LKW says:

quote:

As for Steve nailing anything - such as what? I've explained the reasoning behind the 50/50 bet comment.

To prove an MWP you have to prove that globally it was warmer at the same time.

NAS says:

"Presently available proxy evidence indicates that temperatures at
many, but not all, individual locations were higher during the past 25
years than during any period of comparable length since A.D. 900."

To me, this says that for less than half of individual locations, there is a 25 year period some time in the period 900-1975 when there is evidence of it being warmer than it is now. Let me concede the meaning of "many" and "since AD900" and say that what if 2/3 of individual locations had warmer 25 year periods during an MWP of 900-1200. This range covers 12 25 year periods. So given that the above is true and without taking further evidence into account, the probability that all 2/3 of individual sites were warm at the same 25 year period is much lower than 50%.

This confirms my limited review of temperature reconstruction papers, in which locally detected peaks of temperature are identified, but every local study has peaks at a different period. To me the more likely explanation is that while the MWP was warmer than the LIA, local variability is a better explanation for these peaks.

quote:

Originally posted by realprimate:
eg.

LIKW
Also, the problem for M&M, Wegman and anybody else is that Mann has never produced the actual data and methodology he specifically used.
UNQUOTE

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

When Mann complied, all of the data was available for McIntyre.

Nope you continue to fail to grasp the point I'm making.

The data that was made available did not allow others to replicate the results published in MBH98/99. Both Wahl & Ammann and McIntyre & McKinrick published a much lower level of correlation using the r2 statistic than what was published by Mann.

MBH98/99 claimed a high level of skill using r2. This has not been proven accurate. In fact the corrigendum issued by Mann in Nature acknowledges this.

This isn't difficult to understand.

Had the data and computer code been achieved with the publication of the articles (standard good practice which journals aspire to) then this wouldn't be such an issue.

Nobody denies that the methodology was flawed and that the sampled was tainted by the inclusion of the bristlecone data (which is accepted is not a temperature proxy but does have a hockey stick shape to it).

This shouldn't have been a major issue and for me it isn't as a paper in itself. I'm all for new methodological ideas being tried but the paper needs to be seen as that. The flaws in it are to be expected as these things are never perfect the first time round. Its the usage of the paper and the behaviour of certain individuals which is the issue.

quote:

Originally posted by Steve_M:
LKW says:

quote:

As for Steve nailing anything - such as what? I've explained the reasoning behind the 50/50 bet comment.

To prove an MWP you have to prove that globally it was warmer at the same time.

Nope, this is a nonsense argument otherwise known as a figleaf.

In case you haven't noticed, the Earth doesn't have a global climate nor an average temperature. These are artificial constructs.

We see local variations today as there is no consistent evidence of temperature rises across the globe. Rather, we take an average of all of these local climates to determine changes to this construct that is global temperature.

In fact, if we applied the criteria you suggest then not only is there no MWP but there is no AGW today. The fact that Antarctica has gotten colder despite the rise in greenhouse gases and that the theory of AGW argues for polar amplification invalidates the claim of AGW according to the criteria you have selected.

quote:

In case you haven't noticed, the Earth doesn't have a global climate nor an average temperature. These are artificial constructs.

We can be pedantic as you like. "Warmer" and "colder" are relative concepts. Globally "warmer" means that most weather stations are recording, on average, warmer temperatures, and that the few that are recording cooler temperatures are comfortably balanced out.

On continental scales, six of the continents are showing such warmth. There is also good evidence for ocean energy content going up (*).

Local variations can more easily be explained by changes in atmosphere or ocean circulation, basically meaning that the same amount of energy has been redistributed making one place "warmer" and another "colder". To create a simultaneous global increase in local temperatures you have to get the energy from somewhere else (sun gets warmer) or you have to lose energy slower (earth is better insulated).

In line with global climate models, Antarctica is not warming as quickly. See this Flash animation from my favourite model:

www.metoffice.gov.uk/research/hadleycentre/models/temperature_anim.html

See this for what the AGW theory has to say about polar amplification:

www.realclimate.org/index.php?p=234

More pedantic stuff follows:

* I talk about ocean energy content rising rather than temperature because the structure of ocean temperature and ocean warming is more complex due to its depth and the complexity of its currents. Furthermore, the much larger heat capacity of the ocean means that it wouldn't need to cool much to increase atmosphere temperatures a lot, or warm much to reduce atmospheric temperatures as happens during the El Nino/La Nina (ENSO) cycles. So a plausible cause for global or very large scale regional warming detected on land or in the atmosphere would be a change in ocean currents that bring warmer waters to the surface (and as a consequence cool the ocean). But so far the evidence is that the total ocean energy content is going up, so the energy warming earth isn't from there.

quote:

Originally posted by Steve_M:

quote:

In case you haven't noticed, the Earth doesn't have a global climate nor an average temperature. These are artificial constructs.

We can be pedantic as you like. "Warmer" and "colder" are relative concepts. Globally "warmer" means that most weather stations are recording, on average, warmer temperatures, and that the few that are recording cooler temperatures are comfortably balanced out.

On continental scales, six of the continents are showing such warmth. There is also good evidence for ocean energy content going up (*).

Local variations can more easily be explained by changes in atmosphere or ocean circulation, basically meaning that the same amount of energy has been redistributed making one place "warmer" and another "colder". To create a simultaneous global increase in local temperatures you have to get the energy from somewhere else (sun gets warmer) or you have to lose energy slower (earth is better insulated).

In line with global climate models, Antarctica is not warming as quickly. See this Flash animation from my favourite model:

www.metoffice.gov.uk/research/hadleycentre/models/temperature_anim.html

See this for what the AGW theory has to say about polar amplification:

www.realclimate.org/index.php?p=234

More pedantic stuff follows:

* I talk about ocean energy content rising rather than temperature because the structure of ocean temperature and ocean warming is more complex due to its depth and the complexity of its currents. Furthermore, the much larger heat capacity of the ocean means that it wouldn't need to cool much to increase atmosphere temperatures a lot, or warm much to reduce atmospheric temperatures as happens during the El Nino/La Nina (ENSO) cycles. So a plausible cause for global or very large scale regional warming detected on land or in the atmosphere would be a change in ocean currents that bring warmer waters to the surface (and as a consequence cool the ocean). But so far the evidence is that the total ocean energy content is going up, so the energy warming earth isn't from there.

In other words, you accept that your previous statement was wrong. Well done that man...

quote:

In other words, you accept that your previous statement was wrong. Well done that man...

Might I ask whether you are aware that the strawman argument about the existence of a "global temperature" is straight out of the Christopher Essex and Ross McKitrick school of sceptical thought? Common parlance understands that references to "warmer" and "colder" refer to local anomalies. In context, my original response was clear. Clarification does not imply the previous statement was wrong.

To prove an MWP of significant proportions as compared with current observed warming you have to prove that 1) it rapidly got a lot warmer at many places at the same time, and 2) that it may have got warmer at many of these places than it is now.

Conclusions from the NAS report show that not even the first criterion can be met.

quote:

Originally posted by Steve_M:
To prove an MWP of significant proportions as compared with current observed warming you have to prove that 1) it rapidly got a lot warmer at many places at the same time, and 2) that it may have got warmer at many of these places than it is now.

Conclusions from the NAS report show that not even the first criterion can be met.

And I would also doubt that it has been DISPROVED

quote:

Originally posted by Steve_M:
Conclusions from the NAS report show that not even the first criterion can be met.

I doubt that it has been disproved either!

What's up with this site today? It told me twice that my message had not been posted!

quote:

Originally posted by Steve_M:

quote:

In other words, you accept that your previous statement was wrong. Well done that man...

Might I ask whether you are aware that the strawman argument about the existence of a "global temperature" is straight out of the Christopher Essex and Ross McKitrick school of sceptical thought? Common parlance understands that references to "warmer" and "colder" refer to local anomalies. In context, my original response was clear. Clarification does not imply the previous statement was wrong.

To prove an MWP of significant proportions as compared with current observed warming you have to prove that 1) it rapidly got a lot warmer at many places at the same time, and 2) that it may have got warmer at many of these places than it is now.

Conclusions from the NAS report show that not even the first criterion can be met.

I consider your question a strawman Steve. Since I have repeatedly stated that there isn't the evidence to conclude anything from the Mediaeval Period (something the NAS panel agreed with), the idea that these proxies determine anything is ridiculous. However you continue to state a belief in the ridiculous.

As for the NAS, well considering they were only taking evidence from the friends of Mann its not surprising they came up with the conclusion they did.

As Roseanne D'Arrigo testified at the NAS Panel:

quote:

You have to cherry pick in order to make cherry pie

Also testifying at the NAS panel was Malcolm Hughes (the H in MBH). Hughes stated that the divergence problem with modern proxies (where they are not responding to temperature) means that they could rule out the possibility that the mediaeval period was considerably warmer. You see Steve, trees have an optimum growth period re temperature before declining as the temperature moves beyond that optimum. Its shape is an inverted U when plotted on an X/Y graph.

If you decide to choose another proxy (one not considered by the NAS panel) then different results emerge. Tree lines are an alternative proxy which show a Mediaeval Warm Period in the Northern Hemisphere. North America, Europe and Siberia all have mediaeval tree lines further north than today.

If I wanted to Steve, I could decide to pick apples rather than cherries and produce a large mediaeval warm period. There are a number of proxy data which do show this. However, this would be just as meaningless as the MBH and other multi-proxy studies.

quote:

I consider your question a strawman Steve. Since I have repeatedly stated that there isn't the evidence to conclude anything from the Mediaeval Period

It's not a strawman because many people do hold faith in an MWP as I can attest to having spent a bit of time at climate audit. I'm not sure what position Steve McIntyre holds because he is careful not to upset his allies.

I'm not sure I did understand your position, and now that I do, I'm happy to leave it there.

Tree lines sound interesting. How quickly do they move?

from

http://environment.newscientist.com/article/mg18925431.400

QUOTE
The obscure statistical arguments were overshadowed in late 2005 when Mann refused to give Congressman Barton his computer code. Mann regarded the code as private property, but his opponents claimed he feared refutation of his findings. Mann did eventually publish the code, but the damage was done.

In the meantime, three groups had been scrutinising the claims of McIntyre and McKitrick. Hans von Storch of the GKSS Research Centre in Geesthacht, Germany, concluded that McIntyre and McKitrick were right that temperatures should be analysed relative to the 1000-year mean, not the 20th-century mean. But he also found that even when this was done it did not have much effect on the result. Peter Huybers of the Woods Hole Oceanographic Institution in Massachusetts came to much the same conclusion.

The work of Eugene Wahl of Alfred University, New York, and Caspar Ammann of the National Center for Atmospheric Research in Boulder, Colorado, raised serious questions about the methodology of Mann's critics. They found the reason for the kink in the McIntyre and McKitrick graph was nothing to do with their alternative statistical method; instead, it was because they had left out certain proxies, in particular tree-ring studies based on bristlecone pines in the south-west of the US.

"Basically, the McIntyre and McKitrick case boiled down to whether selected North American tree rings should have been included, and not that there was a mathematical flaw in Mann's analysis," Ammann says. The use of the bristlecone pine series has been questioned because of a growth spurt around the end of the 19th century that might reflect higher CO2 levels rather than higher temperatures, and which Mann corrected for.

What counts in science is not a single study, however. It is whether a finding can be replicated by other groups. Here Mann is on a winning streak: upwards of a dozen studies, some using different statistical techniques or different combinations of proxy records (excluding the bristlecone record, for instance), have produced reconstructions more or less similar to the original hockey stick.
UNQUOTE

Bit of a long extract I know but what's sauce for the Mann goose is sauce for the M&M gander. Note the "serious questions" bit? And Mannn on a "winning streak"?


After 10 years of this there must be definitive account somewhere.

quote:

Originally posted by Steve_M:
To prove an MWP you have to prove that globally it was warmer at the same time.

This applies equally with regards to AGW claims but you always seem to overlook this fact.

quote:

Originally posted by Steve_M:
NAS says:

"Presently available proxy evidence indicates that temperatures at
many, but not all, individual locations were higher during the past 25
years than during any period of comparable length since A.D. 900."

Much of this 25 year increase can be explained through the urban heat island effect.
In other words the locations of the temperature measuring equipment being mostly located in urban areas that exaggerate the actual temperature.

See:
Heat Island Effect

Also see:
Roger Pielke Sr Criticism of the IPCC WG1 Bias

I'm posting this again because the link to 'Watts up with this?' disappeared somehow - it was there when I first posted it because I checked the links.

quote:

Originally posted by Steve_M:
To prove an MWP you have to prove that globally it was warmer at the same time.

This applies equally with regards to AGW claims but you always seem to overlook this fact.

quote:

Originally posted by Steve_M:
NAS says:

"Presently available proxy evidence indicates that temperatures at
many, but not all, individual locations were higher during the past 25
years than during any period of comparable length since A.D. 900."

Much of this 25 year increase can be explained through the urban heat island effect.
In other words the locations of the temperature measuring equipment being mostly located in urban areas that exaggerate the actual temperature.

See:
Heat Island Effect
Watt up with that?

Also see:
Roger Pielke Sr Criticism of the IPCC WG1 Bias

quote:

This applies equally with regards to AGW claims but you always seem to overlook this fact.

No I don't. Six out of seven continents have warmed. Evidence for the 7th (Antarctica) is more equivocal - it has probably warmed slightly over the past 150 years. Ocean heat content is going up. Satellite observations of the mid troposphere show warming trend.

I'm afraid it is very easy to through mud at the temperature record because it is made up of so many sites that there are bound to be some "non-standard" ones. However, users of the data know which ones are good and can therefore quality control their overall assessments.

To suggest a 0.4C rise in the last 25 years is due to the increase in the urban heat island effect is a little over the top. Ironically, adjustments made to the station data in the link you posted (also check climateaudit.org's article on Petaluma if APL's "Watt" link is deleted again) are in the opposite direction to what you say - ie. they have downgraded the amount of warming suggested by the raw data.

Looking at the stations collectively, as has been done in a number of different ways, the bias from urban growth is very small.

PS. the moderators do not like links to blogs and "unofficial sites". Like a naughty schoolchild my account was suspended for a day for pointing to Coby Beck's "How to talk to a climate skeptic" blog and linking to a description of the greenhouse effect on geocities hosted site.

quote:

Originally posted by APL:

Much of this 25 year increase can be explained through the urban heat island effect.
]

Ballcocks.

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

quote:

Originally posted by realprimate:

quote:

Originally posted by APL:

Much of this 25 year increase can be explained through the urban heat island effect.
]

Ballcocks.

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

quote:

Urban heat island effects are real but local, and have a negligible influence (less than 0.006°C per decade over land and zero over the oceans) on these values

The problem with this statement is that the study they are quoting from is Jones et al (1990). There are doubts as to the quality control of the data used here (Soviet Union & China networks) to formulate this effect.

In the United States, a meteorologist called Anthony Watts and colleagues are doing some spade work to give the USHCN this quality control by literally visiting each site for whether they conform to WMO's standards for rural sites. Some of those visited so far have proved wanting in terms of their site location. Watt's site surfacestations.org provide photographic evidence for each location.

This exercise will give a more robust assessment of the quality of the data. It is an excellent project which will enhance the knowledge available. For me, the jury is out as to whether the current benchline for UHIs used by the IPCC is a robust one.

quote:

Originally posted by Steve_M:
.. Six out of seven continents have warmed. Evidence for the 7th (Antarctica) is more equivocal - it has probably warmed slightly over the past 150 years.

This is the trouble with such a catch-all term as "global warming". It is not a concept which has any real meaning, and the difficulties with it are reflected in the difficulties in constructing a meaningful indicator of it.

UHI's a myth.

http://www.realclimate.org/index.php/archives/2004/12/t...heat-island/#more-43

quote:

Originally posted by JL(SFC58,AFCB):

quote:

Originally posted by Steve_M:
.. Six out of seven continents have warmed. Evidence for the 7th (Antarctica) is more equivocal - it has probably warmed slightly over the past 150 years.

This is the trouble with such a catch-all term as "global warming". It is not a concept which has any real meaning, and the difficulties with it are reflected in the difficulties in constructing a meaningful indicator of it.

Especially as AGW refers to the last fifty years only (see the IPCC report). Its somewhat misleading to refer to a longer timespan. The IPCC report also predicts that Antarctica will continue to cool in the next few decades.

quote:

Originally posted by realprimate:
UHI's a myth.

http://www.realclimate.org/index.php/archives/2004/12/t...heat-island/#more-43

Parker does not show the absence of an urban heat island by direct measurements. The claim is that his study demonstrates the absence of an effect on large-scale averages by showing that the temperature trends on calm days is comparable to that on windy days. Go figure.

Also his data set also has the issue of corrupted rural stations on the USHCN. Until all of that network has been tested for quality control then making assumptions either way becomes an expression of faith rather than science.