issue will cause people who haven't yet made up their minds to ask, I wonder what else they're lying about?

Why do some of them try to dismiss the larger issue of credibility, to relegate this and other similar issues by labeling them "side issues?"    

This is how we decide things that cannot be proven either way - we consider the logic of the arguments and the credibility of those making them.    People are convicted of murder not always because the evidence that they committed the murder is so overwhelming but because they took the stand and lied about some other issue, and as a result the jury doesn't believe them.    

Call them "side issues" all you want, but continuing to lie about them destroys your credibility - it creates skeptics.

EDIT - I would think it's obvious, if we oppose revision of history, we would just go back to the history.    The graph would be the one the IPCC included in their 1995 TAR, which was also from Lamb's book.

http://www.john-daly.com/hockey/hockey.h...

At the very least, I would ask that the MWP-deniers explain a SINGLE example of the physical evidence of warmer temperatures as having happened for some other reason.   Just come up with a PLAUSIBLE explanation for ANY of the evidence - your choice.    Higher tree lines, the massive droughts in the American Southwest and eastern Africa, the Greenland colony, lower England becoming wine country and then seeing its wine production decline sharply in the 1300s, only to return in the late 20th century as a result of advances to growing techniques and breeding for cold hardiness......  

Even if somehow the tree ring problems can be resolved, it's still a matter of over-riding a mountain of direct evidence with a few samples of indirect evidence.

Doesn't that require an alternate explanation for the direct evidence?

Melting glaciers in the Alps are revealing artefacts from medieval times!!!!!!

How can that be, if it wasn't warmer during medieval times, and then colder during the LIA?

Answer 3

The oh so infamous hockey stick graph.  This has been debunked for quite some time now.  But some of the die-hard believers and posters in here (Bob, Dana) will always find some way to keep it alive.

Answer 4

The post-war pause in the warming is clearly there as a tiny blip in the rapidly increasing temperatures, and the Medeival Warm Period was a regional event in Europe possibly due to a temporary shift in ocean currents, so it would not appear on a graph derived from ice cores (far from Europe).

Funny that deniers are full of negative characterizations of others, but offer no "corrected" data showing what they'd like the graph to look like... since temperatures still rise upon the increase of atmospheric CO2, regardless of what happened during the Medeival Warm Period.

The "hockey stick" was supposedly debunked by Steve McIntyre, most recently an executive at an oil and gas exploration company (gee, wonder why he'd want to criticise efforts to conserve or replace fossil fuels).  

So what did Mann have to say about McIntyre and McKitrick's criticism of his work?

In turn, Mann (supported by Tim Osborn, Keith Briffa and Phil Jones of the Climatic Research Unit) has disputed the claims made by McIntyre and McKitrick,[12][13] saying the

"...so-called 'correction' was nothing more than a botched application of the MBH98 procedure, where the authors (MM) removed 80% of the proxy data actually used by MBH98 during the 15th century period... Indeed, the bizarre resulting claim by MM of anomalous 15th century warmth (which falls within the heart of the "Little Ice Age") is at odds with not only the MBH98 reconstruction, but, in fact the roughly dozen other estimates now published that agree with MBH98 within estimated uncertainties...".[14]

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

Wait a minute...  to dispute the hockey stick  McIntyre and McKitrick have to remove 80% of the data and place the MWP DURING the Little Ice Age?  No wonder deniers don't show their "corrected" chart.  It disproves many of their other pet claims.

So what does Steve McIntyre have to say about all this?  If you read his own blog, here's what he says about the relevance of his own debunking to the issue of climate change:

"I’m inclined to agree that, for the most part, the Hockey Stick does not matter to the great issue of the impact of 2xCO2."

http://sciencepolicy.colorado.edu/promet...

Steve offers some concerns about statistical process and disclosure and about IPCC process that deserve attention.  But why misrepresent his criticism of those details and disregard his opinion that rising CO2 levels matter?  Steve is one of the few "poster children" for the deniers, yet he apparently doesn't deny global warming himself, so why would anyone else, using him as the alleged justification?  

So in about 5 to 10 minutes of research you can find huge holes in the claims of deniers here, making unsupported allegations about the importance or meaning of Steve Mcintyre's criticism of Mann's procedures.  That won't matter to them of course, they don't want facts, which is why they offer none.

Regardless of how you choose to characterize pre-1850 temperatures (whether you superimpose the MWP on top of the Little Ice Ace) using data from at most 18 data points, the denial lobby industry has been unable to overturn the physics of greenhouse gases or stop the melting of glaciers (which have been melting in an inconvenient hockey stick pattern as well).  

So folks, if there's no warming, show us the "corrected" data.  Show us McIntyre's results, graphed.  Where's the beef?

Answer 5

Anyone who actually follows this will know that there have been several mistakes made in the science and the scientists involved have done what scientists usually do with any scientific theory acknowledge the mistake and correct the error. Deniers don't seem to be able understand this concept at all, given that the 'hockey stick graph' has been independently reviewed, at the request of congress, by the National Research Council and found to be fundamentally correct and yet deniers keep trying to perpetuate the myth that it completely discredited, it isn't, they found the error didn't alter the fundamental premise. I would have far more 'faith' in their findings than the blog sites deniers keep posting a proof.

http://environment.newscientist.com/chan...

And as you mention the Medieval warm period

http://environment.newscientist.com/chan...

Answer 6

http://rds.yahoo.com/_ylt=A0geu8QhSWFILP...

If the link above will explain it is fualty statistics.  Go to the last page, no one would buy into the AGW as long as the medieval warm period was hotter.

Answer 7

The hockey stick data was the basis for the whole global warming argument.  The data was kept secret for a long time because most of the data was made up and the formula that formed the stick would form a hockey stick even if ALL the data was made up.

Believers however still look towards this graph as the holy grail of global warming.

Answer 8

That graph was overly "smoothed", or averaged out.    Scientists learned from that mistake.  Here's a better version, and the MWP is clearly shown.  It's what's scientists have used in reports for years, now.

http://www.globalwarmingart.com/wiki/Ima...

The post war leveling out (it wasn't really cooling), because of smoky pollution, is the tiny flat area almost at the right hand edge.  Taking only the last 100 years or so, lets you see it more clearly.  The red line is the 5 year average, which smooths out short term weather effects, leaving the climate trend.  The green bars are "error bars" showing the uncertainty in the data:

http://data.giss.nasa.gov/gistemp/2007/

Answer 9

This isn't exactly the type of graph you'd want to look at for details.

This would be a better chart to view the MWP:

http://books.nap.edu/openbook/0309102251...