From the University of New South Wales. The logic here seems a bit muddled. If this event where migration of westerly winds towards the south pole happened 15,000 years ago, what makes them think that it happening again now is due to global warming?
Global warming endangers South American water supply
Tuesday, July 29: Chile and Argentina may face critical water storage issues due to rain-bearing westerly winds over South America’s Patagonian Ice-Field to moving south as a result of global warming.
A reconstruction of past changes in the North and Central Patagonian Ice-field, which plays a vital role in the hydrology of the region, has revealed the ice field had suddenly contracted around 15,000 years ago after a southerly migration of westerly winds.
This migration of westerly winds towards the south pole has been observed again in modern times and is expected to continue under a warming climate, likely leading to further ice declines in this area affecting seasonal water storage.
“We found that precipitation brought to this region by Southern Hemisphere westerlies played an important role in the glaciation of the North Patagonian Ice-Fields,” said Dr Chris Fogwill from the Climate Change Research Centre at the University of New South Wales.
“Our research has shown this ice-field significantly reduced in size when those winds moved southwards.”
The North Patagonian Ice-field is vital to maintain seasonal water storage capacity for Argentina and Chile.
“Worryingly, this study suggests the region may well be on a trajectory of irreversible change, which will have profound impacts on agriculture and the increasing dependency on hydroelectric power in Chile and Argentina,” Dr Fogwill said.
The team revealed the importance of the winds on the ice-sheets and consequent water supply by using rare isotopes to uncover changes in the ice-sheet thickness since the last major glaciation. This revealed the decline in the ice-sheet between 15,000 to 19,000 years ago.
Using a separate collection of ocean cores they were then able to determine that this decline coincided with the movement southwards of the westerlies.
The researchers found that a lack of precipitation caused by this movement, coupled with additional warming caused by rapid ice loss saw a sharp decline in glaciers with no seasonal recovery.
Interestingly, the southern part of the ice-field did not appear to be impacted by the movement of these winds. Instead it appeared that ocean currents and temperatures played a more important role in maintaining the ice in this section.
“The ice-field in the Northern and Central region of the Patagonian ice-field are highly sensitive to precipitation and need this to remain healthy,” said Dr Fogwill.
Paper: Rapid thinning of the late Pleistocene Patagonian Ice Sheet followed migration of the Southern Westerlies (DOI: 10.1038/srep02118)
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I guess they missed the fact is no longer warming and has been cooling since at least 2005. Of course, reality doesn’t help get a nice grant so let’s just throw in some maybes and pick up a check.
If conditions similar to today ended the last ice age, and caused a warm-up some 15,000 YA comparable to the one we are experiencing today, then what’s to say that that whatever happened at the beginning of the Younger Dryas Stadial 12,900 YA that triggered a sudden return to ice age conditions that lasted another 1,300 years can’t happen again too?
dbstealey says:
July 30, 2013 at 12:26 pm
Correct. Mk 41/B41 bomb (1961-76) was our most energetic, at max yield of 25 MT.
Also right that a zero altitude air burst is better known as a surface burst.
My fiance writes from Valparaiso:
Aqui hace frio las mañanas sobre todo son muy heladas.
Out of date already.
The jets in both hemispheres moved poleward up to around 2000 but the trend has reversed since then..
Margaret Hardman says:
July 30, 2013 at 9:40 am
Anthony, I don’t see the logic is faulty. An event caused by changing wind patterns 15,000 years ago could be repeated in the near future as wind patterns change as climate changes. No real logic failure there.
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Occam tells us that whatever caused the change in the past is the most likely answer today. And that it will be no more irreversible than it was 15,000 years ago. 15,000 years ago it was cavemen in SUV’s that caused the shift. same today.
Margaret Hardman says:
July 30, 2013 at 9:40 am
Anthony, I don’t see the logic is faulty. An event caused by changing wind patterns 15,000 years ago could be repeated in the near future as wind patterns change as climate changes. No real logic failure there.
The CAGW refuses to look at the palaeo climate record as a whole, which shouts loud and clear that the earths climate and biosphere have been in rude health for most of the Phanaerozoic (last 535 million year period after Cambrian explosion and existence of multicellular life) with CO2 levels higher – by up to 20x – than the present. That the idea of dangerous runaway warming with CO2 in the mere hundreds of ppm is impossible and nonsensical.
But no – instead they find a tiny sliver of palaeo history and play a conjuring trick with it. O look – 15000 years ago climate abruptly warmed, and winds moved south. Now winds are moving south again – ergo climate catastrophe on the way. What if winds move south for other reasons and even in cooling periods? As always a string of hidden assumptions, always fatal in climate research.
I wonder if this paper mentions the term “ice age” or “glaciation” anywhere. I wonder if the authors even know about ice ages. 15000 years ago the earth abruptly warmed with the glacial-interglacial transition starting the Holocene (a false start due to the Younger Dryas). Such glacial-interglacial transitions have happened on a regular basis for the last 3 million years. Is this news to you? I guess its easy to be sucked by peer pressure to thinking that only human input into the atmosphere can change climate, nothing else.
“…migration of westerly winds towards the south pole happened 15,000 years ago, what makes them think that it happening again now is due to global warming?”
Um, just a wild guess; Funding.
The study can be accessed here.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3698495/
Before I went hunting it up, I wondered what could trigger a shift of wind patterns. I’ve been reading about changes in the NH jet stream due to the decreasing temperature grtadient between the tropics and the Arctic and wondered if a similar effect might be occuring in the SH. The cause of the shift in SH westerlies is not discussed in the paper, but the analog that people have queried is there. Climate was warming then.