2010 Likely to be the Warmest Year on Record

[Samm]

It appears as if 2010 is going to be the warmest year since temperature records began 130 years ago. NASA, NOAA and the British Metrology office seem to be predicting this according to this recent article/blog post in the New York Times. http://green.blogs.n...=nytimesscience

 

At this current point in time, it looks as if it's becoming increasingly obvious that anthropogenic climate change is occurring.

Edited December 11, 2010 by Samm

[lemur]

If it was the coldest year on record, would that point to anthropogenic climate cooling?

[Samm]

If it was the coldest year on record, would that point to anthropogenic climate cooling?

 

Well, it really depends if it appears to be part of an underlying trend. If it is, it would be supportive of anthropogenic climate cooling, if it wasn't it wouldn't be.

 

Speaking of underlying trends:

 

Edited December 11, 2010 by Samm

[cypress]

It appears as if 2010 is going to be the warmest year since temperature records began 130 years ago. NASA, NOAA and the British Metrology office seem to be predicting this according to this recent article/blog post in the New York Times. http://green.blogs.n...=nytimesscience

 

At this current point in time, it looks as if it's becoming increasingly obvious that anthropogenic climate change is occurring.

 

 

It is misleading to describe the recent 20 years as if it stands out as a climate record. Relative to the previous few hundred years it is high, but relative to the history of the earth it is not unusual. Historical temperature proxies indicate that the climate has been up to 8 degrees centigrade warmer than today and about 4 degrees cooler during the period mammals are known to have existed on this earth.

 

 

Natural causes have the ability to warm the earth dramatically more than the trend over the past 200 years. This is the null hypothesis. How can it be obvious that something other than the null hypothesis is occurring? How has the null hypothesis been ruled out?

[lemur]

Well, it really depends if it appears to be part of an underlying trend. If it is, it would be supportive of anthropogenic climate cooling, if it wasn't it wouldn't be.

By that logic, if a person is arrested for theft and they are identified as racially similar to other thieves, it is supportive of a theory that criminality is a characteristic of that race; but if the person's racial identity is different from other thieves, it does not indicate anything about the thief's race more generally? So basically you are biased in favor of pattern-supporting evidence and you discount evidence that doesn't support observed patterns until there is sufficient data to indicate a new pattern? Doesn't that seem like weak science to you in any way?

[Samm]

It is misleading to describe the recent 20 years as if it stands out as a climate record. Relative to the previous few hundred years it is high, but relative to the history of the earth it is not unusual. Historical temperature proxies indicate that the climate has been up to 8 degrees centigrade warmer than today and about 4 degrees cooler during the period mammals are known to have existed on this earth.

Natural causes have the ability to warm the earth dramatically more than the trend over the past 200 years. This is the null hypothesis. How can it be obvious that something other than the null hypothesis is occurring? How has the null hypothesis been ruled out?

 

 

Well, I thought that before the industrial revolution, temperatures were relatively stable. Then when levels of atmospheric CO2 increased, temperatures started to rise, faster than ever before. The issue isn't the magnitude of temperature rise, it's the rate of temperature rise. 1 degree Celsius per 150 years is very quick in comparison to natural rates. I mean the graph you're show works on the scale of millions of years, while mine works on the scale of decades. In short, I don't believe this sort of rapid temperature rise has really ever occurred before.

 

Here is a graph constructed from the instrumental record, the black line and the various results of numerous different studies using proxies, the other colours. So, yes the sudden temperature rise looks rather sudden.

 

 

 

By that logic, if a person is arrested for theft and they are identified as racially similar to other thieves, it is supportive of a theory that criminality is a characteristic of that race; but if the person's racial identity is different from other thieves, it does not indicate anything about the thief's race more generally? So basically you are biased in favor of pattern-supporting evidence and you discount evidence that doesn't support observed patterns until there is sufficient data to indicate a new pattern? Doesn't that seem like weak science to you in any way?

 

I'm saying that if it's just noise, and there is no underlying trend either way, it's not really evidence of anything. However, if it later becomes part of an underlying trend, I will not discount it as noise. Instead I'll consider it as noise+underlying trend. The real evidence is in the underlying trend.

Edited December 12, 2010 by Samm

[John Cuthber]

If it was the coldest year on record, would that point to anthropogenic climate cooling?

 

No, it could just be a fluke.

That's the difference between climate and weather.

[cypress]

Well, I thought that before the industrial revolution, temperatures were relatively stable. Then when levels of atmospheric CO2 increased, temperatures started to rise, faster than ever before.

 

Perhaps you are being misled yourself then. So you agree that the current temperature relative to temperatures in the 1600-1800's is not and issue since historically the temperatures have been much higher in the not too distance past, certainly since humans have been on earth.

 

The issue isn't the magnitude of temperature rise, it's the rate of temperature rise. 1 degree Celsius per 150 years is very quick in comparison to natural rates. I mean the graph you're show works on the scale of millions of years, while mine works on the scale of decades. In short, I don't believe this sort of rapid temperature rise has really ever occurred before.

 

If it can be shown that even the rate of rise is not significant, then do you agree we are back to the null hypothesis that natural factors alter global temperatures over time? The long term average temperature is estimated at 17 and the estimated typical variance is 7 degrees C. By that standard, our current temperature is now below the average at about 14 degrees C.

 

Here is a graph constructed from the instrumental record, the black line and the various results of numerous different studies using proxies, the other colours. So, yes the sudden temperature rise looks rather sudden.

 

This wiki graphic is a good example of how one can "trick" the data to make a trend seem more significant by making apples to oranges comparisons. The long term proxies graphed are tree ring proxies, selected because on the whole (averaged over the globe) they tend to de-emphasize the medieval warming and little ice age particularly with respect to any rapid changes. Then when the tree data fails to track the current instrument temperature, the black line substituted to carry on the trend, the tree data is not displayed so as to not tip off the viewer that the data series are apples and oranges. If we are interested in comparing the rate of change in temperature for the current trend to historical rates of change, let's be sure we are comparing the same data type.

 

Here is a consistent ice core proxy that also includes the present time up to 1999. Note that temperature rates of change have been comparable over many thousands of years. The current temperature rise does not stand out, though CO2 concentration does.

 

 

Here is the corresponding article.

 

 

I'm saying that if it's just noise, and there is no underlying trend either way, it's not really evidence of anything. However, if it later becomes part of an underlying trend, I will not discount it as noise. Instead I'll consider it as noise+underlying trend. The real evidence is in the underlying trend.

 

Indeed. Can you identify the underling trend when one does not use data that is Cherry picked for that reason?

[lemur]

I'm saying that if it's just noise, and there is no underlying trend either way, it's not really evidence of anything. However, if it later becomes part of an underlying trend, I will not discount it as noise. Instead I'll consider it as noise+underlying trend. The real evidence is in the underlying trend.

I think you have to distinguish between induction and deduction. Seeking patterns in data is inductive research. Once you become conscious of such a pattern, this is the beginning of theory-building. The pattern itself is not an empirical fact just because you have synthesized it from systematic observations of empirical facts. It is just a stepping stone toward building a more rigorous, falsifiable theory. The theory should explain the observed data and make predictions about new data on that basis. It should contain testable hypotheses that detail reasons why/how the theory could be false or require modification. The goal of science is to shed light on HOW knowledge is misconstrued by identifying indefensible claims/ideas/concepts/etc. Science is not meant to be used to build up knowledge to a level of efficacy that falsifying it becomes unfathomable. That would be verificationism.

 

No, it could just be a fluke.

That's the difference between climate and weather.

It's also generally the difference between any single piece of data and the statistical population it is identified as belonging to. If the population you are studying is "weather events that support dominant climate trend perceptions," then every dry day could be taken as evidence that your climate is predominantly dry; unless you regard your climate as predominantly rainy in which case every dry day would be exceptional. It's basically like doing the glass half full/empty debate instead of just saying there's a glass with 30cl of water in it.

 

 

[Samm]

Perhaps you are being misled yourself then. So you agree that the current temperature relative to temperatures in the 1600-1800's is not and issue since historically the temperatures have been much higher in the not too distance past, certainly since humans have been on earth.

 

I would disagree. Temperatures have been higher, inter-glacial periods, permian etc., but the rate of temperature increase is actually the issue. And I was making a comparison to the climate change we are seeing at the moment, when I said "relatively stable".

 

If it can be shown that even the rate of rise is not significant, then do you agree we are back to the null hypothesis that natural factors alter global temperatures over time? The long term average temperature is estimated at 17 and the estimated typical variance is 7 degrees C. By that standard, our current temperature is now below the average at about 14 degrees C.

 

Yeah, I would agree, if it can be shown.

 

This wiki graphic is a good example of how one can "trick" the data to make a trend seem more significant by making apples to oranges comparisons. The long term proxies graphed are tree ring proxies, selected because on the whole (averaged over the globe) they tend to de-emphasize the medieval warming and little ice age particularly with respect to any rapid changes. Then when the tree data fails to track the current instrument temperature, the black line substituted to carry on the trend, the tree data is not displayed so as to not tip off the viewer that the data series are apples and oranges. If we are interested in comparing the rate of change in temperature for the current trend to historical rates of change, let's be sure we are comparing the same data type.

 

Are you suggesting that we cannot compare temperature records using proxies with direct thermometer records? Why? I understand that temperature proxies may not be as accurate as thermometer records, but a comparison still can be made. The tree ring data was omitted, because it was wrong from that point onwards. It's called the Divergence Problem and if you wish to illustrate a record of temperatures as best you can, you probably should remove the data that is known to be wrong.

 

Here is a consistent ice core proxy that also includes the present time up to 1999. Note that temperature rates of change have been comparable over many thousands of years. The current temperature rise does not stand out, though CO2 concentration does.

 

 

Here is the corresponding article.

 

It's interesting to note, that the last few hundred years are actually squashed into a very small horizontal space, and that the temperature rises depicted in that graph are slow in comparison to the increases occurring at the moment. The reason the CO2 has increased dramatically and the temperature hasn't increased as rapidly, is because the oceans are actually absorbing much of the heat.

 

Indeed. Can you identify the underling trend when one does not use data that is Cherry picked for that reason?

 

 

I don't know, I'm not a climate scientist. I might be able to, but I'm not exactly sure.

 

I think you have to distinguish between induction and deduction. Seeking patterns in data is inductive research. Once you become conscious of such a pattern, this is the beginning of theory-building. The pattern itself is not an empirical fact just because you have synthesized it from systematic observations of empirical facts. It is just a stepping stone toward building a more rigorous, falsifiable theory. The theory should explain the observed data and make predictions about new data on that basis. It should contain testable hypotheses that detail reasons why/how the theory could be false or require modification. The goal of science is to shed light on HOW knowledge is misconstrued by identifying indefensible claims/ideas/concepts/etc. Science is not meant to be used to build up knowledge to a level of efficacy that falsifying it becomes unfathomable. That would be verificationism.

 

Okay. Fair enough.

[JohnB]

Yeah, I would agree, if it can be shown.

 

Samm, I suggest you read up on the "Younger Dryas" period. You are talking about a .7 degree increase in 150 years, (Note that your starting point was the coldest part of the Little Ice Age, so it is unsurprising that it's getting warmer) the Greenland cores show a temp decrease and increase of roughly 15 degrees in under 70 years. Allowing for polar amplification that would mean circa 3 degrees in the tropics.

 

.7 degrees in 150 years or 3 degrees in 70 years, which is the higher warming rate?

 

P.S. You might like to look at the names of the authors of those "different studies". Funny how the same people using the same data get the same answer, isn't it? BTW, if you look here you'll find some hundreds of temperature reconstructions that don't match the wiki graph. By all means have a look at the reconstructions and the proxies used. You will find that temperatures were not, as you say, "relatively stable" at all.

 

It is better to read the literature than to swallow the hype. (And there is plenty from both sides in the climate debate)

Edited December 14, 2010 by JohnB

[Samm]

Samm, I suggest you read up on the "Younger Dryas" period. You are talking about a .7 degree increase in 150 years, (Note that your starting point was the coldest part of the Little Ice Age, so it is unsurprising that it's getting warmer) the Greenland cores show a temp decrease and increase of roughly 15 degrees in under 70 years. Allowing for polar amplification that would mean circa 3 degrees in the tropics.

 

.7 degrees in 150 years or 3 degrees in 70 years, which is the higher warming rate?

Yes, "Younger Dryas", was a very significant event. The temperature changed significantly, because of a massive change in the ocean currents. However, that sort of drastic change is not occurring at the moment, except in the case of levels of atmospheric greenhouse gases. Second of all, it is unsure that the Little Ice Age was global, while we are sure that the current temperature rises are global.

 

Do you dispute the fact that greenhouse gases trap heat?

 

P.S. You might like to look at the names of the authors of those "different studies". Funny how the same people using the same data get the same answer, isn't it? BTW, if you look here you'll find some hundreds of temperature reconstructions that don't match the wiki graph. By all means have a look at the reconstructions and the proxies used. You will find that temperatures were not, as you say, "relatively stable" at all.

 

It is better to read the literature than to swallow the hype. (And there is plenty from both sides in the climate debate)

Yes, I understand that the climate is variable. However, many of the temperature reconstructions are local or confined to a small part of the world. The graph I have shown you depicts global temperature. Additionally, the same people do not use the same data, they use different data, and there are a number of different people actually building that reconstruction.

[JohnB]

Yes, "Younger Dryas", was a very significant event. The temperature changed significantly, because of a massive change in the ocean currents. However, that sort of drastic change is not occurring at the moment, except in the case of levels of atmospheric greenhouse gases. Second of all, it is unsure that the Little Ice Age was global, while we are sure that the current temperature rises are global.

 

Firstly the cause of the YD is unknown. We have theories that range from ocean currents through meteor impacts right down to mammoth farts. None of them properly explain the period. However I used it to illustrate that climate has changed far more rapidly in the past than in the 20th C. You asked if it could be shown that climate could change rapidly, I showed you.

 

You are correct that "that sort of drastic change is not occurring at the moment" because the temp change is much slower than then although todays change is not "drastic" by any means. Note that change in cloud cover of around 1% over the last 150 years is quite capable of explaining all the warming since industrialisation. Are you assuming that planetary cloud cover doesn't change by a percentage point over centennial scales? Do you believe that cloud cover is really that stable? If you agree that clouds could change by that much over that period then you have an alternate hypothesis capable of explaining much of the warming.

 

Secondly I suggest you actually read the papers from your spaghetti graph. You will find that a number of them are not global reconstructions at all, but northern hemisphere ones. In the case of MBH 1999, the entire 14th C comes from one pine tree in the US. Call me a scientific purist if you will, but I doubt that the hemispheric temperature for an entire century can be extrapolated with any accuracy from one tree. If you follow the link I gave you will see temp reconstructions from every continent. I suggest most strongly that if proxies from every continent on the planet show both a MWP and a LIA, then they were indeed global phenomena.

 

Do you dispute the fact that greenhouse gases trap heat?

 

As stated yes. GHGs, specifically CO2 do not "trap" outgoing radiation. They block and reradiate it. This has the effect of slowing the outgoing radiation, not trapping it. The end result is roughly the same but it is better to talk about and understand the correct way that the system works. Rather than a mirror that reflects heat back down it is better to think of it a blanket which slows heat loss.

 

Yes, I understand that the climate is variable. However, many of the temperature reconstructions are local or confined to a small part of the world. The graph I have shown you depicts global temperature. Additionally, the same people do not use the same data, they use different data, and there are a number of different people actually building that reconstruction.

 

My response is partly covered above, but to expand. What do you think a global reconstruction is based on? Local data sets. If you take those local sets of proxies and add them together you get a global set in the same way that you can combine the readings from various temperature stations into a global temperature history. Or, and this is the method preferred by Dr. Mann and some others, you can compare the proxy record to the 20th C instrumental global set and decide that trees etc do not respond to local conditions but to global ones. Quite often all the proxies come from the NH but are calibrated against the data sets from CRU or GISS, so they are NH proxies calibrated against global temps. This is fine if you believe that a warm summer in Melbourne Australia actually effects the growth of a pine tree in Scandinavia.

 

Secondly the graph you put up was of 10 reconstructions, to wit;

1. (dark blue 1000-1991): P.D. Jones, K.R. Briffa, T.P. Barnett, and S.F.B. Tett (1998). , The Holocene, 8: 455-471.

2. (blue 1000-1980): M.E. Mann, R.S. Bradley, and M.K. Hughes (1999). , Geophysical Research Letters, 26(6): 759-762.

3. (light blue 1000-1965): Crowley and Lowery (2000). , Ambio, 29: 51-54. Modified as published in Crowley (2000). , Science, 289: 270-277.

4. (lightest blue 1402-1960): K.R. Briffa, T.J. Osborn, F.H. Schweingruber, I.C. Harris, P.D. Jones, S.G. Shiyatov, S.G. and E.A. Vaganov (2001). , J. Geophys. Res., 106: 2929-2941.

5. (light green 831-1992): J. Esper, E.R. Cook, and F.H. Schweingruber (2002). , Science, 295(5563): 2250-2253.

6. (yellow 200-1980): M.E. Mann and P.D. Jones (2003). , Geophysical Research Letters, 30(15): 1820. doi:10.1029/2003GL017814.

7. (orange 200-1995): P.D. Jones and M.E. Mann (2004). , Reviews of Geophysics, 42: RG2002. doi:10.1029/2003RG000143

8. (red-orange 1500-1980): S. Huang (2004). , Geophys. Res Lett., 31: L13205. doi:10.1029/2004GL019781

9. (red 1-1979): A. Moberg, D.M. Sonechkin, K. Holmgren, N.M. Datsenko and W. Karlén (2005). , Nature, 443: 613-617. doi:10.1038/nature03265

10. (dark red 1600-1990): J.H. Oerlemans (2005). , Science, 308: 675-677. doi:10.1126/science.1107046

 

Note that number 2 is MBH 1999 and is a NH reconstruction and not a global one. Make sure your facts and data are correct before claiming "Global" reconstructions. You should also be aware that some later reconstructions actually use the result of MBH 1999 as one of their proxies. You might also want to check out Figure 5.8 in the Wegman Report which lists the proxies used in 12 studies, many of them are in your graph. Yes Samm, they do quite often use the same data, over and over again. Even when it shown to be contaminated and even when specifically told that due to confounding factors it should not be used.

 

The Tiljander sediment series and Bristlecone pines come immediately to mind. The NAS said that bristlecones shouldn't be used as temp proxies due to CO2 fertilization and other factors, but I presume that since those in the NAS aren't "paleoclimatologists" or whatever they can be ignored. The Tiljander series is so contaminated by local riverworks over the last 200 years that Dr. Tiljander specifically stated that the series should not be used for temp reconstructions as due to the contamination during the entire instrumental period, it could not be calibrated with any sort of accuracy. Yet you find Tiljander in both Mann 2008 and Mann 2009 so I guess that since Dr. Tiljander goes out and gets her hands dirty her opinion about her own cores is not worth listening to. The fact that they are used upside down is a totally different point.

 

Earlier in this thread you said;

and if you wish to illustrate a record of temperatures as best you can, you probably should remove the data that is known to be wrong.

 

So what is your opinion concerning those who continue to use data that is known to be wrong?

[swansont]

 

As stated yes. GHGs, specifically CO2 do not "trap" outgoing radiation. They block and reradiate it. This has the effect of slowing the outgoing radiation, not trapping it. The end result is roughly the same but it is better to talk about and understand the correct way that the system works. Rather than a mirror that reflects heat back down it is better to think of it a blanket which slows heat loss.

 

 

It is much more like a partially reflective mirror. Saying it's a blanket is just a different analogy, but I don't see that it's any better. I think if you asked people how a blanket worked, I suspect a decent fraction of them would say it traps heat (rather than the correct answer of impeding heat transfer; a blanket will keep a cold object cold too). It uses the analogy of conduction and convection instead of radiation, but radiation is actually what we're discussing. The advantage is one of familiarity, but an additional disadvantage is that the usual use is one in which the blanketed object is the original source of the heat, and I have to wonder if that skews understanding of the issue.

 

The reradiation does, colloquially speaking, "trap (some) heat," storing the energy and/or making the temperature go up, until you (eventually) emit the same amount of power as you receive, once you achieve steady-state. I don't see that anyone here necessarily has a problem with the concept using either model.

[JohnB]

I think that I can agree with the partially reflective mirror idea. It's just that most people think of a mirror as being totally reflective. Part of the problem is the simplified diagrams that we use to explain energy transfer within the budget. Many therefore think of the CO2 as a mirror in the troposphere reflecting the radiation back down which is misleading. Also a "trap" is something that you can't get out of so use of the word implies that the heat does not escape when in fact it does, but it takes longer.

 

Another analogy would be the small town on the highway. Cars travelling the highway are doing 100 kph, they slow down to 60 kph to go through the town and then speed up again when they leave. The town slows the rate of travel but doesn't trap you. (Unless you're in a Steven King novel. )

 

In the case of the atmosphere as a whole then I think the blanket idea is far better since we aren't simply talking about radiation but convection as well.

[Samm]

Firstly the cause of the YD is unknown. We have theories that range from ocean currents through meteor impacts right down to mammoth farts. None of them properly explain the period. However I used it to illustrate that climate has changed far more rapidly in the past than in the 20th C. You asked if it could be shown that climate could change rapidly, I showed you.

 

I'm don't think that is entirely correct. I hadn't really realised this at first, but the Younger Dryas appears to be confined to the Northern Hemisphere. This article: What Caused the Younger Dryas Event, by Anders E. Carlson, published in Geology says the following:

 

The North Atlantic region cooled during this interval with a weakening of Northern Hemisphere monsoon strength. The reduction in northward heat transport warmed the Southern Hemisphere due to a process commonly referred to as the bipolar-seesaw

 

So while the Younger Dryas may have been greater in magnitude than the current warming we are seeing now it was actually more limited in terms of extent.

 

Furthermore, there appears to be a prevailing theory among climate scientists. The same article goes on to say:

Although it is generally accepted that the cold event resulted from a slowing Atlantic meridional overturning circulation (AMOC), the forcing of this AMOC reduction remains intensely debated.

 

You are correct that "that sort of drastic change is not occurring at the moment" because the temp change is much slower than then although todays change is not "drastic" by any means.

 

I was referring to the cause of the Younger Dryas event when I stated that, sorry for the misunderstanding.

 

Note that change in cloud cover of around 1% over the last 150 years is quite capable of explaining all the warming since industrialisation. Are you assuming that planetary cloud cover doesn't change by a percentage point over centennial scales? Do you believe that cloud cover is really that stable? If you agree that clouds could change by that much over that period then you have an alternate hypothesis capable of explaining much of the warming.

 

It may be possible for that change to occur, but that doesn't actually mean it did. Secondly, I would like to see a source for that claim, as you have neglected to provide one.

 

Secondly I suggest you actually read the papers from your spaghetti graph. You will find that a number of them are not global reconstructions at all, but northern hemisphere ones. In the case of MBH 1999, the entire 14th C comes from one pine tree in the US. Call me a scientific purist if you will, but I doubt that the hemispheric temperature for an entire century can be extrapolated with any accuracy from one tree. If you follow the link I gave you will see temp reconstructions from every continent. I suggest most strongly that if proxies from every continent on the planet show both a MWP and a LIA, then they were indeed global phenomena.

 

I understand I was wrong when I stated they were all global reconstructions in hindsight. The fact that one of these graphs may have been dubious doesn't invalidate all the other graphs. M.E. Mann and P.D. Jones (2003). , Geophysical Research Letters, 30(15): 1820. doi:10.1029/2003GL017814 is a global reconstruction using 13 different data sets. It alone should be reasonable evidence to suggest that the current warming is unprecedented at least in terms of the last two millennia.

 

As stated yes. GHGs, specifically CO2 do not "trap" outgoing radiation. They block and reradiate it. This has the effect of slowing the outgoing radiation, not trapping it. The end result is roughly the same but it is better to talk about and understand the correct way that the system works. Rather than a mirror that reflects heat back down it is better to think of it a blanket which slows heat loss.

 

Sure. Then would you deny that increased emissions of GHGs would likely cause a warming effect on the climate?

 

My response is partly covered above, but to expand. What do you think a global reconstruction is based on? Local data sets. If you take those local sets of proxies and add them together you get a global set in the same way that you can combine the readings from various temperature stations into a global temperature history. Or, and this is the method preferred by Dr. Mann and some others, you can compare the proxy record to the 20th C instrumental global set and decide that trees etc do not respond to local conditions but to global ones. Quite often all the proxies come from the NH but are calibrated against the data sets from CRU or GISS, so they are NH proxies calibrated against global temps. This is fine if you believe that a warm summer in Melbourne Australia actually effects the growth of a pine tree in Scandinavia.

 

It's interesting that you are saying this. Mann and Jones at least in the aforementioned paper doesn't do actually do that. Here's a paragraph from their paper (emphasis mine):

 

Composite series were formed from weighted combinations of the individual standardized proxy series, employing weights on the individual records that account for the size of the region sampled, and the estimated reliability of the temperature signal as determined by comparison with the instrumental surface temperature record [Jones et al., 1999]. Local (decadal) correlations were calculated between each proxy record and the instrumental grid-box surface temperature records for the regions they represent over the period 1901–1980 (see Figure 1). Proxy records exhibiting negative or approximately zero local correlations (SH record #2 and #3) were eliminated from further consideration in the study.

 

So Mann and Jones, actually take the proxy and compare it to the local instrumental record to see how accurate it is. Then they use that to weight their combinations to form the graph. I'd consider that pretty reasonable myself.

 

Secondly the graph you put up was of 10 reconstructions, to wit;

 

Note that number 2 is MBH 1999 and is a NH reconstruction and not a global one. Make sure your facts and data are correct before claiming "Global" reconstructions.

 

That doesn't invalidate the paper I've mentioned earlier which is number 6 if you want to know. Number 7 is also global, as is number 8, and number 10 appears to be global as well.

 

You should also be aware that some later reconstructions actually use the result of MBH 1999 as one of their proxies. You might also want to check out Figure 5.8 in the Wegman Report which lists the proxies used in 12 studies, many of them are in your graph. Yes Samm, they do quite often use the same data, over and over again. Even when it shown to be contaminated and even when specifically told that due to confounding factors it should not be used.

 

Okay, they do use the same proxies again and again, but they also include different proxies as well, so it's not entirely the same.

 

The Tiljander sediment series and Bristlecone pines come immediately to mind. The NAS said that bristlecones shouldn't be used as temp proxies due to CO2 fertilization and other factors, but I presume that since those in the NAS aren't "paleoclimatologists" or whatever they can be ignored. The Tiljander series is so contaminated by local riverworks over the last 200 years that Dr. Tiljander specifically stated that the series should not be used for temp reconstructions as due to the contamination during the entire instrumental period, it could not be calibrated with any sort of accuracy. Yet you find Tiljander in both Mann 2008 and Mann 2009 so I guess that since Dr. Tiljander goes out and gets her hands dirty her opinion about her own cores is not worth listening to. The fact that they are used upside down is a totally different point.

 

Explain to me the relevance of those Tijander Sediments to this graph. And in what paper was this actually published? I would like to know. I understand that the Pines were used in a number of these graphs, but that doesn't invalidate the darkest blue data set, Jones 98, the lightest blue Briffa 2001, the red-orange Huang 2004 or the darkest red, Oerlemans 2005. It doesn't really appear to matter either way, whether they include Bristlecone Pine data or otherwise, they all appear to be giving the same message.

 

So what is your opinion concerning those who continue to use data that is known to be wrong?

 

Mann 2008 and 2009 are not included in that graph. I'm not even sure if those papers exist. Second of all, I'm pretty sure that not all reconstructions use Bristlecone Pine tree ring data, and yet they all seem to support each other. This article in the Guardian suggests that Mann's data although tainted in the 1999 reconstruction, was generally fairly accurate. And furthermore, those papers were published quite some time ago and I don't think they really can go back and change the data they used.

Edited December 17, 2010 by Samm

[JohnB]

I hit the wrong button earlier and lost the entire post. It's past 1 am so if this redone one isn't what it could be, my apologies.

 

Samm, good post.

 

The cause and extent (of the cold) of the YD period is still being debated. One would have to argue that it was global because the idea that one hemisphere could drop to ice age conditions for over 1,000 years without any effect on the other hemisphere is insane. It would require that there be no mixing across the equator, simply not possible. The effects are also being discussed. Here we find that New Zealand was warmer and here we find that Vanuatu was cooler. We can safely say that the NH cooled, but what the SH did is still open to interpretation.

 

As to the cause, you might find this PPT interesting as it covers a few of the possibilities. It was possibly caused by meltwater release, but whatever the cause it put paid to the megafauna around the planet and wiped out the Clovis people in north america.

 

However, that is neither here nor there. I mentioned the YD to demonstrate that global changes far greater than those of the 20th C have occurred in the past from natural causes. I take it the point is made?

 

It may be possible for that change to occur, but that doesn't actually mean it did. Secondly, I would like to see a source for that claim, as you have neglected to provide one.

Sorry about that. Firstly I would have to say that it is more than possible, it is certain. To say otherwise is to say that cloud cover stays within 1 percentage point on centennial scales, the climate is simply not that stable. As to who I've been reading, Dr. Roy Spencer, the guy who does the UAH satellite temperature series. I get the feeling that he might have some idea of what he is talking about. Clouds are the biggest unknown in the climate system and GCMs treat them as feedbacks only. This is still being debated however, Spencer and Braswell 2010show that clouds can be a forcing but at the same time look like a feedback. CERN are also doing the CLOUD experiments to check on the idea of cloud formation being effected by GCRs. This research is ongoing.

 

The bottom line is that many in the climate community view clouds only as a feedback response to temperature. However if clouds respond to another driver that is not temperature related they then become a forcing for temperature. Note also that the prevailing assumption is that the climate is a closed system that can only be effected by external forcings and temperature changes cannot be derived from purely internal variations. When dealing with a chaotic system opinions and assumptions become important. Lacis 2010showed by using a model that CO2 was the primary driver of the climate system, more important than water even. However to do this they assumed that WV and everything else is a feedback only and that was what was put into the model. Hmmm, you tell the model that only CO2 is a forcing and that everything else is a feedback and then I'm supposed to wonder why your model run shows that only CO2 is a forcing?

 

I understand I was wrong when I stated they were all global reconstructions in hindsight.

 

You weren't wrong, the person who did the graph was wrong, you were mislead. There is a difference.

 

The fact that one of these graphs may have been dubious doesn't invalidate all the other graphs. M.E. Mann and P.D. Jones (2003). , Geophysical Research Letters, 30(15): 1820. doi:10.1029/2003GL017814 is a global reconstruction using 13 different data sets. It alone should be reasonable evidence to suggest that the current warming is unprecedented at least in terms of the last two millennia.

 

For some reason the link to the paper has stopped working. There are many problems with paleothermometry, not least that the error bars are huge after 1,000 years. Personally I'd like to see somebody do it with everything we've got. I'd also like to see somebody do a global reconstruction of the 20th C using say, 13 stations from around the planet. And have it accurate to .1 of a degree or less.

 

Samm, note that I didn't say that all reconstructions get calibrated against global temps, some are and some aren't. You did note the bit about "weighting", depending on the weightings, you can make a result say pretty much anything you wish. I'm not suggesting anything untoward by saying that, or any attempt to mislead, but "confirmation bias" is something to always be worried about. (Even for us sceptics. ) There is a good article here on the work of Dr. Ioannidis concerning this.

 

As to the warming being "unprecedented at least in terms of the last two millennia", big woop. Have a good look at the long term temps and you'll see that the period circa 1775-1875 was arguably the coldest period in the last 8,000 years. The highest temps now don't make it to the lowest temps during the Holocene Optimum. Are you really surprised that temps have risen since we left the Little Ice Age?

 

You might be interested in this paper from JGS concerning prehistoric finds that were under the Swiss glaciers. The finds were grouped "from four distinct windows of time: Neolithic Age (4900 to 4450 cal. yr BP), early Bronze Age (41003650 cal. yr BP), Roman Age (1st3rd century AD), and Medieval times (89th century AD and 1415th century AD)." The results of this paper go both ways; Firstly and obviously it means that the studied glacier has retreated further than at any time in the last 5,000 years or so. Conversely it also shows that there was a "Roman Warm Period" followed by a cold period where the glacier advanced and then a "Medieval Warm Period" where the glacier retreated again. This was followed by a glacial advance for the LIA and then the current warming. Such a timeline doesn't look much like the gradual drop in temps the reconstructions show, does it? Not being mean, but I'll take solid archaeological evidence over a statistical "reconstruction" any day.

 

Well, it's now 2am. So if I've stuffed up or missed something or not made sense, let me know and I'll adress it in another post. Cheers.

Edited December 18, 2010 by JohnB

[cypress]

 

Mann 2008 and 2009 are not included in that graph. I'm not even sure if those papers exist. Second of all, I'm pretty sure that not all reconstructions use Bristlecone Pine tree ring data, and yet they all seem to support each other. This article in the Guardian suggests that Mann's data although tainted in the 1999 reconstruction, was generally fairly accurate. And furthermore, those papers were published quite some time ago and I don't think they really can go back and change the data they used.

 

 

Mann seems to have employed a form of conformational bias to generate a graphic that supported his view of historical and current climate change. He carefully chose a proxy that was known to de-emphasize the medieval warming and 1500-1700 little ice age. Then he chose a subset of that proxy that he could apply statistical analysis and obtain a result that closely matched his previous erroneous and discredited prior results. However because his proxies failed to continue the desired upward trend he was looking for post 1980, he simply tricked the data by dropping the proxy in favor of a a data set that supported his viewpoint better.

 

Here is a rebuttal article pointing out Mann et al's statistical weaknesses and providing a basis as to why one should not put too much stock in Mann's reconstructions.

 

The article generated a firestorm of discussions, much of it is available on the web at various locations.

[swansont]

Here is a rebuttal article pointing out Mann et al's statistical weaknesses and providing a basis as to why one should not put too much stock in Mann's reconstructions.

 

There are criticisms of this paper, but

Using our model, we calculate that there is a 36% posterior probability that 1998 was the warmest year over the past thousand. If we consider rolling decades, 1997-2006 is the warmest on record; our model gives an 80% chance that it was the warmest in the past thousand years.

 

And their own reconstruction is a hockey stick!

[cypress]

If that is your primary conclusion, I doubt your objectivity.

[swansont]

If that is your primary conclusion, I doubt your objectivity.

 

Well argued.

[Samm]

Samm, good post.

 

Thanks actually. I'm glad I'm actually getting recognition from some of the more senior members of this forum, even if they disagree with me.

 

The cause and extent (of the cold) of the YD period is still being debated. One would have to argue that it was global because the idea that one hemisphere could drop to ice age conditions for over 1,000 years without any effect on the other hemisphere is insane. It would require that there be no mixing across the equator, simply not possible. The effects are also being discussed. Here we find that New Zealand was warmer and here we find that Vanuatu was cooler. We can safely say that the NH cooled, but what the SH did is still open to interpretation.

 

Well, if it is true that the YD period is caused by a decrease of heat moving towards the Northern Hemisphere, and the radiative, greenhouse and other forcings stay roughly the same, one would expect a higher concentration of heat in the Southern Hemisphere.

 

As to the cause, you might find this PPT interesting as it covers a few of the possibilities. It was possibly caused by meltwater release, but whatever the cause it put paid to the megafauna around the planet and wiped out the Clovis people in north america.

 

However, that is neither here nor there. I mentioned the YD to demonstrate that global changes far greater than those of the 20th C have occurred in the past from natural causes. I take it the point is made?

 

 

Yes, that point is made. The hypothetical causes were actually quite interesting. Thanks for posting it up there.

 

Sorry about that. Firstly I would have to say that it is more than possible, it is certain. To say otherwise is to say that cloud cover stays within 1 percentage point on centennial scales, the climate is simply not that stable. As to who I've been reading, Dr. Roy Spencer, the guy who does the UAH satellite temperature series. I get the feeling that he might have some idea of what he is talking about. Clouds are the biggest unknown in the climate system and GCMs treat them as feedbacks only. This is still being debated however, Spencer and Braswell 2010show that clouds can be a forcing but at the same time look like a feedback. CERN are also doing the CLOUD experiments to check on the idea of cloud formation being effected by GCRs. This research is ongoing.

 

The bottom line is that many in the climate community view clouds only as a feedback response to temperature. However if clouds respond to another driver that is not temperature related they then become a forcing for temperature. Note also that the prevailing assumption is that the climate is a closed system that can only be effected by external forcings and temperature changes cannot be derived from purely internal variations. When dealing with a chaotic system opinions and assumptions become important. Lacis 2010showed by using a model that CO2 was the primary driver of the climate system, more important than water even. However to do this they assumed that WV and everything else is a feedback only and that was what was put into the model. Hmmm, you tell the model that only CO2 is a forcing and that everything else is a feedback and then I'm supposed to wonder why your model run shows that only CO2 is a forcing?

 

Okay. Roy Spencer... He's said this, it seems a little like a conspiracy theory:

 

Dessler's paper is being announced on probably THE best day for it to support the IPCC's COP-16 meeting here in Cancun, and whatever agreement is announced tomorrow in the way of international climate policy.I suspect – but have no proof of it – that Dessler was under pressure to get this paper published to blunt the negative impact our work has had on the IPCC's efforts.But if this is the best they can do, the scientists aligning themselves with the IPCC really are running out of ideas to help shore up their climate models, and their claims that our climate system is very sensitive to greenhouse gas emissions.The weak reasoning the paper employs – and the evidence we published which it purposely ignores! – combined with the great deal of media attention it will garner at a time when the IPCC needs to regain scientific respectability (especially after Climategate), makes this new Science paper just one more reason why the public is increasingly distrustful of the scientific community when it comes to research having enormous policy implications.

 

I'm just saying that although Spencer may make decent papers, he does seem significantly biased and that much of what he says should be taken with a pinch of salt.

 

The amount of water vapour in the troposphere is considered a feedback for good reason. Naturally it maintains a state of equilibrium based on the temperature. This is because of its very short life in the atmosphere, around 10 days. So, over long periods of time, all other things being equal, the level of water vapour will stay much the same, save for short-term fluctuations. If you have an increase in temperature, you'll have an increase in water vapour in order to maintain the same relative level of humidity. This is a feedback, warming the atmosphere even more. Thus it's a feedback. Sure, this may a fairly superficial explanation, but I believe it's fairly close to the truth.

 

As for clouds, I'm not exactly sure. There seems to be very little if any, external forcing influencing clouds. Cosmic Rays is one, but that has yet to be proven. We know that clouds are influenced by atmospheric conditions, so it seems logical that clouds could be considered a function of the atmospheric conditions. As they may have an affect on temperature, it seems fair that they're considered a feedback.

 

Basically, although clouds and water vapour are important, they aren't the primary drivers of the climate. They play to the whims of the other greenhouse gases, because of their short life in the atmosphere.

You weren't wrong, the person who did the graph was wrong, you were mislead. There is a difference.

 

Yeah. I now realise it's important to look deeper into the issues so that you can make an educated decision.

 

For some reason the link to the paper has stopped working. There are many problems with paleothermometry, not least that the error bars are huge after 1,000 years. Personally I'd like to see somebody do it with everything we've got. I'd also like to see somebody do a global reconstruction of the 20th C using say, 13 stations from around the planet. And have it accurate to .1 of a degree or less.

 

I can tell you the former would make an excellent paper. Remember you'd have to discount the proxies that don't work, and fail to correlate with the instrumental record. The latter, that would be interesting, but I doubt it'd be published as a paper, I'd like to see it as an intellectual exercise. Furthermore, I think that the Mann and Jones 2003 paper did include significant error bars. It doesn't appear as if they purport to have some ridiculous level of accuracy.

 

I think I've found another link to the same paper, though it is in the same domain. Try this.

 

Samm, note that I didn't say that all reconstructions get calibrated against global temps, some are and some aren't. You did note the bit about "weighting", depending on the weightings, you can make a result say pretty much anything you wish. I'm not suggesting anything untoward by saying that, or any attempt to mislead, but "confirmation bias" is something to always be worried about. (Even for us sceptics. ) There is a good article here on the work of Dr. Ioannidis concerning this.

 

That is a good point, would you mind telling me which ones were and weren't? I know that number 7, Mann and Jones 2004 is not. It definitely doesn't calibrate proxies with the global instrumental temperature record, it actually calibrates the proxies with the local temperature record. The paper says the following:

 

The use of instrumental climate data records is an essential component of high-resolution paleoclimatology, as it provides the quantitative information against which proxy climatic indicators must be calibrated. The longer the instrumental record in the vicinity of the proxy site, the greater the potential for accurate assessment of the fidelity of a proxy reconstruction achieved by local calibration approaches.

 

As to the warming being "unprecedented at least in terms of the last two millennia", big woop. Have a good look at the long term temps and you'll see that the period circa 1775-1875 was arguably the coldest period in the last 8,000 years. The highest temps now don't make it to the lowest temps during the Holocene Optimum. Are you really surprised that temps have risen since we left the Little Ice Age?

 

Would you mind sourcing that claim about the Little Ice Age? It doesn't really show up on any of the graphs I'm seeing. And yes, I would expect the temperatures to rise to a normal level at the end of an Ice Age (say no higher than the MWP), as opposed to an unusually high level as we are experiencing now.

 

On the subject of the Holocene Optimum, here is a rough statistical analysis of several proxies in different parts of the world (coloured lines) that provide information on temperatures reaching back to the end of the last ice age. The black line is an average of those temperatures. This provides a rough guide on the temperatures of the Holocene. Note that the temperatures have a resolution of about 300 years which as a result, doesn't actually show the current warming.

 

 

 

This should serve to illustrate that the current temperature increases are actually rather drastic, in that they are occurring too fast for the graph to show. Additionally, it also illustrates that the Holocene Optimum wasn't actually warmer than the temperatures we're currently experiencing, at least on a global scale. You could actually argue that the temperatures were cooler during the Holocene Optimum using this graph, however, the resolution is too low to make a fair comparison.

 

You might be interested in this paper from JGS concerning prehistoric finds that were under the Swiss glaciers. The finds were grouped "from four distinct windows of time: Neolithic Age (4900 to 4450 cal. yr BP), early Bronze Age (4100–3650 cal. yr BP), Roman Age (1st–3rd century AD), and Medieval times (8–9th century AD and 14–15th century AD)." The results of this paper go both ways; Firstly and obviously it means that the studied glacier has retreated further than at any time in the last 5,000 years or so. Conversely it also shows that there was a "Roman Warm Period" followed by a cold period where the glacier advanced and then a "Medieval Warm Period" where the glacier retreated again. This was followed by a glacial advance for the LIA and then the current warming. Such a timeline doesn't look much like the gradual drop in temps the reconstructions show, does it? Not being mean, but I'll take solid archaeological evidence over a statistical "reconstruction" any day.

 

Although I'm the study is probably relatively sound, having only skimmed over it (I'm a little tired of reading through climate science research papers), I can't help object to the nature of the record. It only measures temperatures in the Swiss alps. The climate reconstructions are better measures of the global climate because that is actually what they measure.

 

Well, it's now 2am. So if I've stuffed up or missed something or not made sense, let me know and I'll adress it in another post. Cheers.

 

That's pretty good for a 1 am post.

 

Mann seems to have employed a form of conformational bias to generate a graphic that supported his view of historical and current climate change. He carefully chose a proxy that was known to de-emphasize the medieval warming and 1500-1700 little ice age. Then he chose a subset of that proxy that he could apply statistical analysis and obtain a result that closely matched his previous erroneous and discredited prior results. However because his proxies failed to continue the desired upward trend he was looking for post 1980, he simply tricked the data by dropping the proxy in favor of a a data set that supported his viewpoint better.

 

Here is a rebuttal article pointing out Mann et al's statistical weaknesses and providing a basis as to why one should not put too much stock in Mann's reconstructions.

 

The article generated a firestorm of discussions, much of it is available on the web at various locations.

 

I believe that Swansont addressed most of those points. I would like you to name that proxy, and the study it was used in, so I can better address that claim. Additionally the reason he dropped the proxy data after 1980 was because it was wrong. The tree-ring data disagreed with the instrumental temperature record data. It's called the divergence problem. When you have data that is glaringly flawed, you probably should remove it. That is what they've done there.

Edited December 20, 2010 by Samm

[JohnB]

Thanks actually. I'm glad I'm actually getting recognition from some of the more senior members of this forum, even if they disagree with me.

 

No problems. You are debating well and reading the references. You're also polite which I think is a plus in any debate. (And it's something sadly lacking in the climate debate. Name calling and point scoring seems to be the usual order of the day. As the comments sections of Realclimate or Whats Up With That demonstrate.)

 

Well, if it is true that the YD period is caused by a decrease of heat moving towards the Northern Hemisphere, and the radiative, greenhouse and other forcings stay roughly the same, one would expect a higher concentration of heat in the Southern Hemisphere.

 

Quite possible. I came across the YD event while looking for examples of catastrophic change around the 9,000 BC mark. Meltwater intrusions into the North Atlantic fit the bill and might have been devastating when you work out how much water it takes and how fast it has to be added. Some of the papers on this are very scary. But intensely interesting as it deals with how an ice shield melts. We know the ice "receeded", but did it melt from the front, the top or the bottom? Or a combination? Differing theories lead to very different scenarios concerning the end of the Ice Age and what happened to the areas in front of the ice.

 

Okay. Roy Spencer... He's said this, it seems a little like a conspiracy theory:

Agreed. But if you've been shot enough by enough people you would start to wonder yourself. A good example of what happens to those who don't toe the "consensus" line are some questions asked of Judith Curry recently by the person who edits her "Sourcewatch" page, I'll quote the email in full from here. http://judithcurry.com/2010/10/27/disagreement/#comment-6964

 

Hello again Dr. Curry -

 

People who know climate science are having trouble making sense of

your critiques, and I am having trouble making sense of your

classifying my community’s most blatant global warming denier as “not

an identified “skeptic” (as far as i can tell)”.

 

So I have additional Qs to you – and yes, I realize they’re obnoxious

and I apologize for that, but IMO we need to get at the truth.

 

Has your handwriting been getting shaky lately, or your balance

worsening, or your (verbal, etc) self-restraint just vaporizing? (I

ask since these did noticeably happen to me, & not all at the same

time; fortunately they didn’t persist.)

 

Are you being threatened or blackmailed; either on behalf of you, or

on behalf of others (e.g. family members) close to you, including the

younger generation(s)?

 

Would you take the enhanced [Jeffrey] Dubner oath?

(“I swear that I have never taken money or received services –

whether directly or indirectly — from any political campaign or

political group or government agency or think tank — whether federal,

state, or local — or from anyone else — in exchange for any service

performed in my climate communication endeavors.”)

(“directly or indirectly” would include carrots/sticks for friends and

family members)

 

I’m sorry to ask you so directly, and you’re certainly free not to

answer any of these Qs; but they are the questions I have.

 

So by starting a blog and engaging with sceptics some think it reasonable to assume that she is either mentally impaired or being threatened and/or blackmailed?

 

As for clouds, I'm not exactly sure. There seems to be very little if any, external forcing influencing clouds. Cosmic Rays is one, but that has yet to be proven. We know that clouds are influenced by atmospheric conditions, so it seems logical that clouds could be considered a function of the atmospheric conditions. As they may have an affect on temperature, it seems fair that they're considered a feedback.

 

WRT clouds and the forcing/feedback question. Climatology views clouds only as a temperature feedback, working much the way you describe. In the short term clouds can drive temps, for example a cloudy night is warmer than a cloudless night. The nub of the disagreement in this area concerns whether clouds respond to other forcings as well. GCRs come to mind, also changes in ocean currents. Should clouds respond to these on a long term basis then they are still a feedback to those forcings but they become a forcing in terms of temperature.

 

The question here is this "Do clouds only respond to temperature changes?" If the answer is yes, then they are a temperature feedback, but if the answer is no then they become a feedback for something else, but a temperature forcing. Messy as hell, but that is why Dr. Curry descibed climate as a "wicked problem" in her testimony to Congress.

 

That is a good point, would you mind telling me which ones were and weren't? I know that number 7, Mann and Jones 2004 is not. It definitely doesn't calibrate proxies with the global instrumental temperature record, it actually calibrates the proxies with the local temperature record.

 

I'll do some digging, it's been a while since I've looked at the paleo papers closely. I'll have to get back to you on this.

 

Would you mind sourcing that claim about the Little Ice Age?

 

Look at the graph of Holocene temps you posted. while the resolution isn't great the period around 1500 AD is easily the lowest temps for more than 10,000 years. A point that you might want to consider too. If the resolution of the graph is too low to show the modern "extreme" warming, then it is too low to show any other examples of "extreme" warming as well.

 

Although I'm the study is probably relatively sound, having only skimmed over it (I'm a little tired of reading through climate science research papers), I can't help object to the nature of the record. It only measures temperatures in the Swiss alps. The climate reconstructions are better measures of the global climate because that is actually what they measure.

 

Remember that the "Global" reconstructions are based on interpolating specific sites or small regions, if there was a way to quantify the advance and retreat on the basis of temperature, the Alps could be used as a proxy for paleo reconstructions.

 

Anyway you might be interested in the results of Ljungqvist, F.C. 2010. The data is available on the NOAA siteand the graph looks like this; (Although this is extra tropical NH, not global.)

 

Again much closer to Moberg 2005 than any others.

 

I believe that Swansont addressed most of those points.

 

As much as I admire and respect swansont, a couple of blog articles do not refute a peer reviewed paper. McShane and Wyner has been published in the Annals of Applied Statistics as a discussion paper with invited discussion from both the climate and statistical communities, as well as a reply from McShane and Wyner. http://www.imstat.org/aoas/next_issue.html The papers are at the bottom of the page. I'm still working my way through them and freely admit that the technical bits are way above my pay grade, but it would appear that the statistical community is not as sure of the statistical methodologies used by climatologists as the climatologists are.

 

Additionally the reason he dropped the proxy data after 1980 was because it was wrong..........It's called the divergence problem.

 

That the data diverges from the temperature record is called the Divergence Problem. Dropping the data because it might weaken your case is called being dishonest, alternatively only showing data that strengthens your case is called "Cherry Picking". The data is not "wrong", the data simply is. Truncating the data rather than explaining the divergence can only be called "very poor science".

 

I sincerely doubt that any practicing researcher on this forum would dump part of his/her data from an experiment. they would dump the lot and start again or find a good and sensible reason. Saying it's the "Divergence Problem" is as factually meaningless as saying "Pink fairies did it".

[Ludwik]

It is misleading to describe the recent 20 years as if it stands out as a climate record. Relative to the previous few hundred years it is high, but relative to the history of the earth it is not unusual. Historical temperature proxies indicate that the climate has been up to 8 degrees centigrade warmer than today and about 4 degrees cooler during the period mammals are known to have existed on this earth. ...

 

Yes, indeed. Thank you for showing the graphs.

 

Ludwik Kowalski (see Wikipedia)

[swansont]

As much as I admire and respect swansont, a couple of blog articles do not refute a peer reviewed paper. McShane and Wyner has been published in the Annals of Applied Statistics as a discussion paper with invited discussion from both the climate and statistical communities, as well as a reply from McShane and Wyner. http://www.imstat.org/aoas/next_issue.html The papers are at the bottom of the page. I'm still working my way through them and freely admit that the technical bits are way above my pay grade, but it would appear that the statistical community is not as sure of the statistical methodologies used by climatologists as the climatologists are.

 

I feel compelled to point out that the link pointed to a paper that said "submitted to the Annals of Applied Statistics;" as there was no actual citation given I wasn't aware that there could be any critique in a peer-reviewed setting. The main complaints of the blogs seem to be reflected in the comments I have read. More to the point, though, is that McShane and Wyner still conclude that it is likely that recent temperatures are the highest in the last millennium, and give a reconstruction that shows a sharp increase in temperature in the last century, the very signature of the hockey stick graph.

 

There has been no followup to that, other than to attack my "objectivity."