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Antarctica 2018

Re: Antarctica 2018

Unread postby jawagord » Tue 13 Mar 2018, 09:41:24

Another Antarctic summer, another scientists stranded by sea ice story.

The Laurence M. Gould research vessel, seen in a file image, was unable to reach a team of U.S. researchers stuck on an ice-bound island off Antarctica's coast, the National Science Foundation said, March 10, 2018.

Argentina sent the icebreaker ship after receiving a request for assistance on Friday, the country’s foreign ministry said Saturday. The Argentine ship has helicopters able to reach the group’s camp “regardless of the ice conditions,” the National Science Foundation, a U.S. government agency, said.

https://www.yahoo.com/gma/american-scie ... ories.html
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Re: Antarctica 2018

Unread postby Plantagenet » Tue 13 Mar 2018, 13:01:08

I'm scheduled to be in that area about a year from now. I hope they get things sorted out by then. 8)
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Re: Antarctica 2018

Unread postby dohboi » Mon 19 Mar 2018, 22:36:32

More evidence that ice mass loss from Antarctica is accelerating:

Schröder, L., Horwath, M., Dietrich, R., and Helm, V.: Four decades of surface elevation change of the Antarctic Ice Sheet from multi-mission satellite altimetry, The Cryosphere Discuss., https://doi.org/10.5194/tc-2018-49, in review, 2018.

https://www.the-cryosphere-discuss.net/tc-2018-49/

Abstract. We developed an approach for a multi-mission satellite altimetry analysis over the Antarctic Ice Sheet which comprises Seasat, Geosat, ERS-1, ERS-2, Envisat, ICESat and CryoSat-2. In a first step we apply a consistent reprocessing of the radar alitmetry data which improves the measurement precision by up to 50 %. We then perform a joint repeat altimetry analysis of all missions. We estimate inter-mission offsets by approaches adapted to the temporal overlap or non-overlap and to the similarity or dissimilarity of involved altimetry techniques. Hence, we obtain monthly grids forming a combined surface elevation change time series. Owing to the early missions Seasat and Geosat, the time series span almost four decades from 07/1978 to 12/2017 over 25 % of the ice sheet area (coastal regions of East Antarctica and the Antarctic Peninsula). Since the launch of ERS-1 79 % of the ice sheet area is covered by observations. Over this area, we obtain a negative volume trend of −34 ± 5 km3 yr−1 for the more than 25-year period (04/1992–12/2017). These volume losses have significantly accelerated to a rate of −170 ± 11 km3 yr−1 for 2010–2017. Interannual variations significantly impact decadal volume rates which highlights the importance of the long-term time series. Our time series show a high coincidence with modeled cumulated precipitation anomalies and with satellite gravimetry. This supports the interpretation with respect to snowfall anomalies or dynamic thinning. Moreover, the correlation with cumulated precipitation anomalies back to the Seasat and Geosat periods highlights that the inter-mission offsets were successfully corrected and that the early missions add valuable information.
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Re: Antarctica 2018

Unread postby Plantagenet » Tue 20 Mar 2018, 17:59:08

dohboi wrote:More evidence that ice mass loss from Antarctica is accelerating:

Schröder, L., Horwath, M., Dietrich, R., and Helm, V.: Four decades of surface elevation change of the Antarctic Ice Sheet from multi-mission satellite altimetry, The Cryosphere Discuss., https://doi.org/10.5194/tc-2018-49, in review, 2018.

https://www.the-cryosphere-discuss.net/tc-2018-49/

Abstract. We developed an approach for a multi-mission satellite altimetry analysis over the Antarctic Ice Sheet which comprises Seasat, Geosat, ERS-1, ERS-2, Envisat, ICESat and CryoSat-2. In a first step we apply a consistent reprocessing of the radar alitmetry data which improves the measurement precision by up to 50 %. We then perform a joint repeat altimetry analysis of all missions. We estimate inter-mission offsets by approaches adapted to the temporal overlap or non-overlap and to the similarity or dissimilarity of involved altimetry techniques. Hence, we obtain monthly grids forming a combined surface elevation change time series. Owing to the early missions Seasat and Geosat, the time series span almost four decades from 07/1978 to 12/2017 over 25 % of the ice sheet area (coastal regions of East Antarctica and the Antarctic Peninsula). Since the launch of ERS-1 79 % of the ice sheet area is covered by observations. Over this area, we obtain a negative volume trend of −34 ± 5 km3 yr−1 for the more than 25-year period (04/1992–12/2017). These volume losses have significantly accelerated to a rate of −170 ± 11 km3 yr−1 for 2010–2017. Interannual variations significantly impact decadal volume rates which highlights the importance of the long-term time series. Our time series show a high coincidence with modeled cumulated precipitation anomalies and with satellite gravimetry. This supports the interpretation with respect to snowfall anomalies or dynamic thinning. Moreover, the correlation with cumulated precipitation anomalies back to the Seasat and Geosat periods highlights that the inter-mission offsets were successfully corrected and that the early missions add valuable information.


Thanks for posting this, Doh.

The use of laser altimetry to measure glacier surface height as a proxy for glacier mass balance was first developed right up here in Alaska by a friend of mine, Prof. Keith Echelmeyer. Keith was a glaciologist and one of the greatest scientists its been my pleasure to meet here in Alaska. Keith came up with the idea of doing laser altimetry surveys of Alaska mountain glaciers, flying over a hundred dangerous traverses in bad conditions over mountain glaciers in Alaska in his own personal plane which he had mounted with a laser altimetry instrument he had devised. Keith's data showed that almost all Alaska glaciers are rapidly thinning.

Keith died about 8 years ago, but its great to see that the method he invented is now being utilized from plane-based platforms and satellite based platforms in Alaska, Antarctica and other areas around the world, and giving much the same results----a warming world is causing mountain glaciers and high latitude ice sheets in Antarctica and elsewhere to thin and shrink and sea level to rise just about everywhere.

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RIP old friend Prof. Keith Echelmeyer.......inventor of the laser altimetry method of determining glacier mass balance
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Re: Antarctica 2018

Unread postby jedrider » Tue 20 Mar 2018, 19:21:12

Key Antarctic ice shelf larger than scientists thought
http://www.antarctica.gov.au/news/2018/key-antarctic-ice-shelf-larger-than-scientists-thought

Is this good news or bad news?? Maybe, neutral :)

More ice can NEVER be bad news in our situation, I think.

However, on the other hand, sea level will rise quicker, maybe?
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Re: Antarctica 2018

Unread postby chilyb » Mon 02 Apr 2018, 15:56:18

good day all,

https://www.nature.com/articles/s41561-018-0082-z

Abstract

Grounding lines are a key indicator of ice-sheet instability, because changes in their position reflect imbalance with the surrounding ocean and affect the flow of inland ice. Although the grounding lines of several Antarctic glaciers have retreated rapidly due to ocean-driven melting, records are too scarce to assess the scale of the imbalance. Here, we combine satellite altimeter observations of ice-elevation change and measurements of ice geometry to track grounding-line movement around the entire continent, tripling the coverage of previous surveys. Between 2010 and 2016, 22%, 3% and 10% of surveyed grounding lines in West Antarctica, East Antarctica and at the Antarctic Peninsula retreated at rates faster than 25 m yr−1 (the typical pace since the Last Glacial Maximum) and the continent has lost 1,463 km2 ± 791 km2 of grounded-ice area. Although by far the fastest rates of retreat occurred in the Amundsen Sea sector, we show that the Pine Island Glacier grounding line has stabilized, probably as a consequence of abated ocean forcing. On average, Antarctica’s fast-flowing ice streams retreat by 110 metres per metre of ice thinning.
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Re: Antarctica 2018

Unread postby chilyb » Mon 02 Apr 2018, 16:07:52

quotes from the author of the nature geoscience paper (Konrad, et al.)

https://phys.org/news/2018-04-antarctic ... floor.html

Dr Konrad said: "Our study provides clear evidence that retreat is happening across the ice sheet due to ocean melting at its base, and not just at the few spots that have been mapped before now. This retreat has had a huge impact on inland glaciers, because releasing them from the sea bed removes friction, causing them to speed up and contribute to global sea level rise."

The researchers also found some unexpected behaviour. Although retreat of the Thwaites Glacier grounding line in West Antarctica has sped up, at the neighbouring Pine Island Glacier - until recently one of the fastest retreating on the continent - it has halted. This suggests that the ocean melting at its base may have paused.

Dr Konrad added: "These differences emphasise the complex nature of ice sheet instability across the continent, and being able to detect them helps us to pinpoint areas that deserve further investigation."


Study co-author Professor Andy Shepherd, from the School of Earth and Environment at Leeds, said: "We were delighted at how well CryoSat-2 is able to detect the motion of Antarctica's grounding lines. They are impossible places to access from below, and usually invisible on the ground, so it's a fantastic illustration of the value of satellite measurements for identifying and understanding environmental change."
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Re: Antarctica 2018

Unread postby dohboi » Sun 08 Apr 2018, 22:10:55

Thanks for those, chil.

Here is a science journalists coverage of the same:

http://www.truth-out.org/news/item/4406 ... -come-true

As Antarctic Melting Accelerates, Worst-Case Scenarios May Come True

...underwater melting of Antarctic glaciers is now occurring at a rate that is doubling every 20 years. This means that melting in the ice continent of Antarctica could soon outpace that occurring across Greenland, which would make Antarctica the single largest source of sea level rise...

...The current worst-case scenario outlined by the Intergovernmental Panel on Climate Change (IPCC) is just over 1.5 meters (4.9 feet) of sea level rise by 2100.

The new data, however, confirms a study from nearly five years ago, in which 90 sea level rise experts were surveyed and confirmed that sea level rise this century will exceed IPCC projections...

...the US National Oceanic and Atmospheric Administration's worst-case scenario is 2.5 meters (8.5 feet) by the same year. This worst-case scenario does not factor in the new data from the recent Antarctica study.

...Sea level rise projections of more than three meters are currently being openly discussed...

...rising seas could result in two billion refugees by 2100...based on the current, lower sea level rise projections
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Re: Antarctica 2018

Unread postby Plantagenet » Sun 08 Apr 2018, 23:39:25

dohboi wrote:http://www.truth-out.org/news/item/4406 ... -come-true

As Antarctic Melting Accelerates, Worst-Case Scenarios May Come True
...rising seas could result in two billion refugees by 2100...based on the current, lower sea level rise projections


I wonder how many people will be displaced by the actual amount of sea level rise we're going to see, which will significantly exceed the IPCC, NOAA, and other scenarios.

Not that it matters all that much. The global warming and sea level rise is locked in.....all that remains is to get the popcorn ready and watch how it all plays out. It should be quite a show.....

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Re: Antarctica 2018

Unread postby dohboi » Wed 02 May 2018, 15:20:29

‘Foehn winds’ causing Antarctica’s Larsen C ice shelf to melt in winter

https://www.carbonbrief.org/foehn-winds ... -in-winter

Parts of Antarctica’s Larsen C ice shelf are melting in the depths of winter, when temperatures typically stay well below freezing, research finds.

Between 2015 and 2017, around 23% of the annual surface melt across the ice shelf occured in the winter months, according to results taken from field and satellite observations...
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