Category:Antarctica: Difference between revisions

Thwaites Glacier, Antarctica

2023

October 2023

Where’s All the Antarctic Sea Ice? Annual Peak Is the Lowest Ever Recorded

National Snow and Ice Data Center reports record lows for each month since April.

“Things got really strange,” said Walt Meier, a senior research scientist at the National Snow and Ice Data Center. “It started diverging from anything we’d seen before.”

* https://en.wikipedia.org/wiki/Antarctic_sea_ice

July 2023 | Antarctica's sea ice has melted so fast — and the Earth has remained so much warmer than usual — that scientists are sounding a global alarm. The reason is simple: Antarctic sea ice that always comes back after first melting has not returned. Vast regions of Antarctic coast are exposed that were never bare before.

As physical oceanographer Edward Doddridge put it, referring to this development as "unprecedented" simply "isn't strong enough. For those of you who are interested in statistics, this is a five-sigma event. So it's five standard deviations beyond the mean."

In other words: "If nothing had changed, we'd expect to see a winter like this about once every 7.5 million years."

• https://www.salon.com/2023/07/25/antarcticas-rapidly-melting-ice-is-in-unprecedented-territory/

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The Ice Core Story & Disruptions of the Current Era

Measuring Gasses & Looking at Outgassing of CO2, Methane, & 'Business-as-Usual

Warming, Ice Melt, Interupted Water Flow & Nutrients, Ocean Life ... Connections & the Trendlines

Note the 'Rare gases', also known as the noble gases or the inert gases, a group of six gaseous elements found in small amounts in the atmosphere (and being investigated in current times as they were trapped historically in the Antarctic and are now being retrieved in deep-drilled ice cores): helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn)

(Visit the recent Nature journal science study reported here below at GreenPolicy360)

Full Audio Interview

"A CLOSER VISIT WITH DR. JEFFREY SEVERINGHAUS: HOW DANGEROUS IS THE NEW ANTARCTIC ICE MELT FOR CLIMATE CHANGE?"

"The regular supply of very cold water has been cut off..."

• https://hotglobe.substack.com/p/a-closer-visit-with-dr-jeffrey-severinghaus

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Ice loss from Greenland and Antarctica hits new record

Ice loss from Greenland and Antarctica has increased fivefold since the 1990s, and now accounts for a quarter of sea-level rise.

It is without doubt that climate change is causing our polar ice sheets to melt, thereby driving up sea levels and putting coastal regions around the world at risk.

Since 1992, when satellite records of ice-sheet melt began, the polar ice sheets have lost ice every single year. The highest rates of melt have occurred in the past decade.

Scientists use data from satellites such as ESA’s CryoSat and the European Union’s Copernicus Sentinel-1 to measure changes in ice volume and flow, as well as satellites that provide information on gravity, to work out how much ice is being lost.

A team of scientists compile these records in the Ice Sheet Mass Balance Intercomparison Exercise (IMBIE), which is funded by ESA and NASA. This is used widely, including by the International Panel on Climate Change (IPCC), to understand and respond to the climate crisis.

The latest IMBIE assessment, which was published today, states that between 1992 and 2020, the polar ice sheets lost 7560 billion tonnes of ice – equivalent to an ice cube measuring 20 km each side...

* https://www.esa.int/Applications/Observing_the_Earth/FutureEO/CryoSat/Ice_loss_from_Greenland_and_Antarctica_hits_new_record

* https://twitter.com/ESA_EO/status/1648952388651212802

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Major Study of Ice-melt Impacts Reported in the Nature Journal:

Melting Antarctic ice predicted to cause rapid slowdown of deep ocean current by 2050

New research by Australian scientists suggests 40% slowdown in just three decades could alter world’s climate for centuries

• https://www.theguardian.com/world/2023/mar/30/melting-antarctic-ice-predicted-to-cause-rapid-slowdown-of-deep-ocean-current-by-2050

• https://phys.org/news/2023-03-deep-ocean-currents-antarctica-collapse.html

Abyssal ocean overturning slowdown and warming driven by Antarctic meltwater

• https://www.nature.com/articles/s41586-023-05762-w

Li, Q., England, M.H., Hogg, A.M. et al. Abyssal ocean overturning slowdown and warming driven by Antarctic meltwater. Nature 615, 841–847 (2023). https://doi.org/10.1038/s41586-023-05762-w

Received 20 March 2022; Accepted 25 January 2023; Published 29 March 2023

Nature Issue Date: 30 March 2023

DOI: https://doi.org/10.1038/s41586-023-05762-w | (DOI/Digital Object Identifier)

Abstract

The abyssal ocean circulation is a key component of the global meridional overturning circulation, cycling heat, carbon, oxygen and nutrients throughout the world ocean. The strongest historical trend observed in the abyssal ocean is warming at high southern latitudes, yet it is unclear what processes have driven this warming, and whether this warming is linked to a slowdown in the ocean’s overturning circulation. Furthermore, attributing change to specific drivers is difficult owing to limited measurements, and because coupled climate models exhibit biases in the region. In addition, future change remains uncertain, with the latest coordinated climate model projections not accounting for dynamic ice-sheet melt. Here we use a transient forced high-resolution coupled ocean–sea-ice model to show that under a high-emissions scenario, abyssal warming is set to accelerate over the next 30 years. We find that meltwater input around Antarctica drives a contraction of Antarctic Bottom Water (AABW), opening a pathway that allows warm Circumpolar Deep Water greater access to the continental shelf. The reduction in AABW formation results in warming and ageing of the abyssal ocean, consistent with recent measurements. In contrast, projected wind and thermal forcing has little impact on the properties, age and volume of AABW. These results highlight the critical importance of Antarctic meltwater in setting the abyssal ocean overturning, with implications for global ocean biogeochemistry and climate that could last for centuries.

If greenhouse gas emissions continue at today’s levels, the current in the deepest parts of the ocean could slow down by 40% in only three decades.

This, the scientists said, could generate a cascade of impacts that could push up sea levels, alter weather patterns and starve marine life of a vital source of nutrients.

Antarctic ice melt could disrupt the world’s oceans

The Antarctic overturning circulation is part of a global network of currents that shift heat, oxygen and nutrients around the globe

What happens in Antarctica doesn't stay in the Antarctic

Global warming is accelerating the melting of ice in Antarctica, and the increased amount of fresh water flooding into the ocean is disrupting the flow of the Antarctic overturning circulation, according to a study published in the journal Nature.

• https://www.straitstimes.com/world/antarctic-ice-melt-could-disrupt-the-world-s-oceans-study
• https://www.straitstimes.com/world/europe/monster-iceberg-released-billions-of-tonnes-of-fresh-water-into-ocean

“Changes that happen in one location, such as Antarctica, can then have a global influence because those waters move all throughout the planet,” said study co-author Adele Morrison, a research fellow from the Research School of Earth Sciences at the Australian National University in Canberra.

But there are signs the overturning circulation is slowing, disrupted by the increasing amount of meltwater from Antarctica that is making the waters less salty, and therefore less dense and not sinking with the same force.

And the melting is increasing as growing amounts of greenhouse gas emissions, mainly from burning fossil fuels, are heating up the atmosphere and oceans.

“Our modelling shows that if global carbon emissions continue at the current rate, then the Antarctic overturning will slow by more than 40 per cent in the next 30 years – and on a trajectory that looks headed towards collapse,” said co-author Matthew England, deputy director of the ARC Centre for Excellence in Antarctic Science at the University of New South Wales in Sydney.

Bill McKibben, former GreenPolicy360 adviser explains:

Basically, as melting ice pours fresh water into the ocean around Antarctica, it dilutes the salinity of the sea; that reduces its density and it’s no longer heavy enough to sink, pushing out the water that’s already there. The decomposing organisms that have dropped to the sea floor thus remain locked there, as the whole vast conveyor belt begins to slow. This phenomenon has already been observed in the Arctic, where melting water pouring off Greenland and from melting sea ice has slowed the Arctic Meridional Overturning Current, or AMOC; the Australian scientists behind this new study have confirmed that the same thing is underway in the antipodes. The water that once flowed north, carrying nutrients to the Pacific, Atlantic and Indian oceans will stagnate in place."

"Other studies have predicted additional problems as these currents decline, including moving rainfall bands by a thousand kilometers from their present position. As one scientist put it, the Antarctic current is “on a trajectory that looks headed towards collapse,” and not on a scale of centuries, or even century. On a scale of decades and years. We’re as far from 2050 as we are from Bill Clinton denying he’d had “sexual relations” with “that woman,” which is to say not very far (and also reminder that embarrassing presidents are not in themselves a new phenomenon, even if Trump took it to an entirely new and endlessly more dangerous level).

The scale of the systems we’re now affecting is almost incomprehensible—the flow of the Arctic current is a hundred times larger than the Amazon river. And the speed is incomprehensible. “In the past, these circulations have taken more than 1,000 years or so to change, but this is happening over just a few decades,” one of the study’s author’s said. “It’s way faster than we thought these circulations could slow down.”

But that’s because we’ve built a new planet, one with a markedly different atmosphere. Which changes everything. Even before the epochal news from the Antarctic, the earth’s oceans had been sending distressing signals this spring. In late March, scientists reported that the temperature of ocean waters around the planet was rising abruptly, reaching record levels in recent weeks.

'Doomsday Glacier' Shows Its Underside (It's Breached with Terraces)

• https://www.washingtonpost.com/climate-environment/2023/02/15/glacier-ice-melt-ocean-warming/
• https://www.cnn.com/2023/02/15/world/thwaites-doomsday-glacier-sea-level-climate-intl/index.html
• https://www.nature.com/articles/s41586-022-05586-0

Antarctic Sea Ice Cover at Record Low

• https://www.technologynetworks.com/applied-sciences/news/antarctic-sea-ice-cover-at-record-low-370140

There is currently less sea ice in the Antarctic than at any time in the forty years since the beginning of satellite observation: in early February 2023, only 2.20 million square kilometres of the Southern Ocean were covered with sea ice. Researchers from the Alfred Wegener Institute and the University of Bremen analyse the situation for the Sea Ice Portal. January 2023 had already set a new record for its monthly mean extent (3.22 million square kilometres), even though the melting phase in the Southern Hemisphere continues until the end of February. The current expedition team on board RV Polarstern has just reported virtually ice-free conditions in its current research area, the Bellingshausen Sea.

2022

Antarctica Is in Trouble

• https://gizmodo.com/antarctica-is-in-trouble-1849404679

It’s 70 degrees warmer than normal in eastern Antarctica

‘This event is completely unprecedented and upended our expectations about the Antarctic climate system.’

The coldest location on the planet has experienced an episode of warm weather this week unlike any ever observed, with temperatures over the eastern Antarctic ice sheet soaring 50 to 90 degrees above normal. The warmth has smashed records and shocked scientists.

• https://www.washingtonpost.com/weather/2022/03/18/antarctica-heat-wave-climate-change/

2021

Doomsday Glacier in Antarctica

"If there is going to be a climate catastrophe, it’s probably going to start at Thwaites.”