Friday, April 4, 2014

No Warming Pause? Heat Buried in Pacific




I am skeptical that this hypothesis will actually hold up at all but it is making an important claim. It is that we will have a sharp heat rebound when the trade winds do weaken.  This heat rebound is supposed to reignite the rising curve and generally fully recover all the apparent heat lost top date from their models.

Of course we will see, but this is going to have to be tested over the next ten years cat least.

In the meantime we are been reintroduced to the polar vortex so prevalent when I was young.  That also might continue on for a good decade as well.  I think that I will stay in Vancouver. 


There’s no “warming pause” — trade winds are burying heat in the Pacific



Global average land temperatures have not increased as quickly as many scientists had expected over the past 10 or 15 years, leading some climate skeptics to latch onto the bogus idea of a “global warming pause.” Last year researchers reported that much of the “missing heat” was not in fact missing but rather was being sucked upby the oceans.


Now new research helps explain why excess heat is being absorbed into the sea: big-ass winds.

paper published in the journal Nature Climate Change suggests that the slowdown in surface warming and the acceleration in ocean warming has been largely driven by a phase in a natural ocean cycle called the Interdecadal Pacific Oscillation (IPO). That’s a frightfully cumbersome name, but it’s easy to break down: It’s a swing (“oscillation”) in Pacific Ocean weather that takes decades (“interdecadal”) to shift from one phase to another. Instead of switching every few years, like El Niño and La Niña, an IPO can last 20 to 30 years before flipping from one extreme to the other.


“Global warming hasn’t stalled at all,” Matthew England, a professor at the University of New South Wales in Australia and lead author of the paper, told Grist. “There’s just more heat going into the oceans at the moment.”

Since the turn of the century, the IPO has been in a negative phase, which is marked by strong trade winds in the Pacific. Researchers used models to simulate the effects of these winds on ocean currents and discovered that the strong winds increase the amount of warm water that sinks below the surface, while increasing the amount of cold water that burbles up from ocean depths near the equator.


And that has helped bury extra heat at sea — for now.
From the paper:
Here we show that a pronounced strengthening in Pacific trade winds over the past two decades … is sufficient to account for the cooling of the tropical Pacific and a substantial slowdown in surface warming through increased subsurface ocean heat uptake. …

The net effect of these anomalous winds is a cooling in the 2012 global average surface air temperature of 0.1–0.2◦C, which can account for much of the hiatus in surface warming observed since 2001. This hiatus could persist for much of the present decade if the trade wind trends continue, however rapid warming is expected to resume once the anomalous wind trends abate.

This isn’t the first time in recent history that the oceans have absorbed more than their normal share of extra heat. The paper describes a similar surface-warming hiatus that occurred from the 1940s to the 1970s — the last time the IPO was in this pronounced negative phase.

When the cycle inevitably reverses, the scientists warn that some of the extra heat that’s currently swimming with the fishes will rise up out of the ocean and come back to haunt us landlubbers.

“The IPO oscillates roughly every 20 to 25 years, but the timing is quite unpredictable. What we do know is that when we switch back to a positive IPO phase, the trade winds will be much weaker,” England said. “Longer term, regardless of when the winds relax, this temporary slowdown in surface warming will be overwhelmed by greenhouse gas increases.”


Study links stronger Pacific trade winds to pause in global warming
February 10, 2014

Despite an overwhelming consensus among climate scientists that warming trends over the past century are most likely the result of human activities, some claim that a plateau in global surface air temperatures since 2001 is evidence to the contrary. However, a new study suggests the recent stabilization of air temperatures is a result of abnormally strong east to west trade winds, causing warmth to be stored temporarily beneath the western Pacific ocean.

The joint research, published in the journal Nature Climate Change and conducted by Australian and US researchers, outlines an unprecedented intensification of trade winds, easterly surface winds swirling about near the Earth's equator, which has accelerated the circulation of the Pacific ocean.

This causes heat to be drawn from the atmosphere into the waters below the ocean's surface and the colder water to rise to the top, ultimately leading to cooler average global temperatures.

“Scientists have long suspected that extra ocean heat uptake has slowed the rise of global average temperatures, but the mechanism behind the hiatus remained unclear," said the study's lead author, Professor Matthew England of the University of New South Wales in Sydney, Australia.

According to the researchers, the strengthening of the Pacific trade winds actually dates back to the 1990s. Climate models used previously had not been able to account for the stalling of global surface temperature, as they didn't incorporate the strengthening of these winds.

When England and his fellow researchers added data from the heightened winds to their modeling, they found it accounted for a cooling of 0.1 to 0.2° C (32.18 to 32.36° F) in the 2012 global average surface air temperature, very closely mirroring the offset currently being observed.

"The winds lead to extra ocean heat uptake, which stalled warming of the atmosphere," said Professor England. "Accounting for this wind intensification in model projections produces a hiatus in global warming that is in striking agreement with observations."

While the stronger winds offer respite from an overall warming trend, Professor England warns that in the grand scheme of things, the pause will be short lived and to little effect.

"This pumping of heat into the ocean is not very deep, however, and once the winds abate, heat is returned rapidly to the atmosphere," he said. "When the trade wind strength returns to normal – as it inevitably will – our research suggests heat will quickly accumulate in the atmosphere. So global temperatures look set to rise rapidly out of the hiatus, returning to the levels projected within as little as a decade."

    
About the Author
Nick was born outside of Melbourne, Australia, with a general curiosity that has drawn him to some distant (and very cold) places. Somewhere between enduring a winter in the Canadian Rockies and trekking through Chilean Patagonia, he graduated from university and pursued a career in journalism. He now writes for Gizmag, excited by tech and all forms of innovation, Melbourne's bizarre weather and curried egg sandwiches.   All articles by Nick Lavars


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