From Royal Holloway, University of London
New research published today (Friday 27th June 2014) in the journal Nature Scientific Reports has provided a major new theory on the cause of the ice age that covered large parts of the Northern Hemisphere 2.6 million years ago.
The study, co-authored by Dr Thomas Stevens, from the Department of Geography at Royal Holloway, University of London, found a previously unknown mechanism by which the joining of North and South America changed the salinity of the Pacific Ocean and caused major ice sheet growth across the Northern Hemisphere.
The change in salinity encouraged sea ice to form which in turn created a change in wind patterns, leading to intensified monsoons. These provided moisture that caused an increase in snowfall and the growth of major ice sheets, some of which reached 3km thick.
The team of researchers analysed deposits of wind-blown dust called red clay that accumulated between six million and two and a half million years ago in north central China, adjacent to the Tibetan plateau, and used them to reconstruct changing monsoon precipitation and temperature.
“Until now, the cause of the Quaternary ice age had been a hotly debated topic”, said Dr Stevens. “Our findings suggest a significant link between ice sheet growth, the monsoon and the closing of the Panama Seaway, as North and South America drifted closer together. This provides us with a major new theory on the origins of the ice age, and ultimately our current climate system.”
Surprisingly, the researchers found there was a strengthening of the monsoon during global cooling, instead of the intense rainfall normally associated with warmer climates.
Dr Stevens added: “This led us to discover a previously unknown interaction between plate tectonic movements in the Americas and dramatic changes in global temperature. The intensified monsoons created a positive feedback cycle, promoting more global cooling, more sea ice and even stronger precipitation, culminating in the spread of huge glaciers across the Northern Hemisphere.”
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New theory, eh? Why is that I have known about this theory long before this paper was published?
It has long been known that the onset of the Pleistocene glaciations was associated with the formation of the Isthmus of Panama, but rearrangement of ocean currents was thought the main culprit behind ice sheet formation.
A link to the full article (not paywalled!).
http://www.nature.com/srep/2014/140627/srep05474/full/srep05474.html
I think I will dig up well known but rarely discussed climate theories and sell them off to universities to recycle. I get paid for them, and the universities and/or scientific organizations get the grants from the government. Everyone is satisfied and rich. Is this the American way, now?
Since North and South America are still joined (Panama canal could have little effect) why aren’t we still in an ice age if this was the cause for the one 2.6 million years ago?
Myron Mesecke says:
June 27, 2014 at 9:48 am
… why aren’t we still in an ice age if this was the cause for the one 2.6 million years ago?
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We are still in an ice age.
See! See! The activities of man are causing global warming. We dug the Panama Canal and the planet started to heat up. The only solution to this is to raise taxes, fill in the canal, end the commerce of all products transported by ship, and raise taxes. The prices for food and consumer products will necessarily skyrocket because of this, but it will be compensated for by raising taxes.
It’s always a surprise isn’t it.
The positive feedback loop has been found! Unfortunately it does not portend more warming.
The Panama Canal uses an internal lake and waterway system for the route between the two oceans. The Pacific and Atlantic are not really joined by the canal. A large portion of the Isthmus would have to be completely removed, and the water would probably have to be at least at a 200 metre depth to have a positive effect of stopping this present Ice Age. There is a mountain range on the Isthmus, so it is not a practical engineering feat even with our current resources, knowledge and energy. However, if such a feat was ever achieved, it would probably initially affect the ocean currents and send the planet into another glaciation period for thousands and thousands of years until equilibrium was established again. It would eventually end this Ice Age, but the SA plate is still pushing northward so the Isthmus would form again.
My first visceral reaction was, “Dept. of Geography…” [red alert! it is either nonsense or very old news]
Yep. Closing of the Isthmus is very old news.
Now the idea the increased monsoons can change the surface salinity of the surface waters of Northern Pacific is an interesting idea in that it at once makes the ocean surface easier to freeze and the increased moisture increases snow accumulation rates.
HOW monsoons can do this to the North Pacific, the critical hypothesis, doesn’t get the focus it needs.
Wrong. It still is. Dr. Stevens hasn’t changed it much.
Surprisingly….good grief
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Oh please, Dr. Stevens, it is hardly a discovery. It makes me wonder how scientists get their credentials these days being so absolutely clueless regarding previous scientific research and published papers.
Well, you have to cut these guys some slack. There are always new papers out on old subjects, some of which (may) represent a valuable contribution. (After all, they re still paying for papers that show that men are not — or are — exactly the same as women.)
“It makes me wonder how scientists get their credentials these days being so absolutely clueless regarding previous scientific research and published papers.”
I’d say “out of a Cracker Jack box,” but I don’t want to insult caramel popcorn.
I agree with Meseke above. Conditions have not changed, the isthmus is still there, so why no glaciation? The answer to the puzzle lies elsewhere. The most important fact is the sudden onset of warming. Any theory that does not explain this plausiblly does not work. And please, do not shift the ocean currents around like pieces on a chessboard.
Speaking of changing ocean current…
Is there today any appreciable ocean current heat transport through the Bering Straits? If there is, then because of the broad area and shallow depth, a small change in sea level radially alters the heat flow. I think the situation has some strong elements of positive feedback, at least until the Arctic Ice Cap is attenuated.
Beware of assumptions in models: from: On the Flow Through Bering Strait: A 1 Synthesis of Model Results and Observations by Kinney and Maslowski, et. al. (post 2008)
Square peg, round hole, meet hammer.
Figure 10b has some data on measured Heat Flux based on ?one? bouy from 1979 to 2004. on the order of 4*10*20 J/yr (or 0.4 ZJ/yr)
“The Panama Canal uses an internal lake and waterway system for the route between the two oceans. The Pacific and Atlantic are not really joined by the canal. A large portion of the Isthmus would have to be completely removed, and the water would probably have to be at least at a 200 metre depth to have a positive effect of stopping this present Ice Age. There is a mountain range on the Isthmus, so it is not a practical engineering feat even with our current resources, knowledge and energy. ”
I’m not suggesting we do anything like this, understand, but I’m not convinced that obliterating the isthmus of panama is beyond our present technological capabilities. Take one — or several — moderate sized asteroids, deflect their orbits so they are aimed at Panama cutting across the isthmus, and wait for them to hit. Repeat as necessary. I think that would do it, and at surprisingly little cost — if no one worries about compensating present-day Panamanians for losing their country…
How easy it is for some to forget this salient fact. We should be grateful for every little bit of warming, we can muster. GK
The kids used to make me feel the same way as the Pro AGW proponents do .I just want to give up and shut my mouth, because no amount of arguing or reason will convince them that that triple dip cone from Dairy Queen will have a effect on their supper . Some times it sure feels that the battle will be lost no matter what .
Now how do we say that rising CO2 is causing plate tectonic movement???
Ice Ages, sometimes referred to as Ice Epochs, are time periods, millions of years long, that have ice caps on polar landmasses (see Antarctica and Greenland). They are marked by long periods (100,000 yrs) of extensive ice and glaciers advancing well beyond the arctic circle, also frequently referred to as “ice ages,” interspersed with brief (12,000 yrs) warm periods, called interglacials, when the ice retreats toward the poles. We are currently in an interglacial.
Just because NYC isn’t being threatened by glaciers doesn’t mean the Ice Age is over. There’s still _plenty_ of ice. As we’re 11,500 years into the interglacial, warming is not my biggest worry.
JimS is right. From wikipedia:
“The closing of the Isthmus of Panama about 3 million years ago may have ushered in the present period of strong glaciation over North America by ending the exchange of water between the tropical Atlantic and Pacific Oceans.[48]
Reference [48] dates from 1996 (secondary source, don’t bother).
Notice again the myopic focus on the atmosphere – monsoons etc., and fear of mentioning ocean currents. Mentioning the ocean to in-vogue climate scientists seems to be like mentioning the war to Germans – the result is stony silence.
Guys – there’s an ocean out there that determines our climate. Come on in – don’t be scared of the water!
“Strengthening of monsoons during global cooling” – that’s curious, normally folks consider coolness to equal dryness.
@JimS says:
June 27, 2014 at 10:08 am
@D. Cohen says:
June 27, 2014 at 10:50 am
Google “Operation Plowshare” and “Pan Atomic Canal”. There is no doubt in my mind that a sea-level canal is technically feasible. Politically feasible is an entirely different kettle of fish.