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1 hour ago, Rothbardian said:

You misspelled Arkansas

 

Should have known there was a connection, just look at the dental characteristics of both places... 

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Interesting paper in Nature from the PAGES2K people just now. It shows that ALL of the so-called warming/cooling periods so beloved by anti-science propagandists (Little Ice Age (LIA), Medieval Warm Period (MWP), etc.) of the past 2000 years were likely regional phenomena. ONLY the 20th century trend is shown to be global in "nature" (little pun there, get it?!). This kinda' shows "the climate has always varied like in the MWP and LIA" people to be more than a bit off base with respect to global climate change.

 

Interestingly as well, it uses a sliding window analysis as part of the analysis. I was once assured many climate wars ago that a sliding window analysis was statistically incorrect. They used almost exactly the procedure I outlined then. Oh, and yeah: "hockey stick" confirmed yet again.

 

Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era Nature | Geoscience | VOL 12 | AUGUST 2019 | 643–649. I checked and researchgate already has it if anyone who doesn't have access to a research library really wants to read it for free.  Just google article title + "researchgate".

 

 

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On 9/2/2019 at 9:34 PM, frogtwang said:

Bugatti found out just how fast the Chiron is, flat-out: 305mph

It set the record at Ehra-Lessien, a test track with a 5.4-mile straight.

 

 

 

https://arstechnica.com/cars/2019/09/bugatti-found-out-just-how-fast-the-chiron-is-flat-out-305mph/

 

 

Old but funny youtube of a 1972 e-powered Datsun shutting down muscle cars!

 

 

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On 9/6/2019 at 7:48 AM, NewfoundlandFreeFrog said:

Interesting paper in Nature from the PAGES2K people just now. It shows that ALL of the so-called warming/cooling periods so beloved by anti-science propagandists (Little Ice Age (LIA), Medieval Warm Period (MWP), etc.) of the past 2000 years were likely regional phenomena. ONLY the 20th century trend is shown to be global in "nature" (little pun there, get it?!). This kinda' shows "the climate has always varied like in the MWP and LIA" people to be more than a bit off base with respect to global climate change.

 

Interestingly as well, it uses a sliding window analysis as part of the analysis. I was once assured many climate wars ago that a sliding window analysis was statistically incorrect. They used almost exactly the procedure I outlined then. Oh, and yeah: "hockey stick" confirmed yet again.

 

Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era Nature | Geoscience | VOL 12 | AUGUST 2019 | 643–649. I checked and researchgate already has it if anyone who doesn't have access to a research library really wants to read it for free.  Just google article title + "researchgate".

 

 

 

MWP and/or LIA in:

 

China:

https://science.sciencemag.org/content/342/6158/617

 

Pacific Ocean:

https://link.springer.com/article/10.1007%2Fs00376-017-6238-8

 

Antarctica:

https://www.sciencedirect.com/science/article/pii/S0031018219303190

 

South Africa:

http://co2science.org/data/mwp/studies/l1_coldaircave.php

 

 

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10 hours ago, Burner said:

 

Your 1st two links are reversed. I'll discuss by subject...

 

Article 1 discusses China not globe. It also doesn't fully line up with the MWP in North America and some other locations (note the century long lapse of warming reported here between 1100 and 1201 right in the middle of the MWP elsewhere). The tropical Pacific was actually cooler at this time as well.1 

 

Article 2 is now 6 years old and the latest PAGES2K data were not available then. But it does form part of the evidence. Which is one reason why they say "likely".

 

Article 3 describes Antarctica thusly:

 

Quote

 

• Opposing temperature trends of the Medieval Climate Anomaly (MCA) in Antarctica.

• MCA warming found in Antarctic Peninsula and Victoria Land.

• MCA cooling found in the Ross Ice Shelf region and probably in the Weddell Sea.

 

 

 

That is, the cycles in Antarctica are not even contiguous in time and space continent-wide let alone globally.

 

Item 4, CO2science, is a denier site which simply lists hot and cold anomaly periods found in many individual locations. What it does not mention is they are not contiguous in time and/or space. You have to go in and look. (I have.) EVERY place in the world has warmer and cooler decades/centuries from time to time. That is not global variation (or trends either for that matter). Basically they just are another version of Article 1 expanded to many individual locations except that they (likely intentionally) obfuscate the nonoverlaps unlike Article 1 in order to mis/disinform.

 

All this said, it is clear that natural variation occurs and that something was likely going on to perturb things across large areas or even globally in those years. No one disputes this and it is an active area of research. What is not clear is that the LIA and MWP are cast in stone as global events as some would like to assume...often in the interests of mis/disinformation. What is also clear is that since the late 19th century there is a trend component on top of that natural variation that simply cannot be ignored statistically. It is significant at astronomical levels. And physically there are clear mechanisms at work which have been known since the Civil War.

 

---------------------

1 As an aside not strictly on your point and a bit statistically advanced but specifically relating to this China article (2nd link), I would also note that Fourier analyses ALWAYS find cycles. Whether they exist in reality or not. It is a simple result of Fourier's Theorem. This is analogous to the much simpler fact that any linear trend can be described as a step function even though step changes with things like temps are physically impossible. "Cyclists" form a very small group in climate science as their stats are so iffy and poorly validated. It's one thing to have a theory or mechanism that posits cycles of length X and then to look for said specific predicted cycles in the data. It is a completely different thing to simply subject data to a Fourier analysis and think the cycles found mean anything real. As I said, Fourier analyses of lines of ANY shape can ALWAYS be "explained" arbitrarily near 100% completely (given enough trig components). The only problem is that the specific cycles found in one analysis simply rarely cross validate well to other samples or to further data collection in the future. At a bare minimum, cyclists need to randomly split their data into training sets and validation sets to see if the cycles identified in one half of the data are found in the other half. This is standard practice in studies using other methods suffering from the same condition like factor analysis and machine learning. They did not do this nor can I ever remember seeing a study from these few groups which did. In more everyday terms this is why theory-free technical stock buying/selling strategies relying on the same sorts of stats often do not work any better than throwing darts at stock listings unless specific theory-free "cycles" can  be observed repeatedly across many, many training and validation sets and much time.

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On 9/26/2019 at 8:34 PM, NewfoundlandFreeFrog said:

 

Your 1st two links are reversed. I'll discuss by subject...

 

Article 1 discusses China not globe. It also doesn't fully line up with the MWP in North America and some other locations (note the century long lapse of warming reported here between 1100 and 1201 right in the middle of the MWP elsewhere). The tropical Pacific was actually cooler at this time as well.1 

 

Article 2 is now 6 years old and the latest PAGES2K data were not available then. But it does form part of the evidence. Which is one reason why they say "likely".

 

Article 3 describes Antarctica thusly:

 

That is, the cycles in Antarctica are not even contiguous in time and space continent-wide let alone globally.

 

Item 4, CO2science, is a denier site which simply lists hot and cold anomaly periods found in many individual locations. What it does not mention is they are not contiguous in time and/or space. You have to go in and look. (I have.) EVERY place in the world has warmer and cooler decades/centuries from time to time. That is not global variation (or trends either for that matter). Basically they just are another version of Article 1 expanded to many individual locations except that they (likely intentionally) obfuscate the nonoverlaps unlike Article 1 in order to mis/disinform.

 

All this said, it is clear that natural variation occurs and that something was likely going on to perturb things across large areas or even globally in those years. No one disputes this and it is an active area of research. What is not clear is that the LIA and MWP are cast in stone as global events as some would like to assume...often in the interests of mis/disinformation. What is also clear is that since the late 19th century there is a trend component on top of that natural variation that simply cannot be ignored statistically. It is significant at astronomical levels. And physically there are clear mechanisms at work which have been known since the Civil War.

 

---------------------

1 As an aside not strictly on your point and a bit statistically advanced but specifically relating to this China article (2nd link), I would also note that Fourier analyses ALWAYS find cycles. Whether they exist in reality or not. It is a simple result of Fourier's Theorem. This is analogous to the much simpler fact that any linear trend can be described as a step function even though step changes with things like temps are physically impossible. "Cyclists" form a very small group in climate science as their stats are so iffy and poorly validated. It's one thing to have a theory or mechanism that posits cycles of length X and then to look for said specific predicted cycles in the data. It is a completely different thing to simply subject data to a Fourier analysis and think the cycles found mean anything real. As I said, Fourier analyses of lines of ANY shape can ALWAYS be "explained" arbitrarily near 100% completely (given enough trig components). The only problem is that the specific cycles found in one analysis simply rarely cross validate well to other samples or to further data collection in the future. At a bare minimum, cyclists need to randomly split their data into training sets and validation sets to see if the cycles identified in one half of the data are found in the other half. This is standard practice in studies using other methods suffering from the same condition like factor analysis and machine learning. They did not do this nor can I ever remember seeing a study from these few groups which did. In more everyday terms this is why theory-free technical stock buying/selling strategies relying on the same sorts of stats often do not work any better than throwing darts at stock listings unless specific theory-free "cycles" can  be observed repeatedly across many, many training and validation sets and much time.

 

Thank you for responding to the science and not just calling names. Also, I apologize for my incompetence at posting links. 

 

If you agree that natural climate variation occurs there is not much for us to argue about. Pretty much everyone agrees that carbon dioxide is a greenhouse gas and increasing it in the atmosphere will produce warmer temps. The science is not settled on how much warming. Contrary to your "no one disputes this" sentence, almost everyone on your side of the aisle says carbon dioxide causes global warming, not contributes to global warming. The call is "stop climate change", not "reduce climate change to its natural component."

 

The bottom-line questions are:

(1) What will be the effects on human life if the global average temperature increases a few degrees in the next century? (Unknown, some positive as well as negative, certainly not the doomsday scenarios so popular with the lay media and some politicians.

(2) How much warming can we prevent if we abstain from burning fossil fuels? (Unknown until we know the  proportions of natural and anthropogenic warming)

(3) What will be the economic, political and social costs of not generating affordable energy from fossil fuels? (Unknown, mostly negative, possible catastrophic).

 

Unfortunately, natural climate change is not so much an area of active research. It seems to me most research in  the area aims to find or create evidence to support preferred policies, not to determine truth. Admittedly, my perspective is colored by what gets reported in the lay media, but that seems to be what drives funding and peer review. Dr. Judith  Curry discussed that at length here  

https://judithcurry.com/2018/01/03/manufacturing-consensus-the-early-history-of-the-ipcc/#more-23734

 

and here

https://judithcurry.com/2019/06/21/climate-sciences-masking-bias-problem/

 

 

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52 minutes ago, Burner said:

 

If you agree that natural climate variation occurs there is not much for us to argue about. Pretty much everyone agrees that carbon dioxide is a greenhouse gas and increasing it in the atmosphere will produce warmer temps. The science is not settled on how much warming. Contrary to your "no one disputes this" sentence, almost everyone on your side of the aisle says carbon dioxide causes global warming, not contributes to global warming. The call is "stop climate change", not "reduce climate change to its natural component."

 

You are highlighting a difference with no distinction here.  CO2 causes and contributes to global warming.  There are a number of other things we are dumping into the atmosphere in copious amounts that also causes and contributes to global warming.  Methane, in particular, which is why relying exclusively on natural gas as a bridge to renewables is problematic.

 

52 minutes ago, Burner said:

 

The bottom-line questions are:

(1) What will be the effects on human life if the global average temperature increases a few degrees in the next century? (Unknown, some positive as well as negative, certainly not the doomsday scenarios so popular with the lay media and some politicians.

 

Certainly?  Based on what?  Several of the previous mass extinction events that have occurred during the Earth's history involved climatological rates of change that were significantly slower than what we are currently encountering.

 

52 minutes ago, Burner said:

(2) How much warming can we prevent if we abstain from burning fossil fuels? (Unknown until we know the  proportions of natural and anthropogenic warming)

 

Your contention that "natural" (the fact that we see ourselves as separate from nature is part of our problem) climate change drivers are not well understood is simply not true.  Milankovitch cycles, solar cycles, volcanism, extra-terrestrial collisions ... scientists know about these things and have studied them for centuries now.  The problem is, none of them explain current warming trends.  Some of them indicate that we should be in a looooong period of gradual cooling right now.  Something else is causing the warming, and that something else is us.

 

52 minutes ago, Burner said:

(3) What will be the economic, political and social costs of not generating affordable energy from fossil fuels? (Unknown, mostly negative, possible catastrophic).

 

Ignoring the "mostly negative, possible catastrophic" supposition for a moment, this question is always asked without its necessary corollary, What will be the economic, political, and social costs of not limiting climate change?  We already know the answer to that question, at least in part, as the people of Puerto Rico, the Bahamas, Syria and Europe, Brazil, Houston and Beaumont, and many others can already attest.  And those answers are almost entirely negative and definitely catastrophic.

 

52 minutes ago, Burner said:

Unfortunately, natural climate change is not so much an area of active research. It seems to me most research in  the area aims to find or create evidence to support preferred policies, not to determine truth. Admittedly, my perspective is colored by what gets reported in the lay media, but that seems to be what drives funding and peer review. Dr. Judith  Curry discussed that at length here  

https://judithcurry.com/2018/01/03/manufacturing-consensus-the-early-history-of-the-ipcc/#more-23734

 

 

and here

https://judithcurry.com/2019/06/21/climate-sciences-masking-bias-problem/

 

 

 

 

Judith Curry has been critical of the rhetorical, science communication tactics used by some to sound alarms about climate change, but she has none of the doubts that you express above regarding the science and the potential for catastrophe if we do nothing to change our behavior.  See the currently 8th post on her blog: https://judithcurry.com/2019/08/22/climate-change-whats-the-worst-case/

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1 hour ago, Burner said:

 

Thank you for responding to the science and not just calling names. Also, I apologize for my incompetence at posting links. 

 

If you agree that natural climate variation occurs there is not much for us to argue about. Pretty much everyone agrees that carbon dioxide is a greenhouse gas and increasing it in the atmosphere will produce warmer temps. The science is not settled on how much warming. Contrary to your "no one disputes this" sentence, almost everyone on your side of the aisle says carbon dioxide causes global warming, not contributes to global warming. The call is "stop climate change", not "reduce climate change to its natural component."

 

The bottom-line questions are:

(1) What will be the effects on human life if the global average temperature increases a few degrees in the next century? (Unknown, some positive as well as negative, certainly not the doomsday scenarios so popular with the lay media and some politicians.

(2) How much warming can we prevent if we abstain from burning fossil fuels? (Unknown until we know the  proportions of natural and anthropogenic warming)

(3) What will be the economic, political and social costs of not generating affordable energy from fossil fuels? (Unknown, mostly negative, possible catastrophic).

 

Unfortunately, natural climate change is not so much an area of active research. It seems to me most research in  the area aims to find or create evidence to support preferred policies, not to determine truth. Admittedly, my perspective is colored by what gets reported in the lay media, but that seems to be what drives funding and peer review. Dr. Judith  Curry discussed that at length here  

https://judithcurry.com/2018/01/03/manufacturing-consensus-the-early-history-of-the-ipcc/#more-23734

 

 

and here

https://judithcurry.com/2019/06/21/climate-sciences-masking-bias-problem/

 

 

 

One impt point: "Natural variation" by definition is cyclical though not necessarily regular but rather in time series analysis may be partly or wholely chaotic. Statistically BY DEFINITION cycles do not, can not, "cause" trends. They tend to zero over time. Those seeking to ignore the trends or to blame them on long term forces no one has ever seen or measured almost always miss this statistical fact. Only a constant forcing in one direction can "cause" a trend. So yes, greenhouse gas forcings from CO2 and other greenhouse gases do cause the warming. Unless one can find an as yet unknown forcing that no one else has ever seen.

 

Basically, as I've mentioned before one cannot do most time series stats unless and until seasonal and long term cycles are removed so as to make the resulting residuals stationary (in the technical statistical sense of the word). Statistical methods generally assume stationarity must be achieved before any of the resulting findings can be quantified at all. This is true even for random walks let alone more "normal" (little joke there for the stats people out there!) parametric techniques though in random walk stats what you want to get to is a "drift" parameter separate from the random walk process.

 

Natural variation simply does not work to explain the data. Unless one posits unknown/unmeasured sources which no one else has seen in a century and more of research.

 

This stats lesson comes to you via some very talented national class/world class statisticians who worked at TCU and taught me!

 

Duq covers the rest very well.

 

 

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4 hours ago, NewfoundlandFreeFrog said:

One impt point: "Natural variation" by definition is cyclical though not necessarily regular but rather in time series analysis may be partly or wholely chaotic. Statistically BY DEFINITION cycles do not, can not, "cause" trends. They tend to zero over time...

 

 

I should have added that chaotic and/or unpredictable though known factors such as vulcanism are one of the ressons we often hear "the models are wrong".  That is, climate models (physical not statistical) reproduce the RATE of such factors fine just not the timing. Over time this does not matter as they sum to zero (or a possibly a consistent, estimable bias) which IS modeled accurately. But timing issues make it impossible to be completely correct at any one particular time.

 

A good example is the late 19th century which had some truly awesome events--e.g. Krakatoa--which most definitely cooled things followed by many quiescent years in the early 20th which probably led to a warming cycle as the air recovered. The order might just as well have been reversed. The end result would have shown the same long term trend though some interested more in politics and economics now like to argue that this means the science is somehow clueless. It is not the science which is clueless in this instance.

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23 hours ago, Duquesne Frog said:

extra-terrestrial collisions ...

 

Just great. Traffic was bad enough, now I have to worry about aliens, too.

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1 hour ago, $mooth said:

 

Just great. Traffic was bad enough, now I have to worry about aliens, too.

 

But at least they are green.  Flying bicycles produce no CO2 emissions ...

 

Image result for et bicycle

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4 hours ago, Duquesne Frog said:

 

But at least they are green.  Flying bicycles produce no CO2 emissions ...

 

Image result for et bicycle

 

Methane?

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1 hour ago, Rothbardian said:

 

Methane?

Have you even heard, (or seen, smelt, tasted, or felt!) an alien fart? And if you have how do you know it was methane and not, say, silane (SiH4) or some other organosilicon compound?????

 

Of course, being pyrophoric in air (undergoes spontaneous combustion) that might be one clue, but who knows what devices alien genetics might have developed?

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On 9/30/2019 at 10:40 AM, Duquesne Frog said:

 

You are highlighting a difference with no distinction here.  CO2 causes and contributes to global warming.  There are a number of other things we are dumping into the atmosphere in copious amounts that also causes and contributes to global warming.  Methane, in particular, which is why relying exclusively on natural gas as a bridge to renewables is problematic.

 

 

Certainly?  Based on what?  Several of the previous mass extinction events that have occurred during the Earth's history involved climatological rates of change that were significantly slower than what we are currently encountering.

 

 

Your contention that "natural" (the fact that we see ourselves as separate from nature is part of our problem) climate change drivers are not well understood is simply not true.  Milankovitch cycles, solar cycles, volcanism, extra-terrestrial collisions ... scientists know about these things and have studied them for centuries now.  The problem is, none of them explain current warming trends.  Some of them indicate that we should be in a looooong period of gradual cooling right now.  Something else is causing the warming, and that something else is us.

 

 

Ignoring the "mostly negative, possible catastrophic" supposition for a moment, this question is always asked without its necessary corollary, What will be the economic, political, and social costs of not limiting climate change?  We already know the answer to that question, at least in part, as the people of Puerto Rico, the Bahamas, Syria and Europe, Brazil, Houston and Beaumont, and many others can already attest.  And those answers are almost entirely negative and definitely catastrophic.

 

 

Judith Curry has been critical of the rhetorical, science communication tactics used by some to sound alarms about climate change, but she has none of the doubts that you express above regarding the science and the potential for catastrophe if we do nothing to change our behavior.  See the currently 8th post on her blog: https://judithcurry.com/2019/08/22/climate-change-whats-the-worst-case/

 

This is Dr. Curry, the most rational voice I have found on this subject, discussing climate change and weather in June:  "There is very little  in the way of extreme weather events that can convincingly be attributed to manmade global warming, even if you are assuming that all of the recent warming is manmade. Global warming activists will continue use extreme events as an argument against fossil fuels, even though there is little to no evidence to support this.  Without this argument, there is very little left to worry about in the near term regarding AGW, apart from the slow creep of sea level rise."

https://judithcurry.com/2019/06/13/extremes/

 

Since you are familiar with her blog, I assume you know she believes the uncertainty of the case for catastrophic anthropogenic global warming is vastly understated. As in the conclusions of the blog post you cite:

  • The largest rates of warming that are often cited in impact assessment analyses (e.g. 4.5 or 5 oC) rely on climate models being driven by a borderline implausible concentration/emission scenarios (RCP8.5).
  • The IPCC AR5 (2013) likely range of warming at the end of the 21st century has a top-range value of 3.1 oC, if the RCP8.5-derived values are eliminated. Even the more moderate amount of warming of 3.1oC relies on climate models with values of the equilibrium climate sensitivity that are larger than can be defended based on analysis of historical climate change. Further, these rates of warming explicitly assume that the climate of the 21st century will be driven solely by anthropogenic changes to the atmospheric concentration, neglecting 21st century variations in the sun and solar indirect effects, volcanic eruptions, and multi-decadal to millennial scale ocean oscillations. Natural processes have the potential to counteract or amplify the impacts of any manmade warming.
  • Estimates of 21st century sea level rise exceeding 1 m require at least one borderline implausible or very weakly justified assumption. Allowing for one borderline implausible assumption in the sea level rise projection produces high-end estimates of sea level rise of 1.1 to 1.6 m. Higher estimates are produced using multiple borderline implausible or very weakly justified assumptions. The most extreme of the published worst-case scenarios require a cascade of events, each of which are extremely unlikely to borderline impossible based on our current knowledge base. However, given the substantial uncertainties and unknowns surrounding ice sheet dynamics, these scenarios should not be rejected as impossible.

And, yes, Dr. Curry is appalled at the damage done to science by alarmist disinformation and suppression of debate.

 

As for the difference between cause and contribute, there is a vast distinction there. If we are causing climate change, we can stop climate change. If we are contributing to climate change, it will continue no matter what we do, albeit perhaps a bit slower. Is slowing it down worth the cost? See question 3.

 

We are in fact in a loooong period of cooling, have been for about 3,000 years. Is the last 150 years the end of that trend or one of several multi-century warming interruptions? (Unknown) What caused the warming between 1850 and 1950, when the IPCC says there wasn't enough manmade CO2 in the air to be the cause? What caused nature to turn over warming to humans in 1950?

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On 9/30/2019 at 10:42 AM, NewfoundlandFreeFrog said:

One impt point: "Natural variation" by definition is cyclical though not necessarily regular but rather in time series analysis may be partly or wholely chaotic. Statistically BY DEFINITION cycles do not, can not, "cause" trends. They tend to zero over time. Those seeking to ignore the trends or to blame them on long term forces no one has ever seen or measured almost always miss this statistical fact. Only a constant forcing in one direction can "cause" a trend. So yes, greenhouse gas forcings from CO2 and other greenhouse gases do cause the warming. Unless one can find an as yet unknown forcing that no one else has ever seen.

 

Basically, as I've mentioned before one cannot do most time series stats unless and until seasonal and long term cycles are removed so as to make the resulting residuals stationary (in the technical statistical sense of the word). Statistical methods generally assume stationarity must be achieved before any of the resulting findings can be quantified at all. This is true even for random walks let alone more "normal" (little joke there for the stats people out there!) parametric techniques though in random walk stats what you want to get to is a "drift" parameter separate from the random walk process.

 

Natural variation simply does not work to explain the data. Unless one posits unknown/unmeasured sources which no one else has seen in a century and more of research.

 

This stats lesson comes to you via some very talented national class/world class statisticians who worked at TCU and taught me!

 

Duq covers the rest very well.

 

 

 

Can't argue with you here, as I don't know nothin' 'bout no sadistics. What makes you think we are currently in a trend and not a cycle?

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8 hours ago, Burner said:

 

 

Can't argue with you here, as I don't know nothin' 'bout no sadistics. What makes you think we are currently in a trend and not a cycle?

 

Basically because there is an extremely high amount of statistical, physical, and observational evidence for a positive trend at the same time as we ought to be in a cooling trend from natural factors (e.g., Milankovitch Cycles, etc.). One could posit a model which says we are on the rising wave of a say one or two century supercycle which occurs for reasons which no one studying natural variation for over a century now can identify. But there is simply no evidence of that.

 

Re. Curry...why do you think you find her the most rational? What is your evidence? Why do you not look to the consensus scientific reports? In most cases a consensus of experts is superior to one semi-contrarian who brings no evidence of their own.

 

As for disinformation, search the science journals and search blogs from those who don't publish in science sources for the rate of disinformation and misinformation. I think if you are dispassionate you will find one source is rampant and the other is quite low.

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Coupla' of more points to elaborate on here for all (!) those myriads out there interested in stats!

 

Let's look at the linear regression of Temps predicted from Years over the past 4 decades using aggregated annual results to reduce autocorrelation.

 

Linear regression:

Residual standard error: 0.09503 on 38 degrees of freedom
Multiple R-squared:  0.8233,    Adjusted R-squared:  0.8186 
F-statistic:   177 on 1 and 38 DF,  p-value: 7.035e-16

 

Now let's construct a giant supercycle in which natural variation varies according to the sine of time between 0 and pi/2 predicting temps. That is, only the rising portion of a 160 year cycle for the first 40 years and posit that the remaining 120 years are modeled by sine wave:

Residual standard error: 0.1146 on 38 degrees of freedom
Multiple R-squared:  0.7431,    Adjusted R-squared:  0.7363 
F-statistic: 109.9 on 1 and 38 DF,  p-value: 9.042e-13

 

Note that the "cyclist" model predicts almost as well as the linear model over the past 40 years...only 8% less well with a residual error very close as well. Both are also highly significant. However the forecasts from these two models are markedly different for the next number of decades of course with the one model showing a generally rising trend while the other simply varies about the long term mean severely overpredicting the past and underpredicting the future compared to the predictions of the linear model. 

 

Now what the analyst has to do is ask: "Which model has better underlying physical support?" Clearly, since the cyclic model requires hypothesizing an additional, but unobserved/unmeasured factor (see Occam 's Razor), the correct scientific answer is the linear model.

 

Lastly, re. "cycles", right now the Northern Hemisphere is pointed away from the Sun at perihelion every year. That is the reason that Milankovitch (and Duq) note that we ought to be naturally cooling right now as there is so much more water in the Southern Hemisphere to absorb the warmth and not reflect so much back up to be then reradiated back down.

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While Curry makes a number of points she glosses over others. For example, waiting till you develop lung cancer before stopping smoking is a poor strategy. However much of her main point here is "wait and see what we need". Which reduces to basically just that.

 

ANY problem with decadal lead times needs to be, well, dealt with decades in advance where balance of probabilties rules not certainty.

 

However, in this particular area like many others, uncertainty is NOT necessarily your friend. It might well be your "unexpected" very serious hit. Which is why being proactive is sensible.

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