From the NATIONAL CENTER FOR ATMOSPHERIC RESEARCH/UNIVERSITY CORPORATION FOR ATMOSPHERIC RESEARCH
BOULDER — 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 sea surface temperatures 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 sea ice formation 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 sea ice extent 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 global warming,” 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 surface temperatures 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 sea ice extent should slow and perhaps start to show signs of retreat when averaged over the next 10 years or so,” Meehl said.
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If they stopped looking at their models that might see something I’ve pointed out before. The Antarctic sea ice has been going up in 5 year “hops”. This year, was the end of a five year “cycle” where it is at a low in the cycle so I expect it to rise back up again”
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.antarctic.png
“I expect it to rise back up again” – Why, because it did before?
“Expanding Antarctic sea ice linked to natural variability”
“Shrinking Antarctic sea ice linked to anthroponegic global warming” <– SARC TAG MISSING HERE
The models (in average) do not agree with observations on the Antarctic temperature change.
CMIP 5 rcp8.5 model mean for Antarctic land:
http://climexp.knmi.nl/data/icmip5_tas_Amon_modmean_rcp85_0-360E_-90–60N_n_5lan_+++_1970:2017_mean1_anom_19812010a.png
The temperature increase is similar to the global average
Berkeley Earth Antarctic land temps:
http://climexp.knmi.nl/data/iberkeley_tavg_0-360E_-90–60N_n_5lan_1970:2017_mean1_anom.png
Temperatures are almost flat, much lower than the global average
Models and observations also disagree on global stratospheric cooling, ie real world cools faster than models.
My layman explanation: During the Winters, the cooling stratosphere goes all the way down to the high grounds of interior Antarctica. Cool dry catabatic winds blow out over the surrounding seas and expand the sea ice..
Science at it’s best! To make a long story short, most likely, (to use a warmist term), the models are at odds with reality!
Fool me once …
Fool me twice …
Jeeze, these pore folks are up to 1026 and not looking back. Ha ha
Anything that disagrees with the climate models is natural variation.
Anything that agrees with the climate models is proof that the climate models are correct.
I am really tired of the endless guessing about why Antarctica is freezing while the Arctic is melting until some brilliant soul opines that it is just natural and writes a trivial article about it. The only explanation for this stupidity is the prevalence of non-readers among people viewing the poles. Had they not been too lazy to read my book “What Warming?” or my article in Energy and Environment. volume 22, issue 8. they would know that this is a consequence of the large-scale re-arrangement of the the North Atlantic current system at the turn of the twentieth century. For 2000 years prior to this nothing happened except for a slow cooling of the Arctic. But just at the turn of the century the temperature suddenly turned up and drew a beautiful hockey stick on our graphs. This did not last either and by mid-twentieth century temperature again plummeted to previous levels. This cool period lasted for 30 years until warming again started up in 1970. Warming since then has reduced Arctic sea ice year by year. The ironic part is that all measurements of Arctic sea ice begin in the seventies or later and they have no idea of what went on before. It is certain that none of this warming is greenhouse warming because it is impossible to turn greenhouse warming off without plucking out all carbon dioxide molecules from the air. It is also impossible to turn it on as happened at the start of the century without adding more carbon dioxide to the atmosphere. The Keeling curve and its extensions are relevant here. This leaves just one explanation for the sudden changes that started with the twentieth century: a rearrangement of the North Atlantic current system in such a way that it began to direct warm water of the Gulf Stream into the Arctic. From that follows the steady reduction pf the ice cap, an ice free Russian Arctic in the summer, and opening of the Northwest Passage. And last but not least, total reduction of the summer ice cap by an estimated one third from what its potential size could be. The most significant of these Arctic happenings for climate science is that clearly the greenhouse effect has played no part bin any of the changes that have taken place in the Arctic since the start of the twentieth century.
A BOLDER STORYLINE (that you’ll never see) — The recent trend of increasing global temperatures — seemingly at odds with doomsday predictions of an oncoming Ice Age — can largely be explained by a natural climate fluctuation, according to… blah, blah, blah.
Try that one on a CAGW fanatic, and watch their head explode.
“The team discovered 10 simulations that met the criteria, and all of them showed an increase in Antarctic sea ice extent across all seasons.”
10 out of 262. That means 252 of 262 projections did not accurately represent Antarctic sea ice. Therefore, 96.2% of the simulations were wrong.
But at least that’s better than Meehl et al. 2014 results where 256 out of 262 simulations did not match real world temperatures if continued through 2015: https://e-nautia.com/clubargon/disk/Partage/Hiatus/Nature%20Climate%20change%20sept%202014.pdf
It’s amazing that these same people keep publishing papers that say more than 96% of their model projections are wrong; but if you look hard enough you can find a few that aren’t wrong, in a way, sometimes, maybe.
Even more amazing is their position that averaging those wrong projections will give you a correct one.
“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.”
That paragraph alone invalidates their study. Sea ice has been increasing since record keeping began in 1979. If the positive and negative phases of the IPO cancel out, we are still left with sea ice “slowly increasing” for almost 40 years, contrary to global warming theory.
Other than global warming what has mankind discovered with computer models?
The GIGO principle.
Interesting question. I, too, would like to see any model that has discovered anything. As far as using computer models to correctly predict events, past performance does not guarantee future results, to wit:
“Bad news Barack: Electoral College computer model that’s correctly predicted presidential elections since 1980 shows big WIN for Romney”
http://www.dailymail.co.uk/news/article-2192464/Bad-news-Obama-Electoral-College-model-correctly-predicted-presidential-elections-1980-opts-ROMNEY.html#ixzz4DZ1ueoS1
So, following exactly the scientific logic of this study, I plan to purchase 262 chimpanzees and 262 typewriters. I will put them to work for a while, and see if their results includes a line from Shakespeare’s Hamlet.
It will be worth the wear and tear on the typewriters, because if there is a concordance it will prove, inter alia, that:
1. All chimpanzees’ literary efforts are meaningful. (Considerable confidence).
2. Shakespeare was a chimpanzee. (Less confidence)
3. The skull may not have been Yorick’s (No confidence at all)
4. RGB@duke could probably prove more from it than I can
Must get busy with that grant submission for the DOE right away.
Natural variation v human emissions (in alarmists’ terms):
http://www.climate4you.com/images/NSIDC%20NHandSHandTOTALiceExtension12monthRunningAverage.gif
Globally, for the time being at least, it looks like natural variation is making a comeback.
Those are great graphs and I notice the left and right axes have the same scale – apples to apples. Thank you.
Computers are wonderful tools. They can do complex math a lot, magnitudes, faster than a person can do.
But they are dumb. They can’t think. They have no “memory” of reality. They have no conception of “reality”. All they can do is produce a number or a display (a graph?) based on their programming and numbers punched into the program.
Wonderful TOOLS.
There’s a saying, “The right tool for the right job.”
The climate models have proven they are not the right tool for the job. The don’t match the real world. (A few might come close, here and there.)
Why? Wrong program? Wrong or incomplete numbers?
I don’t know.
But many prefer their output to reality for political or personal reasons in the present.
My concern is the natural variability in logic, reason, motive, and understanding among humans.
Do they ever proof read what they write, and if not where are the peer reviewers?
“climate change is causing the world to warm”. So the cause is climate change, not CO2? But is climate change a cause, or a result?
Everything bad is anthropogenic.
Everything good is natural variability.