It'll be fun to watch the interaction between the informed and the uninformed on this thread.

Wow. Here we go again. The hype is is getting thick with winter approaching again. So now it is the warmest in 1300 years. I feel so much better knowing the scientists are this good with just exactly what has been going on now by tree rings. Hmmm, we already know that the 1930's was a warmer period so looks like their data is very misleading. Oh well this should give Mark and Kipp a warm fuzzy and something to hold onto during the winter months.

Nonsense! Anyone who has followed this knows they manipulated the data and statistical criteria to get the result they wanted and needed to vindicate their earlier flawed findings. See McIntyre climateaudit.org for the mathematically inclined, or if you want the history of the whole sordid affair including the repeated bouncing of the Mann et al paper, go to
http://bishophill.squarespace.com/blog/2008/8/11/caspar-and-the-jesus-paper.html.

The fact is that we can't know whether the earth was warmer or cooler 1000 years ago, but the indications from human history and more recent proxy reconstructions (e.g., Moberg et al) is that there was a lot more natural variability before the industrial revolution than Mann et al find.

It would be good if this blog gave a more balanced reporting of climate developments.

Making the claim that their temperature proxy study is reliable and accurate 1,300 years back continues to be a vital cornerstone of the warmista case. It is vital because the CO2-driven model cannot explain periods in that timeframe that were as warm or warmer than current while CO2 was at pre-industrial levels. AGW theory only holds up if you can eliminate the MWP and earlier optimums in the last 2,000 years. Expect the warmistas to defend at all costs this latest proxy study.

I strongly suggest everyone visit Climate Audit and try to get a handle on Steve McIntyre's criticisms of this latest Mannian proxy approach.

cool, not even as warm as it was during the roman empire. lets start wearing togas

I really can't get excited over .5 degree F increase over a 1300 year average. From January to May for this year 2008 the average temperature was more than .5 degree F below the 100 year average which has been increasing approximately .1 degree F per decade. This informatin can be found at NOAA's US Climate Summary web site.

You've got to give Mann top marks for putting lipstick on his pig with gusto.
Steve was all over this at Climate Audit & his analysis is worth a look irregardless of which side of this debate you are on. Personally I'm amazed Mann hasn't been canned at work but hey this is climate " science " so I guess that says it all.

Bob & Bob, sounds like the data is leaving you all a bit speechless these days!

This can be a false conclusion. Every 1500 year there seems to be a period of rapid and intense warming, which is shown in climatic records and ice cores. These are called Bond events during the Holocene and also Dansgaard-Oeschger events during the previous ice age. During this periods a rapid warm occurs which leads to a extensive melting in northern hemisphere thus disrupting the north Atlantic current and bringing a new cold period again. During this shift the tropical current seems to shift instead to Antarctica and bringing new melting to the south polar cap, while the north is cooling again. When the southern melting achieves a new threshold, the north Atlantic current is again strengthened and a new cycle of northern warming continues.
We have had Bond events around 450BC, 900AD, 2200 BC, 3900 BC, 6200 BC (8.2k event), 7400BC, 9100BC (Young Dryas) and still more 1500 year recurring during the ice age.
If the pattern keeps we are now in a rapid warming stage which will bring extensive melting and then cooling again. That's why we are now in a period warmer than the past 1300-1700 years! Even if human Co2 helps in that, we would only force more the system to trigger this threshold and shift, perhaps in a more violent way.

Bob Tisdale: "It'll be fun to watch the interaction between the informed and the uninformed on this thread."

Oh great and powerful BT, please enlighten all of the brainless scarecrows out there with your breadth of your self-proclaimed "non-scientific" knowledge of this particular thread topic. Have you found some highly correlated TSI and localized SST data charts that go back that far in history that more accurately displays the worldwide temperature data curve back to the MWP?

By the way, can either you or Kipp inform me of what Kipp meant by "So are Bob Tisdale's graphs, as he has built his reputation on Smith Reynolds data, only to find out that they were wrong." Was something discussed about this data while I was on vacation?

Climate crisis' needs brain gain
http://news.bbc.co.uk/2/hi/science/nature/7603257.stm

The most brilliant minds should be directed to solving Earth's greatest challenges, such as climate change, says Sir David King.

The former UK chief scientist

Does he know something you don't? Or don't want to accept...Its not just Hansen who is worried about AGW.

Anyone got any good ideas?

Bret, a complaint. How could you possibly post this without referencing Steve McIntyre? Reply: I did not see Mcintyre's piece on it. Also, Mcintyre's blog on this subject is very long and technical and probably very hard to understand/follow for a majority of people who view this blog. He no doubt put a lot of effort into it. I will post the link.

http://www.climateaudit.org/?p=3512

Follow Steve's demolition of Mann et al's latest attempt. Expect to see that it is no more credible than their previous 1998/99 papers.

My view of Mann's efforts: "If you try to fudge, and don't succeed, try, try again."

Mann should have had the book thrown at him as soon as it became apparent his first set of proxies was carefully selected to create a desired result. If you don't remove a rotten apple, it will spoil the entire barrel.

It was Mann's original effort which introduced us to phrases such as "cherry picked data" and "garbage in; garbage out." This new effort is just more of the same, only the effort is more complex and elaborate, as if attempting to make garbage difficult-to-see makes garbage anything but garbage.

I don't know where we would be if it weren't for people like Steve McIntyre and others at Climate Audit. They have both the time and ability to sort through a muddle of data, and sift out the dubious proxies. They even seem to enjoy the process of spotting the errors in logic. However I am often annoyed at their politeness and diplomacy.

Mann doesn't deserve diplomacy. He deserves a rebuke and removal. We are now seeing what happens if you don't remove a rotten apple: More rot is produced.

It is a waste of people's time to go through the tiresome process of reinspecting his slewed data all over again, but I suppose it must be done.

Mann's new efforts continues to use the tree-ring proxies which cannot be replicated, and which fail to prove what he selected them to prove. The new effort also includes some new proxies which are equally suspect, and which were carefully selected to achieve a premeditated result. Lastly, the new effort omits all proxies which suggest the MWP and Roman Climate Optimum were warmer than current times. Once again, if you remove the suspect proxies from the heaps of other data, (which seems to have only been included to make spotting what is suspect more difficult,) the blade of the hockey stick vanishes.

Mann could not get away with his antics unless he was receiving support from those who are heavily invested in the hockey stick. They need the hockey stick for political and economic gain, and could care less if it is fact or fiction.

This is all rather strange - it looks like we may have reached the so-called "tipping point", but it seems to tie very neatly into the counter-theory of global cooling every 1500 years.

This report from the hockey-stick guys rather oddly seems to put a stick in the spokes of their own AGW wheel.

Were the Russians not predicting something like this about 1990/91? A peak in temps over 20 years followed by a super-lengthy cooling period?

If one paid any attention at all to the current activity at Climate Audit, you would be aware that the publication by Mann et al is being shredded, torn up and filed under "G" as just a re-hash of old data and an attempt to justify keeping the "hockey stick" in play even though it has an illegal curve.

Yesterday I went to the Buffalo Bills game. The forecast was "partly sunny, hi 73." It rained for 2 hrs. I was unprepared for rain and got wet. My point is sometimes the forecasters get the next day wrong. How much confidence can we have in scientists telling us what the weather was like 1300 yrs ago?

Visit Climate Audit and see how Steve M and the contributors there are taking this latest offering from Mann apart piece by piece.

How long before Mann releases the database?

Buehler? Buehler?

Not this guy again! I thought Mann would have given up after scientists and mathematicians much smarter than him found fatal errors in his theory and methodology. Global warming alarmism depends heavily on proxy data cherry picked by the authors of these studies and computer models which simply do what they are told.

Here is an analysis which points out the errors in Mann's latest effort to convince us that our recent climate is warmer than the MWP. I thought Penn State had higher academic standards than this.

http://icecap.us/images/uploads/revivalhockey.pdf

Mann has updated his reconstructions by adding several non-dendro proxies (lake sediment, Lonnie Thompson's ice cores, and speleotherm (cave sediment)). It is way too early to comment on Mann's new reconstructions, but Steve McIntyre did off a few comments:

1)The Finnish Lake sediment data has major problems (if used as a temp proxy); namely that Lake Korttajarvi's data has been influenced by humans -it appears the lake has been used as a catchment since 1720.

2)Lonnie Thompson's Bona-Churchhill's ice core data is unavailable to the public (McIntyre's requested this data for quite some time with no results). How did Mann get this info, and what does it look like it raw form.

3)The Mt Logan and Law Dome ice cores do not show any HS patterns and were not used by Mann. Why is that?

4)Like MBH9X, Mann's raw proxies do not exhibit HS data in and of themselves. In MBH9X, Mann uses a few load bearing proxies and applies an algotrithim to derive the famous HS blade This now infamous PC1). A decade ago the Greybill Bristlecone series produced the late 20th Century blade. Did he do the same with either Lonnie Thompson's ice core series of the speleotherm series taken from Scottland? BTW, the Socotora Island speoleotherm data is also not available to the public; yet, it is an important component in Mann's new paper.

Like MBH9X, the ciritique is not with AGW theory itself, but it is statistical and administrative in nature. Full disclosure of both the raw data as well as the source code should be made by Mann. His claims are that one can arrive at the HS without the controversial Greybill Series (Foxtail Bristlecone data). Should be an interesting debate.

tom:

Nice take on it.

Really, this approach is much more sensible to address temperatures from the past. I mean, tree rings are only so reliable in both time and temperature.

Now if you really want to be accurate, everyone knows you have to look at both stalactites, and stalagmites. I'm glad that Mann et al finally realized this.

I know if I want to see what the high and low temperatures were for last week, I just run down to the corner cave and look at the stalactites and stalagmites, instant and accurate results.

OK, I quit, I can't hold a straight face anymore. Sedimentation and stalactites are more reliable? To within a half a degree fahrenheit over ten years? And then compared to similar temp data over 1,300 years?

And we're supposed to make policy decisions based upon this? How do these guys dream this stuff up and then convince themselves that it is accurate to within .5 degree?

Interesting article on secret government group -
gives some indication why so may of us are confused about AGW.

Jason and the secret climate change war
http://www.timesonline.co.uk/tol/news/environment/article4690900.ece

Ashadowy scientific elite codenamed Jason warned the US about global warming 30 years ago but was sidelined...

I dont get how the fact that it was warmer 1300-1700 years ago is a brick in the wall proving AGW.

That argument is basically saying "Since it was warmer 1500 years ago we know humans are causing global warming."

What!?! You mean the past decade has been warmer than the Medieval Warm Period??? This simply can't be. The researchers at Penn State surely must be conspiring with the government to raise taxes and control our lives. They want to stop our trickle-down wealth redistribution scheme!!

"one brick in the wall"...unfortunately, mr hughes, this brick too will crumble in the AGW house made of straw...peace bros!

I have only 2 questions.
1)
Has Brett Anderson seen the demolition job over at http://www.climateaudit.org/ where Steve McIntyre has exposed the latest version of the hockey stick to ridicule once again?
2)
If so, Brett Anderson, please let us know what you think?

Reply: I just did. Looks like Steve M. put a lot of work and detail into his response to this study. I have not had the time to read through it all.

Oh well this should give Mark and Kipp a warm fuzzy and something to hold onto during the winter months.

REPLY: Yeah, when they are freezing their #&@%$ off!

lets start wearing togas

REPLY: Can't do it. It's too bloody COLD!!!!!

Expect the warmistas to defend at all costs this latest proxy study.

REPLY: Warmistas? I like that. It rings remnants of the "viva la revolution" montra. How very Che, and appropriate, too!...LOL.....

DENY DENY DENY THE GLO-BULL WARMING LIE!!!!!!