Arctic Sea Ice : Forum

Cryosphere => Antarctica => Topic started by: Jim Hunt on January 21, 2016, 12:59:28 PM

Title: 2016 Antarctic Minimum Area/Extent
Post by: Jim Hunt on January 21, 2016, 12:59:28 PM
As my alter ego has just pointed out to the assembled throng over on Twitter (https://twitter.com/GreatWhiteCon/status/690139590393491460), Antarctic sea ice area and extent are both about to drop below the minima of recent years, using Wipneus' "homebrew" AMSR2 metrics at least:

http://GreatWhiteCon.info/resources/antarctic-sea-ice-graphs/ (http://GreatWhiteCon.info/resources/antarctic-sea-ice-graphs/)

Where and when do you suppose the Antarctic minimum will be this year? Should I start a poll or two?
Title: Re: 2016 Antarctic Minimum Area/Extent
Post by: johnm33 on January 21, 2016, 08:06:59 PM
2 to 2.5 looks baked in, some very lonely ice outside of Weddel, and not a lot there!
Title: Re: 2016 Antarctic Minimum Area/Extent
Post by: crandles on January 22, 2016, 12:06:37 AM
Think I counted 6 years lower for time of year on CT. Seems there is some areas that have broken away from hugging coast so I wouldn't be surprised to see CT area to go below 1.5 which would be 2nd lowest on record. (Maybe saying this will cause it to plateau.)
Title: Re: 2016 Antarctic Minimum Area/Extent
Post by: Jim Hunt on January 22, 2016, 01:56:46 PM
The (higher resolution) AMSR2 numbers are racing ahead of the NSIDC & CT metrics. Does this portend sudden drops in those two numbers?

Meanwhile I've set up a poll for the 5 day averaged NSIDC extent as shown by Ch(ant)arctic (http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/).
Title: Re: 2016 Antarctic Minimum Area/Extent
Post by: AbruptSLR on January 22, 2016, 07:52:27 PM
To help those who have not voted yet I provide the two attached NSIDC images issued today.  The second image makes it clear that ice extent is particularly low this year due to the current Super El Nino, which might (or might not) put a record low in reach.

Further, for what it is worth, I note that the austral winter sea ice extent remains anomalously high, which Hansen points reduces radiation from the Southern Ocean into outer space; while the current austral summer low sea ice extent allows the Southern Ocean to absorb solar radiation.  Thus our current situation with a Super El Nino results in a positive feedback mechanism associated with Antarctic sea ice.  Also, I note that climate models project an increasing frequency of strong El Ninos with continued climate change, so I think that our current pattern represents a net-long-term positive feedback mechanism.
Title: Re: 2016 Antarctic Minimum Area/Extent
Post by: Stephen on January 30, 2016, 09:04:06 AM
...
Thus our current situation with a Super El Nino results in a positive feedback mechanism associated with Antarctic sea ice.  Also, I note that climate models project an increasing frequency of strong El Ninos with continued climate change, so I think that our current pattern represents a net-long-term positive feedback mechanism.

Postive in which direction?  Increasing or decreasing sea-ice?

I'm curious as to what variations in Antarctic sea-ice mean for long-term climate change.  My suspicion is that it doesn't mean much at all.  A fascinating side-show, but not as meaningful as Arctic sea-ice, simply because the ice shelves sitting in the centre of it all will remain for a very long time.
Title: Re: 2016 Antarctic Minimum Area/Extent
Post by: AbruptSLR on January 30, 2016, 07:58:19 PM
...
Thus our current situation with a Super El Nino results in a positive feedback mechanism associated with Antarctic sea ice.  Also, I note that climate models project an increasing frequency of strong El Ninos with continued climate change, so I think that our current pattern represents a net-long-term positive feedback mechanism.

Postive in which direction?  Increasing or decreasing sea-ice?

I'm curious as to what variations in Antarctic sea-ice mean for long-term climate change.  My suspicion is that it doesn't mean much at all.  A fascinating side-show, but not as meaningful as Arctic sea-ice, simply because the ice shelves sitting in the centre of it all will remain for a very long time.

I meant positive feedback mechanism in regards to climate change in general.  However, with regard to Antarctic sea ice extent, I believe that once the current El Nino is gone the Antarctic sea ice extent will continue to generally trend upwards (will periodic fluctuations downward) for the about the next 20-years (due to freshening of the Southern Ocean surface water associated with glacial meltwater), and after about 2036 to 2045 the Antarctic sea ice extent will start to trend downward as global warming offsets the freshening effect.  Climate change is complex and reducing it to simplistic generalizations can be counter productive.
Title: Re: 2016 Antarctic Minimum Area/Extent
Post by: Jim Hunt on February 05, 2016, 04:54:25 PM
I arrived to point out to any last minute fence sitters that CT global sea ice area is currently at the lowest ever level for the date, since their records began at least:

http://GreatWhiteCon.info/2016/02/arctic-sea-ice-area-and-extent-lowest-ever-for-the-date/#comment-213366 (http://GreatWhiteCon.info/2016/02/arctic-sea-ice-area-and-extent-lowest-ever-for-the-date/#comment-213366)

However it seems that the poll has already closed itself, so I'm not sure what time zone it thinks it's in. After a not entirely overwhelming response the favourite amongst the 12 voters is a new record somewhere between 2.0 and 2.25 million kmĀ².

Now all we have to do is wait and see what transpires!
Title: Re: 2016 Antarctic Minimum Area/Extent
Post by: Lord M Vader on February 20, 2016, 08:01:03 PM
Seems like the Antarctica sea ice extent is bottoming out at 2,6 million km2. This put this minimum to a preliminary 9 place of the least sea ice extents. The minimum has in a majority of the years since 1979 occurred between 21 and 28 of February. The earliest minimum was reached at February 15 while the latest date is March 6. Only three years have seen the minimum in March.

The lowest observed minimum is 2,29 milion km2 and occurred in 1997.

//LMV