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Scientists puzzled by slowing of Atlantic conveyor belt, warn of abrupt climate change

27th May 2016 / Mike Gaworecki

Scientists are increasingly warning of the potential that a shutdown, or even significant slowdown, of the Atlantic conveyor belt could lead to abrupt climate change, a shift in Earth’s climate that can occur within as short a timeframe as a decade but persist for decades or centuries.

  • Limited ocean measurements have shown that “the Atlantic conveyor belt” is far more capricious than models have previously suggested.
  • From 2009 to 2010, the average strength of key ocean currents in the North Atlantic dropped by about 30 percent, causing warmer waters to remain in the tropics rather than being carried northward.
  • “The consequences included an unusually harsh European winter, a strong Atlantic Basin hurricane season, and — because a strong AMOC keeps water away from land — an extreme sea level rise of nearly 13 centimeters along the North American coast north of New York City,” according to Eric Hand, author of a Science article published this month.

Scientists in the Labrador Sea recently made the first retrieval of data from one of 53 lines moored to the sea floor and studded with instruments that have been monitoring the ocean’s circulatory system since 2014.

Held taut by submerged buoys, these moorings are arrayed from Labrador to Greenland and Scotland. In total, five research cruises are planned for this spring and summer to fetch the data the moorings are busy collecting.

The instrument array, known as the Overturning in the Subpolar North Atlantic Program (OSNAP), measures salinity, temperature, and current velocity of the surrounding water, data that is vital to understanding a set of powerful currents with far-reaching effects on the global climate. These currents are known as the Atlantic Meridional Overturning Circulation (AMOC) — or, more popularly, “the Atlantic conveyor belt” — and they have “mysteriously” slowed down over the past decade, according to Eric Hand, author of a Science article published this month.

Scientists are increasingly warning of the potential that a shutdown, or even significant slowdown, of the Atlantic conveyor belt could lead to abrupt climate change, a shift in Earth’s climate that can occur within as short a timeframe as a decade but persist for decades or centuries.

North Atlantic waters, such as the Greenland, Irminger, and Labrador Seas, are especially salty when compared with water in other parts of the world’s oceans. When AMOC currents, like the Gulf Stream, bring warmer waters from the south to the North Atlantic, the water cools down, releases its heat to the atmosphere, becomes colder, and sinks, since saltier water is denser than fresher water and cold water is denser than warm water.

In a process called “thermohaline circulation” (“thermos” is the Greek word for heat, while “halos” is the word for salt), this cold, salty water then slowly flows back down into the South Atlantic and eventually makes its way throughout the world’s oceans. At the same time, warm, salty tropical surface waters are drawn northward, where they replace the sinking cold water.

1024px-Thermohaline_Circulation_2
This map shows the pattern of thermohaline circulation also known as “meridional overturning circulation”. This collection of currents is responsible for the large-scale exchange of water masses in the ocean, including providing oxygen to the deep ocean. The entire circulation pattern takes ~2000 years. Image via Wikimedia Commons.

In other words, the dynamic at play in the North Atlantic seas are an important driver of the ocean’s circulation system, which is why the region was selected for the OSNAP instrument array. Two other arrays that have been deployed in different waters have already produced some strange results that scientists are eager to learn more about.

“Models suggest that climate change should weaken the AMOC as warmer Arctic temperatures, combined with buoyant freshwater from Greenland’s melting ice cap, impede the formation of deep currents,” Hand wrote in the Science article. “But so far, limited ocean measurements show the AMOC to be far more capricious than the models have been able to capture.”

An array deployed in 2004 between Florida and the Canary Islands, for instance, showed “unexpectedly wild swings” in the strength of the AMOC currents from month to month, Hand reported. From 2009 to 2010, the average strength of the AMOC dropped by about 30 percent, causing warmer waters to remain in the tropics rather than being carried northward.

“The consequences included an unusually harsh European winter, a strong Atlantic Basin hurricane season, and — because a strong AMOC keeps water away from land — an extreme sea level rise of nearly 13 centimeters along the North American coast north of New York City,” Hand said.

Over its first decade of operation, the Florida-to-Canary Islands subtropical array recorded a 25 percent decline in the AMOC’s average strength, which is an order of magnitude more than models suggested could occur due to the effects of climate change.

Meric Srokosz, an oceanographer at the UK’s University of Southampton and the science coordinator for the U.K.-funded portion of the array, told Hand that scientists suspect some natural variation is to blame in the dropoff of the AMOC’s strength, including the 60- to 70-year cycle of varying sea temperatures called the Atlantic Multidecadal Oscillation. Initial analysis of the latest, unpublished data from the array shows the AMOC’s average strength has leveled out, but is still well below where it started in 2004.

“It will take another decade of measurements to separate the climate change effect from natural variability,” Hand wrote.

Threat of abrupt climate change

Models have suggested that there is a threshold below which the AMOC could suddenly shut down altogether — “the doomsday scenario of a frozen Europe exploited in the 2004 disaster movie The Day After Tomorrow,” as Hand put it. “Many climate models suggest that the AMOC should be stable over the long term in a warming world, but plenty of evidence from the recent geological past confirms that the conveyor belt can slow down significantly.”

Full article at :Mongabay

 

 

 

 

 

 

Study suggests the impact of global warming will be quicker and more catastrophic than envisioned, writes Chris Mooney.

If the scientists' study is right, sights like that in Lake Argentina, where chunks of ice broke off the Perito Moreno Glacier this month, could become more common. Photo / AP

Climate scientists’ global warning

By Chris Mooney

Study suggests the impact of global warming will be quicker and more catastrophic than envisioned, writes Chris Mooney.
If the scientists' study is right, sights like that in Lake Argentina, where chunks of ice broke off the Perito Moreno Glacier this month, could become more common. Photo / AP
If the scientists’ study is right, sights like that in Lake Argentina, where chunks of ice broke off the Perito Moreno Glacier this month, could become more common. Photo / AP

An influential group of scientists led by James Hansen, the former Nasa scientist often credited with having drawn the first major attention to climate change in 1988 congressional testimony, has published a dire climate study that suggests the impact of global warming will be quicker and more catastrophic than generally envisioned.

The research invokes collapsing ice sheets, violent megastorms and even the hurling of boulders by giant waves in its quest to suggest that even 2C of global warming above pre-industrial levels would be far too much. Hansen has called it the most important work he has ever done.

The sweeping paper, 52 pages in length and with 19 authors, draws on evidence from ancient climate change or “paleo-climatology”, as well as climate experiments using computer models and some modern observations. Calling it a “paper” really isn’t quite right – it’s actually a synthesis of a wide range of old and new evidence.

“I think almost everybody who’s really familiar with both paleo and modern is now very concerned that we are approaching, if we have not passed, the points at which we have locked in really big changes for young people and future generations,” Hansen said.

The research, appearing on Wednesday in the open-access journal Atmospheric Chemistry and Physics, has had a long and controversial path to life, having first appeared as a “discussion paper” in the same journal, subject to live, online peer review – a novel but increasingly influential form of scientific publishing. Hansen first told the press about the research last year, before this process was completed, leading to criticism from some journalists and also fellow scientists that he might be jumping the gun.

What ensued was a high-profile debate, both because of the dramatic claims and Hansen’s formidable reputation. And his numerous co-authors, including Greenland and Antarctic ice experts and a leader of the United Nations’ Intergovernmental Panel on Climate Change, were nothing to be sniffed at.

After record downloads for the study and an intense public review process, a revised version of the paper has now been accepted, according to both Hansen and Barbara Ferreira, media and communications manager for the European Geophysical Union, which publishes Atmospheric Chemistry and Physics. Indeed, the article is now freely readable on the Atmospheric Chemistry and Physics website.

full story at nzherald.co.nz

 

 

 

 

 

 

 

Huge Fireball In The Sky Prompts Numerous Calls To Police

photo credit: The “fireball” seen from a car’s dashcam in Aberdeenshire. Perth Gazette/YouTube.

Loud booms and sights of a “fireball” were reported in Scotland last night, but fret not. This was likely just a meteor burning up in the atmosphere, and not the end of the world.

The bright streak was seen on Monday evening across Scotland, with most reports and footage coming from Aberdeenshire in the northeast. A spokesperson from Police Scotland told The Guardian that they began receiving calls at around 6.55 p.m. local time, adding that police departments in the south and as far north as Inverness also received calls.

“One told us the sky had been lit up with an object like a fireball. Another caller said there was a very loud bang and others said the house shook,” she said.

“We have checked and been told it was likely to be a meteor shower.”

You can see the fireball in the video below.

Fortunately, fears of a fiery Scottish apocalypse look like they might be unfounded. Experts have concurred that the strange occurrence was most likely to be a meteor.

Professor Sara Russell, Head of the Division of Mineral and Planetary Sciences at the Natural History Museum, explained in an emailed statement: “It’s entirely plausible that this may be a fireball caused by a fragment of an asteroid hitting the Earth’s atmosphere, similar to the event observed over Chelyabinsk, Russia in 2013.”

She added: “The rumbling noises heard indicate that the fireball was fairly local; if it was far away then no sounds would have been heard. The object may have burned up in the atmosphere, or may have resulted in the meteorite landing on the surface of the Earth, perhaps into the sea. By collating all the eye witness reports it will be possible to determine the direction of the fireball and constrain possible fall areas.”

Then again, other theories are out there. Jackie Hendry, local politician for the SNP,tweeted: “Did anyone else see that big white flash in the sky about 20 minutes ago? (Coming into Inverness on A96)…. I reckon it was Tim Peake.”

source IFLScience

 

 

 

 

 

 

 

 

January Smashed Another Global Temperature Record,By

The calendar may have turned to 2016, but temperatures are picking up where 2015 left off. January was record warm, according to data released this week by NASA.

You may recall that last year was the hottest on record for the globe. And by NASA’s accounting, it ended with a bang. This past December was the warmest December on record and the most abnormally warm month on record, too.

That is until now.

This January was the warmest January on record by a large margin while also claiming the title of most anomalously warm month in 135 years of record keeping. The month was 1.13°C — or just a smidge more than 2°F — above normal. That tops December’s record of being 1.11°C — or just a smidge below 2°F — above average.

It marks the fourth month in a row where the globe has been more than 1°C (1.8°F) above normal. Incidentally, those are the only four months where the globe has topped that mark since record keeping began.

RELATED Global Warming Key Driver of 2015’s Record Heat
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2015 Shatters Hottest Year Mark; 2016 Hot on its Heels?
Large swaths of the globe were painted red by warmth to the point where it’s easier to talk about where the heat wasn’t (that would be Antarctica, Scandinavia, East Africa and a few parts of Russia for the record). The telltale signal of El Niño’s heat in the Pacific continues to be notable, but it’s the Arctic that truly stands out as the most abnormally warm place on the planet.

According to NASA, temperatures in some parts of the Arctic averaged up to 23°F above normal for the month. No, that’s not missing a decimal point.

full story at ClimateCentral

 

 

 

 

 

 

 

 

NOAA’s View Of The East Coast Storm From Space

A nighttime portrait

Too much even for Siberia: Worst blizzard in 10yrs turns Omsk into huge snowball (PHOTOS)

@ tatiana_radchenko

The snow has gotten off to an incredible start in Siberia, where a record snowfall has paralyzed many areas of the city of Omsk, with thousands of drivers hopelessly stuck in hellish snowstorm traffic for hours.

You might say it’s nothing special for Siberia, but those who know – namely weather forecasters – believe it could be the most significant snowfall in 10 years.

read the whole article and see the photos at:RT

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