Daily Archives: April 15, 2018

World faces climate chaos over weak circulation of Atlantic Ocean


NEWS HEADLINES CN4
Published on Apr 12, 2018

There could be weather chaos across Europe, US and Africa as scientists warn circulation of the Atlantic Ocean is at its weakest point in more than 1,600 years.

Researchers have found a key cog in the global ocean circulation system has not been running at peak strength since the mid-1800s.

If the system continues to weaken, scientists say it could disrupt weather patterns across the world and cause more rapid increase in sea levels on the US East Coast.

When it comes to regulating global climate, the circulation of the Atlantic Ocean plays a key role.

The constantly moving system of deep-water circulation – sometimes referred to as the Global Ocean Conveyor Belt – sends warm, salty Gulf Stream water to the North Atlantic where it releases heat to the atmosphere and warms Western Europe.

The cooler water then sinks to great depths and travels all the way to Antarctica and eventually circulates back up to the Gulf Stream, according to the study published in the journal Nature.

However, new research suggests this system has been weakening for centuries.

‘Our study provides the first comprehensive analysis of ocean-based sediment records, demonstrating that this weakening of the Atlantic’s overturning began near the end of the Little Ice Age, a centuries-long cold period that lasted until about 1850’, said study co-author said Dr Delia Oppo, of Woods Hole Oceanographic Institution.

Experts believe that as the North Atlantic began to warm near the end of the Little Ice Age, freshwater disrupted the system.

Arctic sea ice, and ice sheets and glaciers surrounding the Arctic began to melt.

This formed a huge natural tap of fresh water that gushed into the North Atlantic.

Researchers say the huge influx of freshwater diluted the surface seawater, making it lighter and less able to sink deep, slowing down the AMOC system.

To investigate the Atlantic circulation in the past, scientists first examined the size of sediment grains deposited by the deep-sea currents; the larger the grains, the stronger the current.

Then, they used a variety of methods to reconstruct near-surface ocean temperatures in regions where temperature is influenced by AMOC strength.

‘Combined, these approaches suggest that the AMOC has weakened over the past 150 years by approximately 15 to 20 per cent’, said lead author Dr. David Thornalley, a senior lecturer at University College London.

Study co-author Dr Jon Robson, a senior research scientist at Reading University, says the new findings hint at a gap in current global climate models.

‘North Atlantic circulation is much more variable than previously thought’, he said.

‘And it’s important to figure out why the models underestimate the AMOC decreases we’ve observed.’

Dr Robson said it could be because the models don’t have active ice sheets, or maybe there was more Arctic melting, and thus more freshwater entering the system than currently estimated.

Another study in the same issue of Nature, led by scientists from the Potsdam Institute for Climate Impact Research, looked at climate model data and past sea-surface temperatures.

They found the AMOC has been weakening more rapidly since 1950 in response to recent global warming.

The AMOC weakening may already have an impact on weather in Europe.

‘Model simulations further suggest that an AMOC weakening could become the main cause of future west European summer atmospheric circulation changes, as well as potentially lead to increased storminess in Europe’, lead-author Levke Caesar from the Potsdam Institute for Climate Impact Research told MailOnline.

‘Additionally an AMOC weakening has also been connected to above-average sea-level rise at the U.S. east coast and increasing drought in the Sahel, the latter because the AMOC influences the position of the Intertropical Convergence Zone.

‘With respect to prevention, it would be prudent to rapidly reduce the emissions of carbon dioxide in order to avoid further destabilisation of the climate system’, Dr Caesar said.

Together, the two new studies provide complementary evidence that the present-day AMOC is exceptionally weak.

Dr Thornalley added: ‘What is common to the two periods of AMOC weakening – the end of the Little Ice Age and recent decades – is that they were both times of warming and melting.

‘Warming and melting are predicted to continue in the future due to continued carbon dioxide emissions.’

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How Climate Change Could Jam The World’s Ocean Circulation

Climate Change News
Published on Jul 17, 2017
How Climate Change Could Jam The World’s Ocean Circulation: climate change science, biology, experiment, environment, glacier, climate control, Temperature, Carbon dioxide, earth weather.
climate: https://youtu.be/wyIyTcG5LBg

How Climate Change Could Jam The World’s Ocean Circulation

Scientists are closely monitoring a key current in the North Atlantic to see if rising sea temperatures and increased freshwater from melting ice are altering the “ocean conveyor belt” — a vast oceanic stream that plays a major role in the global climate system.

Susan Lozier is having a busy year. From May to September, her oceanographic team is making five research cruises across the North Atlantic, hauling up dozens of moored instruments that track currents far beneath the surface. The data they retrieve will be the first complete set documenting how North Atlantic waters are shifting — and should help solve the mystery of whether there is a long-term slowdown in ocean circulation. “We have a lot of people very interested in the data,” says Lozier, a physical oceanographer at Duke University.

A similar string of moorings across the middle of the Atlantic, delving as deep as 3.7 miles from the Canary Islands to the Bahamas, has already detected a disturbing drop in this ocean’s massive circulation pattern. Since those moorings were installed in 2004, they have seen the Atlantic current wobble and weaken by as much as 30 percent, turning down the dial on a dramatic heat pump that transports warmth toward northern Europe. Turn that dial down too much and Europe will go into a deep chill.

Researchers have been worried about an Atlantic slowdown for years. The Atlantic serves as the engine for the planet’s conveyor belt of ocean currents: The massive amount of cooler water that sinks in the North Atlantic stirs up that entire ocean and drives currents in the Southern and Pacific oceans, too. “It is the key component” in global circulation, says Ellen Martin, a paleoclimate and ocean current researcher at the University of Florida. So when the Atlantic turns sluggish, it has worldwide impacts: The entire Northern Hemisphere cools, Indian and Asian monsoon areas dry up, North Atlantic storms get amplified, and less ocean mixing results in less plankton and other life in the sea.

A single Atlantic Ocean current system accounts for up to a quarter of the planet’s heat flux.

Paleoclimatologists have spotted times in the deep past when the current slowed quickly and dramatically, cooling Europe by 5 to 10 degrees C (10 to 20 degrees F) and causing far-reaching impacts on climate. Modelers have tried to predict how human-caused climate change might impact the Atlantic current, and how its slowdown might muck with the world’s weather even more. But years of intensive peering at this question haven’t yet provided much clarity.

Now, debate is raging about whether the recent Atlantic slowdown has been triggered by climate change, or is just part of a normal cycle of fast and slow currents. New studies in the last few years and months have come out supporting both prospects. The new data from the north, Lozier and others hope, might help to sort things out…

Stronger evidence for a weaker Atlantic overturning — PIK Research Portal

THC
04/11/2018. The Atlantic overturning – one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards – is weaker today than any time before in more than 1000 years. Sea surface temperature data analysis provides new evidence that this major ocean circulation has slowed down by roughly 15 percent since the middle of the 20th century, according to a study published in the highly renowned journal Nature by an international team of scientists. Human-made climate change is a prime suspect for these worrying observations.

“We detected a specific pattern of ocean cooling south of Greenland and unusual warming off the US coast – which is highly characteristic for a slowdown of the Atlantic overturning, also called the Gulf Stream System,” says lead-author Levke Caesar from the Potsdam Institute for Climate Impact Research (PIK). “It is practically like a fingerprint of a weakening of these ocean currents.” As the currents slow down, they bring less heat towards the north, causing widespread cooling of the northern Atlantic – the only ocean region that has cooled in the face of global warming. At the same time, the Gulf Stream shifts northwards and closer to shore and warms the waters along the northern half of the US Atlantic coast.

“That region has warmed faster than most other parts of the world ocean in recent decades,” says co-author Vincent Saba from the National Oceanic and Atmospheric Administration (NOAA) Laboratory in Princeton, USA. “This specific ocean temperature pattern has been projected by high-resolution computer simulations as a response to rising carbon dioxide levels in the atmosphere – now it has been confirmed by measurements.”

Measurements of sea surface temperatures confirm computer simulations

For decades, scientists have investigated the dynamics of the Atlantic overturning. Computer simulations generally predict that it will weaken in response to human-caused global warming. But whether this is already happening has so far been unclear, due to a lack of long-term direct current measurements. “The evidence we’re now able to provide is the most robust to date,” says Stefan Rahmstorf from the Potsdam Institute, who conceived the study. “We’ve analysed all the available sea surface temperature data sets, comprising data from the late 19th Century until the present.”

…(read more).

New Studies Show Gulf Stream Slowing As Hurricane Season 2018 Approaches | New American Journal

By Glynn Wilson –

MOBILE, Ala. — As we wait for a massive storm that could dump seven inches of rain here to make it over from New Orleans, this is a good time to talk about the upcoming hurricane season of 2018 and the latest science news about global warming and climate change.

Climate scientists from Colorado State University have already released a prediction saying this year’s hurricane season, which officially begins June 1, could bring an above-average 14 named storms, 7 hurricanes and 3 major hurricanes.

While the Trump administration is still stifling any talk about global warming or climate change and bringing even more anti-science people into the federal agencies even as climate change denier Scott Pruitt may be on the way out at EPA, two new studies raise major alarms that the long-predicted slowing of the Gulf Stream is already in progress and could hasten sea level rise 100 years ahead of schedule.

One study published in the journal Nature, Observed fingerprint of a weakening Atlantic Ocean overturning circulation, was led by the Potsdam Institute for Climate Impact Research. It finds that the Atlantic Meridional Overturning Circulation system, another name for the Gulf Stream, has weakened “around 15 percent” since the mid-20th century, bringing it to “a new record low.”

The system circulates warmer water northward and cooler water south.

“I think we’re close to a tipping point,” climatologist Michael Mann told ThinkProgress in an email interview. The system slow down “is without precedent” in more than a millennium he said: “It’s happening about a century ahead of schedule relative to what the models predict.”

The impacts of such a slowdown include much faster sea level rise, he indicated, along with warmer sea surface temperatures, which feed hurricanes to make them stronger and more devastating when they make landfall.

Both of those effects are already being observed — and together they make devastating storm surges of the kind seen during Superstorm Sandy far more likely.

Another new study in the same issue of Nature “supports this finding and places it in a longer climate history context,” as Potsdam’s Stefan Rahmstorf notes at RealClimate, showing the Gulf Stream moving at its slowest pace in at least 1,600 years.

A video from Potsdam Institute explains how the slowdown is being driven by human-caused climate change: The observed fingerprint of temperature changes in the Atlantic are precisely what the models predicted would happen when the slowdown began in earnest.

Stronger evidence for a weaker Atlantic overturning


Potsdam Institute
Published on Apr 11, 2018

Levke Caesar and Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research on their new paper.

The Atlantic overturning – one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards – is weaker today than any time before in more than 1000 years. Sea surface temperature data analysis provides new evidence that this major ocean circulation has slowed down by roughly 15 percent since the middle of the 20th century, according to a study published in the highly renowned journal Nature by an international team of scientists. Human-made climate change is a prime suspect for these worrying observations.

Article: Levke Caesar, Stefan Rahmstorf, Alexander Robinson, Georg Feulner, Vincent Saba (2018): Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature [DOI:
10.1038/s41586-018-0006-5]

Weblink to the press release: https://www.pik-potsdam.de/news/press…

“But 97% of Scientists Agree!!” Climate Change Activist vs Tucker Carlson

The Liberty Hound
Published on Aug 9, 2017

Is This Fox News’ Most Insane Climate Change Denying Clip Ever?


The Majority Report with Sam Seder
Published on Feb 12, 2015

Fox News’ Outnumbered freaks out over President Obama and Josh Earnest acknowledging that more people are affected by Climate Change than terrorism. Watch Fox’s incredible lies on Obama and climate change… This clip from the Majority Report, live M-F at 12 noon EST and via daily podcast at http://Majority.FM