Antarctic 3x warming – ‘complicated’ link to climate change

A study led by Kyle Clem from Victoria University has found that the South Pole is warming nearly three times faster than the global average. This is linked to tropical variability, and the complexity may be related to climate change but may also help mask it.

The study: Record warming at the South Pole during the past three decades

Over the last three decades, the South Pole has experienced a record-high statistically significant warming of 0.61 ± 0.34 °C per decade, more than three times the global average. Here, we use an ensemble of climate model experiments to show this recent warming lies within the upper bounds of the simulated range of natural variability.

The warming resulted from a strong cyclonic anomaly in the Weddell Sea caused by increasing sea surface temperatures in the western tropical Pacific. This circulation, coupled with a positive polarity of the Southern Annular Mode, advected warm and moist air from the South Atlantic into the Antarctic interior.

These results underscore the intimate linkage of interior Antarctic climate to tropical variability. Further, this study shows that atmospheric internal variability can induce extreme regional climate change over the Antarctic interior, which has masked any anthropogenic warming signal there during the twenty-first century.

A lot of detail follows, but it is explained more simply – Klem Kyle (ZME Science): Antarctica is warming three times faster than the rest of the world

Climate scientists long thought Antarctica’s interior may not be very sensitive to warming, but our research, published today, shows a dramatic change.

Over the past 30 years, the South Pole has been one of the fastest changing places on Earth, warming more than three times more rapidly than the rest of the world.

My colleagues and I argue these warming trends are unlikely the result of natural climate variability alone. The effects of human-made climate change appear to have worked in tandem with the significant influence natural variability in the tropics has on Antarctica’s climate. Together they make the South Pole warming one of the strongest warming trends on Earth.

Scientists have been tracking temperature at the Amundsen-Scott South Pole Station, Earth’s southernmost weather observatory, since 1957. It is one of the longest-running complete temperature records on the Antarctic continent.

Our analysis of weather station data from the South Pole shows it has warmed by 1.8℃ between 1989 and 2018, changing more rapidly since the start of the 2000s. Over the same period, the warming in West Antarctica suddenly stopped and the Antarctic Peninsula began cooling.

One of the reasons for the South Pole warming was stronger low-pressure systems and stormier weather east of the Antarctic Peninsula in the Weddell Sea. With clockwise flow around the low-pressure systems, this has been transporting warm, moist air onto the Antarctic plateau.

South Pole warming linked to the tropics

Our study also shows the ocean in the western tropical Pacific started warming rapidly at the same time as the South Pole. We found nearly 20% of the year-to-year temperature variations at the South Pole were linked to ocean temperatures in the tropical Pacific, and several of the warmest years at the South Pole in the past two decades happened when the western tropical Pacific ocean was also unusually warm.

We know from earlier studies that strong regional variations in temperature trends are partly due to Antarctica’s shape.

The East Antarctic Ice Sheet, bordered by the South Atlantic and Indian oceans, extends further north than the West Antarctic Ice Sheet, in the South Pacific. This causes two distinctly different weather patterns with different climate impacts.

More steady, westerly winds around East Antarctica keep the local climate relatively stable, while frequent intense storms in the high-latitude South Pacific transport warm, moist air to parts of West Antarctica.

Scientists have suggested these two different weather patterns, and the mechanisms driving their variability, are the likely reason for strong regional variability in Antarctica’s temperature trends.

Our analysis reveals extreme variations in South Pole temperatures can be explained in part by natural tropical variability.

These climate model simulations reveal the remarkable nature of South Pole temperature variations. The observed South Pole temperature, with measurements dating back to 1957, shows 30-year temperature swings ranging from more than 1℃ of cooling during the 20th century to more than 1.8℃ of warming in the past 30 years.

This means multi-decadal temperature swings are three times stronger than the estimated warming from human-caused climate change of around 1℃.

The temperature variability at the South Pole is so extreme it currently masks human-caused effects. The Antarctic interior is one of the few places left on Earth where human-caused warming cannot be precisely determined, which means it is a challenge to say whether, or for how long, the warming will continue.

But our study reveals extreme and abrupt climate shifts are part of the climate of Antarctica’s interior. These will likely continue into the future, working to either hide human-induced warming or intensify it when natural warming processes and the human greenhouse effect work in tandem.

So climate changes in the Antarctic are complex and linked to tropical variations, particularly in the South Pacific.

Movement of warm air from the tropics to Antarctica and cold air from Antarctica to the tropics affects New Zealand’s weather and climate.

We’ve been getting a sustained blast of Antarctic air over the past few days and that looks likely to continue through the week, with the next seven day highs predicted to be 8-11 degrees, with lows 4-6 degrees (in Dunedin). It’s deep winter so this isn’t out of the ordinary – except that so far this year snow hasn’t come to much, less than normal, but there’s plenty of winter to go.

While the study shows a rise in temperature at the South Pole since the early seventies it also shows more variability (which is one of the predicted effects of climate change):

Temperature and pressure changes at the South Pole during the modern instrumental record. a,b, Time series of the standardized South Pole annual-mean SAT (a) and running 30-yr SAT trends (°C decade−1) (b), with the 95% CI shaded in grey.

Antarctic ice melt accelerating

One of the fears of global warming was that past a ‘tipping point’ the warming and the effects of the warming could accelerate. A report suggests this could be happening.

DW: Rate of Antarctic ice melt triples since 2012, study finds

The rate of ice loss in Antarctica has tripled since 2012, causing global sea levels to rise at their fastest rate in 25 years, a new study published by an international team of experts said Wednesday

Over the last quarter century, about 3 trillion tons of Antarctic ice melt made ocean levels rise by 7.6 millimeters (0.3 inches), according to the study published in the journal Nature.  About two-fifths of that rise, or 3 millimeters, has occurred since 2012.

The study of Antarctic ice mass changes by scientists working for NASA and the European Space Agency is the most comprehensive to date. It combined 24 satellite surveys and involved 80 scientists from 42 international organizations.

The study found that from 1992 to 2011, Antarctica lost about 83.8 billion tons (76 billion metric tons) of ice per year, causing an annual sea level rise of 0.2 millimeters. Between 2012 and 2017, ice loss per year tripled to 241.4 billion tons, amounting to a 0.6 millimeters sea level rise per year.

“Under natural conditions we don’t expect the ice sheet to lose ice at all,” said lead author Andrew Shepherd of the University of Leeds in England. “There are no other plausible signals to be driving this other than climate change.”

Scientists said much of the retreating ice shelf is caused by ocean-induced melting, when warmer water causes melting from the edges and below ice sheets.

No doubt some will continue to argue against ‘climate change’ but evidence suggests that is increasingly untenable.

The signs look increasingly ominous.

Stuff:  ‘Grim future’ on the horizon as Antarctic ice melt triples

Scientists are uncertain whether this acceleration will continue at the same rate but fear unless political decisions are made to protect Antarctica the results could be catastrophic.

Sea level contribution due to the Antarctic ice sheet between 1992 and 2017, from data gathered by international ...

Better understanding in recent years about ice loss means they now also believe that if greenhouse gas emissions continue to increase as they have done in the past, sea levels could rise by up to two metres by the end of the century – double the previous estimates – putting half a billion lives at risk.

Professor Tim Naish, of the Victoria University of Wellington, who contributed to the study, said the scenario had “sent shockwaves around the world” and painted a “grim future”.

But he said there is still hope if there is concerted global collaboration to tackle global warming.

“There is still time to prevent major meltdown of the ice sheets, and other far-reaching dangerous impacts if nations collectively reduce their emissions in line with the Paris Climate Agreement target of 2C warming above pre-industrial levels,” he said.

“I think the acceleration from Antarctica represents the beginning of the effect on the ocean, which we haven’t seen until about a decade ago.

“But there is still a very valid question as to how we predict that into the future, and whether we can keep that acceleration going for 100 years or whether that part of Antarctica will stabilise a little bit and things will slow down.”

A one to two metre rise in sea levels by the end of this century would have major implications for places like Dunedin, Christchurch, Wellington, Tauranga and Auckland.

There are already issues with the current sea level. ODT: Edgar Centre warped by subsidence

Dunedin’s Edgar Centre sports complex is being lifted and lowered by the tide, as water strips away sand and leaves voids in the reclaimed land beneath the complex, reports show.

…they also showed the entire complex was being warped by subsidence, having dropped by up to 1m, and being affected by the tide as water washed through the sedimentary layers of reclaimed land the venue was built on.

And ‘Bill’ raises a valid concern at The Standard in Let’s Build a Hospital! – they are planning to build a new hospital in Dunedin on reclaimed land, but new buildings – like the stadium, have foundation piles driven down to solid rock.

How much of a rise would be needed to cut Auckland off from New Zealand? It probably isn’t the biggest issue there if the sea rises a metre or two.

Other parts of the world have much bigger worries if they take the increasing amount of scientific evidence seriously.

 

Larsen C ice shelf crack splits

A crack separating the Larsen C ice shelf in Antarctica has been growing over the last decade, increasingly quickly since 2015.

Scientists have now detected a split in the crack, and think that it won’t be long before the ice shelf splits off altogether.

Previous splits:

https://nsidc.org/news/newsroom/larsen_B/index.html

Gizmodo: A Second Giant Crack Has Appeared On Antarctica’s Larsen C Ice Shelf

A 130km-long crack along Antarctica’s Larsen C Ice Shelf has remained stable since February, but scientists have now detected a new branch, one that’s extending about 10km from the main rift. It seems like only a matter of time before the 5000 square kilometre ice shelf plunges into the sea.

Geologists with Project MIDAS, a UK-based research project studying the effects of melting on the Larsen C ice shelf, have been monitoring the crack for several years now, but the rift experienced a sudden growth spurt this past December when it grew by 20km.

In January, the crack advanced another 10km over the course of two weeks. The Larsen C Ice Shelf is fully expected to collapse, or calve, at which time it will lose more than 10 per cent of its ice surface area (a region roughly the size of Delaware). The latest observations suggest this monumental event may happen sooner rather than later.

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The current location of the rift on Larsen C, as of 1 May 2017.

A report from Project MIDAS shows that, as of 1 May 2017, a new branch has appeared along the rift. The fissure emerged about 10km behind the tip of the main channel and is heading towards the ice-front. “This is the first significant change to the rift since February of this year,” write the geologists.

See also What Happens When That Enormous Antarctic Ice Shelf Finally Breaks?

Maybe some of the remnants will float up the coast of new Zealand again, as happened in 2006.

Global sea ice at record low

 

They keep putting out stories like this.

New Scientist: Global sea ice is at lowest level ever recorded

It’s a new low point. The area of the world’s oceans covered by floating sea ice is the smallest recorded since satellite monitoring began in the 1970s. That means it is also probably the lowest it has been for thousands of years.

The latest observations from the US National Snow & Ice Data Center in Boulder, Colorado, show how the ice extent has fallen to a new low this year (bright red trace in the graph below).

picture1

In the Arctic, the low in sea ice coverage is a result of both global warming and unusual weather events probably influenced by global warming.

But in the Antarctic, the current low in seasonal sea ice could just be a result of natural variability.

The extent of Arctic sea ice should be growing rapidly during the northern hemisphere winter. But not only has the Arctic been warming rapidly, this winter repeated incursions of warm air have pushed temperatures even further above average.

Yep, there’s been cold weather in the US and European winters, and we have had an unusually cool summer here, but these are regional and short term variations. In contrast to here Australia has been hot.

And at the bottom of the world there is news of another large ice shelf crack developing: British Antarctic Survey abandons polar base as worrying crack grows in ice

Scientists at the British Antarctic Survey are abandoning their research station for the first time ever this winter after a new worrying crack developed in the ice sheet.

The renowned Halley VI ice base, from which the hole in the ozone layer was first detected, was already scheduled to be relocated 14 miles across the Brunt Ice Shelf because of an encroaching fissure in the ice.

But a new crack has been steadily growing to the north of the base, and computer modelling suggests that it could cause a large iceberg to calve away from the sheet, which could destabalise the area.

It is the latest problem to beset the base.   In 2012, satellite monitoring of the ice shelf revealed the first signs of movement in the chasm that had lain dormant for at least 35 years and, by 2013, it began opening at an alarming pace of one mile per year.  If the base does not move, it could be in danger of tumbling into the chasm by 2020.

To make matters more time critical, in October, a new crack emerged 10 miles to the north of the research station across the route sometimes used to resupply the base.

The base is crucial to studies into global issues such as the impact of extreme space weather events, climate change, and atmospheric phenomena.

That’s a bit ironic, whether the accelerating cracking is coincidental or not.

 

 

Whale Oil cites a social anthropologist as a climate change expert

Cameron Slater continues his anti-climate change agenda at Whale Oil, yesterday posting TURNS OUT THE POLES AREN’T MELTING, NOT THAT OUR MEDIA OR GOVERNMENT WILL SAY ANYTHING.

He quotes from an article featuring claims by Dr Benny Peiser from Global Warming Policy Forum (GWPF). Does Peiser sound like a well educated climate scientist?

Sourcewatch claims:

Benny Peiser (b. 1957) is a UK social anthropologist and AGW denier listed among the Heartland Institute “Global warming experts” despite having no evident expertise in climate science or policy.

Peiser was educated in West Germany and studied political science, English, and sports science in Frankfurt.

Although Peiser is described by Local Transport Today as a ‘climate policy analyst’, it is unclear what academic expertise Peiser brings to bear on his climate policy analyses.

According to a search of 22,000 academic journals, Peiser has published 3 research papers in peer-reviewed journals: Sports Medicine, 2006; Journal of Sports Sciences (2004); and, Bioastronomy 2002: life among the stars (2004). None of these studies are related to human-induced climate change.

Peiser also runs CCNet (network) to counter ‘doomsday scaremongering about the possible effects of climate change’.

Slater would ridicule someone with Peiser’s lack of relevant scientific credentials if they were on the other side of the argument. Ironically he concludes:

I can’t wait for the global fraud trials to begin…if you did in business what these so-called scientists have done you’d be sharing a cell with Bernie Madoff or David Ross.

I doubt if he means Peiser as a “so-called scientist”.

And what about whether the poles are melting? It’s not hard to find alternate more scientific views to Dr Benny Peiser and Cameron Slater.

Smithsonian: Ice Melt at the Poles

It’s confirmed: both Antarctica and Greenland are losing ice—around 350 billion tons each year—and, as a result, sea level has risen 11.1 millimeters worldwide since 1992. This photo shows a summertime channel created by the flow of melted ice, which ultimately carries the water away from the glacier to the sea.

It’s not easy to measure melting ice. But by using data from 10 satellite missions, an international team of 47 scientists put together the most accurate estimate of ice melt to date. Ice melt doesn’t just affect sea level, however: the influx of fresh water could change the salinity of the North Atlantic enough to alter weather patterns in North America and affect ocean organisms.

National Snow and Ice Data Center – Artic Sea Ice News and Analysis

Arctic sea ice extent for November was the 9th lowest in the satellite record. Through 2014, the linear rate of decline for November extent over the satellite record is 4.7% per decade.

Antarctic sea ice has continued to decline at a faster-than-average pace (approximately 122,000 square kilometers, or 47,100 square miles per day through the month of October, compared to the average rate of 112,000 square kilometers or 43,200 square miles per day), and is now about 650,000 square kilometers (251,000 square miles) below the level for the date recorded in 2013. Currently ice extent remains about 700,000 square kilometers (270,000 square miles) higher than the 1981 to 2010 average for this time of year.

But what would they know? They aren’t social anthropologists or agenda promoting bloggers.

But an alternate view has been allowed to counter Slater’s claims. See the thread started by Mythrandir.

Another comment, by Gaynor, remains unchallenged:

What would be so wrong with ice free poles? Don’t we need more land for our growing population?

An ice free north pole (Arctic) would not provide more land, there is no land there.

An ice free Greenland would raise sea levels by about 7 metres.

An ice free Antarctic would raise sea levels by about 61 metres.

That would flood a huge amount of land in more habitable parts of the world.

Source: If the polar ice caps melted, how much would the oceans rise?

If the rising temperature affects glaciers and icebergs, could the polar ice caps be in danger of melting and causing the oceans to rise? This could happen, but no one knows when it might happen.

The main ice covered landmass is Antarctica at the South Pole, with about 90 percent of the world’s ice (and 70 percent of its fresh water). Antarctica is covered with ice an average of 2,133 meters (7,000 feet) thick. If all of the Antarctic ice melted, sea levels around the world would rise about 61 meters (200 feet). But the average temperature in Antarctica is -37°C, so the ice there is in no danger of melting. In fact in most parts of the continent it never gets above freezing.

At the other end of the world, the North Pole, the ice is not nearly as thick as at the South Pole. The ice floats on the Arctic Ocean. If it melted sea levels would not be affecte­d.

There is a significant amount of ice covering Greenland, which would add another 7 meters (20 feet) to the oceans if it melted. Because Greenland is closer to the equator than Antarctica, the temperatures there are higher, so the ice is more likely to melt

Of course it’s very unlikely all the world’s ice will melt in the forseeable future. But a metre or two of sea level rise would cause far more problems than it would help.