2018 sea ice area and extent data

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

September 1^st, 2018:  45+ minutes without being updated.
Seems that they will not update it today.

https://ads.nipr.ac.jp/vishop/#/extent

[Steven]

NSIDC sea ice area is currently 3.33 million km2, which is 9th lowest for the date:

[Jim Hunt]

[ADS-NIPR-JAXA] ASI Extent.

September 1^st, 2018:  45+ minutes without being updated.
Seems that they will not update it today.

Here's the current AMSR2 numbers via Wipneus and Hamburg Uni:

http://GreatWhiteCon.info/2018/09/the-2018-arctic-sea-ice-metric-minima/

[gerontocrat]

NSIDC Total Area as at 1 September (5 day trailing average) = 3,377,562 km2

In addition to Jim's post....

This is 184 k above the 2010-2017 average total area for this date

Total Area loss             38k , which is 10+ k above average

Central Seas loss          36 k,
Peripheral Seas gain        1 k, all seas <5% of max.
Other Seas loss               3 k, all seas <5% of max.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 1 k, area 36 k, < 5% of maximum.
Atlantic Side
- Baffin Sea loss 0 k, area 25 k, <5% of max,
- Greenland Sea gain 1 k, area 55k,
- Barents Sea - finished,
- The Kara Sea area gain 1 k, area 30 k, < 5% of maximum.
- The Laptev Sea area gain 1 k, area 19 k, <5% of maximum.

CAB
- Beaufort Sea loss 6 k,
- The Canadian Archipelago loss 2 k,
- East Siberian Sea loss 8 k .
- The Central Arctic Sea loss 21 k,

Other seas
- St Lawrence -finished,
- Hudson Bay area loss 2 k, Area 11 k,
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 38 k is above average by about 10 k for this day. Extent loss (also 5-day trailing average)) was 28 k, 15 k below average for the day. Daily extent loss last 2 days 70k & 61k, (after gain of 21k and before that losses of 35k, 10k). Daily extent now below 5 million km2.
End of season wobbles. < 2 weeks  to go?

I am giving up making comments even about giving up comments - a mug's game.

[gerontocrat]

2 graphs
- Central Arctic Sea Area,
- Central Arctic Sea Extent.

Compare & Contrast.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

September 2^nd, 2018: 4,749,726 km², an increase of 16,253 km².
2018 is the 8^th lowest on record.

[gerontocrat]

JAXA ARCTIC EXTENT 4,749,726 km2（September 2, 2018）

Just to add to Juan's post...
- Extent is now 213 k km2  (4.5%) above the 2010's average extent on this date,
- and 117 k (2.5 %) above 2017,
- Extent loss to date is now a very large 604 k km2 (6.2 %) below the 2008-2017 average, with 97.8% of the average melting season done.

Resulting minimum from average remaining melt is up to 4.53 million km2. Range of results from last ten years remaining melt is 4.27 to 4.68 million km2 - now raising a real possibility of an end result very much above 2017.

That 2017 feeling has waxed consistently for some time - melting has slowed to below average for many days. There is, on average, just over 2% (10 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss continue to do a 2017 and sharply reduce further or even become gains ? Yes. Indeed, given the increase in extent on 2 September of 16k, a minimum of 4.733 million  km2 (September 1 extent) is possible.

[Darvince]

Just to add to Juan's post...
- Extent is now 148 k km2  (3.1%) above the 2010's average extent on this date,
- and 474 k (1.6 %) above 2017,

Those percentages don't seem to add up... 

[gerontocrat]

Just to add to Juan's post...
- Extent is now 148 k km2  (3.1%) above the 2010's average extent on this date,
- and 474 k (1.6 %) above 2017,

Those percentages don't seem to add up... 

474 should have been 74

Too much of a hurry

[gerontocrat]

NSIDC Total Area as at 2 September (5 day trailing average) = 3,351,300 km2

This is 179 k above the 2010-2017 average total area for this date

Total Area loss             26 k , which is <5 k above average

Central Seas loss          23 k,
Peripheral Seas loss        2 k, all seas <5% of max.
Other Seas loss              2 k, all seas <5% of max.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 0 k, area 35 k, < 5% of maximum.
Atlantic Side
- Baffin Sea gain 1 k, area 25 k, <5% of max,
- Greenland Sea loss 2 k, area 53k,
- Barents Sea - finished,
- The Kara Sea area gain 1 k, area 30 k, < 5% of maximum.
- The Laptev Sea area gain 0 k, area 19 k, <5% of maximum.

CAB
- Beaufort Sea loss 4 k,
- The Canadian Archipelago gain 1 k,
- East Siberian Sea loss 7 k .
- The Central Arctic Sea loss 13 k,

Other seas
- St Lawrence -finished,
- Hudson Bay area loss 1 k, Area 10 k,
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 26 k is above average by <5 k for this day. Extent loss (also 5-day trailing average)) was 25 k, 15+ k below average for the day. Daily extent gain 3k after losses 70k & 61k, gain 21k losses 35k, 10k in previous days.  End of season wobbles continue.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

September 3^rd, 2018: 4,740,691 km², a drop of -9,035 km².
2018 is the 8^th lowest on record.

[gerontocrat]

JAXA ARCTIC EXTENT 4,740,691 km2（September 3, 2018）

Just to add to Juan's post...
- Extent is now 225 k km2  (4.7%) above the 2010's average extent on this date,
- and 103 k (2.2 %) above 2017,
- Extent loss to date is now a very large 616 k km2 (6.3 %) below the 2008-2017 average, with 98% of the average melting season done.

Resulting minimum from average remaining melt is up to 4.54 million km2. Range of results from last ten years remaining melt is 4.33 to 4.70 million km2 - now raising a real possibility of an end result very much above 2017.

That 2017 feeling has waxed consistently for some time - melting has slowed to below average for many days. There is, on average, just 2% (9 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss continue to do a 2017 and sharply reduce further or even become gains ? Yes. Indeed, a minimum of 4.733 million  km2 (September 1 extent) is possible.

[Ned W]

The snakes are back!

The snakes start on 1 June and run through 3 September.  The first of each month is a small black dot, the 15th of each month is a gray circle, and the final date (3 Sept.) is a large white circle.

Anomalies are computed on each date based on the 2010-2018 mean.

Some years' snakes seem to have a clear destination in mind (2012, 2014, 2017).  Others just kind of tie themselves up in knots.

This summer, 2018 has been kind of crawling in loops around the origin (0 extent anomaly, 0 volume anomaly for the decade).

[gerontocrat]

NSIDC Total Area as at 3 September (5 day trailing average) = 3,338,653  km2

This is 190 k above the 2010-2017 average total area for this date

Total Area loss             13 k , which is <5 k above average

Central Seas loss          6 k,
Peripheral Seas loss      5 k, all seas <5% of max.
Other Seas loss            1 k, all seas <5% of max.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea gain 1 k, area 36 k, < 5% of maximum.
Atlantic Side
- Baffin Sea loss 2 k, area 23 k, <5% of max,
- Greenland Sea loss 3 k, area 51k,
- Barents Sea - finished,
- The Kara Sea area gain 0 k, area 30 k, < 5% of maximum.
- The Laptev Sea area gain 0 k, area 18 k, <5% of maximum.

CAB
- Beaufort Sea loss 0 k,
- The Canadian Archipelago loss 3 k,
- East Siberian Sea loss 4 k .
- The Central Arctic Sea loss 0 k,

Other seas
- St Lawrence -finished,
- Hudson Bay area loss 0 k, Area 10 k,
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 12 k is below average by 10 k for this day. Extent loss (also 5-day trailing average)) was 32 k, average for the day. Daily extent loss 66k, after 3k gain, losses 70k & 61k, gain 21k losses 35k, 10k in the previous days.  End of season wobbles continue.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

September 4^th, 2018: 4,732,152 km², a drop of -8,539 km².
2018 is the 8^th lowest on record.

[gerontocrat]

JAXA ARCTIC EXTENT 4,732,152 km2（September 4, 2018）

Just to add to Juan's post...
- Extent is now 240 k km2  (5.1%) above the 2010's average extent on this date,
- and 92 k (1.9 %) above 2017,
- Extent loss to date is now a very large 632 k km2 (6.5 %) below the 2008-2017 average, with 98.3% of the average melting season done.

Resulting minimum from average remaining melt is up to 4.56 million km2. Range of results from last ten years remaining melt is 4.39 to 4.69 million km2 - now raising a real possibility of an end result very much above 2017.

That 2017 feeling has waxed consistently for some time - melting has slowed to below average for many days. There is, on average, just under 2% (8 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss continue to do a 2017 and sharply reduce further or even become gains ? Yes. Indeed, a minimum of 4.732 million  km2 (September 4 extent) is possible.

[gerontocrat]

NSIDC Total Area as at 4 September (5 day trailing average) = 3,331,329  km2

This is 205 k above the 2010-2017 average total area for this date

Total Area loss             7 k , 15 k below average for the day

Central Seas loss          1 k,
Peripheral Seas loss      0.5 k, all seas <5% of max.
Other Seas loss            1.5 k, all seas <5% of max.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea gain 1 k, area 36 k, < 5% of maximum.
Atlantic Side
- Baffin Sea loss 1 k, area 22 k, <5% of max,
- Greenland Sea loss 4 k, area 47 k,
- Barents Sea - finished,
- The Kara Sea area gain 1 k, area 31 k, < 5% of maximum.
- The Laptev Sea area gain 0 k, area 18 k, <5% of maximum.

CAB
- Beaufort Sea gain 6 k,
- The Canadian Archipelago loss 3 k,
- East Siberian Sea loss 6 k .
- The Central Arctic Sea gain 2 k,

Other seas
- St Lawrence -finished,
- Hudson Bay area loss 0 k, Area 10 k,
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 7 k is below average by 15 k for this day. Extent loss (also 5-day trailing average)) was 30 k, average for the day. Daily extent gain 32k, after 66k loss, 3k gain, losses 70k & 61k,  in the previous days.  End of season wobbles continue.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

September 5^th, 2018: 4,717,320 km², a drop of -14,832 km².
2018 is the 8^th lowest on record.

[gerontocrat]

JAXA ARCTIC EXTENT 4,717,320 km2（September 5, 2018）

Just to add to Juan's post...
- Extent is now 258 k km2  (5.5%) above the 2010's average extent on this date,
- and 131 k (2.8%) above 2017,
- Extent loss to date is now a very large 647 k km2 (6.6 %) below the 2008-2017 average, with 98.6% of the average melting season done.

Resulting minimum from average remaining melt is up to 4.58 million km2. Range of results from last ten years remaining melt is 4.43 to 4.69 million km2. Last year saw a last minute burst of melt. An end result significantly above 2017 now seems inevitable .

That 2017 feeling has waxed consistently for what seems a long time - melting has slowed to below average for many days. There is, on average, just over 1% (7 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss continue to reduce even further or even become gains ? Yes. Indeed, a minimum of 4.717 million km2 (September 5 extent) is possible.

[gerontocrat]

NSIDC published their August update a couple of days ago

https://nsidc.org/arcticseaicenews/

[gerontocrat]

NSIDC Total Area as at 5 September (5 day trailing average) = 3,322,362  km2

This is 217 k above the 2010-2017 average total area for this date

Total Area loss             9 k , 12 k below average for the day

Central Seas loss          3 k,
Peripheral Seas loss      2 k, all seas <5% of max.
Other Seas loss            4 k, all seas <5% of max.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea gain 0 k, area 36 k, < 5% of maximum.
Atlantic Side
- Baffin Sea loss 1 k, area 21 k, <5% of max,
- Greenland Sea loss 1 k, area 46 k,
- Barents Sea - finished,
- The Kara Sea area loss 1 k, area 30 k, < 5% of maximum.
- The Laptev Sea area loss 1 k, area 17 k, <5% of maximum.

CAB
- Beaufort Sea gain 2 k,
- The Canadian Archipelago loss 0 k,
- East Siberian Sea loss 10 k .
- The Central Arctic Sea gain 7 k,

Other seas
- St Lawrence -finished,
- Hudson Bay area loss 2 k, Area  8 k,
- The Okhotsk Sea - finished (quickly heading to zero).

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 9 k is below average by 12 k for this day. Extent loss (also 5-day trailing average)) was 31 k, average for the day. Daily extent loss 65k, after gain 32k, 66k loss, 3k gain, losses 70k & 61k,  in the previous days.  End of season wobbles continue.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

September 6^th, 2018: 4,704,891 km², a drop of -12,429 km².
2018 is the 8^th lowest on record.

PS: Have you notice that the 12^th lowest years today, are the 12^th last years?
If we are concern about climate change, should we be looking at this, instead of thinking that we need a catastrophe on a single year to prove a catastrophe on climate?

[kassy]

It would be a good argument in a honest debate but the climate change debate is not done this way.
The catastrophe is not needed as proof but to wake up the sheeple general population to put pressure on our politicians...sadly.

[Rob Dekker]

NSIDC published their August update a couple of days ago



https://nsidc.org/arcticseaicenews/

There are some who argue that sea ice decline stopped in 2007.
But let this NSIDC graph prove them wrong.
We are still declining. It's just that the natural variability is greater than the decline rate over 10 years.

[mostly_lurking]

NSIDC published their August update a couple of days ago



https://nsidc.org/arcticseaicenews/

There are some who argue that sea ice decline stopped in 2007.
But let this NSIDC graph prove them wrong.
We are still declining. It's just that the natural variability is greater than the decline rate over 10 years.

Actually this graph show nothing about what you are saying. It IS actually showing no decline since 2007. I am not arguing the long term trend but in 11 years there is no decline in extent.

[gerontocrat]

JAXA ARCTIC EXTENT 4,704,891 km2（September 6, 2018）

Just to add to Juan's post...
- Extent is now 282 k km2  (6.0%) above the 2010's average extent on this date,
- and 173 k (3.7%) above 2017,
- Extent loss to date is now a very large 666 k km2 (6.8 %) below the 2008-2017 average, with 98.9% of the average melting season done.

Resulting minimum from average remaining melt is up to 4.59 million km2. Range of results from last ten years remaining melt is 4.47 to 4.70 million km2. Last year saw a last minute burst of melt. An end result significantly above 2017 now seems inevitable .

That 2017 feeling has waxed consistently for what seems a long time - melting has slowed to below average for many days. There is, on average, just over 1% (6 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss continue to reduce even further or even become gains ? Yes. Indeed, a minimum of 4.70 million km2 (September 6 extent) is possible.

[oren]

Thank you as usual gerontocrat.
The daily extent gain has been above the daily average gain for two weeks straight. How's that for random variability...

[El Cid]

NSIDC published their August update a couple of days ago



https://nsidc.org/arcticseaicenews/

There are some who argue that sea ice decline stopped in 2007.
But let this NSIDC graph prove them wrong.
We are still declining. It's just that the natural variability is greater than the decline rate over 10 years.

Actually this graph show nothing about what you are saying. It IS actually showing no decline since 2007. I am not arguing the long term trend but in 11 years there is no decline in extent.

Exactly. Just because someone puts a linear fit on the graph, it does not mean that it is right. There was a serious downtrend in extent until 2007. Since 2007, we've been basically going sideways. That is probably because of bathymery constraints and changed (more cloudy) summer weather but it is a fact nonetheless.

OTOH, winter extent still seems to be crawling down...

[pauldry600]

No It still on course to be zero by Summer 2040. or 1m if you ask me.

The general mean is dropping year on year.

The Arctic is fooling us.
The Ice is thinner in most of the Arctic than it was in 2007.

One Summer of favorable conditions and most will be gone.

Might come back for a few years after but that line is an accurate reflection of where its going IMO

[mostly_lurking]

No It still on course to be zero by Summer 2040. or 1m if you ask me.

The general mean is dropping year on year.

The Arctic is fooling us.
The Ice is thinner in most of the Arctic than it was in 2007.

One Summer of favorable conditions and most will be gone.

Might come back for a few years after but that line is an accurate reflection of where its going IMO

Calling it "favorable" is only if you WANT it to melt.   

[Flocke]

NSIDC published their August update a couple of days ago



https://nsidc.org/arcticseaicenews/

There are some who argue that sea ice decline stopped in 2007.
But let this NSIDC graph prove them wrong.
We are still declining. It's just that the natural variability is greater than the decline rate over 10 years.

Actually this graph show nothing about what you are saying. It IS actually showing no decline since 2007. I am not arguing the long term trend but in 11 years there is no decline in extent.

Exactly. Just because someone puts a linear fit on the graph, it does not mean that it is right. There was a serious downtrend in extent until 2007. Since 2007, we've been basically going sideways. That is probably because of bathymery constraints and changed (more cloudy) summer weather but it is a fact nonetheless.

OTOH, winter extent still seems to be crawling down...

Yes, you are right.
There also was no decrease (more like stagnation) between 1981 and 1992, 1990 and 2003/2004, 1993 and 2001. The moderate decreases from 2002 to 2006 and from 2005 to 2009 are more than outweighed by the sharp increase from 1990 to 1996.

[gerontocrat]

For any time of the year
- 1990s < 1980s
- 2000s < 1990s
- 2010s < 2000s
- 2018  < 2000s
average extent.

My guess is that ten years from now the 2020s average will be less than the 2010s average.

[Ned W]

Resulting minimum from average remaining melt is up to 4.47 million km2.

I think you meant something else there.  My calc (based on all years since 2007) is 4.59.  In any case, thanks for the updates.

[Ned W]

Let's keep this thread for 2018 data, please.  A good thread for "when will we go ice-free?" is this one:

How soon could we go ice free?

[Shared Humanity]

NSIDC published their August update a couple of days ago



https://nsidc.org/arcticseaicenews/

There are some who argue that sea ice decline stopped in 2007.
But let this NSIDC graph prove them wrong.
We are still declining. It's just that the natural variability is greater than the decline rate over 10 years.

Actually this graph show nothing about what you are saying. It IS actually showing no decline since 2007. I am not arguing the long term trend but in 11 years there is no decline in extent.

Exactly. Just because someone puts a linear fit on the graph, it does not mean that it is right. There was a serious downtrend in extent until 2007. Since 2007, we've been basically going sideways. That is probably because of bathymery constraints and changed (more cloudy) summer weather but it is a fact nonetheless.

OTOH, winter extent still seems to be crawling down...

Picking 2007 as your starting point to argue there has been a stall in extent decline is no different than picking 1998  to argue that there was a hiatus in warming IMHO.

2007 and 2012 were extraordinary years for melt just as 1998 was an extraordinary year for warming. Take these peaks away and have them end up closer to the linear trend line and suddenly it looks like the decline has continued.

Did the decline in extent stall between 1986 and 1996?

If we look at a longer term extent decline chart, the extent decline stall is even harder to see.

[gerontocrat]

Resulting minimum from average remaining melt is up to 4.47 million km2.

I think you meant something else there.  My calc (based on all years since 2007) is 4.59.  In any case, thanks for the updates.

Yes, you are correct - missed that in the update of previous days commentary. the risk of using a standard template.

[gerontocrat]

NSIDC Total Area as at 6 September (5 day trailing average) = 3,307,794  km2

This is 219 k above the 2010-2017 average total area for this date

Total Area loss             15 k , 12 k below average for the day

Central Seas loss         13 k,
Peripheral Seas loss       1 k, all seas <5% of max.
Other Seas loss             0 k, all seas <5% of max.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 1 k, area 36 k, < 5% of maximum.
Atlantic Side
- Baffin Sea loss 0 k, area 21 k, <5% of max,
- Greenland Sea loss 1 k, area 45 k,
- Barents Sea - finished,
- The Kara Sea area loss 1 k, area 30 k, < 5% of maximum.
- The Laptev Sea area loss 2 k, area 15 k, <5% of maximum.

CAB
- Beaufort Sea loss 5 k,
- The Canadian Archipelago loss 0 k,
- East Siberian Sea loss 11 k .
- The Central Arctic Sea gain 7 k,

Other seas
- St Lawrence -finished,
- Hudson Bay area loss 0 k, Area  7 k,
- The Okhotsk Sea - finished (quickly heading to zero).

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 15 k is below average by 2 k for this day. Extent loss (also 5-day trailing average)) was 18 k, 7k  below average for the day. Daily extent gain 6k,  after loss 65k ,gain 32k, 66k loss, 3k gain, losses 70k in the previous days.  End of season wobbles continue.

[Shared Humanity]

Of course, if you look at a chart of volume, you could argue the extent stall is real.

[binntho]

Of course, if you look at a chart of volume, you could argue the extent stall is real.

There was a 16 year stall between 1982 and 1997, and another 9 years long between 1993 and 2001. The current stall is also 9 years long including current year. Or perhaps it's only that year-to-year variability is very large?

[Stephan]

In my opinion, painting horizontal lines into the ice extent or volume data from 2007 to 2017 is cherry picking at its best. The same was done by AGW deniers with global temperatures, choosing 1998 as an extra warm year as start and drawing a line until 2013 (comparably cool), claiming the pause of global warming is the beginning of a forthcoming cooling. The T rise of 2015 and 2016 and 2017 has stopped them doing that.
It is the long term trend that is important. The natural variability which adds upon the decreasing trend has to be taken into account when interpreting or extrapolating the data.

[Stephan]

It is time for the monthly update of the comparison of actual data with the long term trend.
August 2018 is 0,16 mio. km² below the long term linear trend, see attached graph.

[jdallen]

Of course, if you look at a chart of volume, you could argue the extent stall is real.

... or you could look at 2007-2013 a departure from and pull back to trend which resumes in 2014. I don't think it's safe to use short time scales here when year over year variation can be so noisy.

There was a 16 year stall between 1982 and 1997, and another 9 years long between 1993 and 2001. The current stall is also 9 years long including current year. Or perhaps it's only that year-to-year variability is very large?

Exactly this.

Previously variability annual melt (+/- ~1500KM3) in volume was a much lower fraction of the end of season volume - generally less than 20% the end of season value.

*Now*, that variability is  ~40%... e.g. the drop in melt of 2000KM3 between 2016 (just over 18,000KM3) and 2017 (about 16,000KM3) is nearly half of their averaged end of season volume - about 4450KM3.

The trend as expressed in volume, extent and area is going to dissolve into noise as a result, and will completely cease to be useful predictive metrics.

What I think this reflects is that the *real* trend is what's happening to enthalpy.

[Phil42]

2018 is the 11th year with a minimum below 5'000'000 km². Since 2007, every year with exception of 2009 had a minimum below 5'000'000 km².

Here are the dates when the other 10 years passed the 5 million mark again in the freezing season, ordered from earliest to latest.

2014 - 21. September
2013 - 22. September
2010 - 25. September
2016 - 27. September
2017 - 29. September
2008 & 2015 - 30. September
2011 - 2. October
2007 - 9. October
2012 - 14. October

Let's see which position 2018 will take in this statistic

[Michael Hauber]

On the longer term trends, tamino has a couple interesting post.  In 2015 he find evidence of a statistically significant change in trend over the last 10 years.  In 2017 he doesn't.  I think its borderline.  I think claims of a genuine recovery or halt of ice melt in the last 10 years are nonsense.  But claims that things may have slowed down (perhaps following a Gompertz curve) are reasonable and cannot be easily dismissed as noise.  I'd suggest that the long term linear trend is probably the best description of what is happening, and the recent slow down is an interesting talking point.

[Rob Dekker]

Given the large natural variability in sea ice extent, I think it is rather pointless to talk about short term changes in trend since 2007 or any other year.

For starters, there is no known physical cause that could explain a stop-and-go changes in the trend.

Secondly, climate model simulations under increased GHG forcing show that Arctic sea ice can easily appear flat or in strong decline trend over a 20 year period. Here for example :

https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-11-00201.1

It is important to note, however, that the temporal evolution of the simulated Arctic sea ice cover over the satellite era is strongly influenced by internal variability. For example, while one ensemble member shows an even larger decrease in the sea ice extent over 1981–2005 than that observed, two ensemble members show no statistically significant trend over the same period.

Also Holland et al 2006 already mentioned that climate simulations suggest there could be long stalls of the trend being flat followed by very steep reductions in Arctic sea ice extent :

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2006GL028024

One event exhibits a decrease from 6 million km2 to 2 million km2 in a decade, reaching near ice-free September conditions by 2040.

So don't get fooled about this supposed 'stall in trend' since cherry-picked 2007.
That 'stall' could easily last another decade followed by a very rapid decline.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

September 7^th, 2018: 4,663,054 km², a drop of -41,837 km².
2018 is the 8^th lowest on record.

[gerontocrat]

JAXA ARCTIC EXTENT 4,663,054 km2（September 7, 2018）

Just to add to Juan's post...
- Extent is now 264 k km2  (5.7%) above the 2010's average extent on this date,
- and 148 k (3.2%) above 2017,
- Extent loss to date is now a very large 654 k km2 (6.6 %) below the 2008-2017 average, with 99.2% of the average melting season done.

Resulting minimum from average remaining melt is down a tad to 4.58 million km2. Range of results from last ten years remaining melt is 4.48 to 4.66 million km2. Last year saw a last minute burst of melt. An end result significantly above 2017 now seems inevitable .

That 2017 feeling has waxed consistently for what seems a long time - melting has slowed to below average for many days, but on this day, extent loss more than 10k above average.. There is, on average, just under 1% (5 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that with a late burst of extent loss - Yes.  However extent loss would have to be quite large for 2018 to shift from 8th place. On the other hand, could extent loss become gains ? Yes. Indeed, a minimum of 4.66 million km2 (September 7 extent) is possible.

[binntho]

Slow wing's latest animation over on the melting thread seems to show the Atlantic bulge extending further south almost every day, while the Pacific side is rapidly melting. Increase in extent on one side seems to be masking drops in extent on the other side.

I would guess that the southward movement of the Atlantic front is due to the low-pressure system that's been hovering over the Arctic, but looking at the ever-so-reliable Nullschool animation seems to indicate that this movement will stop and that there might even be some retreat in the next couple of days. All in all it wouldn't surprise me if we had a run of larger than usual drops in extent in the next few days.

[gerontocrat]

NSIDC Total Area as at 7 September (5 day trailing average) = 3,296,203  km2

This is 225 k above the 2010-2017 average total area for this date

Total Area loss             12 k , 6 k below average for the day

Central Seas loss         13 k,
Peripheral Seas gain       1 k, all seas <5% of max.
Other Seas loss             0 k, all seas <5% of max.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 1 k, area 35 k, < 5% of maximum.
Atlantic Side
- Baffin Sea loss 2 k, area 19 k, <5% of max,
- Greenland Sea gain exactly 3,000 km2 (suspicious?), area 48 k,
- Barents Sea - finished,
- The Kara Sea area loss 0.5 k, area 29 k, < 5% of maximum.
- The Laptev Sea area loss 1 k, area 14 k, <5% of maximum.

CAB
- Beaufort Sea loss 5 k,
- The Canadian Archipelago loss 2 k,
- East Siberian Sea loss 13 k .
- The Central Arctic Sea gain 9 k,

Other seas
- St Lawrence -finished,
- Hudson Bay area loss 0 k, Area  7 k,
- The Okhotsk Sea - finished .

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 12 k is below average by 6 k for this day. Extent loss (also 5-day trailing average)) was 27 k, 3k  below average for the day. Daily extent loss 39k after gain 6k, loss 65k ,gain 32k, 66k loss, 3k gain, losses 70k in the previous days.  End of season wobbles continue.


ps: While we wee all looking at the Arctic, there was a different story unfolding at the other end of the planet. See last table.

[Hautbois]

Running back chart update. 2018 enters the throng.