The Problems with CAGW

[sokolow]

1) The LIA and MWP have been proven by various proxies around the globe. They are general warmer and colder times that we know but not to any degree of precision that we are measuring climate today. No where near that. They do try however to mesh such coarse data sets to much more fine datasets of today. Anyway, the LIA is well documented with the Thames Freezing every winter, sea ice affecting shipping lanes in the North Atlantic where we haven't gotten sea ice in the 20th century and this was documented for a few centuries. The way the atmosphere works you don't keep on part of the globe colder and the rest warmer for long periods of time. So the precision is not the idea here.  

 

2) the modern instrument era is trying to detect such small changes in global climate over remote parts of the world. It is rife with uncertainties, adjustments etc.

 

There is a big difference here which you have failed to comprehend. Plus you are so wordy...you obviously aren't a science writer.

Unfortunately you're wrong, and I said that more concisely, on the first page, and you ignored it. ¯\_(ツ)_/¯

[sokolow]

Anyhow you just took undated and vague historical anecdotes about freezes on the Thames and similarly undated and vague sailor tales about icebergs, meshed these two types of data -- not only just coarser and finer relative to one another, but also different phenomena separated in space and time -- together, and then used extremely limited evidence from the North Atlantic to propose a miniature global ice age (during which period it was ??? cooler and or ??? wetter than present conditions (as defined by crazy clock thermometer record we can't trust) in ??? regions) which started (sometime?) in (some region?) for (unknown reasons?) and became generalized (by some other point in time?) then ended (sometime later?) based on "the way the atmosphere works"

Bullß#¡t. You cannot construct a useful climate data set, not even a qualitative one for England and Icelandic waters off of undated Thames freezing accounts written by some ignorant and superstitious pre-modern "natural philosophers" and slap that together with the fantasies of illiterate sailors and call it climate data. Its stories. Its not even for the North Atlantic, let alone for the imagination model that lets you extend your wishful thinking about a "Little Ice Ace" globally.

OK now clearly I don't believe that but what kind of homogenizations, adjustments, and interpolations -- "meshing" -- do you think we'll need to make to the various kinds of natural & human made records in order to actually have a scientific basis for asserting an LIA.

[ORH_wxman]

Proxy data is pretty robust for the little ice age globally...as well as the MWP. Why blizzard will take these but ignore the instrumental record is beyond me.

 

It is still dangerous to splice instrumental and proxy data together though on one graph as one is a low frequency dataset and the other is high. If you do, then it needs to be stated that the two datasets are not measuring the same thing.

[Msalgado]

Proxy data is pretty robust for the little ice age globally...as well as the MWP. Why blizzard will take these but ignore the instrumental record is beyond me.

 

It is still dangerous to splice instrumental and proxy data together though on one graph as one is a low frequency dataset and the other is high. If you do, then it needs to be stated that the two datasets are not measuring the same thing.

Well they are measuring the same thing, just with lower levels of accuracy.  With the appropriate error bars I'm OK with a splice.

[ORH_wxman]

Well they are measuring the same thing, just with lower levels of accuracy.  With the appropriate error bars I'm OK with a splice.

 

 

Yes that is ok to do...though the error bars usually look ridiculous next to the instrumental data...so the graph is really not very useful to look at.

 

In low frequency datasets, the proxy won't catch shorter term temperature swings on scales of decades...so it is reading basically an average temperature over a long period of time...in some cases on the scale of a century or more.

[sokolow]

That its a big claim to assert an LIA is pretty clear when we run the clock back to the 70s and early 80s when it was up for argument on the basis of the relative sparseness and asynchronicity of the evidence that what people were calling the LIA did not represent a sustained period of widespread global cooling. It was even still open to consider whether or not the LIA had even "ended" from a glaciologist's perspective.

Another part of the qualifier that goes into interpreting the LIA is heterogenity in time as well as space -- there's evidence for sustained periods of mild, even warm conditions in the regions that most are used to most classically represent the LIA so its not like we're talking centuries of eternal darkness during which terrified Alpine peasants rose every evening to do dread battle against the roaming armies of wildlings, Others, and frost giants swarming down from beyond The Wall. That people think we can still argue the existence of an LIA regardless rather than writing it off as a romantic notion in European history says a lot about the trust anyone who does so is willing to put on their documentary evidence and proxies.

You can't really assert a globally coherent LIA even on a descriptive, relative basis without a pretty robust matrix of geographically and temporally diverse evidence, and that was basically the point of Jean Grove's big ol' tome on the subject.

[ORH_wxman]

That its a big claim to assert an LIA is pretty clear when we run the clock back to the 70s and early 80s when it was up for argument on the basis of the relative sparseness and asynchronicity of the evidence that what people were calling the LIA did not represent a sustained period of widespread global cooling. It was even still open to consider whether or not the LIA had even "ended" from a glaciologist's perspective.

Another part of the qualifier that goes into interpreting the LIA is heterogenity in time as well as space -- there's evidence for sustained periods of mild, even warm conditions in the regions that most are used to most classically represent the LIA so its not like we're talking centuries of eternal darkness during which terrified Alpine peasants rose every evening to do dread battle against the roaming armies of wildlings, Others, and frost giants swarming down from beyond The Wall. That people think we can still argue the existence of an LIA regardless rather than writing it off as a romantic notion in European history says a lot about the trust anyone who does so is willing to put on their documentary evidence and proxies.

You can't really assert a globally coherent LIA even on a descriptive, relative basis without a pretty robust matrix of geographically and temporally diverse evidence, and that was basically the point of Jean Grove's big ol' tome on the subject.

 

 

We have evidence from South America, Antarctica, New Zealand, North America, Europe, Greenland, and Asia that points to a global LIA.

 

Specifically, the southern hemipshere proxies have been more recent in the literature which argue against a regional climate shift and support a global event. The timing appears consistent with the northern hemisphere LIA between the 15th and 19th centuries.

 

Here's some recent papers post-2010 on the LIA in the southern hemisphere:

 

http://www.sciencedirect.com/science/article/pii/S0012821X11002925

 

http://onlinelibrary.wiley.com/doi/10.1029/2012GL051260/abstract

 

http://www.nature.com/ngeo/journal/v4/n5/full/ngeo1122.html

 

http://centaur.reading.ac.uk/36336/

 

http://link.springer.com/article/10.1007%2Fs00382-013-1876-8#

[blizzard1024]

Proxy data is pretty robust for the little ice age globally...as well as the MWP. Why blizzard will take these but ignore the instrumental record is beyond me.

 

It is still dangerous to splice instrumental and proxy data together though on one graph as one is a low frequency dataset and the other is high. If you do, then it needs to be stated that the two datasets are not measuring the same thing.

 

I never said I was ignoring the instrumental record but there are a lot of uncertainties in the extent and magnitude of the warming since the late 1800s. I believe there has been some warming that's a fact but I believe it has been exaggerated especially lately. There are even more uncertainties in proxy data. To say that the 20th century warming was unparalleled in the magnitude compared to earlier centuries is difficult because of the coarseness of proxy datasets and the degree of the adjustments to the instrumental record. That's my thoughts. so have at it....

[ORH_wxman]

I never said I was ignoring the instrumental record but there are a lot of uncertainties in the extent and magnitude of the warming since the late 1800s. I believe there has been some warming that's a fact but I believe it has been exaggerated especially lately. There are even more uncertainties in proxy data. To say that the 20th century warming was unparalleled in the magnitude compared to earlier centuries is difficult because of the coarseness of proxy datasets and the degree of the adjustments to the instrumental record. That's my thoughts. so have at it....

 

 

Even if you believe the 20th century warming is exaggerated (lets say it was +0.6C instead of +0.8C or +0.9C), it is still quite unique in the entire record. You might be able to argue that some period leading into the MWP perhaps warmed as quickly, however, we don't know for sure and there's good chance it didn't either.  

 

So I think the exact precision of the 20th century temperature rise is fairly irrelevant on that front. Unless you are arguing that it is so butchered, that the warming was less than 0.4C or something. I don't think there is any compelling evidence to make that type of claim though.

[sokolow]

We have evidence from South America, Antarctica, New Zealand, North America, Europe, Greenland, and Asia that points to a global LIA.

Specifically, the southern hemipshere proxies have been more recent in the literature which argue against a regional climate shift and support a global event. The timing appears consistent with the northern hemisphere LIA between the 15th and 19th centuries.

I would definitely agree, I was just going out of my way to emphasize that asserting a globally coherent LIA off of terminal moraine dating, reconstructed ELA variations, exposure dating, borehole temps, and the like, then tying that to proposals for regional and then global climate conditions via models of glacier & ice dynamics is a profound statement of confidence in our theories and methods. We don't get an LIA or MWP for free is all, but my guess is you're on board with that to begin with.

I also think its important to hold onto the heterogeneity built into whatever chosen periodization we use to delineate an LIA because while we treat the 15th to 19th centuries as the core of the global event we also have (just as a for instance) evidence of smaller or larger advances / retreats of the Grosser Aletsch in the 3rd, 6th, 9th, 12th, 14th, 17th, and 19th centuries. Interpreting what that means is complicated by the fact that the Aletsch has a long response time relative to other glaciers in the alps (80 as compared to 15-20 years for small ones), doesn't preserve decadal variability on account of that, and its evidences preferentially record large advance. Same general point you were getting at about proxies up above.

So with a global event defined in no small part by glacial fluctuations, from the glacial archive we end up with a plausible though patchy onset of the event in the maybe-13th-century and its most apparent manifestation in the 15th-to-19th century window. Onset and the coherency of onset, hetereogeneity and variability within the era, together with onset and coherency for exit -- matters for assessment of variability, magnitude, as well as attribution at local, regional, and global scales.

Not that you don't already know that, just by way of underlining that putting a useful start date and end on the LIA isn't free, easy, or obvious either.

Glacier fluctuation by region since 1700.

From the 2007 UNEP report on land ice w/ Zemp and Haeberli lead authors.

[sokolow]

I never said I was ignoring the instrumental record but there are a lot of uncertainties in the extent and magnitude of the warming since the late 1800s. I believe there has been some warming that's a fact but I believe it has been exaggerated especially lately. There are even more uncertainties in proxy data. To say that the 20th century warming was unparalleled in the magnitude compared to earlier centuries is difficult because of the coarseness of proxy datasets and the degree of the adjustments to the instrumental record. That's my thoughts. so have at it....

ORH is exactly right, and right in a way that is really important:

Even if you believe the 20th century warming is exaggerated (lets say it was +0.6C instead of +0.8C or +0.9C), it is still quite unique in the entire record.

And arguably right about this:

You might be able to argue that some period leading into the MWP perhaps warmed as quickly, however, we don't know for sure and there's good chance it didn't either.

Though of course arguing the existence of globally coherent MWP is going to be much more difficult and require more trust in our theories and methods than advancing the idea of an LIA.

[bluewave]

Even if you believe the 20th century warming is exaggerated (lets say it was +0.6C instead of +0.8C or +0.9C), it is still quite unique in the entire record. You might be able to argue that some period leading into the MWP perhaps warmed as quickly, however, we don't know for sure and there's good chance it didn't either.  

 

So I think the exact precision of the 20th century temperature rise is fairly irrelevant on that front. Unless you are arguing that it is so butchered, that the warming was less than 0.4C or something. I don't think there is any compelling evidence to make that type of claim though.

 

Yeah, it looks like a matter of finding the correct TCR.

 

http://troyca.wordpress.com/2014/02/21/breaking-down-the-discrepancy-between-modeled-and-observed-temperatures-during-the-hiatus/

[wildweatherman179]

I would definitely agree, I was just going out of my way to emphasize that asserting a globally coherent LIA off of terminal moraine dating, reconstructed ELA variations, exposure dating, borehole temps, and the like, then tying that to proposals for regional and then global climate conditions via models of glacier & ice dynamics is a profound statement of confidence in our theories and methods. We don't get an LIA or MWP for free is all, but my guess is you're on board with that to begin with.

I also think its important to hold onto the heterogeneity built into whatever chosen periodization we use to delineate an LIA because while we treat the 15th to 19th centuries as the core of the global event we also have (just as a for instance) evidence of smaller or larger advances / retreats of the Grosser Aletsch in the 3rd, 6th, 9th, 12th, 14th, 16th, and 19th centuries. Interpreting what that means is complicated by the fact that the Aletsch has a long response time relative to other glaciers in the alps (80 as compared to 15-20 years for small ones), doesn't preserve decadal variability on account of that, and its evidences preferentially record large advance. Same general point you were getting at about proxies up above.

So with a global event defined in no small part by glacial fluctuations, from the glacial archive we end up with a plausible though patchy onset of the event in the maybe-13th-century and its most apparent manifestation in the 15th-to-19th century window. Onset and the coherency of onset, hetereogeneity and variability within the era, together with onset and coherency for exit -- matters for assessment of variability, magnitude, as well as attribution at local, regional, and global scales.

Not that you don't already know that, just by way of underlining that putting a useful start date and end on the LIA isn't free, easy, or obvious either.

Glacier fluctuation by region since 1700.

image.jpg

From the 2007 UNEP report on land ice w/ Zemp and Haeberli lead authors.

Wait! You mean the earth has been here since before 1900 or 1950? No way! Lol. At least someone finally posted something with data going back past 1900.

[sokolow]

Wait! You mean the earth has been here since before 1900 or 1950? No way! Lol. At least someone finally posted something with data going back past 1900.

Not really a whole lot of point doing speculation about past climates if you regard the homogenizations & quality controls used in producing the instrumental temperature record for the last 100 years as invalid in principle. I guess we can go back to the days of Agassiz and propose that the Earth was subjected to a Tribulation of Ice at some point in the relatively recent past. Recent as in prior to the biblical multitude of generations stretching back to Adam (4004 BCE), as illustrated by the learned Bishop James Ussher in his magnificent Annales (1650).

[The_Global_Warmer]

The problem with CAGW is that it will end our way of life.

 

Good to see methane craters now blowing up over Siberia.  Awesome.

 

http://guardianlv.com/2014/08/scientists-believe-they-might-have-solved-the-siberian-crater-mystery/