Natural climate processes overshadow recent human-induced Walker circulation trends

Natural climate processes overshadow recent human-induced Walker circulation trends
Normal conditions (top), strengthening due to natural variability (middle) and weakening due to greenhouse warming (bottom). Black arrows represent horizontal and vertical winds with the shading on the background map illustrating ocean temperatures. Over the past few decades, natural variability has strengthened the Pacific Walker circulation leading to enhanced cooling in the equatorial central-to-eastern Pacific (middle). Climate models forced by increasing greenhouse gas concentrations simulate weakening of the Walker circulation (bottom). (Right) Temporal evolution of model-simulated Walker circulation trends, with the dark blue line and orange shading denoting anthropogenically-induced changes and the impact of natural processes, respectively. Credit: IBS

A new study, published this week in the journal Nature Climate Change, shows that the recent intensification of the equatorial Pacific wind system, known as Walker Circulation, is unrelated to human influences and can be explained by natural processes. This result ends a longstanding debate on the drivers of an unprecedented atmospheric trend, which contributed to a three-fold acceleration of sea level rise in the western tropical Pacific, as well as to the global warming hiatus.

Driven by the east-west sea surface temperature difference across the equatorial Pacific, the Walker circulation is one of the key features of global atmospheric circulation. It is characterized by ascending motion over the Western Pacific and descending motion in the eastern equatorial Pacific. At the surface, trade winds blow from east to west, causing upwelling of cold water along the equator. From the early 1990s to about 2013, this circulation has intensified dramatically, cooling the eastern equatorial Pacific and triggering shifts in global winds and rainfall (see Figure 1). These conditions further contributed to drying in California, exacerbating mega- and impacting agriculture, water resources and wildfires. Given these widespread impacts on ecosystems and society, the recent Walker circulation trends have become a subject of intense research.

In contrast to the observed strengthening, the majority of climate computer models simulate a gradual weakening of the Walker Circulation when forced by increasing greenhouse gas concentrations (see Figure 1). "The discrepancy between climate projections and observed trends has led to speculations about the fidelity of the current generation of climate models and their representation of tropical climate processes," said Eui-Seok Chung, researcher from the Center for Climate Physics, Institute for Basic Science, South Korea, and lead author of the study.

To determine whether the observed changes in the tropical atmospheric circulation are due to natural climate processes or caused by human-induced climate change, scientists from South Korea, the United States and Germany came together to conduct one of the most comprehensive big-data analyses of recent atmospheric trends to date. "Using satellite data, improved surface observations and a large ensemble of climate model simulations, our results demonstrate that natural variability, rather than anthropogenic effects, were responsible for the recent strengthening of the Walker circulation," said Prof. Axel Timmermann, Director of the IBS Center for Climate Physics at Pusan National University and co-author of this study.

In their integrated analysis, the researchers found that the satellite-inferred strengthening of the Walker circulation is substantially weaker than implied by other surface observations used in previous studies. "Putting surface observations in context with latest satellite products was a key element of our study," said co-author Dr. Lei Shi from NOAA's National Centers for Environmental Information in the United States.

Analyzing 61 computer model simulations forced with increasing greenhouse gas concentrations, the authors showed that although the average response is weakening of the Walker circulation, there are substantial discrepancies amongst the individual model experiments, in particular when considering shorter-term trends. "We found that some models are even consistent with the observed changes in the tropical Pacific, in stark contrast to other computer experiments that exhibit more persistent weakening of the Walker circulation during the observational period," said co-author Dr. Viju John from EUMETSAT in Germany. The authors were able to tease apart what caused the spread in the computer model simulations.

Co-author Prof. Kyung-Ja Ha from the IBS Center for Climate Physics and Pusan National University says, "Natural climate variability, associated, for instance, with the El Niño-Southern Oscillation or the Interdecadal Pacific Oscillation can account for a large part of diversity in simulated tropical climate trends."

Prof. Brian Soden from the Rosenstiel School of Marine and Atmospheric Science, at the University of Miami, United States, said, "The observed trends are not that unusual. In climate model simulations we can always find shorter-term periods of several decades that show similar trends to those inferred from the . However, in most cases, and when considering the century-scale response to global warming, these trends reverse their sign eventually."

The study concludes that the observed strengthening of the Walker from about 1990 to 2013 and its impact on western Pacific sea level, eastern Pacific cooling, and drought in the southwestern United States, was a naturally occurring phenomenon that does not stand in contrast to the notion of projected anthropogenic change. Given the high levels of natural decadal variability in the tropical Pacific, it would take at least two more decades to detect unequivocally the human imprint on the Pacific Walker Circulation (see Figure 1, right panel).


Explore further

Solar variability weakens the Walker cell

More information: Eui-Seok Chung, Axel Timmermann, Brian J. Soden, Kyung-Ja Ha, Lei Shi, Viju O. John. Reconciling opposing Walker circulation trends in observations and model projections. Nature Climate Change. DOI: 10.1038/s41558-019-0446-4
Journal information: Nature Climate Change

Citation: Natural climate processes overshadow recent human-induced Walker circulation trends (2019, April 2) retrieved 23 October 2019 from https://phys.org/news/2019-04-natural-climate-overshadow-human-induced-walker.html
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Apr 02, 2019
Yep, it's the Sun stupid!
The Sun drives these processes whereas human involvement is localized at best. AGWism is as dead as the dark sciences, the acolytes just don't get it yet.

Apr 02, 2019
Yep, it's the Sun stupid!
The Sun drives these processes whereas human involvement is localized at best. AGWism is as dead as the dark sciences, the acolytes just don't get it yet.


You don't get it, as you understand the square root of zero about the science. Or any other science, for that matter. Why comment on things you don't understand? You conveniently missed the part of the article that states;

....was a naturally occurring phenomenon that does not stand in contrast to the notion of projected anthropogenic climate change.


And what is the measured total solar irradiance over the last ~ 4 decades? Show me the science, or belt up about things that you don't understand.

Apr 02, 2019
@cantdrive85.
Yep, it's the Sun stupid! The Sun drives these processes whereas human involvement is localized at best. AGWism is as dead as the dark sciences, the acolytes just don't get it yet.
Mate, now you're just justifying @Castro etc's comments about your denialist trolling/lack of objectivity. You should know better re these solar factors already inherent in the pre-existing dynamics in Earth's weather/climate systems. I explained to you, in...

https://phys.org/...ell.html

...re short-versus-longterm-trend analysis/interpretation of such solar connections with Earth system which have always existed. :)

The point NOW is that all previous patterns/prevailing dynamical sub-systems are being de-stabilised. by the additional RETAINED heat due to ore CO2 than prior to Industrial Revolution. Get a grip on yourself and stick to what you actually know rather than what you are trolling in denial. Thanks and good luck. :)

Apr 02, 2019
Once again, reality hammers another nail into the CO2 filled coffin of AGW Cult's LIES.

as well as to the global warming hiatus

Ah yes. The hiatus, which the AGW Cult brayed, did not happen.

Apr 02, 2019
@antigoracle.
Once again, reality hammers another nail into the CO2 filled coffin of AGW Cult's LIES....Ah yes. The hiatus, which the AGW Cult brayed, did not happen.
Leave it out, mate. Science know about the many TRANSIENT events (major volcanism; and random/cyclic ocean current shifts etc that bring El Nino and el Nina and other 'dipole' swings over decades). And we know about the transient BUFFERING processes that temporarily absorb much of the additional retained heat/energy only to release it again after a time. All these things are well known to cause seeming 'cooling/warming' steps that when taken over longer term still presents a TREND towards warming/instability. Time to stop being a stooge for Russian govt (Putin) and GOP criminals (Trump and his Russian-played dupes); and start thinking/knowing for yourselves. You and your families/friends are not served by such stupidity as you engage in on the net, mate. Wise up.

Apr 02, 2019
And what is the measured total solar irradiance over the last ~ 4 decades?

TSI is a misnomer, all TSI measures is the UV part of the spectrum. It ignores the rest of the EM spectrum, it ignores SW input, it ignores energetic proton flux. TSI is by no means the total solar input to Earth, by a huge margin.

Apr 03, 2019
The point NOW is that all previous patterns/prevailing dynamical sub-systems are being de-stabilised. by the additional RETAINED heat due to ore CO2 than prior to Industrial Revolution.


You can stuff your Chicken Littleisms in a sack there bub.

Take one solar flare, similar to the September 2017 X-class flare for example. During this flare, the TSI dropped significantly, more over several days than what is expected over an entire solar cycle. Now during solar flares, X-ray flux can increase by up to 100x, SW flux can increase by up to 10%, and energetic particles can increase by up to 1000%. Yet, in the shadow of the CME, the TSI drops by up to .3%.
Clearly the Sun is imparting huge amounts of energy on the Earth during these events, yet the TSI drops. There is a clear disconnect in the logic regarding these facts. When the entire energetic spectrum is considered you may have a scientific leg to stand on.
Say objective to me one more time Chicken Little.

Apr 03, 2019
Sorry, X-ray flux can increase by up to 100,000x, solar wind by up to 100x, energetic particles can increase by up to 1000x. That is a tremendous amount of energy directed toward Earth for the TSI to drop.
According to the climate scientists 1+2=-1.

Apr 03, 2019
The silence, from the AGW Cult's Chicken Shites, is deafening.

Apr 03, 2019
@cantdrive85.
Clearly the Sun is imparting huge amounts of energy on the Earth during these events, yet the TSI drops. There is a clear disconnect in the logic regarding these facts. ....Say objective to me one more time Chicken Little.
Why is it you keep missing the salient point I made so many times now for your benefit, mate? No matter what transient input variables from sun, it is the atmosphere of Earth that determines whether said input is re-emitted to space sooner/later depending on the LAG effect from increased CO2 factor added to other GHGases factors.

@Cantdrive, mate, I even gave you the EXAMPLE of Planet MERCURY: ie, without an atmosphere to provide a LAG effect, even the FURNACE-like SOLAR HEAST/ENERGY 'inputs' to Mercury are LOST to space almost immediately on the NIGHT side hemisphere...EVEN while the DAY-side is STILL BAKING in that solar furnace 'input'.

So, mate, please try to THINK and UNDERSTAND.....errrr...ahem!......OBJECTIVELY? :)

Apr 03, 2019
I even gave you the EXAMPLE of Planet MERCURY

LMAO.
Chicken Little is looking all the way to Mercury.
Let's look right here on Earth. Deserts are the hottest places on the planet, yet when the sun sets, their temperatures plummets towards freezing.
Why?
Is it because CO2 is afraid of the deserts?

Apr 03, 2019
@antigoracle.
gave you the EXAMPLE of Planet MERCURY
Deserts are the hottest places on the planet, yet when the sun sets, their temperatures plummets towards freezing. Is it because CO2 is afraid of the deserts?
If you read my posting record you will find that I ALREADY pointed that out too (to someone fixated with atmospheric water vapour as be-all-and-end-all factor in warming climate). I explained THEN that atmosphere has 'dry regions' in it at many locations around globe all the time (shifting according to wind/evaporation etc variables).

The point being that CO2 does NOT form 'clouds' OR 'dry regions' in air, but DISPERSES and PERSISTS at all altitudes/latitudes until 'slowly' (much more slowly than water vapour) removed by known mechanisms.

Hence the heat loss over 'dry air' deserts at night was MY example to point out that 'dry air' was allowing heat loss to upper atmosphere...where it is NOW increasingly LAGGED by CO2 in upper atmospheric column. :)

Apr 03, 2019
LMAO.
So, the CO2 in lower atmosphere is allowing the desert heat to escape while it magically blocks it in the upper atmosphere.
Now, provide a peer reviewed study that confirms that load of tripe.
Unless, of course, you pulled it out your "dry hole".

Apr 03, 2019
@antigoracle.
LMAO.
Now, provide a peer reviewed study that confirms that load of tripe.
Unless, of course, you pulled it out your "dry hole".
The weather bureaus around the globe have been doing weather reports based on locally measured wind/temp/moisture/precipitation data for CENTURIES mate. :)

Are you going to deny even that now?...just because PUTIN is 'playing' you and your fellow RIGHT-WINGnut GOP/TRUMPIAN morons for fools to 'weaponise' your stupidity to divide American society/body-politic? Sure looks like it. And you and your fellows are sure willing 'weaponised stupids' for PUTIN to 'play' with, @antigoracle! Not good.

Apr 03, 2019
Are you going to deny even that now?...just because PUTIN is 'playing' you and your fellow RIGHT-WINGnut GOP/TRUMPIAN morons for fools to 'weaponise' your stupidity to divide American society/body-politic? Sure looks like it. And you and your fellows are sure willing 'weaponised stupids' for PUTIN to 'play' with, @antigoracle! Not good.

LMAO.
Thanks for confirming that you pulled that shite out of your "dry hole".
Keep braying jackass. That's real good.
Now, back to ignoring you.

Apr 03, 2019
@antigoracle.
Are you going to deny even that now?...just because PUTIN is 'playing' you and your fellow RIGHT-WINGnut GOP/TRUMPIAN morons for fools to 'weaponise' your stupidity to divide American society/body-politic? Sure looks like it. And you and your fellows are sure willing 'weaponised stupids' for PUTIN to 'play' with, @antigoracle! Not good.

LMAO.
Thanks for confirming that you pulled that shite out of your "dry hole".
Now, back to ignoring you.
Keep braying jackass. That's real good.
Denial is strong in you 'weaponised stupids' PUTIN is 'playing' as he pleases; and you are so 'easy', mate. It's almost interesting to watch you being 'played' by PUTIN and his troll-factory 'string pullers' (which you must know well the 'feel' of by now, mate). While it is amusing on one level, it is very tragic on many levels, not only for you, @antigoracle,but also for whatever potential for objective good you may have had at one time in your now-very-sad life. Pity.

Apr 03, 2019
Why is it you keep missing the salient point I made so many times now for your benefit, mate?

Right back at ya Chicken Little! The salient point is your Chicken Little claims are baseless conjecture without observational evidence. No MATTER how many WORDS you decide to CAPITALIZE, it doesn't mean you are RIGHT. The Sun drives the Earth's climate, CO2 lags a warming climate and your GHG calamities do not happen. Try some objectivity and THINK for a change.

Apr 03, 2019
GOP/TRUMP
You sound like another sore LOSER.

I thought you would have gotten the message by now, the Kenyan is no longer squatting in the White House. "Elections have consequences.",,,,, guess who said that?

Apr 03, 2019
The consequences in this case appear to be a hurricane that destroyed Puerto Rico, which is a US possession, and flooding in Nebraska.

Maybe they'll all move to Montana. Then you can try to have ICE deport the US citizens as "illegal aliens." Good luck with that.


Apr 04, 2019
@montanaclass.
GOP/TRUMP
You sound like another sore LOSER.
And you sound like one (too many) of the 'weaponised stupids' that Putin is using to divide America and delay climate action to protect the profits from Russia's (ie, Putin and his cronies') fossil fuels exports. Mate, I think the fumes have gotten to your brain tissue and made you 'ripe' for being one of Putin's 'weaponised stupids' being played for fools without them realising it. Pity. Good luck to us all.

Apr 04, 2019
@cantdrive.
Why is it you keep missing the salient point I made so many times now for your benefit, mate?
Right back at ya Chicken Little! The salient point is your Chicken Little claims are baseless conjecture without observational evidence. ....The Sun drives the Earth's climate, CO2 lags a warming climate and your GHG calamities do not happen. Try some objectivity and THINK for a change.
Now you're 'doing a jonesy' to avoid the fact I made a point you can't refute or deny in objective terms. So you go the low route so often trod by those whom you have accused of using the same tactics you are employing now. Not good, mate; you must know by now that I am impartial and objective at all times...and don't let politics or personal factors get in the way of scientific/logical thinking/understanding. I gave you the Planet Mercury example which proves me correct and you incorrect, @cantdrive. Go on, mate, admit it like an honest man instead of 'doing a jonesy' on me. :)

Apr 04, 2019
Now you're 'doing a jonesy' to avoid the fact I made a point you can't refute or deny in objective terms.

If your point had any validity there would be no snow anymore. If your point had any validity we would be seeing your hockey stick temps by now. If you had objectively acknowledged my point you would realize the Sun drives the climate and weather, not plant food that rises reactively to higher temps. If you had addressed the facts objectively you would have acknowledged that Earth's climate is driven by solar activity as the long term charts clearly show.
I gave you the Planet Mercury example which proves me correct and you incorrect, @cantdrive.

No, you only showed your flawed logic which somehow conflates a dried ember of a planet with no atmosphere a fraction of the distance from the Sun to our planet with its large magnetosphere, complex atmosphere and watery surface. Needless to say, you have proven nada.

Apr 05, 2019
@cantdrive85.
If your point had any validity there would be no snow anymore. If your point had any validity we would be seeing your hockey stick temps by now. If you had objectively acknowledged my point you would realize the Sun drives the climate and weather, not plant food that rises reactively to higher temps. If you had addressed the facts objectively you would have acknowledged that Earth's climate is driven by solar activity as the long term charts clearly show.
What 'point' are you 'addressing'? It certainly isn't the one I made. Don't start 'doing a DS' on me as well as 'a jonesy', mate! :)
I gave you the Planet Mercury example which proves me correct and you incorrect, @cantdrive.
No, you only showed your flawed logic which somehow conflates a dried ember of a planet with no atmosphere a fraction of the distance from the Sun...
Can it be you really do not 'get' the point of Mercury being fried but the night-side going to cryogenically cold temps?

Apr 05, 2019
If your point had any validity there would be no snow anymore. If your point had any validity we would be seeing your hockey stick temps by now. If you had objectively acknowledged my point you would realize the Sun drives the climate and weather, not plant food that rises reactively to higher temps. If you had addressed the facts objectively you would have acknowledged that Earth's climate is driven by solar activity as the long term charts clearly show.
I gave you the Planet Mercury example which proves me correct and you incorrect, @cantdrive.

No, you only showed your flawed logic which somehow conflates a dried ember of a planet with no atmosphere a fraction of the distance from the Sun to our planet with its large magnetosphere, complex atmosphere and watery surface. Needless to say, you have proven nada.


Stop commenting on things that you have no understanding of.

Apr 06, 2019
Can it be you really do not 'get' the point of Mercury being fried but the night-side going to cryogenically cold temps?

The same occurs on the moon or any other object without an atmosphere. If your example was of any relevance the day side of Earth would be fried as well, but alas atmospheres insulate that from without such as the SW and react dramatically to inputs with outputs of its own. It is not a closed system as you imagine but a dynamic system that isn't nearly fully understood.

Apr 06, 2019
@cantdrive85.
The same occurs on the moon or any other object without an atmosphere. If your example was of any relevance the day side of Earth would be fried as well, but alas atmospheres insulate that from without such as the SW and react dramatically to inputs with outputs of its own. It is not a closed system as you imagine but a dynamic system that isn't nearly fully understood.
Mate, I chose the EXTREME case of planet Mercury advisedly; to make clear beyond any chance of you/other deniers bringing in trivial 'arguments' which evade the whole point of that extreme example: ie, it is ATMOSPHERE and its density/constituents that DETERMINES the balance of input to output in a planet's system. Hence why I did not choose the easier/closer, but less extreme, Moon case.

The WHOLE point of my example was: Mercury LACKS atmospheric 'lagging'; has EXTREME 'insolation'...yet a CRYOGENIC 'night-side'!

Please admit the point and don't keep 'doing a DS/jonesy' on me mate! :)

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