----------Introduction---------
A comparison of recent temperature trends in isolation of earlier data, say 1998-present, to long(er)-term temperature trends, say 1970-present, reveals that more recent temperature trends are lower than long-term temperature trends. This has led many, including many prominent climate scientists, to refer to the recent period as a “pause”, “hiatus” or “slowdown”. While in isolation of any other context besides two temperature trends, the term “pause” or “hiatus” may be quasi-accurate, much more context is required to determine whether these terms are statistically and, more importantly, physically accurate.
It should be noted that most times when these terms are used by climate scientists, they keep the quotation marks to indicate the mention-form of the word and are not implying an actual physical pause or hiatus in climate change. The subsequent research into the physical mechanism behind the “pause” has continually demonstrated that it is not indicative of a pause in climate change nor does it suggest a drastic reduction in our estimates of climate sensitivity. However, this fact appears to be lost on many who see the “pause” as some kind of death-blow to the anthropogenic climate change theory or to the relevancy of climate change models.
While this subject has been discussed repeatedly in these forums, it has never been the focus but rather used as a jet-pack style argument to change the conversation from the subject at hand to the “pause” (“Well that can’t be right because the Earth hasn’t warmed in X years!”). Revisiting past threads, I cannot find an example of where someone attempted to defend the “pause” as a valid argument against anthropogenic climate change. It is brought up, debunked and then not defended (and then gets brought up again 5 posts later). The hope is to discuss the scientific literature surrounding the “pause” to help readers understand why the “pause” is simply not a valid argument. While some points have been discussed (usually by me) before, this post does contain new research as well as 2014 and 2015 temperature data, which shed even more light on the topic. The post will be split into three parts: 1) the introduction (and a brief discussion on satellite versus surface station temperature data sets), 2) Does the “pause” suggest that climate change is not due to anthropogenic CO2? and 3) Does the “pause” suggest that climate models are deeply flawed?
------Why I Will Be Using Ground-Based Temperature Data Sets-------
Prior to going into the meat of the discussion, I feel it necessary to discuss why I will be using ground-based temperature data sets and not satellite data sets. Perhaps one of the most hypocritical and confused (or purposefully misleading) arguments on many “skeptic” blogs is the disdain for all ground-based temperature data sets and the promotion of satellite temperature data sets. The main contention with ground-based temperature data sets is that they do not include raw data and require homogenization techniques to produce their end result. While I am not here (in this thread) to discuss the validity of such techniques, it is crucial to understand that satellite temperature data sets go through a much more involved and complex set of calculations, adjustments and homogenizations to get from their raw data to their end product. Both what they measure and where they measure it are very important and highlights the deep confusion (or purposeful misdirection) of “skeptic” arguments that ground-based temperatures are rubbish and satellite-based temperatures are “better”.
[ul][li]Satellites measure radiances in different wavelength bands, not temperature. These measurements are mathematically inverted to obtain indirect inferences of temperature (Uddstrom 1988). Satellite data is closer to paleoclimate temperature reconstructions than modern ground-based temperature data in this way.[/li]
[li]Satellite record is constructed from a series of satellites, meaning the data is not fully homogeneous (Christy et al, 1998). Various homogenization techniques are required to create the record. (RSS information)[/li]
[li]Satellites have to infer the temperature at various altitudes by attempting to mathematically remove the influence of other layers and other interference (RSS information). This is a very difficult thing to do and the methods have gone through multiple challenges and revisions. (Mears and Wentz 2005, Mears et al 2011, Fu et al 2004)[/li]
[li]Satellites do not measure surface temperatures. The closest to “surface” temperatures they get are TLT which is an loose combination of the atmosphere centered roughly around 5 km. It is also not even a direct measurement channel (which themselves are not measuring temperature directly) but a mathematically adjustment of other channels. Furthermore, due to the amount of adjustments involved, TLT has constantly required revisions to correct errors and biases (Christy et al 1998, Fu et al 2005).[/li]
[li]See the discussion on Satellite data sets in IPCC Report (section 3.4.1.2)[/li]
[li]Satellite data and the large amount of homogenization and adjustments required to turn the raw data into useful temperature data are still being question to this day. Unlike ground-based adjustments which lead to trivial changes in trends (from the infamous Karl et al 2015), recent research shows that corrections of perhaps 30% are required for satellite data (Weng et al 2013 .[/li][/ul]
None of this is meant to say the satellite temperature data is “wrong” but it very clearly highlights the deep-set confusion in the “skeptic” camp about temperature data sets. If one finds themselves dismissing ground-based temperature data sets because they require homogenization or adjustments while claiming satellite temperature data sets are superior have simply been lead astray by “skeptics” or are trying to lead others astray. Furthermore, it clearly demonstrates that any attempt to compare satellite data (which measures the troposphere) to the surface temperature output of models is completely misguided (*cough*John Christy *cough*). It is for these reasons that I will use ground-based data in the rest of the post.
Again, I would like to state that I do not wish this to be a focal point of this discussion. I am merely outline why I will be using ground-based temperature data sets and my justification for that as, undoubtedly, someone would claim I should be using satellite temperature datasets. In fact, I appear to be in pretty good company; Carl Mears, one of the chief researchers of RSS (and the same Mears from all the papers above), stated:
A comparison of recent temperature trends in isolation of earlier data, say 1998-present, to long(er)-term temperature trends, say 1970-present, reveals that more recent temperature trends are lower than long-term temperature trends. This has led many, including many prominent climate scientists, to refer to the recent period as a “pause”, “hiatus” or “slowdown”. While in isolation of any other context besides two temperature trends, the term “pause” or “hiatus” may be quasi-accurate, much more context is required to determine whether these terms are statistically and, more importantly, physically accurate.
It should be noted that most times when these terms are used by climate scientists, they keep the quotation marks to indicate the mention-form of the word and are not implying an actual physical pause or hiatus in climate change. The subsequent research into the physical mechanism behind the “pause” has continually demonstrated that it is not indicative of a pause in climate change nor does it suggest a drastic reduction in our estimates of climate sensitivity. However, this fact appears to be lost on many who see the “pause” as some kind of death-blow to the anthropogenic climate change theory or to the relevancy of climate change models.
While this subject has been discussed repeatedly in these forums, it has never been the focus but rather used as a jet-pack style argument to change the conversation from the subject at hand to the “pause” (“Well that can’t be right because the Earth hasn’t warmed in X years!”). Revisiting past threads, I cannot find an example of where someone attempted to defend the “pause” as a valid argument against anthropogenic climate change. It is brought up, debunked and then not defended (and then gets brought up again 5 posts later). The hope is to discuss the scientific literature surrounding the “pause” to help readers understand why the “pause” is simply not a valid argument. While some points have been discussed (usually by me) before, this post does contain new research as well as 2014 and 2015 temperature data, which shed even more light on the topic. The post will be split into three parts: 1) the introduction (and a brief discussion on satellite versus surface station temperature data sets), 2) Does the “pause” suggest that climate change is not due to anthropogenic CO2? and 3) Does the “pause” suggest that climate models are deeply flawed?
------Why I Will Be Using Ground-Based Temperature Data Sets-------
Prior to going into the meat of the discussion, I feel it necessary to discuss why I will be using ground-based temperature data sets and not satellite data sets. Perhaps one of the most hypocritical and confused (or purposefully misleading) arguments on many “skeptic” blogs is the disdain for all ground-based temperature data sets and the promotion of satellite temperature data sets. The main contention with ground-based temperature data sets is that they do not include raw data and require homogenization techniques to produce their end result. While I am not here (in this thread) to discuss the validity of such techniques, it is crucial to understand that satellite temperature data sets go through a much more involved and complex set of calculations, adjustments and homogenizations to get from their raw data to their end product. Both what they measure and where they measure it are very important and highlights the deep confusion (or purposeful misdirection) of “skeptic” arguments that ground-based temperatures are rubbish and satellite-based temperatures are “better”.
[ul][li]Satellites measure radiances in different wavelength bands, not temperature. These measurements are mathematically inverted to obtain indirect inferences of temperature (Uddstrom 1988). Satellite data is closer to paleoclimate temperature reconstructions than modern ground-based temperature data in this way.[/li]
[li]Satellite record is constructed from a series of satellites, meaning the data is not fully homogeneous (Christy et al, 1998). Various homogenization techniques are required to create the record. (RSS information)[/li]
[li]Satellites have to infer the temperature at various altitudes by attempting to mathematically remove the influence of other layers and other interference (RSS information). This is a very difficult thing to do and the methods have gone through multiple challenges and revisions. (Mears and Wentz 2005, Mears et al 2011, Fu et al 2004)[/li]
[li]Satellites do not measure surface temperatures. The closest to “surface” temperatures they get are TLT which is an loose combination of the atmosphere centered roughly around 5 km. It is also not even a direct measurement channel (which themselves are not measuring temperature directly) but a mathematically adjustment of other channels. Furthermore, due to the amount of adjustments involved, TLT has constantly required revisions to correct errors and biases (Christy et al 1998, Fu et al 2005).[/li]
[li]See the discussion on Satellite data sets in IPCC Report (section 3.4.1.2)[/li]
[li]Satellite data and the large amount of homogenization and adjustments required to turn the raw data into useful temperature data are still being question to this day. Unlike ground-based adjustments which lead to trivial changes in trends (from the infamous Karl et al 2015), recent research shows that corrections of perhaps 30% are required for satellite data (Weng et al 2013 .[/li][/ul]
None of this is meant to say the satellite temperature data is “wrong” but it very clearly highlights the deep-set confusion in the “skeptic” camp about temperature data sets. If one finds themselves dismissing ground-based temperature data sets because they require homogenization or adjustments while claiming satellite temperature data sets are superior have simply been lead astray by “skeptics” or are trying to lead others astray. Furthermore, it clearly demonstrates that any attempt to compare satellite data (which measures the troposphere) to the surface temperature output of models is completely misguided (*cough*John Christy *cough*). It is for these reasons that I will use ground-based data in the rest of the post.
Again, I would like to state that I do not wish this to be a focal point of this discussion. I am merely outline why I will be using ground-based temperature data sets and my justification for that as, undoubtedly, someone would claim I should be using satellite temperature datasets. In fact, I appear to be in pretty good company; Carl Mears, one of the chief researchers of RSS (and the same Mears from all the papers above), stated:
If this is a topic of interest to people, perhaps starting your own thread would be advisable as I will not be responding to comments on temperature data sets on this thread. Now, onto the actual discussion…Carl Mears said:
