Study seeks to understand variations in the rate of global warming

Study seeks to understand variations in the rate of global warming

A team of climate scientists, including Professor Mat Collins from the University of Exeter, have investigated the role of internal variability in the Earth's climate system in these periods of slow warming.

This internal variability refers to natural variations in regional , such as El Nino and the Pacific Decadal Oscillation, that arise in the absence of changes in forcing from volcanic aerosols, solar activity or human influences.

Scientific opinion is still divided on the precise cause of the current slowdown, although there is evidence that natural internal variability has played a significant role, probably alongside some changes in external forcing. There is also evidence that slow-down events similar to the current one have occurred many times before.

Professor Collins, co-author of the report from Exeter's Mathematics department said: "The fact that the world is warming as a result of human emissions of greenhouse gases is not in doubt, but this paper shows how short-term trends can be quite variable as a result of intrinsic fluctuations in climate.

"More research is urgently needed to understand these fluctuations and learn how predictable they might be."

The new study looks at this issue by using a huge archive of climate model simulations collected from a number of international research centres. These are used to study whether internal variability has the potential to offset the expected global surface warming rate of 0.2K/decade (0.2° C/decade) associated with human influences.

This archive of 15,000 years of simulated climate represents a 'laboratory' in which to study the characteristics of the internal climate variability in the absence of changes in external forcing. This would be impossible to disentangle from the relatively short 150 years of the global observational record where a number of external forcings come into play.

The researchers found that 20-year periods of global cooling in excess of 0.2K/decade can occur as a result of internal variability alone about once every hundred years. Once cooling has been established for 15 years there is a high chance (up to 1 in 4) that this will persist for a further 5 years.

This study also shows that periods of extended global cooling from internal variability alone are associated with more heat being taken up by the sub-surface ocean; when this ends, this heat can be released quite rapidly leading to a period of accelerated global warming.

The implications of these results for the current slow-down in global surface warming are important. They show that the recent slow-down lies within the range of possible internal variations, and so internal variability cannot be excluded as a possible explanation. Furthermore they suggest that persistence of the current slow-down beyond 15 years may be quite likely.

Finally it is entirely possible that once the current slow-down finishes, it may be followed by a period of accelerated global surface warming. Understanding this better is one aspect of managing the risks and opportunities associated with future climate variability and change.

The study was motivated by the fact that global average temperature has not risen as fast as expected in the 15 years since the start of the 21st Century.

This current slowdown in global warming has also be referred to as the "pause" or the "hiatus" in climate science literature, and in the media.

The slowdown has been used by some to call into question the reliability of climate models - but climate scientists know that natural climate variations mean we shouldn't expect to rise smoothly in response to the accumulation of greenhouse gases in the atmosphere. Indeed, the Earth's surface has shown faster and slower periods of warming, even in the last century.

The study uses long "control" simulations of the Earth as it would be if unaffected by human influence, to find out how long these natural oscillations might contribute to a warming slowdown.

The authors studied the statistics of temperature trends that could temporarily enhance - or offset - global warming, on a timescale of one or two decades.

Previous studies have emphasised the role of decadal variability of ocean surface temperatures and the Trade winds in the Pacific Ocean in the warming slowdown, although enhanced volcanic activity, and lower solar activity, are thought to contribute.

The study is led by Met Office climate scientist, Chris Roberts, and colleagues. They point out that this isn't a forecast for a continued warming pause, however.

"We looked at the statistics of hypothetical pauses driven solely by natural variability. It's possible that the current slowdown has other causes as well", said co-author Doug McNeall from the Met Office. "It's important to remember that those other causes - like aerosols from volcanic eruptions or industry - could lengthen a pause in , so we shouldn't be too surprised if the pause continues."


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Last decade's slow-down in global warming enhanced by an unusual climate anomaly

Citation: Study seeks to understand variations in the rate of global warming (2015, February 24) retrieved 17 June 2019 from https://phys.org/news/2015-02-variations-global.html
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Feb 24, 2015
Isn't it great. When the data "supports" your assertion regardless of the result of said data?

Give me a reason to trust you again scientists!

All this proves is we don't know what is going on.

Feb 24, 2015
One article and so many disclaimers, could be, may, should, possible, maybe, probably, high chance, etc.......

Lends much needed credibility to the argument.

Feb 24, 2015
One article and so many disclaimers, could be, may, should, possible, maybe, probably, high chance, etc.......

Lends much needed credibility to the argument.
Exactly right. While this article will get spun in 90 different ways, the take away is actually pretty clear; short term variability is expected, such variability is very hard to predict, the variability still falls within the parameters of the models which project continued warming, and over the long term, the warming affect will take over, as the physics says it must.

Feb 24, 2015
The term "slow warming" implies that some warming has occurred over the past 18 years. But it hasn't.

Similar to rhetorical usage to the term "hiatus" indicating the cessation is temporary when there is no way of knowing whether temperatures will rise or fall in the future.

If the temperature graph was presented as the record for a stock price, the future price of the stock could not be determined.

Feb 24, 2015
The term "slow warming" implies that some warming has occurred over the past 18 years. But it hasn't.
That is, quite simply, wrong. http://www.newsci...GPnF91Y; http://www.thegua...-paused; http://www.smh.co...i8j.html

Similar to rhetorical usage to the term "hiatus" indicating the cessation is temporary when there is no way of knowing whether temperatures will rise or fall in the future.

If the temperature graph was presented as the record for a stock price, the future price of the stock could not be determined.
A disingenuous comparison. At best.

Feb 24, 2015
The UN Groundhog emerged from his den this month and predicted we need to fund research for another six billion years of climate change.

Feb 24, 2015
If the temperature graph was presented as the record for a stock price, the future price of the stock could not be determined.


This is not economics but it is similar in that the outcome can somewhat be determined by human emotional response. As long as humans link climate science to emotional politics we will continue to be ineffective at mitigating future warming.

Feb 24, 2015
PsycheOne claimed
The term "slow warming" implies that some warming has occurred over the past 18 years. But it hasn't
You look pretty stupid with such a claim, do you get paid to be a liar AND a dick at the same time:-

http://woodfortre...ormalise

Pray tell where is there NO warming ?

R U ill, disabled or plain LIAR paid to obfuscate, who pays u btw being ignorant PsycheOne ?

AND
whats more to present it on a public forum so all can see you have NO credibility ?

You do realise that, one day we will be able to match your nick to you directly ;-)

*grin* Then for all to see those that sell integrity for pennies...

LOL

Feb 24, 2015
Science Officer claimed, who SHOULD know better
The UN Groundhog emerged from his den this month and predicted we need to fund research for another six billion years of climate change.
What the f..k r u on about ?

Heard of 'rate of change' ?

Heard of basic physics, infra red, specific heat, total solar insolation ?

Y r U trying to appear as an ignorant mindless d..k who CAN'T do a simple google search ?

Feb 24, 2015
syndicate_51 claimed
Isn't it great. When the data "supports" your assertion regardless of the result of said data?
Give me a reason to trust you again scientists!
All this proves is we don't know what is going on.
For U thats true, if/when U get an education in; Heat, Specific Heat and combinatorial complexity then you might not look so stupid.

R U able to answer this simple question:-

"How can adding a green house gas such as CO2 to the atmosphere NOT increase thermal resistivity ?"

Add your answer in relation to watts per square meter or at least as Joules, something a dick who claims to be a graduate Physical Chemist just CANNOT do despite the fact he worked out Earth's combustion in Joules or watts as 0.1 Total Solar Insolation (TSI).

Water_Prophet - another mere claimant, ie Another dick who only claims & cannot work it out !

Feb 24, 2015
Thanks Mike_massen, it's not exactly rocket science is it? The optical properties of CO2 are not in doubt and calculating the additional heating from more CO2 isn't difficult - but the deniers just can't add it up.

With something like 40% of the US population believing the earth is less than 10,000 years old you can expect a lot of stupid comments, but maybe not at a science site - but the trolls insist on commenting here.

Yes, the rate of heating and what happens day to day can very, so what, it doesn't change the fact that we have a serious problem.

Feb 24, 2015
You're right, max....and good job Mike and Maggnus. I used to put more effort into explaining GHG theory, atmospheric physics, and oceanography to the seemingly ineducable....only to find out I could have saved myself both the time and aggravation had I not made the assumption "seemingly".


Feb 24, 2015
So the 1% of CO2 being added by man is a problem and the other 99 is not. You believers will take into account natural causes when you want to prove the little bit of CO2 being added by man is a problem but don't want to take it into account to disprove the model. If we have a problem with man's contribution then we have a problem with the other 99%. Better come up with better schemes than just cleaning up man's contribution to the system. Better hurry too before natural cooling occurs and disproves your biased thinking. All the thermal radiation from the earth's surface is absorbed by the atmosphere in about 30 meters at current CO2 levels. If you increase CO2 level to 5% from the current 0.048% that distant drops to 29 meters. The natural conclusion is so what.

Feb 24, 2015
Just shut off HAARP you schwacks! HAARP is causing all this.

Feb 24, 2015
Obviously there is a varying impact of CO2 forcing.

Feb 24, 2015
You're right, max....and good job Mike and Maggnus. I used to put more effort into explaining GHG theory, atmospheric physics, and oceanography to the seemingly ineducable....only to find out I could have saved myself both the time and aggravation had I not made the assumption "seemingly".



Ha! If I could assign a 10!!

Feb 24, 2015
So the 1% of CO2 being added by man is a problem and the other 99 is not.
No, it is the amount that exceeds the carbon cycle that is the problem.
You believers..blah blah..better schemes..blah blah.. man's contribution to the system..blah blah.. thermal radiation..blah blah.. increase CO2 level to 5% fr..blah blah... natural conclusion is so what.
Indeed. So what is your need to post such drivel here?

Feb 24, 2015
Anthropogenic contribution of CO2 has to be viewed cumulatively with respect to a existing balanced processes in the carbon cycle.
Source http://cdiac.ornl...faq.html
"The 369.5 ppmv of carbon in the atmosphere, in the form of CO2, translates into 787 PgC, of which 174 PgC has been added since 1850. From the second paragraph above, we see that 64% of that 174 PgC, or 111 PgC, can be attributed to fossil-fuel combustion. This represents about 14% (111/787) of the carbon in the atmosphere in the form of CO2."

Feb 24, 2015
I dont usually participate in these AGW slapfests but I was wondering if anybody has remarked on the location of the so-called polar vortexes over north america
https://dabrownst...ortex-2/

-and the lopsided nature of the last ice age?
http://wiki.alter..._ancient

Feb 24, 2015
I dont usually participate in these AGW slapfests but I was wondering if anybody has remarked on the location of the so-called polar vortexes over north america
https://dabrownst...ortex-2/


Are you asking if there is a correlation (beyond a very simple visual similarity)?

Feb 24, 2015
I've always said ever since my Climategate inquiry submission that there is nothing to distinguish the 20th century change from natural variation. And if anything having studied the subject and people involved for another five years I have seen nothing to suggest the academics involved have any idea how to predict the climate and they were totally totally wrong to suggest they could.

Furthermore, there clear unequivocal evidence that negative feedbacks have prevented warming in past inter-glacial periods and it is simply ridiculous to suggest that we could live at a time when massive positive feedbacks are present in the climate system.

http://scottishsc...buffers/

Feb 24, 2015
but the trolls insist on commenting here.
@maxwell_bean
Most likely because the site is rarely if ever moderated
they get Zephir every now and again, but as long as the pseudoscience idiots make it sound technical, it is left alone (see: creationist jvk, electric universe pseudoscience cantdrive for proof... there are MANY more)

but I was wondering if anybody has remarked on the location of the so-called polar vortexes
@Otto
Yes
and lots of the deniers are getting the weather vs climate problem in their posts when they try to say "im cold, must not be GW"
These studies demonstrate the relationship between warming and destabilizing the jet stream
the latest: http://iopscience...4005.pdf
This supports the previous study: http://marine.rut..._pub.pdf

I have Francis video (from a few years ago)
if you want to watch it, just let me know

Feb 25, 2015
I dont usually participate in these AGW slapfests but I was wondering if anybody has remarked on the location of the so-called polar vortexes over north america
https://dabrownst...ortex-2/


Hey Ghosty-O,

I've noticed the similarity, as well, but it seems to be coincidental. The scalloped-edged contour of the glacial icefront is -or was- due to the average annual deviation of the jetstream in the NH.
Where the icefront is more southerly advanced(or northerly retreated) is where the jetstream was persistently deflected more to the north or more to the south, annually.
The jetstream exhibits this same habit normally, as the cooler, northern air contacts the warmer southern air.
So, the sinusoid glacial icefront "models" the more-or-less stable contour of that contact zone.

Feb 25, 2015
Here's the real takeaway from the study, however:

Finally it is entirely possible that once the current slow-down finishes, it may be followed by a period of accelerated global surface warming. Understanding this better is one aspect of managing the risks and opportunities associated with future climate variability and change.

When this happens --and I say when, not if-- there are going to be vast numbers of people severely impacted, and a consequent great wailing and gnashing of teeth.

This slowdown in the rate of warming is actually only a slowdown in the rate of increase in surface temperatures, while --as most of us are aware-- the oceans have been taking up most of the additional heat for the past several years.

Unfortunately, this heat doesn't just go away and die a quiet death. Sometime in the next 2-5 years, it is going to be rapidly re-emitted into the lower atmosphere, and that is when things are going to get extremely interesting.


Feb 25, 2015
So, in the interim, get as much smug, antiscience deniery in as you can, while you can -sydicate51, Gimp, PsycheOne, Scioff, dadpt, Scottish Sceptic, Shootist, Water_Prophet, ConfoundedSociety, mememine69, ubavontuba and the rest of you tribe of basement fungus trolls.

You think it's dank'n'penicilliny down there right now --just you wait...

Feb 25, 2015
The climate scientist didn't seem to "know" about this fluctuation until everyone noticed that their "models" were wrong. Climate science is the astrology of the scientific world.

Feb 25, 2015
I dont usually participate in these AGW slapfests but I was wondering if anybody has remarked on the location of the so-called polar vortexes over north america
https://dabrownst...ortex-2/


Hey Ghosty-O,

I've noticed the similarity, as well, but it seems to be coincidental. The scalloped-edged contour of the glacial icefront is -or was- due to the average annual deviation of the jetstream in the NH.
Where the icefront is more southerly advanced(or northerly retreated) is where the jetstream was persistently deflected more to the north or more to the south, annually.
The jetstream exhibits this same habit normally, as the cooler, northern air contacts the warmer southern air.
So, the sinusoid glacial icefront "models" the more-or-less stable contour of that contact zone.

Correct:
Essentially the Rockies controls the PJS wave-train in the NH. Like a wall stuck across a stream - water/air curls in behind. Like whipping a washing line.

Feb 25, 2015
kivahut claimed
The climate scientist didn't seem to "know" about this fluctuation until everyone noticed that their "models" were wrong
Contemporary climate models have these things called error bars, just like functions derived in things like engine computers to estimate the fuel needed - all engine computers rely on feedback as the correction mechanism. Climate models get the same feedback from corrections which instrumentation offers and humans feed back in. As such no model can ever be 100% correct ever, its called variation, it's a fundamental re ANY measured quantity.

If you imaging a particular model is wrong and not being manipulated blindly by propaganda then present the link to that model here along with its error bars - can U ?

kivahut shows he has NO science understanding with
Climate science is the astrology of the scientific world
This is why education is SO important, you become mostly immune to the type of rubbish u bark !

Feb 25, 2015
Scottish Sceptic claimed
I've always said ever since my Climategate inquiry submission that there is nothing to distinguish the 20th century change from natural variation
LOL.
U can say it all u like & look foolish as Evidence is against u Eg. Here are temps with CO2, bear in mind humans are now burning approx 230,000 Litres of petrol per second 24/7 !

http://woodfortre...ormalise

Scottish Sceptic, u may be sincere but, your unfortunate lack of appreciation re Physics of greenhouse gases & their origins has misled u :-(

I'm an EE, so your link digression re electronics is of some interest & might appear pertinent to some but, its not valid re the main contributory factor, consider:-

"How can adding a greenhouse gas such as CO2 to the atmosphere NOT increase thermal resistivity (IR to space) ?"

ie. Resistance !

Feb 25, 2015
I've always said ever since my Climategate inquiry submission that there is nothing to distinguish the 20th century change from natural variation. And if anything having studied the subject and people involved for another five years I have seen nothing to suggest the academics involved have any idea how to predict the climate and they were totally totally wrong to suggest they could.

Furthermore, there clear unequivocal evidence that negative feedbacks have prevented warming in past inter-glacial periods and it is simply ridiculous to suggest that we could live at a time when massive positive feedbacks are present in the climate system.

http://scottishsc...buffers/

Oh, hello:
I believe I've come across a certain denier of your name inhabiting the rabbit-hole that is WUWT.
Would it be you?
Or is it just an amazing coincidence?

Feb 25, 2015
syndicate_51 claimed
Isn't it great. When the data "supports" your assertion regardless of the result of said data?
Give me a reason to trust you again scientists!
All this proves is we don't know what is going on.
For U thats true, if/when U get an education in; Heat, Specific Heat and combinatorial complexity then you might not look so stupid.

R U able to answer this simple question:-

"How can adding a green house gas such as CO2 to the atmosphere NOT increase thermal resistivity ?"

Add your answer in relation to watts per square meter or at least as Joules, something a dick who claims to be a graduate Physical Chemist just CANNOT do despite the fact he worked out Earth's combustion in Joules or watts as 0.1 Total Solar Insolation (TSI).

Water_Prophet - another mere claimant, ie Another dick who only claims & cannot work it out !


Sorry pal you forgot latent heat in there too. Scientists can be criminals too ya know. They are no paragon.

Feb 25, 2015
I love all the support for the disclaimers. I tend to look the other way when disclaimers run amok in any kind of assertion.

All this means is a need for better modeling not a turn away from climate study.

Also everybody is so quick to say don't trust anybody unless it's a scientist. Funny. Having known a scientist in the medical field who also happened to be a compulsive liar.

Scientist never try to get "results" for grant money no. They have never succumbed to the temptation of extraordinary funding.

Scientists are humans not paragons.

Feb 25, 2015
Just wait, eventually it will start warming again, and then the "scientists" will say "See!". Grant it, it may start cooling first, but that is just internal variability! I'm sick and tired of hearing that most "scientists" support the "theory" of global warming, predicted by the man-made models. After all the "models" can't be wrong. And true scientists will admit that CO2 build up is the result of warming, and not vice versa.

Feb 25, 2015
........... I'm sick and tired of hearing that most "scientists" support the "theory" of global warming, predicted by the man-made models. After all the "models" can't be wrong. And true scientists will admit that CO2 build up is the result of warming, and not vice versa.

In a word complete bollocks (well 2 words).
First off - the "models" aren't the science. GHG physics has been know of for ~150 years, is empirical knowledge and NOT up for discussion. Like the sky is blue because and prisms refract because.
Models need to start at the correct initial conditions and forecast (at least) the PDO/ENSO) cycle correctly. Since that cannot be done at present, then luck is needed. There was luck on some individual runs that then went on to predict the "pause".
For your info - CO2 can both lead and follow temp.

Oh, and snap - I'm sick and tired of deniers.

http://www.report...use.htm/

Feb 25, 2015
seems to be coincidental
-So why would the jet stream deviate consistently in that location, and if this persisted over many centuries wouldn't this explain the lopsided nature of the ice cover, or even be the thing that precipitates it? And sorry I assume NH isn't New Hampshire. I don't speak climatology.

If you search you can see that this has occurred to others but mostly fringe theorists.

Feb 25, 2015
seems to be coincidental
-So why would the jet stream deviate consistently in that location, and if this persisted over many centuries wouldn't this explain the lopsided nature of the ice cover, or even be the thing that precipitates it? And sorry I assume NH isn't New Hampshire. I don't speak climatology.

If you search you can see that this has occurred to others but mostly fringe theorists.

I explained it for you up-thread a ways, if you'd care to look.
Hint: it concerns the Rockies.....and one reason why winter both last year and this have been very cold.
http://www.geogon...i4.1.htm

"It is thought that Rossby waves may be caused by the presence of substantial mountain barriers such as the Rockies, the Andes or the Tibetan plateau. Mountains help to create the wave like pattern. The ridges swing northwards and upwards around the barrier in a ridge and then swing downwards and southwards on the leeward side."

Feb 25, 2015
Climate is the resultant of the interactions of complex systems. Read Catastrophe Theory if you want to understand climate. The theory is poorly-named, being the study of stable states of systems and their interactions, the destabilization of complex systems, and the number of possible resultant states.

Leave your politics out of it.

Feb 25, 2015
syndicate_51 claimed
Sorry pal you forgot latent heat in there too. Scientists can be criminals too ya know. They are no paragon.
No. Its within the properties of materials as "Specific Heat", besides which particular one and its relative magnitude are you referring to has the greatest issue to address & why - fusion or vapourisation ?

You still havent answered the core question, ie The core essential science which is settled re the thermal properties of greenhouse gases, my question in particular & why did u sidestep it with a shallow attempt at evasion:-

"How can adding a green house gas such as CO2 to the atmosphere NOT increase thermal resistivity ?"

Come on...
Get those lazy neurons out for a change & look at the "unbiasable" facts in Science ?

Feb 25, 2015
I explained it for you up-thread a ways, if you'd care to look
Sorry, I didnt see where you explained how the persistence of the jet stream and 'polar vortex' may be responsible for glacial ice cover over the same area but not elsewhere at similar latitudes.

Feb 26, 2015
syndicate_51 claimed
Sorry pal you forgot latent heat in there too. Scientists can be criminals too ya know. They are no paragon.
No. Its within the properties of materials as "Specific Heat", besides which particular one and its relative magnitude are you referring to has the greatest issue to address & why - fusion or vapourisation ?


Actually, latent heat is the amount of heat absorbed/released during a phase change of a substance at a given temperature, while specific heat is the amount of heat required to change the temperature of a given mass of a substance by a given amount. The particular importance of latent heat in climate change is that it can prevent absorbed heat from immediately being reflected as a temperature change. Melting of ice, and vaporization of water from the oceans, both absorb non-negligible amounts of heat that does not lead to "warming" until the opposite change, freezing or condensation, occurs.

Feb 26, 2015
seems to be coincidental
-So why would the jet stream deviate consistently in that location, and if this persisted over many centuries wouldn't this explain the lopsided nature of the ice cover, or even be the thing that precipitates it? And sorry I assume NH isn't New Hampshire. I don't speak climatology.

If you search you can see that this has occurred to others but mostly fringe theorists.


Sorry, Otto- you are correct. I shouldn't have said "coincidence". The persistent deviation of the jetstream -caused,as runrig noted, by the obstruction presented by the Rockies- over long glaciation timescales is the same deviation that causes the present extent of the deep freeze over North America. So, yeah, that explains the similarity. NH = Northern Hemisphere. If you look closely at the graphic in the link you provided, you'll see that the terminus of glacial advance wavers pretty regularly from north to south over the NH in a sinusoid wave.

Feb 27, 2015
DarkLordKelvin observed
Actually, latent heat (LH) is the amount of heat absorbed/released during a phase change of a substance at a given temperature, while specific heat is the amount of heat required to change the temperature of a given mass of a substance by a given amount..
Quite correct of course, was a tad sloppy & its somewhat ironic re climate change as I have often informed the simplistic deniers here re LH of fusion ie melting ice's immense capacity for absorbing heat whilst temp doesn't rise - Eg in relation to an aspect of the so called pause also in concert with oceans specific heat.

Better to have said to syndicate_51
No. Its within the properties of materials as "Enthalpy", besides which particular "latent heat" and its relative magnitude are you referring to has the greatest issue to address & why - fusion or vapourisation ?
In that respect, still awaiting his considered response to questions on that issue raised in my posts to him...

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