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Topics - Stephan

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Antarctica / Getz Ice Shelf Discussion
« on: February 14, 2020, 07:02:49 PM »
Calving at the easternmost part of the Getz Ice Shelf.
It happened some weeks ago (most likely on Jan 30). A slim part (1 km deep, 15 km long) has separated from the ice shelf and floats now in Amundsen Sea.
A detailed analysis of this region between Jan 10, 2020 and Feb 13, 2020 showed in addition several mini- and microcalvings (all circled in yellow).

See attached picture.

[PS: Neven, we should close the Getz-B47 thread]

Antarctica / Crosson and Dotson Ice Shelves Discussion
« on: February 13, 2020, 07:18:19 PM »
PIIS has pulled all attention in the last weeks, but a few 100 km west another ice shelf had a major calving event.
Between Feb 1 and Feb 11 a part of the Dotson Ice Shelf lost a 25*3 km piece of ice. The days in-between were too cloudy for an evaluation in EOSDIS, so a more exact dating is not possible.

See attached image.

Science / 2020 Mauna Loa CO2 levels
« on: January 12, 2020, 04:33:11 PM »
Last year next week had an average of 411.7 ppm. Extrapolating the actual values will result in a 2.3 ± 0.3 ppm increase. From mid January on the values generally rise much higher than in late autumn or December.

I got the weekly value last year wrong (I took the average value of the week later and did not carefully look at the scale of the y-axis - sorry). Therefore my Sunday evening CO2 posting begins with an excuse.

Week beginning on January 5, 2020:     413.37 ppm
Weekly value from 1 year ago:             409.94 ppm
Weekly value from 10 years ago:          388.21 ppm
Last updated: January 12, 2020

The annual increase stays above 3.4 ppm. This is no good news for this year. It has just begun - and unfortunately with this massive increase.
The high variability of the last weeks has disappeared. The values are much more in line, daily and hourly averages.
We have the same CO2 level than in April last year. This means we are three months before schedule.

Last year next week had an average of 410.7 ppm. Extrapolating the actual values will result in a 2.3 ± 0.3 ppm increase. From mid January on the values generally rise much higher than in late autumn or December.

Science / Trends in Atmospheric SF6
« on: October 04, 2019, 07:27:49 PM »
NOAA has created a new site "Trends in Atmospheric SF6" on its website.
It reports monthly about the actual SF6 concentrations at sea level. SF6 is a very powerful GHG and per kg 26,087-fold more intense than CO2; converted into molar activity the factor is 86,678. I translated the CO2 equivalent into the concentration graph. It is not much (we talk about ppt concentrations), but more than nothing, and constantly increasing (higher than linearly = acceleration).

The latest value is for May 2019:
May 2019:     9.90 ppt
May 2018:     9.55 ppt
Last updated: September 18, 2019

The annual increase is 0.35 ppt, above all average annual increase rates (see below)
Annual increase rates (averaged over 5 years):
1998-2003: 0.20 ppt
2003-2008: 0.24 ppt
2008-2013: 0.29 ppt
2013-2018: 0.33 ppt
See attached graphs (concentration and increase rates, expressed as percentage)

Link to the website:

Science / Trends in Atmospheric N2O
« on: October 03, 2019, 03:46:44 PM »
NOAA has opened a new site within its website

It shows the actual [delayed by four months] concentration of nitrous oxide (N2O) and it seems to be updated once a month (like the trends in CH4 site)
May 2019:     331.7 ppb
May 2018:     330.7 ppb
Last updated: September 18, 2019
The website also includes the annual averages and the annual increase rates:
The annual increase rate May 2019 of 1.0 ppb is slightly below the 2018 average increase (1.17 ppb).
The average increase rate of 2001-2009 was 0.74 ppb.
The average increase rate of 2010-2018 was 0.98 ppb.

Antarctica / Sea Ice in Amundsen Sea / Pine Island Bay
« on: September 29, 2019, 05:32:03 PM »
I start this topic to discuss the different patterns of sea ice and its melting during austral summer which should be separated from Thwaites Glacier / Pine Island Glacier calving events (see the individual threads).
I compared the last for years (see attached pictures from EOSDIS Worldview), which differ widely in extent and structure of the sea ice. I chose clear days, so all pictures are from around end September, but not at the same date. In this time of the year the changes from day to day can be relevant.
2016 saw in general a low sea ice cover in that area, 2017 had the closest ice cover. All pictures show the SE→NW flow of the ice.

Science / Trends in atmospheric CH4
« on: July 11, 2019, 09:59:23 PM »
The February 2019 numbers of methane were recently published:
February 2019:     1865.4 ppb
February 2018:     1856.2 ppb
Last updated: June 05, 2019
The March 2019 numbers of methane were recently published:
March 2019:     1866.4 ppb
March 2018:     1857.5 ppb
(increase by almost 9 ppb)
Last updated: July 05, 2019
Eyeballing from the graph the increase was a little lower than March 2018, but bigger than March 2017.

Greenland and Arctic Circle / Motzfeldt Lake, South Greenland
« on: June 19, 2019, 09:01:37 PM »
For a while now I watch that lake close to Narssarsuaq growing, i.e. the glacier feeding it is receding. The lake is approx. 150 m above sea level. In 2005 the distance between the calving front and the upper corner where the glacier divides was around 4.8 km (according to Google Earth). In June 2016 (upper photo) this distance reduced to 4.3 km, red arrow. Now (June 2019) it has further reduced to around 3 km, red arrow (lower photo). At the moment this lake drains out to the south. I wonder when the waters of this huge lake will make their way (green arrow) into the western part of the glacier (X). And I also wonder whether this drainage wouldn't disturb or destroy this part of the glacier leading to further receding.

Antarctica / The Ross Ice Shelf Thread
« on: February 17, 2019, 09:04:01 PM »
I just wondered that the largest Antarctic Ice Shelf - the Ross Ice Shelf - does not have its own thread. You can see it constantly growing, almost no cracks at its northern edge, apart from two or three seemingly elder ones. And so it didn't show larger calving events for many years or even decades.
Yesterday the northeasternmost corner of it showed a minor calving, an area of around 10 x 2 km broke off, in an area already full of cracks, see attached picture.

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