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Messages - Stephan

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1
Arctic sea ice / Re: When will 2020 JAXA extent cross 2012?
« on: September 15, 2020, 08:33:39 PM »
I subracted 0.45 M km² from the 2019 extent and this line crosses the 2012 path on October 10, 2020. I think the refreeze will be delayed this year (as it was 2019) because of all the warm water masses around the actual ice edge. Therefore 2020 should roughly follow 2019, but at a slightly lower level.

2
Science / Re: 2020 Mauna Loa CO2 levels
« on: September 13, 2020, 05:42:11 PM »
Outlook:
Last year's next week has had an average of about 408.6 ppm. Extrapolating the actual values into the near future will lead to an annual increase of around 2.5 ± 0.25 ppm.
It is Sunday evening here in Germany, and the latest weekly average of Mauna Loa CO2 is available.

Week beginning on September 6, 2020:     411.37 ppm
Weekly value from 1 year ago:                  408.75 ppm
Weekly value from 10 years ago:              386.26 ppm
Last updated: September 13, 2020

The annual increase of 2.62 ppm is still higher than the 10 y average of 2.51 ppm/a.
Last week's values were highly variable intra-day with some hourly averages below 408 ppm. The lowest daily average was 410.8 ppm. With about 0.7 ppm until the annual minimum is reached there may be one or two days' average below 410 ppm, but I do not think that a whole week's average will go below that threshold.

Outlook:
Last year the following week had an average of about 408.4 ppm. The annual increase should therefore be in the range of 2.4 ± 0.3 ppm.

3
Science / Re: Where are we now in CO2e , which pathway are we on?
« on: September 12, 2020, 08:42:21 PM »
A short explanation of this plot would be helpful, wdmn, including the designation of x and y axes.
I guess it is worldwide temperature the last 10,000 years?

4
Antarctica / Re: Antarctic Icebergs
« on: September 11, 2020, 09:38:41 PM »
The sun still does not shine at the South Pole, but Amundsen Sea is north and bright enough to allow EOSDIS to make new pictures.

So the first look I took was on my pet iceberg that has lost parts of its SW tip some months ago (details in the Thwaites Gl. thread).

I took the opportunity and evaluated the movement of B-22A between 15. Nov 2019 and 11. Sept 2020.
It moved slowly in NW direction (around 5 km). I checked different places and spots on this iceberg, measured the distance between the two dates and added them into the attached picture. As far as I evaluated there seems to be no turning around of the iceberg.

5
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: September 11, 2020, 07:19:14 PM »
I added the monthly extent value for August 2020 into my long-term plot where I calculate the extent anomalies from 1979 up to now.
The average (1979-2020) August extent is now 6.18 M km². August 2020 had an average extent of 5.09 M km², which is 1.09 M km² less than that long-term average.
The much higher than normal losses in July 2020 had pushed the actual value below the red long-term linear trend line, where it remains in August. The difference is -0.54 M km² (calculated from the linear trend line this August should have been at 5.63 M km²).
The slope of the long-term linear trend line has become steeper by two digits (-0.0553 instead of -0.0551).

See attached graph.

6
Science / Re: Where are we now in CO2e , which pathway are we on?
« on: September 10, 2020, 08:45:34 PM »
To finalize my update on greenhouse gases here is the summary of the four postings in the individual gas concentration threads.

More radiative forcing of the "NOAA gases" (CO2, CH4, N2O, SF6) in May 2020 than in Apr 2020 or in May 2019.

The values [W/m²], change to Apr 2020 and change to May 2019:
CO2 2.170   (+ 0.011)    (+ 0.031)   
CH4 0.520   (+ 0.000)    (+ 0.005)
N2O 0.205   (+ 0.000)    (+ 0.004)
SF6  0.0053 (+ 0.0000)  (+ 0.0002)
sum  2.900  (+ 0.011)   (+ 0.040)

The relative annual increase is 1.36 %.
It also means never before since we measure these gases has their radiative forcing been so strong.

7
Science / Re: Trends in atmospheric CH4
« on: September 10, 2020, 08:32:31 PM »
Here is the latest monthly average of Mauna Loa CH4 concntration:

May 2020:     1874.7 ppb
May 2019:     1861.9 ppb
Last updated: September 05, 2020

This is an annual increase of 12.8 ppb. This is the highest annual increase since March 2015!

I set an index = 100 for the 1980 average [1601.2 ppb]. May 2020 is at 117.1 compared to that index.


8
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 02, 2020, 09:14:09 PM »
I wonder what you are looking at. Yellow line is volume. Connect 1987 to 2019 and extrapolate.

And then insert some weather induced negative spikes like 1981, 2007 or 2010-2012, subtract them from the linear trend line and the BOE is reached even earlier than 2029...

9
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: August 23, 2020, 05:22:43 PM »
Another daily loss of Chukchi Sea Ice Area like yesterday - and the ice area will become negative...

10
Science / Re: 2020 Mauna Loa CO2 levels
« on: August 16, 2020, 06:58:40 PM »

Outlook.
Next week of last year came in at 410.3. Best guess would be an annual increase of 2.5 ± 0.25 ppm.
Another week has passed, here are the latest NOAA numbers on CO2 (Mauna Loa):
Week beginning on August 9, 2020:     412.74 ppm
Weekly value from 1 year ago:            410.30 ppm
Weekly value from 10 years ago:        388.86 ppm
Last updated: August 16, 2020

The annual increase is at 2.44 ppm, the 10y average increase is at 2.24 ppm/a.
This week showed slightly decreasing CO2 values, in parts with a high intra-day variability.

Outlook:
Next week last year had an average of around 409.9 ppm. An annual increase of 2.4 ± 0.25 ppm seems likely.

11
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: August 15, 2020, 07:42:39 PM »
NSIDC sea ice area - evaluation "relative area wise" Aug 01-Aug 14, 2020:

The big laggard:
CAB       -   3%
On the slow side:
CAA       - 13%
medium rate ice loss:
Beaufort  - 25%
Kara        - 28%
ESS        - 31%
Grønland - 36%
The front runners:
Laptev     - 55%
Chukchi   - 58%

Hudson, Baffin and Barents almost melted out - no analysis.

PS: Gerontocrat: Welcome back here - we all missed you!

12
Glaciers / Re: Alpine Glaciers / Europe
« on: August 13, 2020, 06:59:41 PM »
The Turtmanngletscher in Wallis (Switzerland) has recently lost 600 m of its length.
https://www.wetteronline.de/wetterticker/klima-gletscherabbrueche-in-den-alpen-202008135095162
(in German)

13
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: August 12, 2020, 09:06:30 PM »
Juan C & Gerontocrat: seems like good odds that melting rate this month could be record low unless it doesn't speed up soon.
JAXA Arctic Sea Ice losses in August (31.7. to 31.8. of each year, values in M km²). Bold: Exceptional values, compared to the other years.
2005: -1.48
2006: -1.25
2007: -1.82
2008: -2.25
2009: -1.53
2000s ave: -1.61
2010: -1.63
2011: -1.83
2012: -2.59
2013: -1.64
2014: -1.54
2015: -2.12
2016: -2.20

2017: -1.77
2018: -1.69
2019: -1.70
2010s ave: -1.87

2020 has so far lost 0.53 M km². A little more than a third of the month has passed, and the slope of decrease decreases towards the end of the month. A place in the lower part of the ranking list seems possible.

14
Greenland and Arctic Circle / Re: Greenland 2020 Melting Season
« on: August 10, 2020, 10:03:59 PM »
Another sad picture from Freya 2 on a mild and rainy summer day.

15
Arctic sea ice / Re: Global sea ice area and extent data
« on: August 10, 2020, 07:41:46 PM »
JAXA Global Sea Ice Extent as of August 09, 2020.
2020 now is #3 in the list. At average decreases in the Arctic and much higher than average gains in the Antarctic in the last days have forced 2020 to lose its pole position.

All values in M km².
2017: 22.32
2019: 22.35
2020: 22.50
2012: 22.74
2018: 22.78
2007: 22.88
2016: 23.06
2011: 23.24
2002: 23.36
2010s: 23.37
2015: 23.50
2000s: 24.27
1990s: 25.07
1980s: 25.64

16
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: August 08, 2020, 09:01:58 PM »
I added the monthly extent value for July 2020 into my long-term plot where I calculate the extent anomalies from 1979 up to now.
The average (1979-2020) July extent is now 9.13 M km². July 2020 had an average extent of 7.28 M km², which is 1.85 M km² less than that long-term average and the lowest on record so far.
The much higher than normal losses in July 2020 pushed the actual value below the red long-term linear trend line by 0.66 M km² (calculated from the linear trend line this July should have been at 7.94 M km²).
The slope of the long-term linear trend line has become steeper by two digits (-0.0551 instead of -0.0549).

See attached graph.

17
Science / Re: Where are we now in CO2e , which pathway are we on?
« on: August 07, 2020, 06:48:09 AM »
Yes, you're absolutely right.
As I only monitor the four gases whose concentration NOAA regularly publishes (CO2, CH4, N2O, SF6) their sum is smaller than the sum of all greenhouse gases. Therefore I talk about the "NOAA gases" in my first sentence.

18
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: August 06, 2020, 09:42:42 PM »
It is time for the monthly update of my extrapolation when the extent [Ausdehnung], volume [Volumen], thickness [Dicke] and area [Fläche] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times (valid for volume and thickness, not for extent and area in the winter months). The July value now includes 2020.
Volume in July 2020 is close to the long term trend, thickness for July 2020 lies well above the long term trend lines, whereas extent (lowest on record) and area (lowest on record) dip below it. The "BOE numbers" increased by averaged 6 years (volume) and decreased by 2 years (extent) or by 5 years (area) compared to July 2019. Thickness "BOE number" did not change.
So there is a further conversion between the "late values" (area, extent) and the "early value" (volume).
The order (earlier → later BOE) generally is volume < thickness < area < extent.

Please note that this is not a forecast but a trend!
See attached table, now widened to see the linear function value (y-AA) at t = 0. stg = slope.

Click to enlarge it.

19
Science / Re: Where are we now in CO2e , which pathway are we on?
« on: August 06, 2020, 07:45:33 PM »
More radiative forcing of the "NOAA gases" (CO2, CH4, N2O, SF6) in Apr 2020 than in Mar 2020 or in Apr 2019.
The values [W/m²], change to Mar 2020 and change to Apr 2019:
CO2 2.159   (+ 0.022)    (+ 0.035)   
CH4 0.520   (+ 0.000)    (+ 0.004)
N2O 0.205   (+ 0.000)    (+ 0.004)
SF6  0.0053 (+ 0.0000)  (+ 0.0002)
sum 2.889  (+ 0.021)   (+ 0.045) (rounding difference)
The relative annual increase is 1.58 %

20
Science / Re: Trends in atmospheric CH4
« on: August 06, 2020, 07:36:11 PM »
It is the fifth of the new month. Therefore the monthly averages of the "NOAA gases" are available. Here is the value of CH4:

April 2020:     1876.3 ppb
April 2019:     1865.3 ppb
Last updated: August 05, 2020

This is an annual increase of 11.0 ppb. This increase is in the upper half of what has been observed in the last years.

I set an index = 100 for the 1980 average [1601.2 ppb]. April 2020 is at 117.2 compared to that index.

Attached the development since 1980. A much more complicated pattern than the CO2, N2O or SF6 graphs.

21
Science / Re: Trends in Atmospheric N2O
« on: August 06, 2020, 07:31:35 PM »
It is the fifth of the new month and so the average values of the "NOAA gases" are available.
Here is the value of N2O:

April 2020:     332.7 ppb
April 2019:     331.6 ppb
Last updated: August 05, 2020

The annual increase of 1.1 ppb is identical to March 2020.

I set an index = 100 to the average of 1980 [301.1 ppb]. April 2020 has a relative value of 110.5 compared to 1980.

Attached a graph of the development of atmospheric N2O since around 1980. Please not that prior to 2000 only two values per year exist - therefore the annual cycling is not visible in that part of the graph.
Slight exponential behaviour - please compare the values with the linear trend line.

22
Science / Re: Trends in Atmospheric SF6
« on: August 06, 2020, 07:24:23 PM »
It is the sixth of the new month and so the average values of the "NOAA gases" are available.
Here is the value of SF6:

April 2020:     10.20 ppt
April 2019:       9.88 ppt
Last updated: August 05, 2020

The annual increase is 0.32 ppt. It is about average of what has been observed in the last decade.

I set an index of 100 for the year 1980 [0.848 ppt]. April 2020 is at 1,202.

Attached a graph of the SF6 development. I added a linear trend line - not because I think the growth is linear, but more to show its exponential nature.

23
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: August 05, 2020, 10:57:49 PM »
I also added some money to that gofundme.  :)

24
Greenland and Arctic Circle / Re: Greenland 2020 Melting Season
« on: August 01, 2020, 07:16:12 PM »
Please have a look at the sad state Freya Gletscher is in at the moment.
And please check the temperature (+ 8.6°C at an altitude of 1.053 m above sea level).
Never before on an August 1st since this webcam has been installed this glacier has looked so vulnerable and damaged.

25
Science / Re: 2020 Mauna Loa CO2 levels
« on: July 26, 2020, 08:39:16 PM »
Outlook:
Next week last year had an average of only 410.2 ppm. Therefore an annual increase of almost 3 ppm shall be expected.

It is Sunday evening, and the actual Mauna Loa CO2 values are available:
Week beginning on July 19, 2020:     413.90 ppm
Weekly value from 1 year ago:          411.32 ppm
Weekly value from 10 years ago:       390.21 ppm
Last updated: July 26, 2020

The annual increase is back above the long-term trend. The CO2 concentrations rose by 2.58 ppm, the 10 y average increase is 2.37 ppm.
This week showed stable slightly falling levels as expected for this time of the year, followed by a more wobbly up and down (intraday).

Outlook:
The next week last year had an average of about 410.3 ppm. With slightly further decreasing values the annual increase should stay above the 10 y average.

26
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: July 24, 2020, 08:37:40 PM »
Evaluation of the individual seas "relative area wise" July 11-23, 2020
The big laggard:
CAB        -   6%
On the slower side:
Grønland - 15%
Chukchi   - 16%
Beaufort  - 20%
CAA         - 25%
Fast ice area losers:
ESS         - 48%
Kara        - 48%
Barents    - 52%
Ahead of the others:
Hudson    - 65%
Baffin      - 67%
The "winner":
Laptev     - 78%

Just as a note: Hudson, Baffin, Barents, Kara and Laptev contain together only ca. 0.22 M km² of ice. Big daily losses are no longer possible there. So it is up to ESS, Chuckchi, CAA and mostly Beaufort to speed up to keep the pace ice melt had in July 2020.

27
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 24, 2020, 07:53:00 PM »
Please find the two charts now in the time frame from 1975 to 2100. The trend lines are bolder now for better visibility. (October and August volume trend lines are now superimposed; there is no trend line missing)
Important note: Extrapolations into the far future offer very little guidance. So please do not shout at me when the December volume does not reach zero in 2062 but ten years earlier or later...  ;)

28
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 21, 2020, 07:37:04 PM »
Hi Stephen, I would like to understand your table better could you please explain it in a little more detail.

Hi Tony,

I collect all monthly averages from NSIDC and PIOMAS in four individual spreadsheets. Then I create the plots of area, extent, volume and thickness vs. time.

I then select every data row (one for each month) and apply a linear and a logarithmic function for each of these four values (area, extent, volume and thickness) for every month. Then I calculate when these functions reach zero (the x axis, this is my "BOE number"). These values are then summarized in the big colourful table I present here every month. In addition I add the slope of the linear function into that big table. From this you can see that the slope is much steeper in the summer and autumn months than for the rest of the year.

Every month a new set of values is included into the spreadsheets and then I recalculate the BOE number and compare it to the value I had calculated a year ago. These differences are usually very small (we are in the 42nd year of satellite observation), but they are not negligible.

In the end once volume disappears in the mid 2020s the other values (area, extent and thickness) also tend to zero. This discrepancy (or mismatch) has been widely discussed in this thread about 2 years ago.

I hope this explanation helps a little. If you have further questions, don't hesitate to ask further questions.

kind regards from Germany Stephan

PS: I am well aware that "BOE" is defined as an area of 1 M km² and not 0 M km² of ice.

29
Arctic sea ice / Re: The 2020 melting season
« on: July 19, 2020, 09:24:08 PM »
Update of Jim Pettits "step by step" milestone graph.
The second "7 day step" in a row. And the third single digit number in a row. Unprecendented.
The only comparison is June/July of 2013 (!) where a 8 day interval was followed by a 6 day interval and a 10 day interval.
For those who don't have the link: http://iwantsomeproof.com/extimg/sie_nsidc_max_min_plus_step_days.png
See attached graph.

30
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: July 17, 2020, 07:43:22 PM »
Gerontocrat,
thank you very much for the tables and graphs. What would ASIF look like without your (and Juan's) precise and regular information?

31
Arctic sea ice / Re: Global sea ice area and extent data
« on: July 15, 2020, 08:42:08 AM »
For the first time this year 2020 is the lowest on record (according to JAXA). All values in M km². The "top four list" is:
2020 - 22.68
2017 - 22.70
2019 - 22.79
2011 - 22.84
The huge drop of 184.000 km² in the Arctic and a slightly less than average increase around Antarctica of 70.000 km² made that possible.

32
Arctic sea ice / Re: Arctic Image of the Day
« on: July 13, 2020, 10:15:10 PM »
A mystical fog bow caught on Freya Gletscher Webcam 1 yesterday.

33
Science / Re: 2020 Mauna Loa CO2 levels
« on: July 12, 2020, 06:24:09 PM »
Outlook:
Last year next week averaged at 412.1 ppm, a big drop compared to the week before. When this cyclic drop starts this week, the annual increase stays slightly above 2 ppm. When the daily changes of next week follow this week's path, we will end up with an annual increase close to 3 ppm.
Anything seems to be possible...

It is Sunday evening - time for an update of Mauna Loa CO2 levels.

Week beginning on July 5, 2020:     415.24 ppm
Weekly value from 1 year ago:        412.12 ppm
Weekly value from 10 years ago:     390.39 ppm
Last updated: July 12, 2020

The cyclic drop of CO2 has not started yet, therefore the annual increase is 3.12 ppm. The 10-year annual increase is 2.48 ppm. At the moment there is no sign for a start of this drop.

Therefore the Outlook remains very "unstable". Last year next week had an average of 412.1 ppm. When the actual values do not change significantly during the next week an annual increase of 3.3 ppm seems to be possible. When the cyclic drop will finally start next week, then this annual increase will be (much) lower than that.

34
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 12, 2020, 05:11:30 PM »
It is time for the monthly update of my extrapolation when the extent [Ausdehnung], volume [Volumen], thickness [Dicke] and area [Fläche] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times (valid for volume and thickness, not for extent and area in the winter months). The June value now includes 2020.
Volume, area and thickness for June 2020 lie a little bit above the long term trend lines, extent is at the trend line. The "BOE numbers" increased by averaged 2 years (area) and 1 year (volume) and decreased by 1 year (thickness) and 2 years (extent) compared to June 2019.
The order (earlier → later BOE) generally is volume < thickness < area < extent.

Please note that this is not a forecast but a trend!
See attached table. stg = slope.

35
Greenland and Arctic Circle / Re: Greenland 2020 Melting Season
« on: July 09, 2020, 05:11:28 PM »
Melting continues on Freya Gletscher, although today it is below freezing.
A lot of snow has gone, the most visible changes compared to the last days (loss of snow / greying / melt ponds / melt streams) are circled in green.
I checked the same day in previous years. Not even 2016 showed the disastrous state the glacier is in. 2017 and 2019 had much more snow.

Edit: Added the picture of Cam2 - the ice is in a bad state also in the upper part of Freya Gletscher.

36
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: July 09, 2020, 04:02:39 PM »
The Miami SLR mitigation effort with building walls will generate a lot of CO₂ emissions.
Miami is build on porous limestone, if I remember correctly, so I think the water will come up behind the walls and therefore render the mitigation effort useless apart from exceptional storm surges. Massive retreat seems inevitable.
Am I correct with this line of thinking?
Yes you are correct.
With rising sea levels more pumping is required to keep the roads clear from king floods which appear slightly more often every year. But pumping out the water will slowly refill the voids in the limestone from below, accompanied by a replacement of fresh ground water depots beneath Miami and surroundings by brackish saltier water.

37
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: July 08, 2020, 05:09:54 PM »
Evaluation of sea ice area "relative area wise" Jun 22-Jul 07, 2020
One sea with increasing sea ice:
CAA        + 15 %
One laggard:
Beaufort - 4 %
Slow decrease in:
CAB        - 15 %
Grønland - 17 %
ESS        - 18 %
Medium decrease:
Chukchi  - 27 %
High decrease, almost identical:
Kara      - 51 %
Laptev   - 52 %
Hudson  - 54 %
Baffin    - 54 %
Barents  - 54 %
Okhotsk, Bering, St. Lawrence melted out. No analysis.

38
Science / Re: 2020 Mauna Loa CO2 levels
« on: July 07, 2020, 08:50:40 PM »
I invite you to read NOAA's statement about this "Most Frequently Asked Question" in these days:
https://www.esrl.noaa.gov/gmd/ccgg/covid2.html
Short summary:
The lockdown's effect on CO2 emissions is too small and too short-lived (many countries including most of Europe have already re-turned into a state close to before the lockdown). The "missing" CO2 is too little to be recognizeable in the natural fluctuation. And it is too early to be statistifically significant. Maybe next year we can draw valid conclusions from the effect of CoViD-19 on atmospheric CO2.

39
Science / Re: Where are we now in CO2e , which pathway are we on?
« on: July 06, 2020, 09:47:28 PM »
More radiative forcing of the "NOAA gases" (CO2, CH4, N2O, SF6) in Mar 2020 than in Feb 2020 or in Mar 2019.
The values [W/m²], change to Feb 2020 and change to Mar 2019:
CO2 2.137   (+ 0.005)    (+ 0.033)   
CH4 0.520   (+ 0.001)    (+ 0.003)
N2O 0.204   (+ 0.001)    (+ 0.003)
SF6  0.0053 (+ 0.0000)  (+ 0.0002)
sum 2.868  (+ 0.007)   (+ 0.040)
The relative annual increase is 1.41 %

40
Science / Re: Trends in Atmospheric N2O
« on: July 06, 2020, 09:08:57 PM »
It is the fifth of the new month and so the average values of the "NOAA gases" are available.
Here is the value of N2O:

March 2020:     332.8 ppb
March 2019:     331.7 ppb
Last updated: July 05, 2020

The annual increase of 1.1 ppb has risen back to the values we were used to in the last years.

I set an index = 100 to the average of 1980 [301.1 ppb]. March 2020 has a relative value of 110.5 compared to 1980.

41
Science / Re: Trends in Atmospheric SF6
« on: July 06, 2020, 09:05:00 PM »
It is the sixth of the new month and so the average values of the "NOAA gases" are available.
Here is the value of SF6:

March 2020:     10.18 ppt
March 2019:       9.85 ppt
Last updated: July 05, 2020

The annual increase is 0.33 ppt. It is about average of what has been observed in the last decade.

I set an index of 100 for the year 1980 [0.848 ppt]. March 2020 has now passed the relative value compared to that index of 1,200 (= 12-fold; imagine that would be the increase rate of CO2!)

42
Science / Re: 2020 Mauna Loa CO2 levels
« on: July 05, 2020, 07:56:43 PM »
Outlook:
Last year's next week had an average of about 413.3 ppm. Therefore the annual increase should be around 2.5 ppm. The week after that a rapid decrease towards the seasonal minimum in October begins.
Sunday evening - time for an update of Mauna Loa CO2 levels.
Week beginning on June 28, 2020:     415.43 ppm
Weekly value from 1 year ago:           413.39 ppm
Weekly value from 10 years ago:       391.14 ppm
Last updated: July 5, 2020

The annual increase is now at 2.05 ppm. The 10-year average annual increase is 2.43 ppm. The daily values decreased smoothly and remarkably stable without too many fluctuations.

Outlook:
Last year next week averaged at 412.1 ppm, a big drop compared to the week before. When this cyclic drop starts this week, the annual increase stays slightly above 2 ppm. When the daily changes of next week follow this week's path, we will end up with an annual increase close to 3 ppm.
Anything seems to be possible...

43
Arctic sea ice / Re: Global sea ice area and extent data
« on: July 02, 2020, 09:37:03 PM »
I compared the actual JAXA sea ice extent of July 1, 2020 with the averages of the past decades.
In the Arctic the same value was achieved on average in the
2010s:   4.7. (+   3 d later)
2000s: 13.7. (+ 12 d later)
1990s: 22.7. (+ 21 d later)
1980s:   1.8. (+ 31 d later)
In the Antarctic the same value was achieved on average in the
2010s: 27.6. (+ 4 d earlier)
2000s: 25.6. (+ 6 d earlier)
1990s: 28.6. (+ 3 d earlier)
1980s: 29.6. (+ 2 d earlier)
Summarized this means more insolation in the Arctic respectively more freezing heat to be released around Antarctica in comparison to the earlier decades:
2010s:   +   7 days
2000s:   + 18 days
1990s:   + 24 days
1980s:   + 33 days,
where the changes are large in the Arctic and probably negligible in the seas around Antarctica.

44
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: June 30, 2020, 07:52:08 PM »
Evaluation of sea ice area "relative area wise" June 16-June 29.
There are two laggards:
CAB        - 4%
Beaufort  - 7%
Three seas with a slow decrease:
ESS         - 14%
Chukchi   - 18%
Grønland - 20%
Among the faster seas are:
Barents   - 26%
CAA         - 29%
The leaders are:
Laptev     - 32%
Baffin       - 35%
Kara        - 38%
Hudson    - 39%
Okhotsk, Bering and St. Lawrence were not evaluated (they almost melted completely)

45
Science / Re: 2020 Mauna Loa CO2 levels
« on: June 28, 2020, 04:45:18 PM »
It is Sunday evening and I'd like to post the latest weekly average of Mauna Loa CO2.

Week beginning on June 21, 2020:     416.05 ppm
Weekly value from 1 year ago:           413.50 ppm
Weekly value from 10 years ago:       391.44 ppm
Last updated: June 28, 2020

The annual increase of 2.55 ppm is very close to the 10 year average (2.56 ppm/a). The values have slightly decreased during this week. In the last days the intra-day variability (which had been extreme end of second last week) has come down to average values.

Outlook:
Last year's next week had an average of about 413.3 ppm. Therefore the annual increase should be around 2.5 ppm. The week after that a rapid decrease towards the seasonal minimum in October begins.

46
Science / Re: 2020 Mauna Loa CO2 levels
« on: June 21, 2020, 07:14:12 PM »
Outlook:
Next week last year had an average value of 414.1 ppm. Extrapolating the actual trend into the next week I expect an annual increase of about 2.2 ppm.

Let's go back to the actual data. It is Sunday evening here in Germany and the latest Mauna Loa CO2 values are available.

Week beginning on June 14, 2020:     416.42 ppm
Weekly value from 1 year ago:          413.77 ppm
Weekly value from 10 years ago:       391.79 ppm
Last updated: June 21, 2020

The annual increase was 2.65 ppm, slightly higher than the 10 year average of 2.46 ppm.
Since June 14 the intra-day variations were large, since June 19 no daily averages were possible.
Therefore it is too speculative to give any useful outlook.

47
Science / Re: 2020 Mauna Loa CO2 levels
« on: June 21, 2020, 08:36:10 AM »
So, let's widen our attention to the radiative forcing increase since 1980
(using the "NOAA gases" CO2, CH4, N2O and SF6).
The increase in radiative forcing, using 100-months averages were:
1980-1988: + 0.0319 W/m² per year
1986-1995: + 0.0271 W/m² per year
1995-2003: + 0.0309 W/m² per year
2003-2011: + 0.0321 W/m² per year
2011-2019: + 0.0388 W/m² per year.

All these values include the square-root relation between concentration and radiative forcing that you correctly mentioned.

I do not see a flattening, but, in contrast, a steady increase of the rates. This is equivalent to an acceleration.

48
Science / Re: 2020 Mauna Loa CO2 levels
« on: June 20, 2020, 06:09:25 PM »
1. Clearly, we are not having exponential growth anymore, we're on a linear growth path.
I do not agree. The rates are slightly increasing. The later you look the steeper is the slope.

I averaged 100-month increase rates of Mauna Loa CO2:

1959-1967: + 0.77 ppm/year
1967-1975: + 1.10 ppm/year
1975-1984: + 1.50 ppm/year
1984-1992: + 1.52 ppm/year
1992-2000: + 1.59 ppm/year
2000-2009: + 1.99 ppm/year
2009-2017: + 2.34 ppm/year
2012-2020: + 2.48 ppm/year

These data are not compatible with "linear growth path".

See also the annual increase (raw data) in the attached graph. y-axis: increase in ppm/year

49
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: June 16, 2020, 08:46:32 PM »
It is time for the monthly update of my extrapolation when the extent [Ausdehnung], volume [Volumen], thickness [Dicke] and area [Fläche] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times (valid for volume and thickness, not for extent and area in the winter months). The May value now includes 2020.
Volume and thickness for May 2020 lie well above the long term trend lines, extent is at the trend line whereas area dips below it. The "BOE numbers" increased by averaged 3 years (thickness) and 2 years (volume) and decreased by 4 years (extent) compared to May 2019.
The order (earlier → later BOE) generally is volume < thickness < area < extent.

Please note that this is not a forecast but a trend!
See attached table. stg = slope.

50
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: June 14, 2020, 05:29:59 PM »
I took the monthly extent value for May 2020 and added it into my long-term plot where I calculate the extent anomalies from 1979 up to now.
The average (1979-2020) May extent is now 13.13 M km². May 2020 had an average extent of 12.36 M km², which is 0.77 M km² less than that long-term average.
The more or less parallel to normal development in May 2020 kept the actual value above the red long-term linear trend line by 0.35 M km² (calculated from the linear trend line this May should have been at 12.01 M km²).
The slope of the long-term linear trend line has thus further decreased by one digit (-0.0549 instead of -0.0550).

See attached graph.

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