Expanding Antarctic sea ice linked to natural variability

Antarctic
Credit: Ted Scambos, University of Colorado, NSIDC

The recent trend of increasing Antarctic sea ice extent—seemingly at odds with climate model projections—can largely be explained by a natural climate fluctuation, according to a new study led by the National Center for Atmospheric Research (NCAR).

The study offers evidence that the negative phase of the Interdecadal Pacific Oscillation (IPO), which is characterized by cooler-than-average in the tropical eastern Pacific, has created favorable conditions for additional Antarctic sea ice growth since 2000.

The findings, published in the journal Nature Geoscience, may resolve a longstanding mystery: Why is Antarctic sea ice expanding when climate change is causing the world to warm?

The study's authors also suggest that sea ice may begin to shrink as the IPO switches to a positive phase.

"The climate we experience during any given decade is some combination of naturally occurring variability and the planet's response to increasing greenhouse gases," said NCAR scientist Gerald Meehl, lead author of the study. "It's never all one or the other, but the combination, that is important to understand."

Study co-authors include Julie Arblaster of NCAR and Monash University in Australia, Cecilia Bitz of the University of Washington, Christine Chung of the Australian Bureau of Meteorology, and NCAR scientist Haiyan Teng. The study was funded by the U.S. Department of Energy and by the National Science Foundation, which sponsors NCAR.

Expanding ice

The sea ice surrounding Antarctica has been slowly increasing in area since the satellite record began in 1979. But the rate of increase rose nearly five fold between 2000 and 2014, following the IPO transition to a negative phase in 1999.

The new study finds that when the IPO changes phase, from positive to negative or vice versa, it touches off a chain reaction of climate impacts that may ultimately affect at the bottom of the world.

When the IPO transitions to a negative phase, the sea surface temperatures in the tropical eastern Pacific become somewhat cooler than average when measured over a decade or two. These sea surface temperatures, in turn, change tropical precipitation, which drives large-scale changes to the winds that extend all the way down to Antarctica.

The ultimate impact is a deepening of a low-pressure system off the coast of Antarctica known as the Amundsen Sea Low. Winds generated on the western flank of this system blow sea ice northward, away from Antarctica, helping to enlarge the extent of sea ice coverage.

"Compared to the Arctic, global warming causes only weak Antarctic sea ice loss, which is why the IPO can have such a striking effect in the Antarctic," said Bitz. "There is no comparable natural variability in the Arctic that competes with global warming."

Sifting through simulations

To test if these IPO-related impacts were sufficient to cause the growth in observed between 2000 and 2014, the scientists first examined 262 climate simulations created by different modeling groups from around the world.

When all of those simulations are averaged, the natural variability cancels itself out. For example, simulations with a positive IPO offset those with a negative IPO. What remains is the expected impact of human-caused climate change: a decline in Antarctic sea ice extent.

But for this study, the scientists were not interested in the average. Instead, they wanted to find individual members that correctly characterized the natural variability between 2000-2014, including the negative phase of the IPO. The team discovered 10 simulations that met the criteria, and all of them showed an increase in Antarctic sea ice extent across all seasons.

"When all the models are taken together, the natural variability is averaged out, leaving only the shrinking sea ice caused by ," Arblaster said. "But the model simulations that happen to sync up with the observed natural variability capture the expansion of the sea ice area. And we were able to trace these changes to the equatorial eastern Pacific in our model experiments."

Scientists suspect that in 2014, the IPO began to change from negative to positive. That would indicate an upcoming period of warmer eastern Pacific Ocean on average, though year-to-year temperatures may go up or down, depending on El Niño/La Niña conditions. Accordingly, the trend of increasing Antarctic sea ice extent may also change in response.

"As the IPO transitions to positive, the increase of Antarctic extent should slow and perhaps start to show signs of retreat when averaged over the next 10 years or so," Meehl said.


Explore further

Changes in Antarctic sea ice production due to surrounding ice conditions

More information: Antarctic sea-ice expansion between 2000 and 2014 driven by tropical Pacific decadal climate variability, Nature Geoscience, DOI: 10.1038/ngeo2751
Journal information: Nature Geoscience

Citation: Expanding Antarctic sea ice linked to natural variability (2016, July 4) retrieved 20 August 2019 from https://phys.org/news/2016-07-antarctic-sea-ice-linked-natural.html
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Jul 04, 2016
May be the world is not warming at all??

Jul 04, 2016
"Expanding Antarctic sea ice linked to natural variability"

Uh oh, trouble brewing in warming land? We need geek to fix this. Maybe he can string some long extension cords from his neighbor's house & get this ice formation process reversed?

Jul 04, 2016
In other words, they don't don't know.

Jul 04, 2016
In other words, they don't don't know.


........don't know what?

Jul 04, 2016
We can have any region locally depart from the planetary average for periods of time. By the data made available, The overall direction is still looking warmer, at this point.
(Altho, you couldn't tell by my location...)

Jul 04, 2016
Everything is ultimately a "natural climate fluctuation"

More globalist BS. If it does not fit the narrative, remove it from the data set

In trading I do not remove data because flux is part of the data

It would be nice if real scientists used real money, not ponzi counterfeit USA dollars, and did some real science. Instead there is a flood of similar studies with seemingly predetermined conclusions, chasing after Federals Reserve debt notes like mortgage lenders chasing homeowners before the big blow up

Similar studies "proved" that cigarettes were harmless and that marijuana made white women have sex with black men

Jul 04, 2016
So hypocritical that any kind of cooling trend can be explained by "natural variability" while any warming trend has to have have exaggerated headlines and screams with it.

Amazing that for once we agree on something. But I enjoy honesty it is much more fun! The crashing of dogma on the razor sharp rocks of facts is always great entertainment

Jul 05, 2016
global warming causes only weak Antarctic sea ice loss

LOL
Oh, the mysteries or is that magic, of man-made CO2. Tell us globull warming, why don't you like the Antarctic? Ah, but wait, now that the IPO has flipped, it won't be long before they start braying it's globull warming.

Jul 05, 2016
May be the world is not warming at all??

Evidence shows that earth is warming, your questioning shows your inability to prove that it does not.

Jul 05, 2016
global warming causes only weak Antarctic sea ice loss

LOL
Oh, the mysteries or is that magic, of man-made CO2. Tell us globull warming, why don't you like the Antarctic? Ah, but wait, now that the IPO has flipped, it won't be long before they start braying it's globull warming.


No it's the cold stark reality that your oil bosses and their conglomorates producing billions of tons of toxic gasses released into earth's atmosphere is destroying the earth, Long what ? It's been proven for more than a decade, but bonobo can't comprehend nor understand evidence yes... ;)

Jul 05, 2016
Everything is ultimately a "natural climate fluctuation"

More globalist BS. If it does not fit the narrative, remove it from the data set

In trading I do not remove data because flux is part of the data

It would be nice if real scientists used real money, not ponzi counterfeit USA dollars, and did some real science. Instead there is a flood of similar studies with seemingly predetermined conclusions, chasing after Federals Reserve debt notes like mortgage lenders chasing homeowners before the big blow up

Similar studies "proved" that cigarettes were harmless and that marijuana made white women have sex with black men


Clearly an antigorale sock that had to smoke some kind of weed to produce such a mindless answer... ;)

Jul 05, 2016
So hypocritical that any kind of cooling trend can be explained by "natural variability" while any warming trend has to have have exaggerated headlines and screams with it.



And rightfully so warming Backed by countless of evidence.

Jul 05, 2016
So hypocritical that any kind of cooling trend can be explained by "natural variability" while any warming trend has to have have exaggerated headlines and screams with it.
Errr, maybe you missed the fact that CO2 causes warming, not cooling. This is pretty duh. "CO2 can't cause cooling so teh sciensetis is teh wrnog!!!11!!one!" Typical denier logic.

Jul 05, 2016
Errr, maybe you missed the fact that CO2 causes warming, not cooling.

Interesting how the US actually cooled during the time it burned more fossil fuels than any other country.

http://www.giss.n...nsen_07/

Errr, you definitely missed the fact that you need a brain...

Jul 05, 2016
Interesting how the US
Interesting how you keep quoting US figures like it's the whole world.

Here is your New Clue™: It's not. Please be careful; your New Clue™ is sharp and you might cut yourself. Please consult a local fact dealer for instructions before attempting to use it.

Duhhh ummmm.

Jul 05, 2016
Errr, maybe you missed the fact that CO2 causes warming, not cooling.

Interesting how the US actually cooled during the time it burned more fossil fuels than any other country.

http://www.giss.n...nsen_07/

Errr, you definitely missed the fact that you need a brain...

Read the link all the way thru. Saw nothing stated about fossil fuel usage. Perhaps I missed that sentence...
As to cooling, neither the graph nor the paper said that. It did indicate lessened warming trend (than the rest of the globe)
Nonetheless, it was an interesting read, until stated at the end (disappointingly) - we don't know yet...
I did say earlier in the thread that regional variations can still be evident...

Jul 05, 2016
Interesting how you keep quoting US figures like it's the whole world.

LOL.
Uninteresting how you keep parroting that same catechism from the AGW Cult like you don't have a brain. You claim CO2 can only cause warming, yet (here's your hint) the US cooled while it emitted more CO2 than any other country.

Jul 05, 2016
Saw nothing stated about fossil fuel usage.

WG, nice try.
"top 10 nations as measured by their cumulative emissions between 1850 and 2007. The US tops the list by a wide margin
1. US: 339,174 MT or 28.8%
2. China: 105,915 MT or 9.0%
3. Russia: 94,679 MT or 8.0%
4. Germany: 81,194.5 MT or 6.9%
5. UK: 68,763 MT or 5.8%
6. Japan: 45,629 MT or 3.87%"
https://www.thegu...e-change

Jul 05, 2016
Uninteresting how you keep parroting that same catechism from the AGW Cult
Ummm, the US makes up 9,833,517 km² and the Earth's surface area is 510,072,000 km². This is simple physical fact.

Source: Wikipedia articles on the United States and Earth, duh. Can you find those?

The US is 9.9/500 of the Earth. That's about 1/50th.

Were you born an idiot or did you have to practice?

Jul 05, 2016
WG, nice try.
No, he hit it out of the park and as usual you're denying it. Your source didn't mention US fossil fuel usage; you had to bring another source.

You're lying again, @antigore.

Jul 05, 2016
Y'know, I don't think using the "contiguous US" as a reference point is valid. Why not use "contiguous North America", referring to the whole land mass, instead?
I think it would represent a more substantial data point.

Jul 05, 2016
Wouldn't help much.

North America's area is 24,709,000 km², and 25/500 is 1/25.

So the US is 2% of the area of the Earth, and North America is 4%. It's still peanuts.

Jul 05, 2016
Y'know, I don't think using the "contiguous US" as a reference point is valid. Why not use "contiguous North America", referring to the whole land mass, instead?
I think it would represent a more substantial data point.

The US has a more comprehensive temperature and emissions record. If you can find data for North America, send me the link.

Jul 05, 2016
No, he hit it out of the park and as usual you're denying it. Your source didn't mention US fossil fuel usage; you had to bring another source.

Wow! You are really that retarded, no wonder you can't even muster an original insult.
LOL.

Jul 05, 2016
2%.

'Nuff said.

Jul 06, 2016
It is natural when it expands and man-made when it contracts. OK, now I get it!
It is called "Hypothesis myopia"

Jul 06, 2016
It is natural when it expands and man-made when it contracts. OK, now I get it!
It is called "Hypothesis myopia"


Nope. One is the ability to read statistics and the other is...not having enough education to read statistics (at best...or just cherry picking at worst)
Article on PO today that shows you the difference:
http://phys.org/n...ers.html

Jul 06, 2016
This comment has been removed by a moderator.

Jul 06, 2016
2%.

'Nuff said.

What are you trying so hard to say?
If you had a brain, that's how much of it you would use.

Jul 06, 2016
Interesting how you keep quoting US figures like it's the whole world.

LOL.
Uninteresting how you keep parroting that same catechism from the AGW Cult like you don't have a brain. You claim CO2 can only cause warming, yet (here's your hint) the US cooled while it emitted more CO2 than any other country.


monkey's got 2 corn pits in his skull, i can here them pop into popcorn when he tries to think :D

Jul 06, 2016
Uninteresting how you keep parroting that same catechism from the AGW Cult
Ummm, the US makes up 9,833,517 km² and the Earth's surface area is 510,072,000 km². This is simple physical fact.

Source: Wikipedia articles on the United States and Earth, duh. Can you find those?

The US is 9.9/500 of the Earth. That's about 1/50th.

Were you born an idiot or did you have to practice?

He was born one, but practices to be the goty of all idiots, 10 years of posting with his socks 24/7 on physorg, rightfully made him succeed in it... :D :D

Jul 06, 2016
2%.

'Nuff said.

What are you trying so hard to say?
If you had a brain, that's how much of it you would use.

no he's got a big brain, the steamy overthinked head of yours is starting to pop the 2 little corns into popcorn, i can can hear them, if you listen, you could too... pop.......pop..pop... :D

Jul 09, 2016
LOL...keep at it. Maybe one day you will understand

Jul 09, 2016
Funny how stuff that contradicts Global Warming are just 'natural' variations while any bad weather (too hot, too cold, too wet, too dry.... it doesn't matter) 'proves' Global Warming.

Jul 10, 2016
LOL...keep at it. Maybe one day you will understand

thanks my monkey goracle sock, i know you only trying to comment at the top of your ability, now that it's all popcorn in that skull of yours, but me and my science friends are doing very well on this site contributing to scientific brilliance.... :D

Jul 11, 2016
2%.

'Nuff said

2% of the land mass, yet nearly 30% of the emissions of CO2. And no warming..
Hmmm...


Jul 13, 2016
2% of your 2 braincells currently functioning trying to understand science ?

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