Doomsday glacier could give way any day now

 From Just Have A Think

Yes, the danger isn't immediate.  But when the "plug" holding the Thwaites glacier goes, it will start a process which could raise the sea level by 3 metres over the next few decades.

Record winter temperatures in Antarctica

 

On King George Island the landscape has changed from mostly white to brown, grey and green. Photograph: Luis Muñoz

From The Guardian

Temperatures in the Antarctic climbed above 15C this month, shattering the previous winter heat record for the usually frozen region and raising concerns about the speed of climate breakdown.  [Reminder: since this is the Southern Hemisphere, it is mid-winter now, the equivalent of December in the N.H.]

The new winter peak temperature was logged by the Argentinian Esperanza base on the Trinity peninsula on 6 June amid a protracted heatwave, when the maximum daily temperature exceeded zero degrees for three consecutive weeks.

Scientists said the high of 15.4C broke the previous record set at the same station in 1998 by 2C. “This is absolutely crazy,” said Raúl Cordero, an Ecuadorian climate professor at the University of Groningen. “It is also about 20C above normal for this time of the year. That is a huge anomaly.”

Unusually strong warm winds from the north blew across much of the Antarctic peninsula. One Chilean weather station, Boonen Rivera, registered temperatures of close to 13C, Cordero said.

On King George Island, 100 miles (160km) from Esperanza, researchers said the landscape had changed from mostly white to brown, grey and green after temperatures hit 4.6C on 6 June.

“Last weekend was very strange. The temperatures here went very high so everything outside melted,” said Luis Muñoz, a Chilean glaciologist. “Usually there is 20cm of snow and a lot of ice on the ground at this time.”

Muñoz said he and a colleague, Natalia Mestre, climbed to the 500-metre peak of the nearby Collins glacier last Wednesday and were surprised to find rain melting the ice. “There was a direct impact on the glacier, which should be receiving snow now. It should not be suffering ablation at this time of the year. This is obviously not good for the glacier.”

The Antarctic region is coming under increasing human pressure, directly in the form of resource exploration and tourism and indirectly through the burning of fossil fuels, which is heating the planet.

Scientists warn that some of the region’s biggest glaciers, such as Thwaites and Pine Island, are approaching or may even have passed a tipping point that could push up global sea levels by four metres. Antarctic ice melt has also been found to slow global ocean circulation.

Cordero said a single winter of heatwaves, no matter how amazing, would not by itself make a huge difference to sea levels, but it signified more alarming long-term trends. “This heatwave happened because of extremely strong westerlies,” he said. “This has been happening with increasing frequency since the 1980s, and that is known to be related to climate change.”

 We are doing too little to slash emissions.  We need to do it as soon as possible, not in 10 or 20 years' time.   In almost every country around the world, the combination of wind, solar and batteries is as cheap as or cheaper than coal and much cheaper than gas.  EVs, outside the US and Europe, are as cheap as petrol/diesel cars, and obviously much cheaper to run as well.  It's a marriage made in heaven: clean electricity to drive your vehicle fleet, and a huge mobile battery resource which helps stabilise the grid.  Let's just do it, instead of phaffing around.

Simultaneous global cascading catastrophes

 From Prof Eliot Jacobson

A quick reminder that we are witnessing the beginning of simultaneous cascading global catastrophes.

Polar ice keeps on plunging

 From Rick Thoman

Arctic-wide sea ice extent is the lowest in 47-year NSIDC satellite record for February 7, and it's the lowest by a lot: 430,000 km² of "lost ice" compared to the previous lowest (2017) and about 2.2 million km² less than was typical on February 7 in the early 1980s. #Arctic #SeaIce #ClimateChange

From Professor Eliot Jacobson

Breaking News! Code UFB!!! Global sea-ice extent is now at an all-time record low in recorded history, with global sea-ice extent now 2.14 million square kilometers below the 1991-2020 average. Images of the current Arctic and Antarctic sea-ice extent are in the following posts in this thread.

Yet companies, politicians and techbros continue to pretend they are doing something and they care.  They really, really do.

Global sea ice reaches new record low

 From Prof Eliot Jacobson

Global sea ice plunging to record lows

 From a post by Peter Dynes

Global Sea Ice taking a nose dive to record lows. We are losing over 25,000 tonnes of Ice from the Arctic per second. That’s a lot of Ice. Earth's heating rate will accelerate the more sea ice we lose. The general public is totally unaware of this danger.

Air, ocean and ice climate records tumbled in 2023

From Weatherzone

The World Meteorological Organization has confirmed that 2023 was an astonishing year for our planet’s climate, with records obliterated in the atmosphere, hydrosphere and cryosphere.

 

Atmosphere

Global air temperatures frequently made headlines around the world in 2023 as records fell month after month.

Every calendar month from June to December set a new global average near-surface air temperature record for that time of year.

This string of exceptional warmth in the second half of 2023 pushed the annual global mean air temperature to 1.45°C (±?0.12?°C) above the 1850 to 1900 pre-industrial baseline. According to the WMO, this was the highest annual mean temperature on record, beating the previous record from 2016 by 0.16ºC.

Oceans

The record warmth in Earth’s atmosphere last year was also mirrored in the oceans, with global sea surface temperatures reaching record-breaking levels from March onwards.

Every month from April to December set a new respective monthly record in 2023, while a new daily sea surface temperature record was observed in August (note that this has since been exceeded in 2024).

 

Image: Daily global sea surface temperatures between 1979 and 2024 to date, based on the ERA5 dataset. Source: Copernicus Climate Change Service

The global mean sea level also reached a new record height in 2023, driven by abnormal ocean warmth and increased melting of glaciers and ice sheets.

According to the WMO, “the rate of global mean sea level rise in the past ten years (2014–2023) is more than twice the rate of sea level rise in the first decade of the satellite record (1993–2002).”

Ice

Parts of the cryosphere – the frozen portions of our planet – also broke records in 2023.

Antarctic sea-ice extent reached record lows for the seasonal minimum extent in February and maximum extent in September.

Glacier melt was also pushed to new levels in 2023. According to the WMO, “preliminary data from the global set of reference glaciers for the hydrological year 2022-2023 show they experienced the largest loss of ice on record.”

What made 2023 so warm?

Climate change and El Niño were both contributing factors to the record-breaking warmth in 2023. However, these drivers alone aren’t enough to account for the magnitude of last year’s abnormal warmth.

According to the Copernicus Climate Change Service, other influences that may have contributed to the exceptional state of the climate in 2023 are:

• Enhanced stratospheric water vapour due to the eruption in January 2022 of the Hunga Tonga–Hunga Ha'apai volcano
• Reduced aerosols due to lower sulphur dioxide emissions by shipping
• The approach of the current solar cycle to its peak.

These influences are still an active topic of research and may continue to influence Earth’s global climate system in 2024. Monitoring Earth’s global climate system is an essential part of understanding how the climate is changing and what steps need to be taken, now and in the future, to mitigate its effects.

Antarctic ice sheet melting 20 times faster than we thought

From a toot by Bread & Circuses

We do NOT want the Antarctic Ice Sheet to melt any faster than it already is. The risks of so much fresh water pouring into the ocean are massive — not only increased sea level rise, but also more greenhouse gas emissions going into the atmosphere, plus the potential for serious disruption to the global food chain. (See https://climatejustice.social/@breadandcircuses/110174993496613175)

And now we get this terrible news...
____________________________

"Antarctic ice can melt 20 times faster than we thought"

Melting ice sheets in Antarctica can retreat much faster than scientists previously thought. A study published in the journal Nature found that at the end of the last Ice Age, parts of the Eurasian Ice Sheet retreated up to 2,000 feet per day. This rate is 20 times faster than previous measurements. These changes far outpace even the fastest-moving glaciers studied in Antarctica, which are estimated to retreat as quickly as 160 feet per day.

“Our research provides a warning from the past about the speeds that ice sheets are physically capable of retreating at,” Christine Batchelor, study co-author and physical geographer from Newcastle University, said in a statement. “Our results show that pulses of rapid retreat can be far quicker than anything we’ve seen so far.”
____________________________

FULL STORY -- https://www.popsci.com/environment/antarcti

Before boosting this post from 10 April, I added the chart below showing current Antarctic sea ice extent anomalies, which are shocking in their departure from the norm. Although sea ice is different from ice sheets on land, they do interact — as sea ice declines and weakens, it allows for faster collapse of glaciers when they reach the ocean.

#Environment #Climate #ClimateChange #ClimateCrisis #ClimateAction #ClimateEmergency #Ocean

Accelerated melt of ice sheets now unmistakable

From The BBC

If you could shape an ice cube out of all the ice losses from Greenland and Antarctica over the past three decades, it would stand 20km high.

An international group of scientists who work with satellite data say the acceleration in the melting of Earth's ice sheets is now unmistakable.

They calculate the planet's frozen poles lost 7,560 billion tonnes in mass between 1992 and 2022.

Seven of the worst melting years have occurred in the past decade.

Mass loss from Greenland and Antarctica is now responsible for a quarter of all sea-level rise.

This contribution is five times what it was 30 years ago.

The latest assessment comes from the Ice Sheet Mass Balance Intercomparison Exercise, or Imbie.

This project, which is supported by the US and European space agencies, issues regular reviews of the state of the planet's ice sheets.

This is the third such report, and like the previous studies, it has collated and reviewed all available satellite measurements.

It includes the observations from orbit of some 50 spacecraft missions from 1992. That particular year was when orbiting instruments best suited to studying the elevation and velocity of ice started overflying the poles routinely.

The 7,560 billion tonnes of ice lost from Greenland and Antarctica during the study period pushed up sea-levels by 21mm.

Almost two-thirds (13.5mm) of this was due to melting in Greenland; one-third (7.4mm) was the result of melting in Antarctica.

"All this has profound implications for coastal communities around the world and their risk of being exposed to flooding and erosion," said Dr Inès Otosaka from the UK's Centre for Polar Observation and Modelling (CPOM), who led the latest assessment.

"It's really important that we have robust estimates for the future contribution to sea-level rise from the ice sheets so that we can go to these communities and say, 'Yes, we understand what is happening and we can now start to plan mitigations'," she told BBC News.

Warmer air is melting the top of the Greenland Ice Sheet (NASA/GODDARD/MARIA-JOSÉ VIÑAS)

Antarctic sea ice reaches record low

From The Guardian

For 44 years, satellites have helped scientists track how much ice is floating on the ocean around Antarctica’s 18,000km coastline.

The continent’s fringing waters witness a massive shift each year, with sea ice peaking at about 18m sq km each September before dropping to just above 2m sq km by February.

But across those four decades of satellite observations, there has never been less ice around the continent than there was last week.

“By the end of January we could tell it was only a matter of time. It wasn’t even a close run thing,” says Dr Will Hobbs, an Antarctic sea ice expert at the University of Tasmania with the Australian Antarctic Program Partnership.

“We are seeing less ice everywhere. It’s a circumpolar event.”

In the southern hemisphere summer of 2022, the amount of sea ice dropped to 1.92m sq km on 25 February – an all-time low based on satellite observations that started in 1979.

But by 12 February this year, the 2022 record had already been broken. The ice kept melting, reaching a new record low of 1.79m sq km on 25 February and beating the previous record by 136,000 sq km – an area double the size of Tasmania.

In the southern hemisphere’s spring, strong winds over western Antarctica buffeted the ice. At the same time, Hobbs says large areas in the west of the continent had barely recovered from the previous year’s losses.

“Because sea ice is so reflective, it’s hard to melt from sunlight. But if you get open water behind it, that can melt the ice from underneath,” says Hobbs.

Hobbs and other scientists said the new record – the third time it’s been broken in six years – has started a scramble for answers among polar scientists.

The fate of Antarctica – especially the ice on land – is important because the continent holds enough ice to raise sea levels by many metres if it was to melt.

While melting sea ice does not directly raise sea levels because it is already floating on water, several scientists told the Guardian of knock-on effects that can.

Sea ice helps to buffer the effect of storms on ice attached to the coast. If it starts to disappear for longer, the increased wave action can weaken those floating ice shelves that themselves stabilise the massive ice sheets and glaciers behind them on the land.

One major area of concern is a marked loss of ice around the Amundsen and Bellinghausen seas on the continent’s west.

Even as the average amount of sea ice around the continent grew up to 2014, these two neighbouring seas saw losses.

That’s important because the region is home to the vulnerable Thwaites glacier – known as the “doomsday glacier” because it holds enough water to raise sea levels by half a metre.

“We don’t want to lose sea ice where there are these vulnerable ice shelves and, behind them, the ice sheets,” Prof Matt England, an oceanographer and climate scientist at the University of New South Wales, says.

“We are probably starting to see signs of significant warming and retreat of sea ice [in Antarctica]. To see it getting to these levels is definitely a concern because we have these potentially amplifying feedbacks.”

Data provided by scientists Dr Rob Massom, of the Australian Antarctic Division, and Dr Phil Reid, of the Bureau of Meteorology, shows two-thirds of the continent’s coastline was exposed to open water last month – well above the long-term average of about 50%.

“It’s not just the extent of the ice, but also the duration of the coverage,” Massom says. “If the sea ice is removed, you expose floating ice margins to waves that can flex them and increase the probability of those ice shelves calving. That then allows more grounded ice into the ocean.”

Massom and Reid published a study last year that found that, since 1979, the Amundsen Sea region was seeing longer periods without ice and more of the coastline was being exposed to open ocean conditions.

Dr Ted Scambos is a sea ice expert at the University of Colorado Boulder who also works on Antarctic sea ice at the university’s National Snow and Ice Data Center – a world centre for monitoring ice at the poles.

He said the downturn in sea ice in Antarctica “is causing the scientific community to wonder if there’s a process that’s related to global climate change”.

Antarctica is hard to study not just because of its remoteness, but in the challenges of gathering data around a continent exposed to huge variations in wind and storms from all sides.

Scambos said: “Since 2016 there has been a fairly sharp downturn [in sea ice] and especially with these back-to-back record years as well as many months being at near record lows, it’s causing the scientific community to wonder if there’s a process related to global climate change.”

He said while the most recent record could be related partly to a La Niña climate system that tends to deliver warmer winds to the continent’s peninsular, that didn’t explain the losses in other areas.

“We’re still trying to get to grips with what’s different now,” he says. “But it’s clear that reduced sea ice will have an impact. It’s going to have an impact on the continental ice because so much of the coast will be exposed.”

For many years Antarctica had seemingly been confounding some climate models as sea ice had – on average – slightly increased until a crash in 2016.

Dr Ariaan Purich, a climate scientist at Monash University, looked at why the sea ice didn’t behave as some expected.

She said it was likely caused by changing winds and, counterintuitively, meltwater from the land entering the ocean that made it easier for ice to form.

One study suggested that a warming ocean had also contributed to the sudden 2016 drop in sea ice.

“All the models project that as the climate warms, we expect to see [Antarctic sea ice] decline,” she says. “There’s widespread consensus on that. So this low sea ice is consistent with what the climate models show.”

Antarctic scientists are now scrambling to work out what’s happening. Are the drops in sea ice and the back-to-back record lows just a natural phenomenon in a continent notoriously difficult to study? Or are these records another clear sign the climate crisis is beating down on the frozen continent?

“Antarctica might seem remote but changes around there can affect the global climate and the melting ice sheets affect coastal communities around the world,” says Purich.

“Everyone should be concerned about what’s happening in Antarctica.”

Map of Antarctica showing the duration in days of sea ice around the continent between February 2022 and February 2023 compared with the long-term average between 1981/82 and 2010/11. Red shows areas where ice was absent for longer than usual, and blue shows were ice was present for longer. Photograph: Dr Phil Reid, Bureau of Meteorology, Hobart: Data: Nasa

Starlink now available in Antarctica

McMurdo Station, Antarctica

From Teslarati

Elon Musk was not kidding when he stated that Starlink is designed to provide high-speed internet access to everywhere in the globe. Starlink recently had a milestone in this regard, with SpaceX confirming that the satellite internet system is now on all seven continents, including Antarctica.

The idea of Starlink providing high-speed internet access to Antarctica seemed farfetched just a few years ago. But as per SpaceX’s post on Twitter, it is now possible to provide internet access to extremely remote locations like Antarctica thanks to Starlink’s space laser network, which reduces the need for ground stations.

The National Science Foundation praised Starlink, noting that scientists in Antarctica are “over the moon” due to the satellite internet service. The NSF also noted that the Starlink terminal had been installed at the McMurdo Station, a US Antarctic research station on the south tip of Ross Island.

“NSF-supported USAP scientists in #Antarctica are over the moon! Starlink is testing polar service with a newly deployed user terminal at McMurdo Station, increasing bandwidth and connectivity for science support,” the NSF wrote on Twitter.

McMurdo Station is the largest community in Antarctica, capable of supporting up to 1,258 residents. It also serves as one of three US-based Antarctic science facilities that operate year-round. With all months of the year having an average temperature below freezing, Starlink’s capability to provide internet access to such a location is indeed very impressive.

Starlink is quickly growing into Elon Musk’s latest disruptor, and with its coverage of Antarctica, the satellite internet system is proving that it does have what it takes to provide its services across the globe. SpaceX definitely seems to be ramping its mainstream efforts for the internet service, with Elon Musk noting recently that the private space company has had conversations with Apple for possible Starlink connectivity for iPhones.

Doomsday glacier could melt 'with just a small kick'

From the ABC (Australian Broadcasting Corporation)

Scientists have used an unmanned submarine to map underwater terrain near a massive melting glacier in West Antarctica for the first time, showing it has the potential to retreat at twice the speed observed by satellites over the past decade.

The Thwaites Glacier, named after glacial geologist Fredrik Turville Thwaites, is known as the "doomsday glacier" in some circles because of its potential to significantly raise global sea levels, as well as its vulnerability to rapid melting due to warming ocean water.

A team of researchers from the United States, the United Kingdom and Sweden travelled to Antarctica on the icebreaking research vessel Nathaniel B. Palmer in early 2019 to map a former grounding zone of the glacier — the area where an ice shelf attached to solid ground gradually transitions into a floating ice shelf.

The researchers hoped that by studying Thwaites Glacier's past retreat, they could gain a new understanding of what it has the potential to do in the future, amid speculation it could be a possible candidate for climate engineering projects to prevent further collapse.

They used a bright orange autonomous underwater vehicle (AUV) named Rán, mounted with two types of geophysical sensors, to produce 3D scans of the underwater surface.

The 19-hour mission produced about 13 square kilometres of new geophysical data, gathered from between 50 and 90 metres above the sea floor.

By analysing the amplitude and spacing of ridges left by the glacier on a raised part of the sea bed — an isolated underwater outcrop they called "the bump" at the south-west corner of the glacier's tongue — they were able to determine that the markings, or "ribs", had been left by the glacier lifting and settling with the ocean tide each day.

They found the Thwaites Glacier was indeed susceptible to rapid retreat, having been shrinking at a rate of more than 2.1 kilometres per year when the markings were left.

That is twice the rate of retreat observed via satellite between 2011 and 2019, previously thought to have been the upper limit of the glacier's potential shrinking speed.

The University of Florida's Dr Alastair Graham, who led the mission to Antarctica and was lead co-author of a study published on Monday in Nature Geoscience, said the glacial retreat documented by the team would have occurred sometime over the past two centuries, possibly as recently as the mid-1900s.

While he called the opportunity to map the area "truly a once-in-a-lifetime mission", he was at pains to point out that what they had found shattered the previously held hope that Antarctic ice sheets could be sluggish and slow to respond to changes in climate.

"Just a small kick to Thwaites could lead to a big response," Dr Graham said.

Dr Robert Larter, a marine geophysicist and co-author of the study, said once the glacier retreats beyond a shallow ridge in its bed, it has the potential to shrink at an even greater rate.

"Thwaites is really holding on today by its fingernails, and we should expect to see big changes over small timescales in the future — even from one year to the next," he said.

Multibeam bathymetry images captured by Rán show "ribs" and melting channels on underwater terrain near the Thwaites Glacier.(Nature Geoscience)

Microplastics in freshly fallen Antarctic snow

 From The Guardian

Research published in The Cryosphere journal identified microplastics in freshly fallen snow in Antarctica for the first time. Photograph: Alex Aves

Microplastics have been found in freshly fallen snow in Antarctica for the first time, which could accelerate snow and ice melting and pose a threat to the health of the continent’s unique ecosystems.

The tiny plastics – smaller than a grain of rice - have previously been found in Antarctic sea ice and surface water but this is the first time it has been reported in fresh snowfall, the researchers say.

The research, conducted by University of Canterbury PhD student, Alex Aves, and supervised by Dr Laura Revell has been published in the scientific journal The Cryosphere.

Aves collected snow samples from the Ross Ice Shelf in late 2019 to determine whether microplastics had been transferred from the atmosphere into the snow. Up until then, there had been few studies on this in Antarctica.

“We were optimistic that she wouldn’t find any microplastics in such a pristine and remote location,” Revell said. She instructed Aves to also collect samples from Scott Base and the McMurdo Station roadways – where microplastics had previously been detected - so “she’d have at least some microplastics to study,” Revell said.

But that was an unnecessary precaution – plastic particles were found in every one of the 19 samples from the Ross Ice Shelf.

“It’s incredibly sad but finding microplastics in fresh Antarctic snow highlights the extent of plastic pollution into even the most remote regions of the world,” Aves said.

Plastic pollution has been found from the summit of Mount Everest to the depths of the oceans. People are known to inadvertently eat and breathe microplastics and another recent study found that the particles cause damage to human cells. A study last year found that airborne microplastics are “spiraling around the globe”.

Aves found an average of 29 microplastic particles per litre of melted snow, which is higher than marine concentrations reported previously from the surrounding Ross Sea and in Antarctic sea ice.

Samples taken from immediately next to the scientific bases on Ross Island, Scott Base and McMurdo Station threw up larger concentrations – nearly three times that of remote areas.

There were 13 different types of plastic found, with the most common being PET – the plastic commonly used to make soft drink bottles and clothing.

Atmospheric modelling suggested they may have travelled thousands of kilometres through the air, however it is equally likely the presence of humans in Antarctica has established a microplastic ‘footprint’, Revell said.

“There was a photo we found of some marker flags that are put out for use for wayfinding around the base…those colors matched the most commonly colored microplastics that we found in the environment.”

Revell’s prior research has shown that microplastics in the atmosphere can trap radiation emitted by the Earth and contribute to climate change. Dark microplastics in icy surfaces could absorb sunlight and lead to localised warming, she said. The plastics can also be toxic for animals and plant life.

“We’re still learning a lot about the impacts, but from what we know so far, it’s not very good.”

Antarctic heatwave ― unpredicted ice shelf collapse

From New Atlas

In the same week that record-setting temperatures were logged in East Antarctica, satellite images have revealed the complete collapse of its Conger Ice shelf, a first for the region. The ice shelf isn't all that big in the grand scheme of things, but its demise was uncharacteristic in a place known to be the coldest on Earth.

The heatwave to strike East Antarctica last week saw the mercury rise as high as -11.8 °C (10.76 °F) at the Italian-French operated Concordia research station on March 18, the highest on record for any month of the year. These temperatures were around 40 °C (72 °F) above the average for March, with scientists attributing  them to "atmospheric rivers" that trapped heat over the region.

Meanwhile, satellite images show that around March 15, the Conger Ice shelf which covers 1,200 square km (463 square miles) and is around the size of Manhattan, completely collapsed. For context, the Larsen B Ice Shelf on the Antarctica Peninsula measured 3,250 square kilometers (1,250 square miles), until it collapsed over the course of month in 2012.

It might be small by comparison, but the Conger Ice Shelf's collapse is not insignificant as these events tend to take place in West Antarctica, with East Antarctica generally thought of as stable. Indeed, although it had been retreating since January 2020, this is the first time an ice shelf collapse has been observed in the region and was completely unpredicted, according to researchers at the Woods Hole Oceanographic Institution.

“Although the Conger ice shelf was relatively small, it is one of the most significant collapse events anywhere in Antarctica since the early 2000s when the Larsen B ice shelf disintegrated, and is most likely, a sign of what might be coming,” said Catherine Walker, a glaciologist at the Woods Hole Oceanographic Institution.

Source: Woods Hole Oceanographic Institution

Satellite images of the Conger Ice Shelf prior to its collapse

Catherine Walker/WHOI

Satellite images on March 23 show the disintegration of the Conger Ice Shelf

Catherine Walker/WHOI

Record heatwaves at *both* poles

 From The Guardian

Startling heatwaves at both of Earth’s poles are causing alarm among climate scientists, who have warned the “unprecedented” events could signal faster and abrupt climate breakdown.

Temperatures in Antarctica reached record levels at the weekend, an astonishing 40C above normal in places.

At the same time, weather stations near the north pole also showed signs of melting, with some temperatures 30C above normal, hitting levels normally attained far later in the year.

At this time of year, the Antarctic should be rapidly cooling after its summer, and the Arctic only slowly emerging from its winter, as days lengthen. For both poles to show such heating at once is unprecedented.

The rapid rise in temperatures at the poles is a warning of disruption in Earth’s climate systems. Last year, in the first chapter of a comprehensive review of climate science, the Intergovernmental Panel on Climate Change warned of unprecedented warming signals already occurring, resulting in some changes – such as polar melt – that could rapidly become irreversible.

The danger is twofold: heatwaves at the poles are a strong signal of the damage humanity is wreaking on the climate; and the melting could also trigger further cascading changes that will accelerate climate breakdown.

As polar sea ice melts, particularly in the Arctic, it reveals dark sea that absorbs more heat than reflective ice, warming the planet further. Much of the Antarctic ice covers land, and its melting raises sea levels.

Scientists warned that the events unfolding were “historic”, “unprecedented” and “dramatic”.

Michael Mann, director of the Earth System Science Centre at Pennsylvania State University, said the extreme weather being recorded was exceeding predictions to a worrying extent.

“The warming of the Arctic and Antarctic is cause for concern, and the increase in extreme weather events – of which these are an example – is a cause for concern as well,” he said. “The models have done a good job projecting the overall warming, but we’ve argued that extreme events are exceeding model projections. These events drive home the urgency of action.”

The latest unprecedented weather patterns follow a series of alarming heatwaves in 2021, most notably in the US Pacific north-west, where previous records were shattered by several degrees as temperatures climbed close to 50C.

Mark Maslin, professor of earth system science at University College London, said: “I and colleagues were shocked by the number and severity of the extreme weather events in 2021 – which were unexpected at a warming of 1.2C. Now we have record temperatures in the Arctic which, for me, show we have entered a new extreme phase of climate change much earlier than we had expected.”

The Associated Press reported that one weather station in Antarctica beat its all-time record by 15C, while another coastal station used to deep freezes at this time of year was 7C above freezing. In the Arctic, meanwhile, some parts were 30C warmer than average.

James Hansen, former NASA chief scientist and one of the first to warn governments of global heating more than three decades ago, told the Guardian the heating of the poles was “concerning” and that sea ice in the Arctic this year could shrink far enough to break a decade-old record on its lowest extent.

“The average sea ice thickness has been declining, so it’s ripe for large sea ice loss,” he warned. “The effect of reduced sea ice cover is to amplify Earth’s energy imbalance that’s caused by increasing greenhouse gases (GHGs) -- the GHGs reduce outgoing heat radiation, thus causing a net imbalance that’s heating the planet.

“Reduced sea ice cover increases the planetary energy imbalance, as a dark ocean reflects less sunlight than sea ice does.”

We need to halve emissions over the next 10 years.  We need to phase out coal power stations; switch to EVs and carbon-free iron and steel.  These are all technically feasible.  Only the willpower is lacking.

The doomsday glacier

The research vessel ‘Nathaniel B. Palmer’ was surrounded overnight by icebergs while exploring the Thwaites Glacier in 2019.

This long piece from Rolling Stone is most interesting, and scary, and you should read it in full.  Some excerpts:

One thing that’s hard to grasp about the climate crisis is that big changes can happen fast. In 2019, I was aboard the Nathaniel B. Palmer, a 308-foot-long scientific research vessel, cruising in front of the Thwaites Glacier in Antarctica. One day, we were sailing in clear seas in front of the glacier. The next day, we were surrounded by icebergs the size of aircraft carriers.

As we later learned from satellite images, in a matter of 48 hours or so, a mélange of ice about 21 miles wide and 15 miles deep had cracked up and scattered into the sea.

It was a spooky moment. Thwaites Glacier is the size of Florida. It is the cork in the bottle of the entire West Antarctic ice sheet, which contains enough ice to raise sea levels by 10 feet. The mélange that disintegrated was not part of the glacier itself, but a mix of icebergs and sea ice that had cozied up next to it. Still, the idea that it could just fall apart overnight was mind-blowing.

As it turns out, the ice breakup I witnessed was not a freak event. A few weeks ago, scientists participating in the International Thwaites Glacier Collaboration, a $25 million five-year-long joint research program between the National Science Foundation in the U.S. and the Natural Environment Research Council in the U.K., presented their latest research. They described the discovery of cracks and fissures in the Thwaites eastern ice shelf, predicting that the ice shelf could fracture like a shattered car window in as little as five years. “It won’t scatter out into sea as quickly as what you saw when you were down there,” Erin Pettit, a glaciologist at Oregon State University and one of the lead principal investigators in the ITGC, later told me. “But the basic process is the same. The ice shelf is breaking up and could be gone in less than a decade.”

If Thwaites Glacier collapses, it opens the door for the rest of the West Antarctic ice sheet to slide into the sea. Globally, 250 million people live within three feet of high tide lines. Ten feet of sea level rise would be a world-bending catastrophe. It’s not only goodbye Miami, but goodbye to virtually every low-lying coastal city in the world.

But predicting the breakup of ice sheets and the implications for future sea level rise is fraught with uncertainty. Depending on various emissions scenarios in the latest Intergovernmental Panel on Climate Change report, we could have as little as one foot of sea level rise by the end of the century, or nearly six feet of sea level rise (of course, rising seas won’t stop in 2100, but that date has become a common benchmark). “The difference between those [models] is a lot of lives and money,” says Richard Alley, a glaciologist at Penn State University and one of the great ice scientists of our time. Alley adds: “The most likely place to generate [the worst scenario] is Thwaites.”

Or to put it more urgently: “If there is going to be a climate catastrophe,” Ohio State glaciologist Ian Howat once told me, “it’s probably going to start at Thwaites.”

The trouble with Thwaites, which is one of the largest glaciers on the planet, is that it’s also what scientists call “a threshold system.” That means instead of melting slowly like an ice cube on a summer day, it is more like a house of cards: It’s stable until it is pushed too far, then it collapses.

Thwaites is very different from other big glaciers, such as those in Greenland. For one thing, it is not melting from above, due to warmer air temperatures. It’s melting from below, due to warmer ocean water eating away at its underbelly. More importantly, the terrain beneath the West Antarctic ice sheet is peculiar. “Think of it as a giant soup bowl filled with ice,” Sridhar Anandakrishnan, an expert in polar glaciology at Penn State University, once told me. In the bowl analogy, the edge of the glacier — the spot where a glacier leaves the land and begins to float — is perched on the lip of the bowl 1,000 feet or more below sea level. Scientists call that lip the “grounding line.” Below the lip, the terrain falls away on a downward slope for hundreds of miles, all the way to the Transantarctic Mountains that divide East and West Antarctica. At the deepest part of the basin, the ice is about two miles thick.

What this means is that once the warm water gets below ice, it can flow down the slope of the bowl, weakening the ice from below. Through a mechanism called “marine ice-cliff Instability,” you can get what amounts to a runaway collapse of the ice sheet that could raise global sea levels very high, very fast.

[Read more here]

Big change in sea level rise

 From Open Mind (Tamino)

The most interesting thing about Frederikse et al. is that not only do they publish a new sea level reconstruction based on tide gauge data, to reckon how much sea level has risen, they also attempt to reckon where that sea level rise came from.

Here’s their estimate of sea level since 1900:

And here’s what it says about the rate of sea level rise, according to my usual analysis: a lowess smooth in red, and PLF (Piece-wise Linear Fit) in blue:

Several things are clear. First, the rate of sea level rise has changed over the years, sometimes faster (the 1910s, 1930s, 1940s, 1990s, 2000s), sometimes apparently not even rising (the 1920s, 1960s), but the 2010s are “off the chart,” a colorful way of saying that sea level rise was significantly faster than previous decades.

The latest rate, according to these data, is about 5 mm/yr. Over a century, that’s half a meter (about 20 inches). That’s the global amount, lots of places will see more or less because of local conditions (particularly, vertical land movement). It seems to me to be extremely unlikely, downright implausible in fact, that the average over this century will be less than that.

Perhaps more important is that Frederikse et al. also attempted to quantify the causes of sea level rise. Mainly, those are put in three categories: steric (thermal expansion of sea water), melting of land ice (glaciers and ice sheets), and terrestrial water storage (TWS). The contribution of land ice melt is further subdivided into three categories: glaciers, Greenland, and Antarctica.

Here is their estimate of each factor’s contribution to sea level rise since 1900:

Glacier melt has raised sea level more since 1900 than any other factor, but has not shown much recent sign of acceleration, and appears to be slower now than in the first half of the century. Greenland melt was also a major factor in the early 20th century, and has shown signs of both deceleration and acceleration with high rates recently. Steric change caused sea level fall in the first decade of the 1900s, but has risen steadily since and is now moving fast. TWS has caused an overall drop in sea level since 1900, of about 10 mm. Antarctica has countered with about 10 mm net contribution to sea level rise, but took quite a while to get started.

I applied the same analysis to the contributions, as I did to the sea level data itself. Fascinating results emerge, and the most striking is the rate of sea level rise/fall due to Antarctic ice melt:

This leads me to suspect that much of the reason behind the enhanced rate of sea level rise in the last decade is that after nearly a century of inaction, Antarctica has started to kick in.

In the long run (to the end of this century and beyond), we don’t expect TWS to be a major factor. Thermal expansion will continue, as fast or faster than now but not tremendously so; it takes a long time for heat to penetrate deep into the ocean. Glaciers will keep melting, but probably not much faster than now if at all. The fact is that even if we melt all the world’s alpine glaciers and the extra heat penetrates far into the ocean, we’ll still only get about 1 meter of sea level rise, and it will take a long time — longer than this century — for that to happen.

Then there are the big boys: Greenland and Antarctica. If all of Greenland melts there’s 7 meters of sea level rise, and if Antarctica goes, over 50.

Greenland and Antarctica aren’t going to melt this century. But they might dramatically increase the rate at which they discharge ice into the ocean. According to Richard Alley, a leading glaciologist, this tends to happen where the ice and the ocean meet, and the two phenomena which bring it about are the disintegration of floating ice sheets, and calving-cliff retreat.

When an ice sheet disintegrates it tends to happen quickly; we’ve seen the picture of the Larsen B ice shelf falling apart in a matter of days, after having survived many thousands of years. When it did, it no longer acted as a “buttress” to hold back land-based ice from reaching the sea. The flow rate just about doubled — in the twinkling of an eye, geologically speaking.

Computing how it works is straightforward, in that we know all the physics. It’s also impossible, in that there are too many variables and processes to keep track of them all, even with a supercomputer. So, models are developed to simulate processes, and they’re getting better — we’ve actually learned a lot — but according to Richard Alley, we still have a lot to learn before we’re ready to make reliable predictions.

When the rates at which ice is discharged double or triple, if that happens in enough places — and especially in east Antarctica — the rate of sea level rise could become terrifyingly high. Imagine 30 mm/yr — six times the present rate — more than an inch per year. That’s 3 meters per century, and 3 meters is about 10 feet so goodbye, Miami. Goodbye, New Orleans. Goodbye, a lot of places.

And, according to Richard Alley … this is what keeps him up at night.