The "Pause" - A Review of Its Significance and Importance to Climate Science 77

[rconnor]

----------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:

My particular dataset (RSS tropospheric temperatures from MSU/AMSU satellites) show less warming than would be expected when compared to the surface temperatures. All datasets contain errors. In this case, I would trust the surface data a little more because the difference between the long term trends in the various surface datasets (NOAA, NASA GISS, HADCRUT, Berkeley etc) are closer to each other than the long term trends from the different satellite datasets. This suggests that the satellite datasets contain more “structural uncertainty” than the surface dataset

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…

 

[cranky108]

In case I messed it, when did we have a stable climate after the last ice age? I don't remember that date in my history books.

And how much of this is caused by CO2, and how much is caused by CH4? These facts must be out there, as there is proposed regulation on both, and we want to be sure we don't reduce too much, or the tempeture would go the other way.

What is the expected fuel shift after coal-->Natural gas-->? Could it be wood, and what is the right amount of deforestation that can be allowed to support the wood economy?

 

[rconnor]

In case I messed it, when did we have a stable climate after the last ice age? I don't remember that date in my history books.

For around 10,000 years during the Holocene (Shakun et al 2012 or NOAA’s PCN or Pages 2K Consortium). Coincidently, this was the period were human civilizations were allowed to grow and thrive.

we want to be sure we don't reduce too much, or the temperature would go the other way

The natural carbon cycle appears to be well suited to support the temperatures of the Holocene. Anthropogenic CO2 emissions are outside the natural cycle and thus throw off the atmospheric concentration of CO2 (nice little animation), leading to a shift from the Holocene to the Anthropocene (just as orbital tilts or large volcanic activity have lead to previous shifts in climate). However, stopping all CO2 emissions today would not cause atmospheric CO2 concentrations to plummet to zero. Once, you add carbon to the natural carbon cycle, it takes a very long time to remove.

A particular CO2 molecule only stays in the atmosphere from ~5 years before being absorbed by the upper ocean or biosphere (natural sink). However, that particular molecule is more-or-less replaced by CO2 released from the biosphere and ocean (natural source), which roughly balances the net change in atmospheric CO2 concentrations. This is the fast carbon cycle and it does not significantly impact the atmospheric concentration from year-to-year. It is the additional of anthropogenic CO2 emissions, from burning fossil fuels, that injects more CO2 into this system, thus raising the atmospheric CO2 concentration. The slow carbon cycle is the process that “removes” CO2 from the fast carbon cycle. This involves carbon absorbed by the deep ocean (ocean invasion), reaction with CaCO3 and with igneous rock and then with weathering. This process takes hundreds to thousands of years (Montenegro et al 2007, Archer and Brovkin 2008, Archer et al 2009). It can be seen in past climate changes as expressed in Archer et al 2009,

Sediment cores from the deep ocean reveal a climate event 55 million years ago that appears to be analogous to the potential global warming climate event in the future. Isotopes of carbon preserved in CaCO3 shells reveal an abrupt release of carbon to the atmosphere-ocean system, which took about 150 thousand years to recover.

The image below from, from this Nature article, illustrates this very well:
[image

http://www.nature.com/climate/2008/0812/images/climate.2008.122-f1.jpg

]

This is actually an incredibly important issue to understand. Once we reach certain CO2 concentrations, we can’t just magically reverse everything back to normal by stopping all emissions. This is something that adaptionists don’t seem to understand. They think that if it becomes a serious problem, we can then just stop emissions and everything will return to normal. That’s not the way things work. Solomon et al 2008 examines this issue. See the graph below which shows the long-term impact of abruptly halting all emissions at different points.
[image

http://www.pnas.org/content/106/6/1704/F1.large.jpg

]

Now some might think that this is evidence that reducing our CO2 emissions is pointless. However this completely and utterly misses the point. What this tells us, very clearly, is that we need to prevent atmospheric CO2 concentrations from rising much higher because, once they do, they are stuck near those levels (and temperatures) for a very, very long time (on human scales). There’s no magic eraser when it comes to fiddling with atmospheric CO2 concentrations, we need to prevent it through mitigation efforts. As the title of a quasi-follow up paper to Solomon et al 2008, Matthews and Solomon 2013, says irreversible does not mean unavoidable.

 

[beej67]

What is the expected fuel shift after coal-->Natural gas-->? Could it be wood, and what is the right amount of deforestation that can be allowed to support the wood economy?

Technically, wood is carbon neutral. As long as the wood you use is new wood you planted over areas that weren't previously wooded that is.

Regardless, the IPCC thinks that planting trees warms the planet, so there's this great dichotomy between their doctrine and their modeling.

rconnor, the middle graph here:

...presumes that carbon is the only warming source of any significance. Correct? Just checking.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[cranky108]

And what of: "And how much of this is caused by CO2, and how much is caused by CH4? These facts must be out there, as there is proposed regulation on both, and we want to be sure we don't reduce too much, or the tempeture would go the other way."?

Because as we have developed coal and oil, we have released massive amounts of CH4. The CO2 released likely can be measuered but the CH4 flared, or seeped out likely can't.

Before you start regulating CO2, we need to be sure we are regulating the right carbon.

If CH4 is the real problem and not CO2, then there should be a credit for capturing and burning CH4, and not taxing CO2.

Just maybe coal mines should mined for CH4.

 

[zdas04]

Cranky,
Methane in the atmosphere primarily comes from natural seeps. A new one was just discovered off Alaska that is releasing approximately 6 BSCF/day along a line nearly 200 miles long. There is a huge seep off the coast of Japan that is 10 times that size. There are certainly several thousand other methane seeps in the oceans of the world (otherwise the bacteria that thrive on CH4 would not be so ubiquitous around the world). Controlling methane in the atmosphere is a problem on the scale of controlling water vapor in the atmosphere. You can't do either one, so you must demonize CO2. Contemporary CH4 from the decomposition of biological wastes is something like 4% of the a VERY conservative estimate of the seeps. CH4 from industrial activities is less than 0.000001% of the seeps. EPA keeps trying to "fix" this problem by making industry report minuscule releases of CH4. It would be laughable if the data collection effort was not costing industry several billion dollars/year.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[ornerynorsk]

Is it plausible/conceivable that anthropomorphic co2 matters for naught with that volume of methane seepage? Knowing nothing about O&G, I would have never guessed the methane seepage amounted to that much. Does the co2 really even matter?

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[rb1957]

ohh, dear ...

another day in paradise, or is paradise one day closer ?

 

[rconnor]

Cranky108/orenynorsk, much of what zdas04 stated is correct but it requires some more context, especially when discussing it in terms of climate change (which I don’t believe was zdas04’s intent).

Zdas04 was quite correct in pointing out the large amount of methane released from seafloor methane seeps. However, an important point (relevant to climate change) is that not all of the methane released from seafloor methane seeps makes its way to the atmosphere. Most of it is dissolves into the water and is microbially oxidized (see the commentary from the lead author of Sharke et al 2015). While important areas of study, seafloor methane sweeps do not appear to have a very large impact on changes to atmospheric methane concentrations and, therefore, changes to radiative forcing (but it does have some impact). (Also note, “changes to” is important. Similar to solar activity, changes in forcings are essential to understanding the recent changes in our climate. Of course, in an absolute sense, solar activity and natural methane emissions are extremely important to our climate. However, they become less impactful when discussing the changes in our climate – which is the relevant topic.)

Atmospheric methane concentrations are important to climate change research, as it is a very potent greenhouse gas (interesting post on the relative “strength” of methane and CO2), and is actively studied by the scientific community (also see AR5 WGI Chapter 8). However, the concentration of methane in the atmosphere is ~200x less than CO2 (methane is at ~1,800 ppb or 1.8 ppm while CO2 is at 400 ppm) and methane concentrations are not growing at the rate CO2 concentrations are (sourece – NOAA AGGI). Therefore, currently, the impact on radiative forcing is small (but not trivial) in comparison with CO2.

However, atmospheric methane may become very important as a feedback to a warming planet. Melting permafrost could release large amounts of methane readily to the atmosphere. This would be a positive feedback that would amplify warming (Lawrence et al 2008, Schuur et al 2015, Schaefer et al 2014). It is important to point out that very massive and abrupt releases of methane into the atmosphere are “very unlikely” (>10% probability) (source), so reports of runaway methane feedbacks do not appear to be well supported.

In the end, is methane important – absolutely, especially as a feedback to warming. Does it make CO2 irrelevant – no, in fact, it likely only adds more importance to reducing CO2 emissions.

…or, y’ know, you could think all this research is some attempt to demonize CO2 in order to instill freedom-restricting laws and regulations [source pending].

I might not necessarily agree with the latter but so it goes.

 

[ornerynorsk]

Given the climate history of the earth, is not warming inevitable? I'm puzzled as to how the aforementioned freedom-restricting laws and regulations (LOL), together with the benevolent thievery that will invariably accompany them, are going to change anything long-term? Wouldn't our resources be put to better use planning for the inevitable? Instead of re-building places like New Orleans, begin to relocate them? The only science that is truly settled is that we've got a lot of coastal cities that are going to end up in the drink. It's not if, but when. We know this from history. The greatest asset of human-kind is our adaptability to change, not putting our head in the sand and focusing on a possibly single, unverified cause. My opinion only, not really looking to enter the hot debate, but just wanted to sound off.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[rb1957]

IMHO warming and cooling are equally likely (together with a very small likelihood of "no change").

IMHO the scale of sealevel change is not certain.

Will "Big Business" be the ruination of the world? possibly.
Will "Big Government" save us? I don't think so.

The sooner we develop fusion power the better.

another day in paradise, or is paradise one day closer ?

 

[cranky108]

'Instead of re-building places like New Orleans' FYI, even if there were no rise in ocean level, New Orleans will be below sea level. The fact is the sub-plate that New Orleans sits is sinking, and the drying of the soil has only added to the lowering of the ground level.

Are there any other city examples that anyone wants to use, that maybe sinking anyway?

Soil run-off has been adding to the land levels during flooding for a long time. But with our controlling of rivers , and river levels, most of the silt has been deposited in the ocean. This loss of soil has been a crime committed by our government, by the advice they have given to farmers over the years. The whole grow fence row to fence row, has caused so much over production, and additional water usage, that we are now paying farmers to not grow crops. Let alone cutting down trees that stop wind and water depletion of the soil. This along with growing crops that the climate is not suited for, which more depletes the water tables to support.

I'll get off my soap box now.

 

[hokie66]

There are some big sinkers, cranky. The worst is probably Mexico City, then Venice, with Houston and Shanghai also in trouble in areas.

 

[jhardy1]

At an altitude of > 2,000 metres, we are all in very serious trouble if sea level rise affects the inhabitants of Mexico City!

http://julianh72.blogspot.com

 

[hokie66]

Yes, but I thought we were talking about sinking cities as well. Lowering of ground water means they have a lot of buildings where the ground floor is now the basement.

 

[cranky108]

Again Mexico City is an example of a city that is sinking despite carbon levels. I mean it was built on a lake, what can you expect.

With the last earthquake Mt Everest dropped in elevation. Was that because of man made carbon?

All I'm saying is pick examples that make since with the topic you are explaining. Not things we all know is for a different reason.

Venice was built in a swamp, yes we know it is sinking.

 

[rconnor]

Given the climate history of the earth, is not warming inevitable?

Possibly. We appear to have been at an optimum for temperatures for around 10,000 years during the Holocene after coming out of the last ice age (i.e. we’ve been sitting at the “peak” of temperatures for ~10,000 years). So it’s likely that the next major natural cycle is not going to warm us but cool the planet.

Outside of massive volcanic events or asteroids, most of Earth’s past changes in climate are due to Milankovitch cycles (i.e. changes initiated by orbital tilts and then largely driven by CO2 and methane releases), which have a roughly predictable period. The next cycle, which would cause a glaciation, we expect to occur in the next 50,000 to 100,000 years (Berger and Loutre 2002, Hollan 2000). So it’s very unlikely to be impactful before humans can significantly impact temperatures.

Furthermore, past changes in Earth’s climate took thousands to tens of thousands of years to develop. So while the Earth may eventually (and I mean “eventually” in geological time scales) warm beyond where we are now, the process would have been orders of magnitude slower than what we are currently seeing (and isn’t expected for hundreds of thousands of years). I’ll also point out when rapid changes in climate did occur in the past, the biosphere was severely impacted (see the end of the Permian, Triassic, etc.) (Jourdan et al 2014, Burgess et al 2014). “It’s changed before” is a really, really bad argument for mitigation skeptics.

Instead of re-building places like New Orleans, begin to relocate them?

Possibly we could. Intra-country moves would be costly but likely doable in well-off nations. How about moves in poorer areas such as Indonesia? How about inter-country moves (i.e mass forced migration)?

Frankly, it’s a bit absurd when we are asking, rather nonchalantly, “couldn’t we just pick up and move entire cities/countries?” while categorically rejecting efforts to prevent such situations, believing they are misguided attempts to restrict our freedom [source pending] and bankrupt our economy [source pending]. And I don’t mean this to you personally ornerynorsk, plenty of other posters share the same thoughts. They (without references or supporting evidence) claim that mitigation measures will lead to economic ruin and, in the same breath, (without references or supporting evidence) claim that we can simply and seemingly painlessly adapt to the changes.

It’s a pretty terrible risk assessment when people reject the negative consequences of inaction (or focus on the “better” end of the uncertainty spectrum while ignoring the “worse” end), ignore the costs of adaptation and hyperbolize the costs of action. Rather, one should aim to understand the science of the situation (as is done in WGI), determine the possible range of consequences of inaction (as is done in WGII) and determine if action or inaction has a larger net cost/benefit (as is done in WGIII). It’s almost as if the IPCC is doing exactly what any reasonable engineer would do when faced with a risk assessment...

My opinion only, not really looking to enter the hot debate, but just wanted to sound off.

Fair enough. I’m certainly not expecting to change your opinion. There’s the science of what we expect to happen (which I’ve tried to outline) and the subjective decisions on what we should do about it (which I’ve only discussed in response to someone else bringing it up); you seem to be discussing the latter. I’m just afraid that people’s opinions on the latter obscure their ability to examine the former…and then they use the obscured, predetermined examination of the former to further justify their opinion on the latter.

 

[cranky108]

So why is NOAA being so hush-hush about data that should prove there point? What are they hiding?

See this is the problem, being so restrictive with data just yells that there is a problem with the data.
If you want to know where the mistrust begins, this is a good example of where.

Maybe if congress were to pull the funding of NOAA, they might be more willing to share there data.

 

[rconnor]

Am I to guess you are referring to Lamar Smith’s latest effort to control science request for information? If so, there’s no grand conspiracy of NOAA hiding the “Truth”, it’s just Lamar Smith is being a twit, again.

And what does this have to do with anything we just discussed (which, I thought was quite interesting)?

 

[ornerynorsk]

“It’s changed before” is a really, really bad argument . . . .

Actually, it's quite a good argument. It's an exceptionally good argument. One needs to be a tad naïve to believe that the climate is not going to change, with or without the catalyst of human intervention. The sky is not falling, it merely continues to do what it has been doing for a very, very long time. Our atmosphere, the oceans, the plates, the celestial bodies, etc are not static. And in all of these things that are in constant flux there are patterns and cycles. To stop it you would need to stop the clockworks of the universe.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[rconnor]

One needs to be a tad naïve to believe that the climate is not going to change, with or without the catalyst of human intervention.

Agreed. Every bit of evidence from paleoclimatology indicates that the Earth’s climate has changed throughout the past. Natural glacial-interglacial periods have been the norm and I would suspect will continue to. That bit of the science you seem to readily accept. However, it seems that’s where you stopped reading.

The same science that you use to, correctly, state that “it’s changed before” also states that the present changes are completely unexplainable by natural forces. (1) Natural warming from the past ice age ended around 10,000 and the Holocene started, (2) the next natural cycle would be a return to a glacial period, not more warming, (3) that is not expected to occur for ~50,000 to 100,000 years and (4) the current rate of warming is orders of magnitude faster than natural warming periods. So while “it’s changed before” naturally, no natural forcing can explain the current warming.

Furthermore, the same science you use to, correctly, state that “it’s changed before” also states that CO2 has always been instrumental in climate change and the planet is, indeed, quite sensitive to atmospheric CO2 concentrations. To believe that the current and future increases in CO2 concentrations will not impact the climate goes against the fact “it’s changed before”.

In addition, the same science you use to, correctly, state that “it’s changed before” also states that rapid changes in climate lead to substantial changes in the biosphere. Mass extinction events are almost always linked to past rapid changes in climate. We also know the extent of sea-level rise during rapid warming is certainly non-trivial. To think that the current rate of warming, which is very rapid in comparison to past changes, will have minimal impact on us goes against the fact “it’s changed before”.

So I’d highly recommend against using “it’s changed before” as an argument against mitigation efforts because “it’s changed before” actually demonstrates that (1) recent warming cannot be explained by natural cycles, (2) Earth is quite sensitivity to atmospheric CO2 concentrations and (3) rapid changes in climate have lead to significant disturbances in the biosphere and topology of the planet. “It’s changed before” may be one of the best arguments in support of mitigation. To think otherwise is simply selectively agreeing with certain aspects of the science, while ignoring the rest.

Of course I’m repeating myself but perhaps this time you might read the full post.