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Antarctica 2019

Antarctica 2019

Unread postby Tanada » Thu 03 Jan 2019, 19:16:16

Into the ice world: Drilling into Antarctica's Mt Erebus

Herald science reporter Jamie Morton is profiling a series of new studies taking place in Antarctica, where he travels to this month. Today, he talks to the University of Waikato's Professor Craig Cary.

Hidden within Antarctica's most active volcano could be a key to understanding life on other planets – and now scientists plan to drill into it.

The geothermal features found on Mt Erebus, overlooking New Zealand's Scott Base, are home to an abundance of micro-organisms with some extremely unusual features.

Scientists believe they may even have the potential to change how we understand life itself.

In a previous study, Waikato University microbiologist Professor Craig Cary and colleagues dug just 12cm into the soil on the mountain to find a remarkable variety of bacteria living just below the surface.

Cary said those very near the surface were very closely related with other such organisms living in geothermal systems elsewhere in the world – a finding that suggested these microscopic beings were being continually dispersed around the planet through the atmosphere.

"In this case, they could have originated from a massive volcano going off sometime in the past and moving them around the world and into other geothermal sites."

But, more interestingly, they also discovered bacteria that are not only appear endemic to Erebus but ancient when compared to those living today.

"As we went deeper and deeper into the soil, it wasn't just novel bacteria we were finding – but possibly bacteria that are adapting to the novel geochemistry, or gases, at Erebus," he said.

"We have known for over a hundred years that there are bacteria that can live and grow on energy bound up in certain chemicals common to geothermal systems when normal carbon-based food is limited.

"What is new on Erebus is that these chemicals are not abundant and yet we find bacteria thriving in this carbon limited environment."

"We know there's a lot of unique geochemistry on Erebus – but so far have not figured out how any bacteria are actually able to utilise it."

In a new three-year programme, just awarded a $935,000 grant from the Marsden Fund, a team led by Cary and Dr Matt Stott of the University of Canterbury will return to Erebus to investigate further.

They'd first drill directly into the volcano and use some new exciting approaches to grow the bacteria, before using a range of genomic methods to work out how they function and survive.

The team hoped to uncover new biological mechanisms for life that have never been seen, yet remained theoretically feasible.

"Put simply, we only know what we know," Cary said.

"Our current notion of life is very constrained around what we've already found and have been able to grow.

"And, at Erebus, we believe there is an isolated system with novel geochemistry that can drive completely unusual mechanisms to support life – and this would be appropriate for looking for life on other planets."

It's not the only major new study exploring Antarctica's incredible microbial communities.

Another project, led by Cary's Waikato University colleague Dr Adele Williamson, is attempting to reveal how the hardy microbes that live amid the McMurdo Dry Valleys' alien-like conditions can survive by repairing their own DNA.


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Re: Antarctica 2019

Unread postby Plantagenet » Fri 04 Jan 2019, 17:32:00

Antarctic sea ice hits record low extent for January

antarctic-sea-ice-melts-record-low-january-

Normally sea ice in Antarctica shrinks through January and into late February as the Antarctic summer progresses, but on Jan. 1 the Antarctic sea ice was already at a record low extent for the month.

There is an extraordinary amount of sea ice melting going on right now in Antarctica.

Every day of melting in January creates a new record.

Most likely in Feb or early March we'll see the all-time record low for Antarctic sea ice extent!

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Re: Antarctica 2019

Unread postby Tanada » Sat 05 Jan 2019, 21:40:31

On December 26, Antarctic sea ice extent fell below the low mark for this date, set in 2016, and has continued to track below all other years. Notably, the November to December 2016 period was considered an extreme excursion of Antarctic sea ice at the time. However, since then Antarctic sea ice extent has continually remained below the 1981 to 2010 median and mostly below the interquartile extent (below 75 percent of the 30-year range of values). This change in behavior, which began during the austral spring of 2016, contradicts prior characterizations of Antarctic sea ice cover as slowly expanding, yet highly variable. Instead, another strong decline through late December 2018 has taken the extent below the November and December 2016 levels to new record lows. Antarctica’s high year-to-year variability (record high extents for December were observed as recently as 2014 and 2007) suggests that a conclusive sea ice trend associated with the warming air and ocean around Antarctica has yet to reveal itself.


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Re: Antarctica 2019

Unread postby Tanada » Sat 05 Jan 2019, 21:41:31

On January 1, Antarctic sea ice extent stood at 5.47 million square kilometers (2.11 million square miles), the lowest extent on this date in the satellite record (since 1978). This value is 30,000 square kilometers (11,600 square miles) below the previous record low for January 1, set in 2017, and 1.88 million square kilometers (726,000 square miles) below the 1981 to 2010 average. Extent declined at a rate of 253,000 square kilometers (97,700 square miles) per day through December, considerably faster than the 1981 to 2010 mean for December of 214,000 square kilometers (82,600 square miles) per day. Indeed, the rate of Antarctic ice extent loss for December 2018 is the fastest in the satellite record, albeit close to 2010 and 2005.


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Re: Antarctica 2019

Unread postby dohboi » Mon 14 Jan 2019, 21:34:13

https://www.axios.com/antarctica-ice-lo ... ac863.html

Antarctica is losing ice six times faster than in 1980s
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Re: Antarctica 2019

Unread postby GHung » Thu 31 Jan 2019, 09:26:17

Gigantic hole two-thirds the size of Manhattan discovered in Antarctic glacier

A massive cavity two-thirds the size of Manhattan has been discovered growing in an Antarctic glacier, signaling rapid ice decay that has shocked scientists.
The huge hole -- measuring almost 1,000 feet (300 meters) tall -- was found growing at an "explosive rate" at the bottom of a glacier in West Antarctica, said NASA's Jet Propulsion Laboratory in a statement Wednesday.
The Thwaites Glacier is around the size of Florida, and the team of NASA-led scientists researching it had expected to find "some gaps" between the ice and bedrock.

"The size and explosive growth rate of the newfound hole, however, surprised them," they said.

The cavity was "big enough to have contained 14 billion tons of ice, and most of that ice melted over the last three years," they added.
By observing the undersides of Antarctic glaciers, researchers hope to calculate how fast global sea levels will rise in response to climate change. ....

....The glacier holds "enough ice to raise the world ocean level a little over 2 feet (65 centimeters)," said the team. Thwaites also "backstops neighboring glaciers that would raise sea levels an additional 8 feet (2.4 meters) if all the ice were lost," they added.
https://www.cnn.com/2019/01/31/health/a ... index.html
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Re: Antarctica 2019

Unread postby Plantagenet » Thu 31 Jan 2019, 12:35:31

Once that hole under the Thwaites Glacier gets big enough, the ice in the glacier above will begin to collapse down into the hole, calving off huge bergs. This is a very rapid process, and the glacier front will begin to retreat as it comes off its grounding line.

This kind of rapid calving retreat is how Glacier Bay was created in 100 years up here in Alaska, and how Jacobshaven glacier is currently retreating in Greenland.

One of the most wonderful experiences I ever had was camping on a ledge next to glacier in SE Alaska to make time-lapse movies of the ice calving off over the course of several days. The giant ice collapses and the spectacular impulse waves produced by the calving ice are amazing to see.

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Rapid ice retreat in Glacier Bay, Alaska

I expect this process will begin at the Thwaites fairly soon.

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Re: Antarctica 2019

Unread postby chilyb » Fri 01 Feb 2019, 12:54:34

Here is the study featured in GHung's link above:

http://advances.sciencemag.org/content/5/1/eaau3433\

The glaciers flowing into the Amundsen Sea Embayment, West Antarctica, have undergone acceleration and grounding line retreat over the past few decades that may yield an irreversible mass loss. Using a constellation of satellites, we detect the evolution of ice velocity, ice thinning, and grounding line retreat of Thwaites Glacier from 1992 to 2017. The results reveal a complex pattern of retreat and ice melt, with sectors retreating at 0.8 km/year and floating ice melting at 200 m/year, while others retreat at 0.3 km/year with ice melting 10 times slower. We interpret the results in terms of buoyancy/slope-driven seawater intrusion along preferential channels at tidal frequencies leading to more efficient melt in newly formed cavities. Such complexities in ice-ocean interaction are not currently represented in coupled ice sheet/ocean models.


rockdoc123, if you are still out there, I'd be interested in learning if you think this new finding of "irreversible" sub-sea melt fits together with the model of ice sheet dynamics DeConto and Pollard published in Nature. Based on our prior discussions, you seem to be one of the more well-versed on the subject around here.

Here's a link to the 2016 Nature article again:

https://www.nature.com/articles/nature17145

Here we use a model coupling ice sheet and climate dynamics—including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs—that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated.


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Re: Antarctica 2019

Unread postby dohboi » Wed 06 Feb 2019, 15:14:17

MICI = Marine Ice Cliff Instability
Thanks to alsr at asif for links and text

The linked article (and following associated references), cites recent model work about ice sheet stability that gives more conservative estimates of abrupt ice mass lost from ice sheets this century, than that predicted by Pollard & DeConto (2016). However, for me one critical consideration about these findings is the both Pollard & DeConto declined to serve as co-authors for this work because they believe that the projected SLR are too conservative.

Title: "Studies shed new light on Antarctica’s future contribution to sea level rise"

https://www.carbonbrief.org/studies-she ... level-rise

Extract: "The findings of the new study show that “the jury’s definitely still out on MICI”, says Edwards. There is a real lack of published studies that incorporate the process, she says, adding: “We really need much higher resolution models to try including it, which test different representations.”

However, it certainly “does not mean that MICI is irrelevant and must be forgotten”, says Dr Cyrille Mosbeux, a postdoctoral scholar at the Scripps Institution of Oceanography who was not involved in either study. He tells Carbon Brief: “We still need to take account for as many processes as possible” in sea level rise estimates.

As “very little is known about MICI and it is hard to predict its effect in the future”, the new findings emphasise the need for improved models and continued observations around Antarctica, he adds.

Considering the theory of MICI was proposed less than eight years ago, it is still very early in terms of refining the estimates of what impact it could have. However, as scientific disagreements go, this is definitely the more cordial kind. Both DeConto and Pollard were originally co-authors on the new paper. They later recused themselves because they felt the results coming from Edwards’s statistical model were not consistent with what they were seeing from their own physics-based glacier model."

See also:

Edwards, T. L. et al. (2019) Revisiting Antarctic ice loss due to marine ice-cliff instability, Nature, doi:10.1038/s41586-019-0901-4

https://www.nature.com/articles/s41586-019-0901-4

&
Golledge, N. R. et al. (2019) Global environmental consequences of twenty-first-century ice-sheet melt, Nature, doi:10.1038/s41586-019-0889-9

https://www.nature.com/articles/s41586-019-0889-9

&
Seroussi, H. (2019) Fate and future role of polar ice sheets, Nature
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Re: Antarctica 2019

Unread postby dohboi » Wed 06 Feb 2019, 15:31:14

https://www.mprnews.org/story/2019/02/0 ... hAlK_mhNb0

What changes Will Steger saw on his latest Antarctica trip
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Re: Antarctica 2019

Unread postby Plantagenet » Wed 06 Feb 2019, 15:59:37

The rapid retreat of huge tidewater glaciers in Alaska and Greenland due to. MICI is very well documented.

I don’t se any reason why the same process shouldn’t also operate in Antarctica

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