New research shows projected changes in the winds circling the Antarctic may accelerate global sea level rise significantly more than previously estimated.
Changes to Antarctic winds have already been linked to southern Australia’s drying climate but now it appears they may also have a profound impact on warming ocean temperatures under the ice shelves along the coastline of West and East Antarctic.
“When we included projected Antarctic wind shifts in a detailed global ocean model, we found water up to 4°C warmer than current temperatures rose up to meet the base of the Antarctic ice shelves,” said lead author Dr Paul Spence from the ARC Centre of Excellence for Climate System Science (ARCCSS).
“The sub-surface warming revealed in this research is on average twice as large as previously estimated with almost all of coastal Antarctica affected. This relatively warm water provides a huge reservoir of melt potential right near the grounding lines of ice shelves around Antarctica. It could lead to a massive increase in the rate of ice sheet melt, with direct consequences for global sea level rise.”
Prior to this research by Dr Spence and colleagues from Australian National University and the University of New South Wales, most sea level rise studies focused on the rate of ice shelf melting due to the general warming of the ocean over large areas.
Using super computers at Australia’s National Computational Infrastructure (NCI) Facility the researchers were able to examine the impacts of changing winds on currents down to 700m around the coastline in greater detail than ever before.
Previous global models did not adequately capture these currents and the structure of water temperatures at these depths. Unexpectedly, this more detailed approach suggests changes in Antarctic coastal winds due to climate change and their impact on coastal currents could be even more important on melting of the ice shelves than the broader warming of the ocean.
“When we first saw the results it was quite a shock. It was one of the few cases where I hoped the science was wrong,” Dr Spence said.
“But the processes at play are quite simple, and well-resolved by the ocean model, so this has important implications for climate and sea-level projections. What is particularly concerning is how easy it is for climate change to increase the water temperatures beside Antarctic ice sheets.”
The research may help to explain a number of sudden and unexplained increases in global sea levels that occurred in the geological past.
“It is very plausible that the mechanism revealed by this research will push parts of the West Antarctic Ice Sheet beyond a point of no return,” said Dr Axel Timmerman, Prof of Oceanography at University of Hawaii and an IPCC lead author who has seen the paper.
“This work suggests the Antarctic ice sheets may be less stable to future climate change than previously assumed.”
Recent estimates suggest the West Antarctic Ice Sheet alone could contribute 3.3 metres to long-term global sea level rise.
With both West and East Antarctica affected by the change in currents, in the future abrupt rises in sea level become more likely.
According to another of the paper’s authors, Dr Nicolas Jourdain from ARCCSS, the mechanism that leads to rapid melting may be having an impact on the Western Antarctic right now. Dr Jourdain said it may help explain why the melt rate of some of the glaciers in that region are accelerating more than scientists expected.
“Our research indicates that as global warming continues, parts of East Antarctica will also be affected by these wind-induced changes in ocean currents and temperatures,” Dr Jourdain said.
“Dramatic rises in sea level are almost inevitable if we continue to emit greenhouse gases at the current rate.”
Abstract
The southern hemisphere westerly winds have been strengthening and shifting poleward since the 1950s. This wind trend is projected to persist under continued anthropogenic forcing, but the impact of the changing winds on Antarctic coastal heat distribution remains poorly understood. Here we show that a poleward wind shift at the latitudes of the Antarctic Peninsula can produce an intense warming of subsurface coastal waters that exceeds 2 °C at 200-700 m depth. The model simulated warming results from a rapid advective heat flux induced by weakened near-shore Ekman pumping, and is associated with weakened coastal currents. This analysis shows that anthropogenically induced wind changes can dramatically increase the temperature of ocean water at ice sheet grounding lines and at the base of floating ice shelves around Antarctica, with potentially significant ramifications for global sea level rise.
It is absolutely amazing what a difference having that ‘r’ at the end of one’s name makes! (Spence Spencer) Must be that ‘r’ that allows Dr. Spencer to achieve and demonstrate his genius as a true scientist versus the modeled wannabe ‘Spence the alarmist’ who claims that his supercomputer program does exactly what his programmers wanted.
:>
or is that
Got many more online IDs?
Computer models and super computers do exactly what they’re told to do; not one bit more and not one bit less.
Models, super duper computers and alarmist teachers can not make all the broken models in the world real nor factual.
Models and super duper pooper computers all follow the programming maxim that “garbage in means garbage output”. We’ll give you a couple guesses where those models and lumps of microelectronics get all their garbage to ingest… S P E N C E
(remember, no ‘r’)
Meanwhile those other well constructed lumps of orbiting microelectronics, called satellites, have kept Antarctica under observation and yes, they can confirm that it is quite cold in Antarctica and the ice is still growing.
Perhaps there is a ship planning on visiting Antarctica later this year and you could try for a berth? Make sure you bring plenty of bananas and peanut butter…
“””””……JimS says:
July 8, 2014 at 8:55 am
“When we first saw the results it was quite a shock. It was one of the few cases where I hoped the science was wrong,” Dr Spence said…….””””””
So how many times have I asserted, that the only thing that statistics is good for, is to predict how “shocked” you will be when you see the real results.
So Dr Spence, for once you pegged it on the money; the “science” IS wrong.
“Changes to Antarctic winds have already been linked to southern Australia’s drying climate…”
The claim is sciency-sounding but safely blurry. There’s a reason: most of Australia experienced a half century of drying climate from the mid-1890s to post WW2. The whole continent since 1950 is a wetter place overall, except for the south-west tip of WA. It’s true that the north is much wetter since the 1970s but that rain was not subtracted from the south.
You can always find a drought over a large area of Oz at any given time (except maybe the mid-1970s) so maybe our experts are just taking pot luck with their comment. Since the latest bad drought has been in the north east of the continent their clever little throw away line might look weak when examined…But we were supposed to examine it, were we?
A half century of rainfall deficit in Australia is a lot to ignore, but many people termed climate scientists manage to do just that. They love the long term deficit but hate the dates on it.
Imagine what fantasy Dr Spence conjure up with the second most powerful computer in the Universe; Deep Thought
..could conjure…
“The southern hemisphere westerly winds have been strengthening and shifting poleward since the 1950s. This wind trend is projected to persist under continued anthropogenic forcing, but the impact of the changing winds on Antarctic coastal heat distribution remains poorly understood. Here we show that a poleward wind shift at the latitudes of the Antarctic Peninsula can produce an intense warming of subsurface coastal waters that exceeds 2 °C at 200-700 m depth.”
The winds exist now according to the paper,
So measure the sea temp at 200-700m depth. Can you find the “intense warming of substrate coastal waters that exceeds 2°C” that your theory predicted?
If so, publish your theory. If not, quietly re-think.
Publishing a paper on modelling that seems to have a clear prediction that is measurable and not providing any experimental measurements certainly is not science. DO SOME MEASUREMENTS. DO SOME SCIENCE
I read this the other day on the Sydney Morning Herald (SMH) website, linked to by a Peter Hannam, a notorious alarmist. I read the article up to the word model and then ignored it. Another day, another alarmist article at the SMH.
Oh golly gosh! It can’t be that wicked Co2 sneaking in under the Thwaites Glacier and melting it faster, can it?
And all along I thought it was nasty old volcano or four.
They haven’t shown anything, it’s simply model output, just like the IPCC’s diverging projections with observation. Garbage in, garbage out. Here are what some other models show. More garbage.
If you haven’t had enough of the garbage then you can find more garbage HERE.