All posts tagged: AMOC

Collapse of AMOC ocean current may already be locked in

Collapse of AMOC ocean current may already be locked in

Published by skeptic

A visualisation of Atlantic Ocean currents based on sea surface temperature data NASA/Goddard Space Flight Center Scientific Visualization Studio A potentially catastrophic collapse of the Atlantic Ocean currents that control Europe’s climate may already be inevitable. Based on model simulations, researchers estimate that there is a 10 to 23 per cent chance that such a collapse is locked in. “There is a significant probability that we’re already committed to collapse, and we can’t change that even now,” says Phil Holden at the Open University, UK. The Atlantic Meridional Overturning Circulation (AMOC) carries warm, salty water from the tropics into the North Atlantic Ocean, where it cools, sinks and then returns south. This circulation regulates the climate across Europe, Africa and the Americas. Recently, there have been signs that this vital current system is weakening, including by slowing in some areas, partly because the melting of the Greenland ice sheet caused by climate change is making the salty water less dense, so that it sinks more slowly. Some scientists have suggested that the AMOC could collapse, …

Slowdown of AMOC ocean current may be gradual and reversible

Slowdown of AMOC ocean current may be gradual and reversible

Published by skeptic

A visualisation of Atlantic Ocean currents based on satellite imagery KARSTEN SCHNEIDER/SCIENCE PHOTO LIBRARY The Atlantic Meridional Overturning Circulation (AMOC) could weaken under a flood of Greenland meltwater, but this slowdown would be gradual and it would reverse if global warming were halted, according to a state-of-the-art climate model. The AMOC is a system of currents that brings warm, salty, tropical water into the North Atlantic Ocean, where it cools, sinks and returns southwards along the seabed. Fresh water melting from the Greenland ice sheet appears to be mixing with this dense seawater and slowing its cascade down to the ocean floor. Because Greenland is now losing 30 million tonnes of ice every hour, some scientists fear the AMOC could face an abrupt and irreversible collapse, plunging Europe into near-Arctic conditions. One study found the AMOC could cross a tipping point within decades. But modelling research by Oliver Mehling at Utrecht University in the Netherlands and his colleagues has found that while continued rapid Greenland melt could steadily weaken the AMOC under global warming, this decline …

Cuts to US ocean programme will hinder monitoring of El Niño and AMOC

Cuts to US ocean programme will hinder monitoring of El Niño and AMOC

Published by skeptic

One of the Ocean Observatories Initiative’s mooring spheres being lifted out of the sea Rebecca Travis / Woods Hole Oceanographic Institution In the winter of 2013-2014, the strong winds of the jet stream shifted north, allowing a mass of warm water dubbed “the blob” to swell across more than 1500 kilometres of the north Pacific Ocean. Floating instruments moored to the seabed off Alaska, Washington and Oregon alerted scientists and the fishing industry to the arrival of this water, which was up to 4°C hotter than normal. They were part of the Ocean Observatories Initiative (OOI), five mooring arrays off the US west and east coasts and Greenland. Announcing $220 million in funding for the programme in 2023, the US National Science Foundation (NSF) said the OOI was needed to monitor “critical organs of the Earth”. But last month the NSF announced that these arrays would be largely removed from the water following funding cuts by the administration of US President Donald Trump. As a planet-warming El Niño climate phase warmed the water further in …

Mysterious ‘cold blob’ in the Atlantic suggests the AMOC is weakening

Mysterious ‘cold blob’ in the Atlantic suggests the AMOC is weakening

Published by skeptic

The “cold blob” appears in a data visualisation showing average temperatures in 2015, relative to the 1951-80 average NASA Scientific Visualization Studio/Goddard Space Flight Center Over the past 150 years, Earth’s entire surface has been warming, except for one patch of the north Atlantic. Located south-east of Greenland, this area has cooled by as much as 1°C and is known as the “warming hole” or the “cold blob”. Scientists have been split over why this cold blob exists, but the latest evidence backs up the idea that it is caused by a weakening of the Atlantic Meridional Overturning Circulation (AMOC), the system of currents that transports warmth from the tropics to Europe. The AMOC carries warm, salty water from the Gulf of Mexico towards the north Atlantic, where it cools and sinks, flowing back south along the ocean floor. Scientists are concerned that the surge of freshwater from Greenland’s melting ice is making this salty water less dense, so it sinks more slowly, weakening the circulation. Some research suggests the AMOC could cross a tipping …

Cleaning up air pollution could weaken vital AMOC ocean current

Cleaning up air pollution could weaken vital AMOC ocean current

Published by skeptic

Smog contains particles that reflect the sun’s rays and cool Earth’s surface Dennis MacDonald/Alamy Cleaning up air pollution in Europe and North America could result in more weakening of the Atlantic Meridional Overturning Circulation (AMOC), an ocean current that is critical for Europe’s climate. The smog and soot dirtying the air around the world claim some 7 million lives every year and induce illnesses that affect many others. Yet aerosols – small particles of substances like sulphur dioxide that make up most ground-level pollution – tend to reflect sunlight and brighten clouds, which wards away some of the sun’s heat. In recent years, research has revealed how cutting air pollution from sources such as shipping has caused global temperatures to rise even faster. “As we reduce aerosols, they’re going to unmask warming,” says Michael Diamond at Florida State University. To date, scientists’ understanding of how aerosols impact the climate has been limited to running the same kind of global simulations that are used to study the greenhouse effect. These global models have shown “if there’s …

A vast dam across the Bering Strait could stop the AMOC collapsing

A vast dam across the Bering Strait could stop the AMOC collapsing

Published by skeptic

The Bering Strait separates Alaska and Russia Ocean Color/OB.DAAC/OBPG/NASA It would be an engineering project on a truly epic scale, but we may one day need to consider building a dam between Alaska and eastern Russia. The audacious proposal would be designed to stave off the worst consequences of the collapse of a vital ocean current, and researchers have been mulling it over this week at a major conference. The idea comes from Jelle Soons and his colleague Henk Dijkstra at the University of Utrecht in the Netherlands, who study the Atlantic Meridional Overturning Circulation or AMOC. This current system, which includes the Gulf Stream, is a major reason why northern Europe has a relatively mild climate for its latitude. However, we know the current is weakening. There is huge uncertainty about what would happen if it collapses, but some models suggest it could see temperatures in northern Europe drastically plunge. Soons thought a dam could be a possible intervention after hearing about how during the Pliocene era, from roughly 5.3 to 2.6 million years …

Volcanic eruptions in the distant past may have led to ocean current collapse

Volcanic eruptions in the distant past may have led to ocean current collapse

Published by Jenni Sidey

A massive volcanic eruption can cool the planet within months. What happens next may take centuries. Currently, this potential consequence is a large part of current research being conducted on the Earth’s climate system, focusing on the Atlantic Meridional Overturning Circulation (AMOC). A subset of ocean currents, the AMOC distributes and redistributes heat across the Northern Atlantic Ocean, which helps to maintain a relatively mild climate in Northern Europe. If there is a weakening or collapse of the AMOC in the future, there will likely be a drastic change in the climate of this area and other areas connected to the AMOC. Volcanic Forcing and Ocean Circulation Sensitivity An international team of scientists, including teams from the Niels Bohr Institute at the University of Copenhagen, conducted research to determine if volcanic eruptions act as a driving force for more expansive changes within the AMOC coordinate system. Their results suggest that the AMOC is likely far more responsive to disturbances from outside forces than was previously realized. Records of explosive volcanism during the Holocene. (CREDIT: Science) …

Iceland sees AMOC current collapse as a national security risk

Iceland sees AMOC current collapse as a national security risk

Published by Sam Flores

REYKJAVIK, Iceland — It is just one scenario among many, but by far the most cataclysmic. Sometime over the next 100 years, human-driven warming could disrupt a vital ocean current that carries heat northward from the tropics. After this breach, most of the world would keep getting hotter — but northern Europe would cool substantially, with Iceland at the center of a deep freeze. Climate modeling shows Icelandic winter extremes plunging to an unprecedented minus-50 degrees Fahrenheit. Sea ice could surround the country for the first time since it was settled by Vikings. Source link