Posts Tagged ‘Antarctic’

Antarctica


The article says ‘The satellite measurements start in 1979’, but the USGS Landsat satellite project has been ‘imaging the Earth since 1972’. The researchers say in the abstract of their paper: ‘In stark contrast to the Arctic, there have been statistically significant positive trends in total Antarctic sea ice extent since 1979. However, the short and highly variable nature of observed Antarctic sea ice extent limits the ability to fully understand the historical context of these recent changes.’ The UK Met Office reported in October 2021: ‘Antarctic sea ice reached a maximum extent (to date) of 18.75 million sq km on 1st September 2021 (Figure 7), which is very close to the 1981-2010 average maximum extent of 18.70 million sq km.’
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A study led by Ohio University researchers shows that the increase of sea ice surrounding Antarctica since 1979 is a unique feature of Antarctic climate since 1905—an observation that paints a dramatic first-ever picture for weather and climate implications on the world’s southernmost continent, says Phys.org.

Dr. Ryan Fogt’s study, published today in Nature Climate Change, is the first to detail sea ice extent surrounding the entire continent though all four seasons over the last century.

Weather, especially winds and temperatures, contribute to sea ice changes. Fogt is professor of Geography in OHIO’s College of Arts and Sciences.

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Ice core sample [image credit: Discovering Antarctica]


Previous studies indicated temperature change preceded CO2 change, but the BBC says they occurred ‘in parallel’ or ‘in lockstep’, obscuring the key role of insolation while waffling about supposedly ‘heat trapping’ gases.
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Efforts are about to get under way to drill a core of ice in Antarctica that contains a record of Earth’s climate stretching back 1.5 million years, says BBC News.

A European team will set up its equipment at one of the highest locations on the White Continent, for an operation likely to take four years.

The project aims to recover a near-3km-long cylinder of frozen material.

Scientists hope this ice can help them explain why Earth’s ice ages flipped in frequency in the deep past.

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Antarctic sea ice [image credit: BBC]

We’re asked to believe this is just a blip in the relentless march of supposedly human-caused global warming, but let’s give it a few more years to see how things progress.
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Antarctica’s frigid winter temperatures are in contrast to trends in the rest of the world, which overall recorded its fourth hottest summer, says LiveScience.

Between April and September, a research station sitting on a high plateau in Antarctica, registered an average temperature of minus 78 degrees Fahrenheit (minus 61 degrees Celsius).

That’s the coldest temperature recorded since record keeping began in 1957, and about 4.5 F (2.5 C) lower than the most recent 30-year average, according to The Washington Post.

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antarcmap

Antarctica

More meltdown than melting. The author reckons ‘Tackling global warming will be the central project of the 21st Century’, but the NSIDC graphic below doesn’t suggest anything alarming. No doubt the BBC will be offsetting all those supposedly wicked ‘carbon emissions’ from flying a reporter round the world. Sadly the trip only extended to West Antarctica, parts of which are close to a significant volcanic region, whereas the majority of the ice is in East Antarctica. See: Scientists discover 91 volcanoes below Antarctic ice sheet. In 2015 a NASA study reported ice gains exceeding losses in Antarctica as a whole, with the net losses being in the west and the net gains in the east.
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A trip to a melting glacier will shape how the BBC’s new climate editor reports on climate change, says the BBC.

You cannot help but be awed by the scale of Antarctica, the great white continent.

I visited just before the pandemic struck and it is impossible not to feel humbled in the presence of something that seems so much bigger and more powerful than you.

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Antarctic sea ice [image credit: BBC]


Warming, but not global – is the polar see-saw hypothesis in play here? In any case, it seems climate models are falling short again.
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Sea ice in the Southern Ocean defies predictions.

Observations show that ice extent in the Antarctic has been growing slightly, reports The Global Warming Policy Forum (GWPF).

Paul Holland, a climate modeler with the British Antarctic Survey, has spent the last ten years studying Antarctica’s sea ice and the Southern Ocean.

Lately, he has been scrutinizing the seasons of Antarctica and how fast the ice comes and goes.

Holland thinks these seasons may be a key to a conundrum: If Earth’s temperatures are getting warmer and sea ice in the Arctic has been shrinking fast, why then is sea ice in the Antarctic slowly increasing?

Opposite poles

Sea ice is simply frozen seawater. Although found only in the Arctic and the Antarctic, it influences Earth’s climate in big ways. Its bright surface reflects sunlight back into space. Icy areas absorb less solar energy and remain relatively cool.

When temperatures warm over time and more sea ice melts, fewer bright surfaces reflect sunlight back into space. The ice and exposed seawater absorb more solar energy and this causes more melting and more warming.

Scientists have been watching this feedback loop of warming and melting in the Arctic. To them, Arctic sea ice is a reliable indicator of a changing global climate. They pay the most attention in September when Arctic sea ice shrinks to its smallest extent each year. Measured by satellites since 1979, this minimum extent has been decreasing by as much as 13.7 percent per decade.

Antarctic sea ice, on the other hand, has not been considered a climate change indicator. Whereas Arctic sea ice mostly sits in the middle of land-locked ocean—which is more sensitive to sunlight and warming air—Antarctic sea ice surrounds land and is constantly exposed to high winds and waves.

According to climate models, rising global temperatures should cause sea ice in both regions to shrink. But observations show that ice extent in the Arctic has shrunk faster than models predicted, and in the Antarctic it has been growing slightly.

Researchers are looking much closer at Antarctica, saying, “Wait, what is going on down there?” Holland is one of those intrigued.

“The Antarctic case is as interesting as the Arctic case,” Holland said. “You can’t understand one without understanding the other.”

Minding the models

To Holland, the discrepancy calls parts of the climate models into question.

Continued here.

NASA pdf: https://cdn.earthdata.nasa.gov/conduit/upload/756/NASA_SOP_2014_unexpected_ice.pdf

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The NLCs are playing a game of hide-and-seek this season, bemusing regular observers.

Spaceweather.com

Jan. 8, 2021:

They’re back. Noctilucent clouds (NLCs), recently missing, are once again circling the South Pole. And, in an unexpected twist, they’ve just appeared over Argentina as well.

“This is a very rare event,” reports Gerd Baumgarten of Germany’s Leibniz-Institute of Atmospheric Physics, whose automated cameras caught the meteoritic clouds rippling over Rio Grande, Argentina (53.8S) on Jan. 3rd:

A second camera recorded the clouds at even higher latitude: Rio Gallegos (51.6S). At this time of year, noctilucent clouds are supposed to be confined to the Antarctic–not Argentina. In the whole history of atmospheric research, NLCs have been sighted at mid-southern latitudes only a handful of times.

“Personally, I am thrilled to see NLCs in Argentina, as I had not expected them to occur so far north,” says Natalie Kaifler of the German Aerospace Center (DLR), who operates a lidar (laser radar) alongside one of Baumgarten’s…

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Is it a coincidence that we’re just past the end of the lowest sunspot cycle for over a century?

Spaceweather.com

Dec. 28, 2020: Something strange is happening 50 miles above Antarctica. Or rather, not happening. Noctilucent clouds (NLCs), which normally blanket the frozen continent in December, are almost completely missing. These images from NASA’s AIM spacecraft compare Christmas Eve 2019 with Christmas Eve 2020:

“The comparison really is astounding,” says Cora Randall of the University of Colorado’s Laboratory for Atmospheric and Space Physics. “Noctilucent cloud frequencies are close to zero this year.”

NLCs are Earth’s highest clouds. They form when summertime wisps of water vapor rise up from the poles to the edge of space. Water crystallizing around specks of meteor dust 83 km (~50 miles) above Earth’s surface creates beautiful electric-blue structures, typically visible from November to February in the south, and May to August in the north.

A crucial point: Noctilucent clouds form during summer. And that’s the problem. Although summer officially started in Antarctica one week…

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Antarctica


If they were hoping to see a steady rate of change that matched carbon dioxide emission levels, they were disappointed. Natural variations inconveniently got in the way, two in particular: ‘When two extreme snowfall events in 2009 and 2011 dropped around 600 gigatons of snow and ice, the East Antarctic Ice Sheet thickened so much that it temporarily halted the entire continent’s ice losses, said Wang—a pattern that had previously escaped notice.’
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A new analysis of long-term satellite records shows the East Antarctic Ice Sheet is unexpectedly dependent on fluctuations in weather.

This study may improve models of how much sea levels will rise, says Eos News.

As more coastal communities face the looming threat [Talkshop note: unsupported assertion] of rising sea levels, it’s more important than ever to accurately predict changes in one of the greatest potential sources of sea level rise—the melting of Antarctica’s massive ice sheet.

Recently, scientists analyzed nearly 2 decades’ worth of data from sensitive NASA satellites documenting mass changes in the Antarctic Ice Sheet.

They found the ice inventory ebbed and flowed across the continent in unexpectedly variable patterns.

Traditionally, some groups of Antarctic researchers have assumed the rate of change across the ice sheet is constant, but they drew their conclusions from data sets that spanned only a few years, said Lei Wang, a geodesist at The Ohio State University who will present this research at AGU’s virtual Fall Meeting 2020.

“These long data records give us the capability to characterize the ice sheet’s variation over a range of timescales,” rather than just modeling seasonal variations and short-term trends, Wang said.

Understanding Long-Term Trends

The Antarctic Ice Sheet, the largest mass of ice on Earth, is divided into two unequal portions, with the East Antarctic Ice Sheet covering about two thirds of the continent. The West Antarctic Ice Sheet, although smaller, has historically been more closely studied because it’s melting faster. (The East Antarctic Ice Sheet sits on bedrock above sea level, said Wang, so it is less susceptible to the effects of the warming ocean.) NASA estimates Antarctica has lost 149 billion metric tons of ice per year since 2002.

When so much ice is involved, projections of how sea levels will respond are uncertain—especially when trends already are so difficult to gauge.

Indeed, the field still argues about sea level changes in the past century, said Jim Davis, the study coauthor and a geodesist at the Lamont-Doherty Earth Observatory at Columbia University. “We’ve got to get to the point where we can talk about what’s happening this year in sea level change,” he said.

To do that, researchers need a more sophisticated model of how Antarctica’s shield of ice is evolving.

Full article here.

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Is La Niña having an effect on Antarctica already?

Spaceweather.com

Dec. 2, 2020: Consider it the tip of the iceberg. Noctilucent clouds (NLCs) over the south pole are AWOL.

“Normally we see the first NLCs of the southern season around Nov. 21st,” says Cora Randall of the University of Colorado’s Laboratory for Atmospheric and Space Physics (LASP). “But this year, it’s already December and we’re still waiting.”

Above: What a different one year makes. NASA’s AIM spacecraft took these pictures of NLCs over Antarctica on Nov. 29, 2019 (left) and Nov. 29, 2020 (right)

Missing NLCs is just one of the curious weather patterns currently underway at the southern end of our planet.

Making a list: (1) Earth’s southern ozone hole is not only open, but also the biggest it’s ever been in December. (2) The air above Antarctica is currently at record cold levels for this time of year–the result of an icy polar vortex that refuses to break…

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Credit: earthhow.com


As Accuweather explains here, research has shown that a combination of conditions at solar minimum can create this effect.
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The European Union’s Earth observation program said Tuesday that the ozone hole over Antarctica has swelled to its largest size and deepest level in years, reports Phys.org.

Experts at the Copernicus Atmospheric Monitoring Service said a strong, stable and cold polar vortex has driven the expansion, and called for greater international efforts to ensure countries abide by an international accord to phase out use of ozone-depleting chemicals.

Vincent-Henri Peuch, who heads the service, said in a statement that the ozone hole was “definitely” among the largest in the last 15 years.

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So when global temperatures failed to behave as models expected due to inevitable but hard to predict natural variation, they were forced to re-think – or just think? The GWPF concludes, at the risk of stating the obvious: ‘The lesson of the hiatus is that we do not understand internal climatic variability as much as many think we do, and our predictive power is less than many believe.’
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Researchers from the Universities of Princeton, California, Tokyo, Kyushu and the Scripps Institution of Oceanography, say the recent hiatus in global temperature increase has led to a surge in climate science.

The global effort to understand the global warming hiatus they say has led to increased understanding of some of the key metrics of global climate change such as global temperature and ice-cover.

Searching for an answer to the hiatus, they say, meant that the scientific community grappled with difficulties with these climate metrics, in particular the fact that they do not unequivocally portray the same story about global warming.

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Kangerlussuaq Fjord, Greenland [image credit: notsogreen.com]


Less than a year ago NASA was reporting from Greenland: Jakobshavn Glacier Grows for Third Straight Year, and ‘The glacier grew 22 to 33 yards (20 to 30 meters) each year between 2016 and 2019.’ So this new report may be, to some degree at least, already obsolete since it says: ‘The largest thinning rates were between 4 and 6 m a−1 in Jakobshavn and Kangerlugssuaq glaciers’.
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Sea levels have risen by 14mm since 2003 due to ice melting in Antarctica and Greenland, scientists have said.

Nasa launched a satellite to measure global heights in 2018 and spotted the rise after bouncing laser pulses against sheets of ice, says the London Evening Standard.

The study found that Greenland lost an average of 200 billion tonnes of ice per year, and Antarctica lost an average of 118 billion tonnes.

One billion tonnes of ice is enough to fill 400,000 Olympic-sized swimming pools.

A team led by researchers at the University of Washington compared the data with measurements taken by the satellite between 2003 and 2009.

The findings, published in the journal Science, found the loss of ice from Antarctica and Greenland outweighs any gains from accumulated snow.

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The researchers estimate that carbon dioxide levels in the atmosphere were well over 1000 parts per million in those days, compared to 400+ ppm today. Antarctica and Australia were much closer together.

Antarctica was covered in rainforest in the time of the dinosaurs, according to a new study, Metro News reports.

Researchers have found evidence the South Pole had a climate and forests similar to New Zealand today in a startling discovery. The team discovered soil from an ancient rainforest from the Cretaceous period within 900 km of the South Pole.

The analysis carried out by an international team of researchers of roots, pollen and spores shows the world was a lot warmer than previously thought.

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Significant changes since 2007 or so are observed but not explained, which seems to leave them open to interpretation. To get that ball rolling the recent solar slowdown could be mentioned.
A 2015 NASA study said that ‘an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.’

Using the latest satellite technology from the European Space Agency (ESA), scientists from the University of Bristol have been tracking patterns of mass loss from Pine Island — Antarctica’s largest glacier, reports SciTechDaily.

They found that the pattern of thinning is evolving in complex ways both in space and time with thinning rates now highest along the slow-flow margins of the glacier, while rates in the fast-flowing central trunk have decreased by about a factor of five since 2007.

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Rinks Glacier, West Greenland
[image credit: NSIDC]


Estimates are always uncertain to some degree – that’s why they’re called estimates. So an uncertain estimate can’t be all that useful. They admit ‘there are still key deficiencies in the models’ — but these are usually ignored when alarmist climate predictions are headlined. As ever, ice-related sea level claims should be taken with a large pinch of salt.

Estimates used by climate scientists to predict the rate at which the world’s ice sheets will melt are still uncertain despite advancements in technology, new research shows.

These ice sheet estimates feed directly into projections of sea-level rise resulting from climate change, says Phys.org.

They are made by measuring how much material ice sheets are gaining or losing over time, known as mass balance, to assess their long-term health.

Snowfall increases the mass of an ice sheet, while ice melting or breaking off causes it to lose mass, and the overall balance between these is crucial.

Although scientists now have a much better understanding of the melting behaviour of ice sheets than they did in previous decades, there are still significant uncertainties about their future melt rates, researchers found.

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Unusual goings-on seen in the skies over New Zealand.

Spaceweather.com

Dec. 4, 2019: An atmospheric wave nearly half as wide as Earth itself is supercharging noctilucent clouds (NLCs) in the southern hemisphere. NASA’s AIM spacecraft detected the phenomenon in this series of south polar images spanning Nov. 27th through Dec. 2nd:

fiveday

“This is a clear sign of planetary wave activity,” says AIM principal investigator James Russell of Hampton University, which manages the Aeronomy of Ice in the Mesosphere mission for NASA.

Planetary waves are enormous ripples of temperature and pressure that form in Earth’s atmosphere in response to Coriolis forces. In this case, a 5-day planetary wave is boosting noctilucent clouds over Antarctica and causing them to spin outward to latitudes where NLCs are rarely seen.

On Dec. 1st, Mirko Harnisch saw the clouds from Dunedin, New Zealand. “I was enjoying the late-evening sky over the Southern Ocean just after 11 pm local time when these wispy blue-ish clouds appeared,”…

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Image credit: extremetech.com


A 2016 article in Astronomy Now reported:
“Scientists found radioactive iron-60 in sediment and crust samples taken from the Pacific, Atlantic and Indian Oceans.

The iron-60 was concentrated in a period between 3.2 and 1.7 million years ago, which is relatively recent in astronomical terms, said research leader Dr. Anton Wallner from The Australian National University (ANU).

“We were very surprised that there was debris clearly spread across 1.5 million years,” said Dr. Wallner, a nuclear physicist in the ANU Research School of Physics and Engineering. “It suggests there were a series of supernovae, one after another.

“It’s an interesting coincidence that they correspond with when the Earth cooled and moved from the Pliocene into the Pleistocene period.” [bold added]

In August this year a new find was reported…
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The rare isotope iron-60 is created in massive stellar explosions, says ScienceDaily. Only a very small amount of this isotope reaches the earth from distant stars.

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‘Long-term’ here means really long-term. The 21k year precession period quoted looks like that of the perihelion.

In the past million years, the high-altitude winds of the southern westerly wind belt, which spans nearly half the globe, didn’t behave as uniformly over the Southern Pacific as previously assumed.

Instead, they varied cyclically over periods of ca. 21,000 years, reports ScienceDaily.

A new study has now confirmed close ties between the climate of the mid and high latitudes and that of the tropics in the South Pacific, which has consequences for the carbon budget of the Pacific Southern Ocean and the stability of the West Antarctic Ice Sheet.

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A reconstruction of the Anglian ice sheet in Precambrian North London (credit: BBC / The Natural History Museum, London)


This might rattle a few cages in climate-land.

An analysis of air up to 2 million years old, trapped in Antarctic ice, shows that a major shift in the periodicity of glacial cycles was probably not caused by a long-term decline in atmospheric levels of carbon dioxide, writes Eric W. Wolff in Nature.
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During the past 2.6 million years, Earth’s climate has alternated between warm periods known as interglacials, when conditions were similar to those of today, and cold glacials, when ice sheets spread across North America and northern Europe.

Before about 1 million years ago, the warm periods recurred every 40,000 years, but after that, the return period lengthened to an average of about 100,000 years.

It has often been suggested that a decline in the atmospheric concentration of carbon dioxide was responsible for this fundamental change.

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Ross Ice Shelf, Antarctica


Is there an element of circular reasoning here? Carbon dioxide levels have historically followed temperature changes, bringing any supposed causation into question.

Upside-down “rivers” of warm ocean water may be one of the causes of Antarctica’s ice shelves breaking up, leading to a rise in sea levels.

But a new study suggests an increase in sea ice may lead to a much more devastating change in the Earth’s climate — another ice age, reports Fox News.

Using computer simulations, the research suggests that an increase in sea ice could significantly alter the circulation of the ocean, ultimately leading to a reverse greenhouse effect as carbon dioxide levels in the ocean increase and levels in the air decrease.

“One key question in the field is still what caused the Earth to periodically cycle in and out of ice ages,” University of Chicago professor and the study’s co-author, Malte Jansen, said in a statement. “We are pretty confident that the carbon balance between the atmosphere and ocean must have changed, but we don’t quite know how or why.”

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