Study suggests three periods of global warming slowdown since 1891 due to natural temporary causes

June 7, 2018 by Bob Yirka, Phys.org report
Plinian column of the eruption of Sarychev (Russia) on 12 June 2009. Credit: NASA

A team of researchers from the U.K., 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 (GST) since the late 19th century and what they found.

In this new effort, the researchers looked at GST as registered by multiple sources around the globe over the past 127 years, noting the slow march of increases. More specifically, they noted the three previously identified slowdowns in GST 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 GST increases—they have been slowly increasing overall for more than a century. They then offer possible explanations for the three main observed slowdowns in GST 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, which is also the one on which many global skeptics rely, was likely caused by a combination of La Niña events and volcanism. They further note that the third slowdown was not a stopping point—temperatures continued to rise, they just did so at a slower pace.

The researchers 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 .

Explore further: Heat still on despite warming slowdown

More information: Chris K. Folland et al. Causes of irregularities in trends of global mean surface temperature since the late 19th century, Science Advances (2018). DOI: 10.1126/sciadv.aao5297

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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Shootist
1 / 5 (4) Jun 07, 2018
all causes are ultimately natural and temporary.

ALL Causes.

The climate changes, it's what chaotic systems do.
Lino235
1 / 5 (3) Jun 07, 2018
But, of course, the El Nino and La Nina are CONSEQUENCES of volcanism. This is absurd. A climatologist 25 years ago said that weather patterns were easy to predict for the Pacific---just look and see if a volcano has erupted in the Southwest Pacific.

Ken_Fabian
5 / 5 (4) Jun 07, 2018
A climate system that is inherently susceptible to change - always been changing - is more susceptible to short term changes to atmospheric GHG concentrations, not less. It's the vehicle that can't stay on a straight line that is most likely to run off the road. During a period of relative climate stability - cooling but slowly, with our agriculture dependent on that stability - introducing drastic and irreversible changes to our climate system, with every expert assessment concluding the harms will exceed the benefits, to dismiss concerns for the consequences and with it the need for strong actions looks dangerously unwise as well as negligent.
ZoeBell
Jun 07, 2018
This comment has been removed by a moderator.
Parsec
5 / 5 (2) Jun 08, 2018
We can for example see three periods of https://wattsupwi...ance.png from 1896 to 1910, from 1941 to 1975, and then from 1998 to 2013..


Evidence?
Thorium Boy
2.7 / 5 (7) Jun 08, 2018
Didn't the People's Directorate on Propaganda order that all media outlets substitute "climate change" for "global warming" some time ago? Isn't the title of the article a violation?
barakn
5 / 5 (3) Jun 08, 2018
The climate changes, it's what chaotic systems do.
Your argument has been simplified to the point of meaninglessness. Many chaotic systems have what are known as attractors, states that a system will tend to stay near even as they constantly change. It's what allows me to predict it will not snow in Fort Worth in July.
ZoeBell
Jun 08, 2018
This comment has been removed by a moderator.
Ken_Fabian
5 / 5 (4) Jun 08, 2018
ZoeBell - I call nonsense. A rough correlation between global temperatures and length of day changes does not mean we can and should ignore what is understood about physical climate processes. We should not dismiss and ignore demonstrable causation (GHG's) in favour of something with no demonstrated causation. Why do you want that science to be wrong (anything but CO2) so much you would clutch at a straw like this?

We have an enormous body of knowledge about how our climate system works - and the forewarning of the consequences of excess FF burning is an extraordinary example of excellence in science for the long term benefit of humanity.
Newtonionsky
1 / 5 (1) Jun 10, 2018
Ken_Fabian- I call nonsense on your assertions. We have lots of data points from the last few years of studying climate. Data is not knowledge. Like saying sky and water must be same just because they are both blue. That's a rough correlation;) excess FF burning has historically been a local effect ie. London and death fogs. Any claim as such going back to 1850 given the incredibly tiny human population and global climate effect seems unreal in any fashion considering any volcano can create large regional effects but again temporary. No one should be saying we shouldn't be living cleanly as possible and realistic. China produces a huge amount of pollution but they are working on it as they very quickly industrialized in dramatic fashion. But it's just a blip in time. In time Africa will see a resurgence and we can only imagine the pollution they will create as go thru their industrial age. Mankind still lives in caves, we call them apartments and houses. Nothing has really changed.
antigoracle
1 / 5 (4) Jun 10, 2018
More ignorance from the Chicken Littles, who blindly believe in the utter bullshit of their AGW Cult and their PATHOLOGICAL "science". So, the slow down in globull warming was ALL NATURAL, but the opposite is all manmade.
Ken_Fabian
5 / 5 (2) Jun 10, 2018
Newtonionsky - you aren't calling nonsense on my assertions, you are calling nonsense on the studies coming out of every institution that actually studies these questions, all the way to bodies like National Academies of Sciences, Royal Society that draw on expertise across every science discipline to critique and review important science. Should it surprise you that people might take their carefully considered expert assessments over yours?

Antigoracle - calling the carefully considered expert assessments on these questions BS/cult/pathological doesn't make that so. It is nonsense namecalling, not science.

People like me - willing to face this world changing issue head on with eyes open - are not going to be diverted by real "chicken littles", so taken with their economic alarmist fears of replacing fossil fuels that they would rather believe millisecond variations of Earth's rotation (total sunlight reaching Earth unchanged!) can explain global warming than face it head on.
antigoracle
1 / 5 (3) Jun 11, 2018
People like me - willing to face this world changing issue head on with eyes open - are not going to be diverted by real "chicken littles", so taken with their economic alarmist fears of replacing fossil fuels that they would rather believe millisecond variations of Earth's rotation (total sunlight reaching Earth unchanged!) can explain global warming than face it head on.

WOW!!
This Chicken Little faces globull warming, head on with his eyes open, yet he smashes it into absolute stupidity.
So, typical of the Chicken Little to claim their eyes are open, while remaining blind to the fact that their minds are closed to reality. It's an absolute fact that during the 1930s, North America and indeed the world saw the most extreme weather, during a time when human produced CO2 was insignificant to today.

http://www.c3head...938.html
Ken_Fabian
5 / 5 (2) Jun 12, 2018
Millisecond differences in day length, some extreme weather events 80 years ago, what smashing stupidity next? I won't be following these links down rabbit holes into the labyrinth of climate science denial memes. I've been there - if they don't lead in circles they lead away from the large body of sound science - what is known with a lot of confidence - into a distracting maze of mutually contradictory claims, unsupported suppositions, accusations, conspiracy theories.

I trust our institutions and the methodologies of modern science - it isn't faith or belief; they have demonstrated excellence and earned that trust over and over.

Because accurate record keeping and constant review and critique are built into them, embedded falsehoods at the scale and scope required to sustain "false" climate science through decades of intense scientific interest and scrutiny is laughable.

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