Global Warming Concensus Broken

[djolds1]

Any error that implies cooling gets lots of publicity from anti-AGW groups. It becomes high profile. Then it is corrected, you hear about this.

The pro-AGW crowd has hyped its assurance of unquestionable accuracy ("the science is done") to the Heavens. They should expect swift kicks to the groin whenever the slightest tarnish shows on the halo. If you're going to claim impeccability, you'd darn well better be impeccable.

In any case the true argument is not warming vs cooling (though some think it is). The true argument relates to how accurate are the climate models.

Concur.

At which point common sense kicks in. If standard weather prediction can barely manage a week out, if economic models which have better data and algorithms then the climate models can barely manage a quarter ahead, why should any credence be given to century forecast models, much less the tremendously expensive policy prescriptions that are bolted onto those forecasts before they're even released (re: Hansen)?

Duane

[djolds1]

Well if solar-induced cooling is large and long-lasting it will be great news for the world - give us enough time to find easier solutions.

See the Medieval Climate Optimum and the Little Ice Age.

Times of Warmth are Times of Plenty.

Times of Cold are Death.

Duane

[bcglorf]

One important point that a few posters here seem to miss. Climate models are about global temperature changes. These are much less variable than local temperature changes, which can show many long-term and short-term pertutbations due to changes in weather patterns.


Agreed, but the tree ring data aren't measuring the last 100 years badly on some local datasets, it is across the board. Finding tree ring data that fits the instrumental record is the exception, not the norm and that is a big deal. It's an even bigger deal when we see a consistent breaking point at the start of the instrumental record. Reconstructions of historic temperature consistently show a startling leap in temperature for the last 150 years. But when you look at the raw data, there are 2 datasets. The proxy data, which doesn't contain the leap and the instrumental record that does. The proxy data is then calibrated/corrected to account for the difference in an attempt to make it 'more' accurate. It's BS and if you read through the methodology for tree ring and ice core datasets you will see it consistently. Look at the raw data for the proxies and try to find the 'startling' leap that is supposed to have hit in the last 150 years, it simply isn't there in the proxy datasets. I've been going through numerous journal articles and have yet to find one with raw proxy data that shows an unprecedented leap in the last 150 years before it is calibrated to the instrumental record.

[Maui]

* 1905: After a strong swing, PDO changed to a "warm" phase.
* 1946: PDO changed to a "cool" phase. [See the blue section of the graph on the right]
* 1977: PDO changed to a "warm" phase.[3]
* 1998: PDO index showed several years of "cool" values, but did not remain in that pattern.[4]
* 2008: The early stages of a cool phase of the basin-wide Pacific Decadal Oscillation.[5]

In all cases in the 1900s, PDO "regime shifts" were related to similar changes in the Tropical ocean.

Simon,

Getting back to PDO and the 75% thing (sorry, I had meant to do this a yesterday, but was busy). I used the dates you provided in which the PDO was in transition and therefore should have been close to neutral in terms of its influence. I compared the estimated global temp (source):

1905 -0.406 C (from 1961 - 1990 mean)
1946 -0.132 C
1977 -0.046 C
1998 0.317 C
2007 0.420 C

So, to me it looks like if you "subtract" PDO, you are left with a fairly steady climb in temperature. I think Pielke's 75% is probably analogous to saying that the difference in temperature from one day to the next is mostly due to the weather pattern and only slightly due to the climatological difference in average temperature between the two days. But that's not to say that the climatological trend in average temperature over a number of weeks or months is not meaningful.

[hanelyp]

I recall an article published before the claims that global warming was a 'proved fact' were taken seriously. It discussed changes in temperature measurement methods over the last century or so, and how those changes might effect the data. For example measuring ocean temperature by hauling up a bucket up water on deck and sticking in a thermometer, vs a thermometer in a water intake of a ship.

The heat island effect of cities growing up around weather stations also needs to be accounted for.

The denial of shortcomings in the models and evidence constitutes fraud.

[Maui]

I still insist the biggest problem with the 'unprecedented' warming argument and defense of it is the temperature record itself... The strongest argument brought out is tree ring data, but tree ring data does NOT show anything abnormal in the last 100 years.

To expand upon what Tom has said (that you can't take one single study and use it against all others), I think a fair place to look is the report the National Academy of Sciences put together at the request of Republican Sherwood Boehlert. They considered hundreds upon hundreds of studys concerning not only tree rings, but also ice isotopes, glacier size, and boreholes. They present charts that do show marked warming over the past century from not only tree rings, but a wide array of sources.

Concerning tree rings, take a look at Chapter 4

In your post you refer to 2 studies on tree rings. Here are the studies taken into account by the NAS's report (on tree rings alone):

* Grissino-Mayer and Fritts 1997
* Kullman 1998
* Körner 1999
* Grace 1988
* Junttila 1986
* Loveys et al. 2002
* MacDonald et al. 1998
* Esper and Schweingruber 2004
* Paulsen et al. 2000
* Lloyd and Graumlich 1997
* Kjällgren and Kullman 2002
* Daniels and Veblen 2003
* Biondi et al. 2005
* Deslauriers et al. 2003
* Rossi et al. 2006
* Mikola 1962
* Kalela-Brundin 1999
* Helama et al. 2002
* Fritts et al. 1991
* Hunt Jr. et al. 1991
* Scuderi et al. 1993
* Berninger et al. 2004
* Misson 2004
* LaMarche 1974
* Vaganov et al. 2006
* Jones et al. 1998
* Hughes 2002
* Cronin 1999
* Schweingruber 1988
* Fritts and Swetnam 1989
* Biondi et al. 1994
* Kienast and Schweingruber 1986
* Villalba et al. 1994
* Buckley et al. 1997
* Tardif et al. 2003
* Piovesan et al. 2005
* Bunn et al. 2005
* Tardif and Bergeron 1997
* Bräker 2002
* Wigley et al. 1984
* Grissino-Mayer 2003
* Baillie and Pilcher 1973
* Wigley et al. 1987
* Yamaguchi 1991
* Stokes and Smiley 1996
* Holmes 1983
* Grissino-Mayer 1997
* LaMarche and Harlan 1973
* Friedrich et al. 2004
* Eckstein et al. 1984
* Webb 1983
* Conkey 1986
* Briffa et al. 2002
* Wang et al. 2002
* Fritts 1976
* Cook and Kairiukstis 1990
* Biondi and Swetnam 1987
* Biondi and Waikul 2004
* Cook et al. 1995
* Grudd et al. 2002
* Briffa et al. 1992
* Esper et al. 2003
* Bunn et al. 2004
* Esper et al. 2002
* Gunnarson and Linderholm 2002
* Naurzbaev et al. 2002
* Trotter et al. 2002
* Hughes et al. 1984
* Fritts 1991
* D’Arrigo et al. 2006
* Xoplaki et al. 2005
* Pollack and Smerdon 2004
* Oerlemans 2005
* Camardi 1999
* Jacoby and D’Arrigo 1995
* Briffa et al. 1998
* Barber et al. 2000
* Lloyd and Fastie 2002
* Wilmking and Juday 2005
* Vaganov et al. 1999
* Briffa et al. 2004
* Hoyt 2006
* D’Arrigo et al. 2001
* Büntgen et al. 2005
* Cook et al. 2004
* Bugmann 1996
* Naurzbaev et al. 2004
* Luckman and Wilson 2005
* Helle and Schleser 2004
* Biondi et al. 1999
* Anchukaitis et al. 2006
* LaMarche et al. 1984
* Graybill and Idso 1993
* Knapp et al. 2001
* Bunn et al. 2003
* Tang et al. 1999
* Nicolussi et al. 1995
* Hamilton et al. 2002
* Hättenschwiler et al. 2002
* Graumlich 1991
* Kienast and Luxmoore 1988
* Körner 2003
* Vitousek et al. 1997
* Kostiainen et al. 2004

Based on these studies and the studies on the other forms of evidence on temperature, they conclude:

After considering all of the available evidence, including the curves shown in Figure S-1, the committee has reached the following conclusions
...
Large-scale surface temperature reconstructions yield a generally consistent picture of temperature trends during the preceding millennium
...
It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries. This statement is justified by the consistency of the evidence from a wide variety of geographically diverse proxies.

And they also present charts showing a number of the different sources together, such as:


If you want to start debating each of these above studies and arguing their validity and applicability vs Yadav and Singh, we can. (and yes, I understand a good majority of those aren't primarily temperature reconstructions, but rather a context for the ones that are) But don't pretend that you have the definite answer based on one study.

Also look at the temperature record graphs of the last 1000 years from the 2008 Gussow-Nuna Geoscience Conference. They look absolutely nothing like the radical hockey stick graph Mann et al. try to play up.
link:http://www.cspg.org/conventions/Gussow2 ... ts/015.pdf

Yeech. You probably should have looked at those charts a little closer before citing these for your argument. Both actually show marked warming in the past 100 years very similar to the hockey stick (approx 1 degree celcius) The trick is the scale (particularily in the first) is very different from the scale used for Mann's classic hockey stick:




Oh, and btw, if you look above, you will see the NAS report did reference the work of this author (Brian Luckman)

[tomclarke]

At which point common sense kicks in. If standard weather prediction can barely manage a week out, if economic models which have better data and algorithms then the climate models can barely manage a quarter ahead, why should any credence be given to century forecast models, much less the tremendously expensive policy prescriptions that are bolted onto those forecasts before they're even released (re: Hansen)?

It is necessary to be careful applying "common sense" to science. Sometimes what happens is counter-intuitive.

However in this case the difference between "climate" and "weather" is easy to understand.

Weather is chaotic and unpredictable. It means the temperature at any one time, at any one place on earth can't be predicted.

Climate (if defined to be global avergae temperature) is much more predictable, it depends on heat flows in and out from the earth as a whole. There is still some noise, but much less than for weather. The models predict average characteristics (specifically temperature) and also predict the typical variation. But this variation is small enough that trends can be seen.

There remains a real argument about how accurate are these models - it is very complex. The modellers themselves don't know how accurate they are, but the best estimates of accuracy make the situation looking forward 50 years with no action now something between very bad and catastrophic.

There is then another argument (political) about when is the best time to make changes, how we do this, who changes most, etc.

It is understandable in view of the significance of this, and the inherent uncertainties in modelling such a complex system as the earth, that many people are unwilling to accept the scientific consensus. Which is why the science is being validated, extended, and explained in an unprecedented way.

As time goes by the scientific uncertainties decrease, the predictions change as necessary. In recent years not much change has been necessary - but there is still a very big gap betwen best and worst case 5% confidence limit scenarios.

If Simon is right, as solar radiation changes are better understood and incorporated into models, there will be a significant change in predictions. Maybe then we will all be less worried. But currently most experts don't believe this. (Yes, some experts do, but few who are actively publishing peer-reviewed papers in the relevant area).

Best wishes, Tom

[tomclarke]

The pro-AGW crowd has hyped its assurance of unquestionable accuracy ("the science is done") to the Heavens. They should expect swift kicks to the groin whenever the slightest tarnish shows on the halo. If you're going to claim impeccability, you'd darn well better be impeccable.

I have sympathy with your dislike of public statements that appear to minimise uncertainty. I think this is the nature of the terrain. Politics is not good at dealing with uncertainty. The IPCC reports don't say the science is all done, in fact they highlight lots of uncertainty, but they do say that the range of uncertainty is such that AGW seems difficult to deny. But an accurate statement has to be stated in terms of a range of future scenarios, with different A-CO2 inputs, and confidence bars on results. This is very complex and does not fit headlines or political speeches.

So what do people do? They answer "you are not sure so go do more science before we take action" arguments by saying "the case is now proven". Meaning that chances of it not being proven are less than 5%.

Given such a complex & large interlocked set of data, physics, models, you don't expect mistakes never to happen. You don't expect every single bit of evidence to point in the same direction. you loook at the whole lot, impartially, try to see how it fits together, what are the possibilities. You go on revising your opinion as new evidence comes to light.

That is science. And it is being done by the IPCC scientists - though the IPCC report is not just science. It is science packaged for politicians & public with some input from said politicians (to make it seem less scary).

It is not pretty. But consider this: how else - assuming for one moment that most of the scientists in this area are right - can decision-makers be appropriately informed?

Best wishes, Tom

[djolds1]

At which point common sense kicks in. If standard weather prediction can barely manage a week out, if economic models which have better data and algorithms then the climate models can barely manage a quarter ahead, why should any credence be given to century forecast models, much less the tremendously expensive policy prescriptions that are bolted onto those forecasts before they're even released (re: Hansen)?

It is necessary to be careful applying "common sense" to science. Sometimes what happens is counter-intuitive.
However in this case the difference between "climate" and "weather" is easy to understand.

Weather is chaotic and unpredictable. It means the temperature at any one time, at any one place on earth can't be predicted.

The better example are the economic models funded by the various finance banks. Both climate and the economy are massively complex chaotic systems. The finance modelers are among the best that mathematics has to offer. They have billions of dollars of motivation to tweak their predictive models right, moreso than the climate academics, and even then the absolute best they can manage is barely 1-2 quarters.

There remains a real argument about how accurate are these models - it is very complex. The modellers themselves don't know how accurate they are, but the best estimates of accuracy make the situation looking forward 50 years with no action now something between very bad and catastrophic.

I have run across too many instances of careless or nearly willful errors built into the models to lend them much credence. One of the models was assigning a cooling trend to urban heat islands for chrissakes. The examples go on and on. And the persistent inability of the models to backcast during the period when matters were "settled" raises serious questions about the credibility of those involved.

This planet has seen no runaway heating episodes since a continent took up residence at the south pole. It has however seen many, many runaway cooling episodes. The Medieval Climate Optimum was no catastrophe, quite the opposite. Predicting that another minimal heating trend will be catastrophic is simply ludicrous.

There is then another argument (political) about when is the best time to make changes, how we do this, who changes most, etc.

There's also a political question attaching to the credibility of Hansen and other "scientific" individuals of his ilk. The funds flowing into climate science these days are 1-2 orders of magnitude above where they were in 1990. That's a huge gravy train, and I doubt those feeding at the tough want to stop the buffet. Science is operated by human beings, and human beings are subject to all human weaknesses.

It is understandable in view of the significance of this, and the inherent uncertainties in modelling such a complex system as the earth, that many people are unwilling to accept the scientific consensus. Which is why the science is being validated, extended, and explained in an unprecedented way.

There's another word for consensus. Groupthink.

Duane

[djolds1]

The pro-AGW crowd has hyped its assurance of unquestionable accuracy ("the science is done") to the Heavens. They should expect swift kicks to the groin whenever the slightest tarnish shows on the halo. If you're going to claim impeccability, you'd darn well better be impeccable.

I have sympathy with your dislike of public statements that appear to minimise uncertainty. I think this is the nature of the terrain. Politics is not good at dealing with uncertainty. The IPCC reports don't say the science is all done, in fact they highlight lots of uncertainty, but they do say that the range of uncertainty is such that AGW seems difficult to deny. But an accurate statement has to be stated in terms of a range of future scenarios, with different A-CO2 inputs, and confidence bars on results. This is very complex and does not fit headlines or political speeches.

It is not the job of science to do politics. It is the job of science to discover and describe fact.

Only the most fundamental physical theories deserve near absolute certainty. Newtonianism, GR, QM. The derivative sciences have a nice track record of serious and consistent error. Consider genetics c.1990. Everyone "knew" that humans had 100,000 genes and near everything about human biology was determined by those base pairs. "We have certainty." But after the Human Genome Project? "Oops." Only 20,000 genes or so, protenomics plays a huge and unexplored role, and oh, btw, we're finding that some acquired traits are passed on. Weird.

It is not pretty. But consider this: how else - assuming for one moment that most of the scientists in this area are right - can decision-makers be appropriately informed?

Assuming that the apocalyptic claim is right is always the wrong response.

Duane

[tomclarke]

The better example are the economic models funded by the various finance banks. Both climate and the economy are massively complex chaotic systems. The finance modelers are among the best that mathematics has to offer. They have billions of dollars of motivation to tweak their predictive models right, moreso than the climate academics, and even then the absolute best they can manage is barely 1-2 quarters.

OK - there is a vast difference between economic and physical models. The physics is quantititative and bears some resemblance to reality. All assumptions are questioned, validated, etc.

Economics has no direct relationship to reality. It is not a science. Classical economics is based on the idea that market actors are rational - obviously not true. The various modern strands of the subject can't do much better because economic cycles depend on human hopes and fears, and are as difficult to forecast as people. And on top of this built-in uncertainty the system, like weather, is chaotic.

To address your other points:

yes models are not always correct. in fact given the complexity, it would be astonishing if any early models were correct. But these models have been developing over many years, with peer review and open discussion. If the consensus is consistently flawed this can be proved and corrections made.

That brings me to your second point. You need to assume that the scientific peer review process breaks down. That real mistakes in models go unchallenged because of some built-in biass.

I do not have figures, but surely the US government is putting money into climate research and hoping for anti-AGW results? So is it clear that the balance of money is on one side?

In any case if there were a major mistake in the modelling assumptions then this would be news of the highest significance. The scientist who could prove this would get a Nobel prize and plaudits from anti_AGW interests all over the world. Surely that is some motivation to try to find mistakes?

The research is challenged, every day, from interests and a few scientists wanting to disprove the consensus. That is as it should be. But so far I don't notice anti-AGW arguments winning the debate. Their arguments are not ignored, they are carefully, and openly, debated.

Best wishes, Tom

[MSimon]

OK - there is a vast difference between economic and physical models. The physics is quantititative and bears some resemblance to reality. All assumptions are questioned, validated, etc.

Well yeah. Except the GCMs are not physics models. That would be way too complicated for current computing resources. They are parameterized. And the parameters are best estimates (or like water vapor WAGS) and we are still finding new and significant parameters. BTW what is the parameter for tree growth at latitude 42N vs temp, water, soil nitrogen, type of tree, solar input, cloud cover, etc. etc. etc. At what latitude to trees change from coolers to warmers. Can you delineate that vs species and how tree extent of a given species varies with all other parameters? Now do that for all the major varieties of vegetation and crops. And with crops let me know what the plantings for each year will be vs economic conditions.

But I know - it all averages out.

Now tell me: when your most significant parameter could be +5 or -5 how good can the GCMs be?

In electronics models where everything can be known to .1% and the parameters (diode junctions, transistors, capacitor soakage, etc.) are well defined a good model run gets you to within 5% of the experimental answer. And average model goes to 10%. And a poor model (out at the limits of the limits of the parameters (real fast or real slow) 20%.

So let me see 5% of 300K is +/- 15deg K. 10% +/- 30 deg K. 20% +/- 60 deg K.

Did I mention that climate model parameters are not as well known as electronic model parameters? And the temperature record used to calibrate the proxies is approximately useless. Good enough to decide shorts, jacket, or overcoat. But 1 deg C accuracy? Surely you jest.

BTW the hockey stick graphs are what you get when you use a Butterworth filter (or in the digital realm an IIR filter) of high order on the data. The bumps like the Medieval Warm, The Maunder Minimum, and the Dalton Minimum get flattened and the end points (the current situation) get exaggerated.

Pielke is right. The best the models can do is sensitivity analysis (which is what us electronicers use our models for). And that is only useful if you get the parameters right. Otherwise all you can do is a sensitivity analysis on the parameters. i.e. if the WV parameter has this value then heating will be X otherwise if it has that value the heating will be -Y.

And every time something new is found the Real Climate guys add another epicycle to their theory. And every epicycle added proves unprecedented warming. If my reputation (such as it is) was worth nothing to me I might change my mind for enough money. Or I might be willing to trash my reputation for a lot more than that. So far no one has offered me that much. I'm willing to open negotiations. It is going to cost a hell of a lot more than a Senate Seat though.

===

I was involved in the analysis of temp measuring instruments at Climate Audit and the bucket, intake water, readings on the bridge discussions also.

Not to mention the heat island "corrections" which if you look at some of the station problems are impossible and will depend on which way the wind is blowing. Oh yeah and the quality and age of the paint on the Stevenson boxes. And their height above ground. And the moisture in the soil. And a gazallion other things. Like instrument quality variations.

Readings on the bridge of a ship are especially interesting when the bridge goes from 30 ft above a wooden ship with sails to 100 ft above an iron ship with engines. And the readings are not taken by scientists but ordinary seamen whose interest in accuracy may leave something to be desired. Not to mention dead reckoning errors. Variation in the quality of the navigators, etc. etc. etc. Did I leave out gun decking the logs? A quaint procedure to be sure.

Did I mention that with cooling water intakes you have a problem of following in the heated wake of another ship in calm seas? And the epicycle for that one? It all averages out.

And out of all this crap - bad models, bad data, we can predict future climate to within 1 deg K 100 years hence.

Did I leave out volcanic variability? Any one know the parameter for that? Because you know them aerosols can be a bitch.

But I love this discussion. Every time I bring up a problem I get a link to a Real Climate epicycle. Luckily those Real Climate guys have thought of everything. Or will soon.

[bcglorf]

From the list of references you give for NAS's report you'll notice that Brifa and Schweingruber show up multiple times in the list. They are also the authors of the article I pointed out above: "Large-scale temperature inferences from tree rings: a review". The one were they note as part of their large scale review
The near hemispheric scale record of temperature estimates in Fig. 5 displays a clear underlying cooling trend during the second half of the 20th century. No such trend is seen in the summer (or any other seasonal) instrumental record. Fig. 6a shows how the trend in latewood density averaged across all northern site trees (i.e. selecting the chronologies from north of 50jN) begins to diverge from the April–September mean temperature record for the same northern land areas, after about 1960. This phenomenon can be recognised on larger geographical scales, virtually across the whole northern sampling network, and has been illustrated and discussed previously for subcontinental scale regions (Briffa et al., 1998b).
If you read their report they graph the divergence and it's very striking, it drove them to try and correct for it as I described in my previous post. I'll also draw attention to their stating "this phenomenon can be recognised on larger geographical scales", I'm not just making things up in stating this isn't a local issue, from the mouths of the top experts it's recognised on a large scale.



You reference the above graph as though it doesn't illustrate exactly what I'm talking about. The graph shows the last 1k years of multiproxy data, and in it there are anomalies far greater than those of the last 150 years. Even your quote from NAS regarding the data states "global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries.", but the graph goes back much farther than 4 centuries, if we go back over a thousand years, the current trends aren't historically unprecedented like panic mongers try to claim.



Again if you look at the above graph, tell me honestly that the last 150 years jump out as radically divergent from the rest of it. The fact of the matter is, it doesn't and looks not much different than natural variation from the thousand year time frame it stretches over.


And the above graph is the best one of all. Look very closely at the legend and the last decade the graph covers. The Red,Green and Purple lines that represent the actual proxy data appear to be currently peaking, and do NOT stand out as particularly unusual against the thousand year record. The black line that looks all scary is the NH Land temperatures. The graph only goes to slightly before 2000, I'll bet you adding the last 10 years of data shows the curve back down and that the proxies do NOT spike up along the black line.

[MSimon]

So what do people do? They answer "you are not sure so go do more science before we take action" arguments by saying "the case is now proven". Meaning that chances of it not being proven are less than 5%.

And you know why they are so sure? Statistically derived evidence? Why no. Because they say so.

When Al Gore gives up his airplane and moves to a smaller house I'll believe in global warming.

When China stops building 1 coal fired plant a week I'll believe something can be done.

[Maui]

You reference the above graph as though it doesn't illustrate exactly what I'm talking about. The graph shows the last 1k years of multiproxy data, and in it there are anomalies far greater than those of the last 150 years. Even your quote from NAS regarding the data states "global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries.", but the graph goes back much farther than 4 centuries, if we go back over a thousand years, the current trends aren't historically unprecedented like panic mongers try to claim.

I'm sorry to disappoint you, but I'm not a panic mongerer. But in my opinion, from the reading I have done on the subject, I do feel the consensus that humans are causing GW via CO2 is very well supported. I would be very open to debates about exactly how bad AGW would be for the Earth (though I will take a stance that until we are fairly confident about just how bad it is for the planet, it is irresponsible to not err on the side of caution in terms of our response).

For now I'm just trying to drive home the point that there is very strong support for AGW. As such, I am not trying to fear-monger that "the Earth is hotter that it has ever been". I am simply trying to hammer home that there is ample support for AGW. Basically, that involves getting people to admit:

1) The principles behind the idea that adding CO2 to the atmosphere will cause the temperature of the Earth to rise is straightforward and not a stretch in any sense. (As far back as 1896 it was suggested that doubling Earth's atmospheric CO2 could cause a 5 degree C rise in temps). Without debating magnitude at this point, do you agree?

2) We are in fact adding CO2 to the atmosphere to the tune of a 50% increase since the industrial revolution. While I agree it cannot suggested with any kind of certainty that the Earth's temperature is outside of a typical range (yet), do you agree it appears very likely that we are outside of a normal range in terms of CO2?

3) Since the industrial revolution (and I'm just focusing on the last 150 years), the temperature of the Earth has risen a significant amount (in the neighborhood of 1 degree celcius) Agree?

4) There are no other factors that we currently know of that scientists agree correlate nearly as well to this rise in temperature as does CO2. Agree?

The Red,Green and Purple lines that represent the actual proxy data appear to be currently peaking, and do NOT stand out as particularly unusual against the thousand year record. The black line that looks all scary is the NH Land temperatures. The graph only goes to slightly before 2000, I'll bet you adding the last 10 years of data shows the curve back down and that the proxies do NOT spike up along the black line.

You confuse me with this line of argument (coupled with your "divergence" line of debate) What are you trying to argue? That proxy data from tree rings would be more accurate than a wide-array of satillite and groud-based mearsurements over the past several decades? If they did not match up well, I think it would be extremely hard to argue anything except that tree rings are, in fact, a poor proxy for measuring historical temperature.

Fortunately for the sake of your argument that tree rings show Earth's temperature within a "normal" range, in this graph you can see the tree ring proxy data closely following measured temperature up to the point it cuts out. Whether or not the data would actually continue to follow the measured temperature in my mind is irrelevant, because you are not going to convince me that tree rings are a more accurate way to measure temperature over the past several decades than the multitude of more direct ways it is measured.