More excuses for “the pause”.
A team of researchers from the U.K. Met Office, Sweden and Australia has found that three periods of global warming slowdown since 1891 were likely due to natural causes rather than disruptions to the factors causing global warming. In their paper published on the open access site Science Advances, the group describes their study of global mean surface temperatures (GMST) since the late 19th century and what they found.
In this new paper, the researchers looked at GMST as registered by multiple sources around the globe over the past 127 years, noting the slow march of temperature increases. More specifically, they noted the three previously identified slowdowns in GMST increases—the time periods from 1896 to 1910, from 1941 to 1975, and then from 1998 to 2013. They then looked at factors that could have contributed to these slowdowns and found natural causes for each.
The team first reports that their study showed results similar to others regarding GMST increases—they have been slowly increasing overall for more than a century. They then offer possible explanations for the three main observed slowdowns in GMST increase. For the first slowdown, they found evidence of El Niño and La Niña weather patterns that likely reduced heating by producing more cloud cover.
For the second slowdown, they found evidence of increased volcanism—smoke and ashes from volcanoes can block sunlight.
The team asserts that the third slowdown, aka “the pause” which is also the one on which many global warming skeptics like us here at WUWT follow, was likely caused by a combination of La Niña events and volcanism.
They also claim that the third slowdown period wasn’t a stopping point, and they say temperatures continued to rise, they just did so at a slower pace.
They also looked at data from studies of the sun and found that there was a slowdown in energy output from 2001 to 2010, which was also a likely contributor to the third slowdown. In other words, the sun’s TSI does have an effect, and that works both ways. It seems nature is still in control.
They write:
Our main conclusion is that the most robust influence on the 1998–2013 slowdown resulted from the cooling effects of reduced TSI forcing between 2003 and 2011 (Fig. 6B, i) followed by a trend toward increasing La Niña conditions and a negative IPO in its second half. The negative IPO is in turn likely to have been enhanced by regional anthropogenic aerosol forcing (43). Cooling throughout the slowdown was slightly but significantly enhanced by persistent but small increases in volcanic forcing.
Reconstructions for slowdown period 3, 1997–2015 and its three main sub-periods, where the observed time series include the lead-in period 1995–1996. (A) Average reconstruction of GST for slowdown period 3: 1997–2015. The linear trends are for 1998–2013 (thin lines) and 2001–2010 (thick lines). Otherwise as for Fig. 2A. (B) Reconstruction of WMO GST for slowdown period 3: 1997–2015. Otherwise as for Fig. 2B. (C) Linear components of total temperature change over slowdown period 3. (a) 1998–2013; (b) 2001–2010; (c) 2001–2013. Stars denote significance at the 1% level or better. Otherwise as for Fig. 2C. (D) Summary of the contributions of significant forcing (at <1% level) factors to GST trends (°C per decade) during (a) warming periods and (b) slowdown periods. The period 2001–2013 is used to represent slowdown period 3 where the appreciable but not significant ENSO-induced trend is shown.
The paper: (open access) http://advances.sciencemag.org/content/4/6/eaao5297.full
Causes of irregularities in trends of global mean surface temperature since the late 19th century, Science Advances (2018). DOI: 10.1126/sciadv.aao5297 Chris K. Folland et al.
Abstract
The time series of monthly global mean surface temperature (GST) since 1891 is successfully reconstructed from known natural and anthropogenic forcing factors, including internal climate variability, using a multiple regression technique. Comparisons are made with the performance of 40 CMIP5 models in predicting GST. The relative contributions of the various forcing factors to GST changes vary in time, but most of the warming since 1891 is found to be attributable to the net influence of increasing greenhouse gases and anthropogenic aerosols. Separate statistically independent analyses are also carried out for three periods of GST slowdown (1896–1910, 1941–1975, and 1998–2013 and subperiods); two periods of strong warming (1911–1940 and 1976–1997) are also analyzed. A reduction in total incident solar radiation forcing played a significant cooling role over 2001–2010. The only serious disagreements between the reconstructions and observations occur during the Second World War, especially in the period 1944–1945, when observed near-worldwide sea surface temperatures (SSTs) may be significantly warm-biased. In contrast, reconstructions of near-worldwide SSTs were rather warmer than those observed between about 1907 and 1910. However, the generally high reconstruction accuracy shows that known external and internal forcing factors explain all the main variations in GST between 1891 and 2015, allowing for our current understanding of their uncertainties. Accordingly, no important additional factors are needed to explain the two main warming and three main slowdown periods during this epoch.
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Were they not cooking the books, they’d also have noted that the early 20th century warming cycle was hotter than the late 20th century warming.
Also notable is that the pronounced cooling from the 1940s until the PDO flip of 1977 occurred under steadily rising atmospheric CO2.
We talk a lot about variations in solar insolation but the effective changes are largely due to reactive cloud cover, diminishing when aerosols are high and increasing when SST increases under clear sky conditions – Willis’s climate governor.
Also jiggering of temperatures to massively push down the high of mid 1930s to 40s and to
reverse the two sharply declining temperature periods to gradually ascending periods which they now call pauses greatly understates natural variation. Indeed in reality much of the 0.8C rise over the present century occurred ny 1940, almost 80yrs ago and long before CO2 had an effect. This is a huge increase in global temperature with no CO2 increase to cause it.
Remember the worry over the coming global glaciation during the 60s and 70s (history revision doesnt work on me. I have lived from the late 30s warming and gone through the cold scare) This means that most of the warming since 1979 was recovery back to the 1930s warm period. This also means that we can expect two of thesse big declines a century. Sea ice measurement also started at the end of a 40yr decline in temperatures.
I guess a little off topic, we just got this through :
http://www.weatherzone.com.au/news/climate-change-related-disaster-relief-is-increasing-demand-on-defence-department-senate-hears/528027
When is government going to realise that this is all based on a false premise?
which “inevitably” leads to the conclusion that much of the late 20th c. warming was due to the following peak in this cycle. Leaving the impact of GHG to be much lower.
They will not speak it but they are finally getting around to admitting that much of the shouting was about mis-attribution and conveniently blinkering the discussion to “the late 20th c. ” and ignoring the early bits with did not fit.
I can’t believe that they are still doing naive direction regression of volcanic “forcing” against the temperature record. Temperature ( energy ) is the integral of power input ( the “forcings” are power flux ).
Since the climate system will react to any change in temperature with predominantly negative feedbacks, you need to do a convolution with the response function of the system to find the temperature response and then try to regress it against the record.
All this assumes that the system can be linearised but that has been the assumption for the last 30 years. They just have not worked out how to do it properly yet.
Here is one attempt at detecting the appropriate response function and fitting it to Mt Pinatubo period:
https://judithcurry.com/2015/02/06/on-determination-of-tropical-feedbacks/
The result is a much stronger volcanic forcing with fits remarkably well to the SST record. Quite coincidentally it is very close to what the GISS ( Lacis, Hansen et al ) team were publishing in the early 90s, when they were still working on “basic physics” instead of arbitrary tweaking of a plethora of fudge factors in an attempt to reconcile their models output with the record.
Here is one attempt at detecting the appropriate response function and fitting it to Mt Pinatubo period:
https://judithcurry.com/2015/02/06/on-determination-of-tropical-feedbacks/
So they finally admit that natural factors can overwhelm the effect of 110 ppmv extra CO2…
If we may assume that the warming periods as good as the pauses are mainly naturally caused, the maximum effect of all that extra CO2 is only that the slope of the last full about 60 year temperature cycles (PDO anyone?) is slightly steeper than the previous one(s). Someone eager to calculate that?
AI models with some skill predict the pause using historical temperature data.
https://ipa.org.au/publications-ipa/freedomwatch/recent-warming-natural
‘In our new paper in GeoResJ, we not only use the latest techniques in big data to show that there would very likely have been significant warming to at least 1980 in the absence of industrialisation, we also calculate an Equilibrium Climate Sensitivity (ECS) of 0.6°C. This is the temperature increase expected from a doubling of carbon dioxide concentrations in the atmosphere. This is an order of magnitude less than estimates from General Circulation Models, but in accordance from values generated from experimental spectroscopic studies, and other approaches reported in the scientific literature [9,10,11,12,13,14].’
This is old news to Australians, however its good to see the Met is catching up, only a small way to go.
As commented elsewhere, it helps if the data has not been ‘interpreted’.
It is a different ball game now and those of you who think the past is going to be a guide to what is going to happen to the climate moving forward are in a word wrong.
That makes eminent sense – “natural causes” , I am sure, are the reasons for a lot of things happening on our planet! You don’t need rocket scientists to tell you that (or make it a news item).
A pause…from 1998 to 2013? I thought only skeptics/deniers believed such a thing took place.
You looked at: “GMST as registered by multiple sources around the globe over the past 127 years, noting the slow march of temperature increases”
and you saw: More excuses for “the pause”.
You are one sad, sick puppy making up schist like this . Go and see a therapist.
After poring over the paper (TG no paywall), all the mumbo jumbo merely confirmed two things I’ve thought for years about pauses and causes….
1. While there is a warming trend due to CO2, it is so minuscule that a few random events – like a major Nino or a volcano – can negate the statistical trend for the next (or past) twenty years.
2. The biggest forcing of warming trends is interpolation, adjustment, and filling in the blanks of a scattered, intermittent, and incomplete data record from flawed and poorly calibrated stations.
What business does anyone have claiming a “GST” good to 0.01C in the year 1900? Or 1955, when there still wasn’t anything within a thousand miles of much of the earth? Or today?
It’s all rubbish!
Another one for Pruitt to table in court, 🙂 I’d love to see him just table one document and advise the Judge the other 5 TON of documents are on the truck outside!
Anthony must have a huge list, I know http://notrickszone.com/ does!
Nothing new in what they say really but it is an admission of who actually are the deniers.
It’s a Trojan Horse approach they are trying. They acknowledge the Pause, making them sound fair and balanced, so they can make the natural cooling effect as large as they want, leaving the greenhouse gas warming effect that much larger. We are supposed to buy into the logic of this (which is actually very shoddy logic indeed). But it might capture a few fence-sitters.
I quote: “…they noted the three previously identified slowdowns in GMST increases—the time periods from 1896 to 1910, from 1941 to 1975, and then from 1998 to 2013. They then looked at factors that could have contributed to these slowdowns and found natural causes for each.”
First, let’s see what natural source moght be available and how it might work.. When you look at NOAA global temperature charst you see two graohs: world temperature graph and a carbon dioxide graph for the same time. Their appearance cannot be more different. Global temperature goes up and down and exhibits the changes I quoted above while carbon dioxide is smooth except a for a slight curvature from human-produced CO2. From the wording of the article they apparently have given ip the thought that carbon dioxide is warming up the world. A wise decision indeed, because carbon dioxide, if it works, will cause only warming and cannot explain how cooling is possible. cooling periods noted above. And if it is not carbon dioxide, what could it be? The cooling periods they mention are rel, and so is a thirty year warming from 1910 ton1940. If carbon dioxide did that thirty-year warming there must be some visible sign that carbon dioxide is active in some way but there is none, In particular, In trhe year 1910 ehere cwas an abrupt change ooling change from cooling to earming. If carbon dioxide did that there is no trace of it on the CO2 curve. The explanation escapes us because we are too focused on carbon dioxide. If in its place we put a generic “greenhouse gas” we immediately see what is going on. There are other greenhouse gases, among them water vapor, in the astmosphere. Therew is actually an order of magnitude mpre water vapor in the air than there is of carbon dioxide gas. Obvipusly. Water vapor is the likely hreenhouse gas responsible for global warming. And for the observed cooling spells too. Those may be understood as a result of changing global wind patterns and perhaps also a volcanic action now and then.
Seems to me that if it’s behind the pause, then it’s behind the warming as well.
Pause? What pause? /sarc
The great reversal begins….
So how does this fit in with the previous 60-odd explanations from various ‘experts’ for the ‘pause’, or with the claims by other ‘experts’ that there never was a ‘pause’ at all?
“The time series of monthly global mean surface temperature (GST) since 1891 is successfully reconstructed from known natural and anthropogenic forcing factors, including internal climate variability, using a multiple regression technique. ”
STOP
You cannot use a “multiple regression technique” on a chaotic process, and climate is such a process. You did. You got crap.
Next.
This line of defense has already been tried.
Trouble is, if natural forces are strong enough to stop postulated global warming, they also are strong enough to have it happen, you just have them on the opposite sign, as they already did in the past. Which is just the skeptic idea.
Do I get this correctly that these guys have found new explanations for three periods of cooling (not warming) in the past century. If so, then this triggers a few (probably naive) questions (I have not read the paper; so maybe they authors do answer my questions to the extent that they make sense):
i) How come that they have investigated only these three periods? Is there a good reason for that? I mean, wouldn’t I want to know the relevance of the natural forcings throughout the entire century? Or is it the case that they have investigated the entire century and they have fond that the research so far has only gotten the cooling periods wrong, but has been spot on regarding the warming periods? That would really be quite the surprise. After all, the simple fact in itself that we had an incomplete understanding of natural forcings that cool the planet suggests that there is a good chance that we keep overlooking important ways in which natural forcings might increase the temperatures.
And wouldn’t it always be positive for the credibility of the results of the authors to show that their findings regarding the cooling periods does not contradict anything that we think about the warming periods?
ii) Are these new results much different from what was known so far? If that is the case does that mean that the existing climate models have been calibrated in a bad way? That is, if the things discovered in this paper are quantitatively important then the existing models must have tried to replicate the past climatic developments on the basis of wrong assumptions regarding which control knobs are admissible. Or do I misunderstand the way how climate models are assessed (I would consider it most natural to see if they do well in explaining past developments)?
Of course, any cooling or lack of warming is caused by natural factor & all warming is CO2.
Funny how natural factors only work in one direction /sarc
Seriously, talk about being blind to the facts & believing your own BS …anyone objectively looking at this would see that natural factors work in both directions.
“Slowdowns,” my foot! In GMST estimates unbiased by UHI-corrupted data, there was a substantial decline, culminating in 1976, below the 20th-century mean that produced negative anomalies as great as the positive ones seen subsequently. While “global dimming” due to pollution may have been somewhat a factor, the timing of the decline was entirely consistent with a ~60yr quasi-periodic oscillation. That still-unexplained oscillation shows up frequently in paleo-reconstructions during the Holocene.
The new trend starting this year will be cooling global temperatures.