An Explanation for the Pattern of Warming
I have been arguing for some time that what the pattern of global warming suggests is a rising trend due to AGW with an alternating trend from some other cause superimposed on it, the latter having a period of about sixty years. On that interpretation, the period of stable to slightly falling temperatures from about 1940 to 1970 and the period of roughly stable temperatures from 2002 on represent periods when the two trends were pushing in opposite directions and so roughly canceling each other, the rapid warming from about 1910 to 1940 and 1970 to 2002 periods when they were reinforcing each other.
The conventional explanation for the mid-century pause is that it was due to aerosols producing a temporary cooling effect. That became less plausible, at least to me, when the pause reappeared, roughly on schedule. If I am correct, the IPCC models, by special casing the earlier pause instead of treating it as part of a recurring pattern, overestimated the average rate of warming, treating periods when the two trends reinforced as if they were the norm, the period when they canceled as a special case.
I have now come across an article in the Proceedings of the National Academy of Sciences that supports my interpretation of the pattern, based on analysis of the 353 year Central England Temperature Series, the longest instrumental temperature record that exists. The authors conclude that there is a recurrent multidecadal oscillation with a period of about seventy years, likely due to the Atlantic Multidecadal Oscillation. They reject the aerosol explanation and conclude that:
The conventional explanation for the mid-century pause is that it was due to aerosols producing a temporary cooling effect. That became less plausible, at least to me, when the pause reappeared, roughly on schedule. If I am correct, the IPCC models, by special casing the earlier pause instead of treating it as part of a recurring pattern, overestimated the average rate of warming, treating periods when the two trends reinforced as if they were the norm, the period when they canceled as a special case.
I have now come across an article in the Proceedings of the National Academy of Sciences that supports my interpretation of the pattern, based on analysis of the 353 year Central England Temperature Series, the longest instrumental temperature record that exists. The authors conclude that there is a recurrent multidecadal oscillation with a period of about seventy years, likely due to the Atlantic Multidecadal Oscillation. They reject the aerosol explanation and conclude that:
The underlying net anthropogenic warming rate in the industrial era is found to have been steady since 1910 at 0.07–0.08 °C/decade, with superimposed AMO-related ups and downs that included the early 20th century warming, the cooling of the 1960s and 1970s, the accelerated warming of the 1980s and 1990s, and the recent slowing of the warming rates.
Almost precisely my conjecture—I slightly underestimated the period of the oscillation—with an explanation and a lot more data.
posted by David Friedman @ 7:16 PM
34 comments
34 Comments:
To what "pause" are you referring?
The global mean temperature hasn't risen since 2002.
To what "pause" are you referring?
The one that was evident until the "adjustments" were made to the temperature data. Funny how earlier decades of the 1900's get cooler and 1980's and later get warmer.
http://climatecenter.fsu.edu/does-noaa-adjust-historical-climate-data
"The one that was evident until the "adjustments" were made to the temperature data. "
That's a funny thing. Temperature is collected by an irregular set of volunteers around the world, at varying time of day, using a variety of gear which changes over time (thermometers break), with surrounding circumstances (buildings go up, trees go down, etc) that change over time. When "raw" data is used, folks who think climate change is bunk scream bloody murder that scientists are stupid for not knowing about, for example, the urban heat island effect. OTOH, when they do adjust the data to address these issues, the same folks complain that scientists are "manipulating" the data.
Every year since 2000 has been warmer than any year prior, with the sole exception of 1998. 1998 is the year that folks who deny that climate change is happening and/or caused by humans usually cite as proof that the planet isn't warming. Any statistician will tell you that using an outlier as a baseline is bad practice at best, and lying at worst.
@hightide
"Every year since 2000 has been warmer than any year prior, with the sole exception of 1998."
False. Though there has been some increase in recent years, much of that has been cancelled out by decreases resulting in an overall "pause" pattern since 1997 (note: not 1998).
Note also that nobody mentioned 1998 (with one commenter above citing 2002), and yet you went on to demolish an argument that nobody other than your imaginary "folks" had made.
Hightide: You are confusing level with rate of change.
Suppose, to simplify matters, that temperature rose until 2002 and was constant thereafter. Every year since 2000 would be warmer than any year prior. That's evidence that temperature is high, not that it is rising. To find out if it is rising you fit a straight line to the data from 2002 on (since that's when I claim the pause started). I did that a while back, with NASA data through 2013. The slope was zero. My guess is that if I added 2014, which was warm, the slope would be slightly positive, but with zero easily inside the error range.
I note that everyone commenting is so eager to refight old fights that nobody has commented on the actual post.
Daivic
The temp anomalies in the first graph are tiny wriggles. How is it possible for anyone to discern temp changes from these tiny changes?They are almost too small to measure and because of the time element most likely inaccurate. How anyone can create a religion out of AGW is hysterically amusing.
> I note that everyone commenting is so eager to refight old fights that nobody has commented on the actual post.
... which is a pity. This blog is my number one source of climate-related news (I once read an IPCC report, but only because it was linked here) and articles like this make it worthwhile.
Also, your, say, unagitated style allows to share your articles with minimal chance of triggering the typical heated responses.
Professor Friedman, it would be interesting to work on the data some more. There are methods to remove the trend from the time series, and so on. What they have called running mean (loess) could have been more aggressive to make your point more noticeable. Where can I find the data?
> I note that everyone commenting is so eager to refight old fights that nobody has commented on the actual post.
The battle over AGW has moved far away from the scientific battlefield and is now almost solely in the domain of politics (or religion, I suppose, depending on one's internal purity of thought). Can you envision a sufficiently strong scientific argument that would silence either side?
The warmist's hand has been weakened somewhat by the absence of recent warming. Their response has been an Orwellian rewrite of historical temperature data where possible, redefining the language, and simply stalling while they hope for the day where nature may again conspire to aid them in their quest to demonize mankind's progress and bring the evils of unrestrained capitalism firmly within the grip of right thinking men who know what is best for all of us.
Just more of Heinlein's "Bad Luck".
Hi,
If sulfur dioxide emissions caused the cooling trend from approximately 1940-1975, then if human emissions of sulfur dioxide peaked and are starting downward, global warming should pick up pace.
It's difficult to definitively assess global anthropogenic sulfur dioxide emissions, but Steven Smith and others estimated emissions from 1850 to 2005. And Klimont and Smith estimated emissions up to 2011.
Emissions appear to be headed down, so global warming should be kicking in big-time.
Anthropogenic SO2 emissions, 1850-2005
Last decade of SO2 emissions
Ricardo:
One source of data is:
http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt
That goes back to 1880.
But there are lots of other data out there, such as the very long English series that the article I linked to used and ice core data from Antarctica and Greenland that goes much much farther back. My guess is that the problem is at this point too complicated for amateurs to do much at the level of basic analysis. My initial argument was based on just eyeballing the graph plus my suspicion of people who fit an anomaly in the data by adding an extra variable to account for it, and I was interested to find some professionals in the field who provided support for my conjecture on considerably solider ground.
There are a number of papers casting doubt on the so-called "hiatus", so accepting it as a given isn't quite correct.
There's also the issue of ocean heat content, which shows no "hiatus" at all; see
https://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/heat_content2000m.png
There are a number of papers casting doubt on the so-called "hiatus", so accepting it as a given isn't quite correct.
Fortunately "papers" aren't quite the same as data. As Judith Curry points out, NOAA pointedly ignores more complete, and conflicting data sets.
http://judithcurry.com/2015/06/04/has-noaa-busted-the-pause-in-global-warming/
As I mentioned earlier, "Their response has been an Orwellian rewrite of historical temperature data where possible". This is just more of the same. Just keep stalling until nature finally turns around so warmists can claim their theories are now being proven to be correct by accurate, correlated data.
Would it be feasible to control ocean level rise by massive rerouting of river water to deserts? Say, build a huge damn right before Charles River enters the ocean, and a gynormous pump(s) and pipes to send that water to Nevada and West Texas.
The Australian centre is pretty useless so you could divert a lot of sea water with the use of pumps etc.
David Friedman writes:
"... the problem is at this point too complicated for amateurs ... I was interested to find some professionals in the field who provided support for my conjecture on considerably solider ground."
Good luck with that David. I've experienced similar frustration but in different subjects.
Thank you for the professional energy you pour into climatology. And thank you for creating, in this blog, a salon in which an amateur such as I can fancy himself a participant in deep discussion.
I probably misunderstand your "suspicion of people who fit an anomaly in the data by adding an extra variable to account for it", insofar as I am struck that is what you have done. Didn't you add an "alternating trend from some other cause" as a way to reduce a complex graph to the sum of two simpler graphs? That adding of two simpler stories seems justifiable to me, in a science where there are still too many loose causes running around.
Fortunately "papers" aren't quite the same as data. As Judith Curry points out, NOAA pointedly ignores more complete, and conflicting data sets.
I take Judy Curry very lightly, because she's just not that credible given her history of erroneous claims and statements.
There are other papers besides Karl et.al. that need to be addressed. And no, the UAH and RSS data aren't "more complete" - they're not even measuring the same thing, and they conflict, badly, with each other.
I take Judy Curry very lightly, because she's just not that credible given her history of erroneous claims and statements.
I'm sure by that you mean since she broke with the orthodoxy and became an excommunicate of the Church of AGW. It's always entertaining to witness the spectacle presented when the Righteous metaphorically stone the apostate. Perhaps you'll get that RICO case going someday and actually get us behind bars.
Please don't forget Argos, it DOES measure oceanic temperatures.
But hey, I'm not a climate scientist. I'm just a guy that likes to look at data and has a skeptical nature. Maybe impoverishing the West is just the thing to keep the Maldives from going underwater, Manhattan from drowning, and the world from burning.
Did you see the chart of ocean heat content I presented earlier?
No "hiatus".
PS - If you like to look at data, there's lots of climate data to examine. If you dig in, honestly, you'll see that climate scientists have it right. Richard Muller let the data lead him,and he accepts man-made climate change.
No "hiatus".
How about more charts:
HadSST2&3
http://www.climate4you.com/images/HadSST3%20GlobalMonthlyTempSince1979%20With37monthRunningAverage.gif
While there are global positive temperature anomalies for Argo:
http://bobtisdale.files.wordpress.com/2013/05/figure-26.png
The Northern Hemisphere stubbornly refuses to warm:
http://bobtisdale.files.wordpress.com/2013/05/figure-54.png
http://bobtisdale.files.wordpress.com/2013/05/figure-64.png
I would say there are exceedingly strong indications more data is needed before the dubious policy selections as have been proposed by most proponents of AGW theory can be supported when they come with such severe downsides. Even the US EPA administrator was forced to admit recently that proposed regulations, while massively burdensome to the US economy, would have no effect on purported warming.
Better to discuss adaptation strategies should the unlikely worst case occur. I'm sure the Dutch could teach us how to protect Manhattan. I'm pretty sure that's doable while I'm almost positive attempting to cut mankind's CO2 emissions to any appreciable degree while waiting for severely lagging global climate indicators is most assuredly not.
It's unfortunate you're letting potential policies dictate what you, "Attempting", accept about the data and the science; that's putting the cart before the horse.
The data are what they are. What one wants in response is pretty much irrelevant.
We could probably afford to protect Manhattan like the Dutch have protected their country, but the same cannot be said for the far poorer nations, like Bangladesh. Ideas about what to do with the ~160 million Bangladeshis?
The data are what they are.
There's the rub. Once you move past the wildly inaccurate theoretical models, raw speculative fiction, activist position papers passed along as science, and get to the real, and unmodified, data I'm not sure there's much to do about anything.
Anonymous:
The IPCC high emissions scenario assumes continued economic growth for the rest of the century. I haven't done the calculations, but my guess is that brings Bangladesh to something like the current standard of the Netherlands, and surely far above what the Netherlands was when they initially diked, centuries back. And it isn't as if a meter of SLR floods all, or even a sizable fraction, of Bangladesh.
Take a look at the adjustable flood map at:
http://flood.firetree.net/
Set it for one meter and see how much of Bangladesh floods.
Once you move past the wildly inaccurate theoretical models, raw speculative fiction, activist position papers passed along as science, and get to the real, and unmodified, data I'm not sure there's much to do about anything.
Look into Muller's "BEST" project. The "real, and unmodified, data". The result? Verification that the other surface temperature analyses are correct.
David, that's just Lomborg paraphrased.
Not quite that simple.
http://scienceblogs.com/gregladen/2015/03/12/lomborg-tells-bangladesh-not-to-worry-about-sea-level-rise
And no, the UAH and RSS data aren't "more complete" - they're not even measuring the same thing, and they conflict, badly, with each other.
You should probably update/correct the Wikipedia page on satellite measurements:
Wikipedia on satellite temperature measurements
From that page:
To compare to the trend from the surface temperature record (approximately +0.07 °C/decade over the past century and +0.17 °C/decade since 1979) it is most appropriate to derive trends for the part of the atmosphere nearest the surface, i.e., the lower troposphere. Doing this, through December 2013:
RSS v3.3 finds a trend of +0.125 °C/decade.[25]
UAH v5.5 finds a trend of +0.136 °C/decade.[36]
From https://www.skepticalscience.com/trend.php, 1982-2015:
UAH: 0.163 ±0.075 °C/decade (2σ)
RSS: 0.136 ±0.076 °C/decade (2σ)
BEST: 0.180 ±0.043 °C/decade (2σ)
Karl(2015): 0.177 ±0.054 °C/decade (2σ)
From https://www.skepticalscience.com/trend.php, 1979-2016 (i.e. *all* data, for both satellite temperature trend assessments):
UAH: 0.139 ±0.064 °C/decade (2σ)
RSS: 0.121 ±0.076 °C/decade (2σ)
It doesn't look to me like they "conflict, badly, with each other." They're about half a standard deviation apart.
But you're right, they're both significantly lower than the surface temperature trend analyses.
UAH and RSS measure temperatures over a column of the lower troposphere, the station-based analyses measure surface temperatures. Similar but far from identical.
We know why rejectionists prefer RSS over all the other analyses. Rather transparent on their part.
Land/ocean
HadCRUT4: 0.158 ±0.039 °C/decade (2σ)
NOAA: 0.146 ±0.037 °C/decade (2σ)
Karl(2015): 0.153 ±0.041 °C/decade (2σ)
Global
GISTEMP: 0.158 ±0.041 °C/decade (2σ)
BEST: 0.164 ±0.039 °C/decade (2σ)
HadCRUT4 krig v2 (Cowtan/Way): 0.174 ±0.042 °C/decade (2σ)
Karl(2015): 0.163 ±0.048 °C/decade (2σ)
"UAH and RSS measure temperatures over a column of the lower troposphere, the station-based analyses measure surface temperatures."
Yes, and if one were trying to assess the effects of greenhouse gases on global temperature, which would be more appropriate (satellite measurements of the lower troposphere, or surface temperature measurements)?
Satellite data are highly problematic (courtesy Tamino, https://tamino.wordpress.com/2015/09/24/exogenous-redux):
Balloon-borne thermometers aren’t the only data source for tropospheric temperature; there are also estimates from satellites. But they don’t actually measure temperature, they measure microwave brightness, from which we try to infer temperature at different levels within the atmosphere. Different channels (different microwave frequencies) respond with different strength to different levels of the atmosphere. But, none of them responds to a thin layer at a definitive altitude, they all respond broadly to pretty much the entire atmosphere, although they’re more sensitive to certain levels. This makes it a tricky problem to disentangle the information from different channels in order to estimate temperature in a well-defined atmospheric layer. It’s especially problematic because all channels respond, at least in part, to the stratosphere, which is known to be cooling because of increased CO2.
There is also a serious difficulty splicing together data from all the different satellites that have been used (more than a dozen). And, there’s the issue of different response depending on the angle at which the satellite is looking at the atmosphere, and some dispute about how the satellites’ orbits have altered over the years. All in all, it makes piecing together an accurate satellite temperature estimate quite difficult — which is one of the reasons satellite data have been revised and updated so often. The upshot is, that all those claims deniers constantly make about how the satellite data are somehow “better” than surface temperature data or balloon-borne thermometer data, are wrong. There’s very good reason to doubt.
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Professor Friedman,
I have played a little with the data here:
https://rpmcruz.shinyapps.io/warming
This is all stuff I have not studied in much depth. But I think you can have phenomena resembling alternating cycles without assuming the time series has a 3-decade dependency. I have only introduced some randomness every year and some feedback loops based on the last couple of years.
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