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2015 Arctic Sea Ice Thread

BenBurch

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BenBurch
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As in prior years, this is a thread on Arctic Sea Ice for tracking sea ice over the course of the 2015 melt season.

This thread is approved by the moderator team for the limited purposes described, anything more than incidentally beyond that may be subject to moderator action.

Rule;

1. This is not an AGW thread.
2. This is about Sea Ice only.
3. You may speculate on the trajectory of Sea Ice melting in here.
4. You may post data from official sources and news articles from the science press in this thread.
5. No politics.
6. See rule 5.

Now, to start us off let us discuss the three measures of Sea Ice that are often misunderstood;

Sea Ice Extent; This is the total area of sea that is at least 15% ice-covered, so this can include a lot of open water, no open water, or anything in between. This is an easy measurement to make, and is useful for navigation; unless you are an icebreaker you do not want to sail into an area that is 15% ice. However, this is a very misleading measurement at times when you want to ascertain how much ice has melted.

Sea Ice Area; This is a better measurement in that it considers just the area taken up by ice. If 1 km2 is 20% ice-covered, that is .2 km2 area. So though this measurement CAN track Extent fairly closely, there is no guarantee it will, and it can diverge markedly under the right conditions. However, this tells you nothing about the thickness of the ice; It can be 1 cm thick, or 3 m thick and it is all the same in this measure, what counts is the area it covers. This measurement is a good way to judge the amount of sunlight rejected to space by white ice as opposed to dark water.

Sea Ice Volume; This is the actual physical volume of ice in polar waters. It is probably the best measure of how far the loss of polar ice has progressed.

Anomaly plots; When you compare the ice that on average would have been found on a particular date or range of dates, in any of the above measures, and subtract that from the number you measure, you get the first derivative of the that measure, and you can see how much ahead or behind the average you are. This is very useful as it is difficult to look at the sinusoidal annual cycle these numbers go through, and get a sense of comparison between two cycles. This removes the annual signal and just shows you how it had been modulated.
 
This year's extent curve is likely to "repeat" 2011's, faster at first, then slower, with a slightly higher minimum extent in the end. I expect this year's minimum extent to be between 4.3 and 4.9 million square kilometres, and minimum volume to be around 5,200 km3. But let's everybody make a prediction by June 1st.

This year, slightly positive values of ENSO plus the RRR, no good for ice melting. If a full-fledge Niño starts during the Northern Autumn, 2017 or 2018 may be "da year!".
 
OK. Then we only have thicker ice in the 5 or 6 million square kilometres of sea ice that are suppose to remain through Summer and thinner ice in the rest of the banquise. That's why higher volume - lower extent.

And multi-year ice exports through Fram Strait have being about normal so far (you need to make a movie with all the images here- they're not updating that so often now), so that ice pack is not going to become thinner any soon.

I see this year's about repeating 2011's.
 
aleCcowaN said:
OK. Then we only have thicker ice in the 5 or 6 million square kilometres of sea ice that are suppose to remain through Summer and thinner ice in the rest of the banquise. That's why higher volume - lower extent.

And multi-year ice exports through Fram Strait have being about normal so far (you need to make a movie with all the images here- they're not updating that so often now), so that ice pack is not going to become thinner any soon.

I see this year's about repeating 2011's.
Click to expand...

I suspect you are right unless some very unfavorable weather comes to pass.
 
GodMark2 said:
That's'a be one BIG animated GIF... over 6mb so far and I haven't even gotten to the 90's yet.
Click to expand...

Last 20+ years



Some recent changes

https://diablobanquisa.files.wordpress.com/2015/02/ani_39_05_2015.gif?w=420

You can see there how the old ice cracks and so it exposes water to be frozen quickly, a self-compensating mechanism that tends to keep the ice volume and the all-important downward flux of brine as stable as possible (anyway we humans manage to disturb that)
 
BenBurch said:
I suspect you are right unless some very unfavorable weather comes to pass.
Click to expand...

A El Niño season favours the melting process north of Alaska and Eastern Siberia while it makes for milder winds north of Greenland and around the Fram Strait, pointing to Kara and Laptev seas.

Anyway, more than half of the surplus gained since 2012 is gone now, and everything continue to point in the same path. Today that surplus should be one thousand cubic kilometres above 2012's and 2013's. The sea ice volume rebound maxed some 3,200 km3 if my memory serves.
 
What's going to happen to the Arctic Ocean ice if the thermohaline structure slows more or even stops as this anticipates

What’s going on in the North Atlantic?
Filed under: Climate Science — stefan @ 23 March 2015
2213EmailShare
The North Atlantic between Newfoundland and Ireland is practically the only region of the world that has defied global warming and even cooled. Last winter there even was the coldest on record – while globally it was the hottest on record. Our recent study (Rahmstorf et al. 2015) attributes this to a weakening of the Gulf Stream System, which is apparently unique in the last thousand years.

The whole world is warming. The whole world? No! A region in the subpolar Atlantic has cooled over the past century – unique in the world for an area with reasonable data coverage (Fig. 1). So what’s so special about this region between Newfoundland and Ireland?

- See more at: http://realclimate.org/index.php/ar...-atlantic/comment-page-2#sthash.ASouTySt.dpuf
Click to expand...

Seems we might end up with more ice cover and a colder Northern Europe and a lot of heat piling up elsewhere.
 
Last edited:
At Start of 2015 Melt Season, Arctic Sea Ice is in a Terrible State

From Robert Scribbler

https://robertscribbler.wordpress.c...season-arctic-sea-ice-is-in-a-terrible-state/

"With April 8 achieving a new record low extent of 14,073,000 square kilometers — 95,000 square kilometers below the previous record low of 14,168,000 set in 2006."

"High anomaly departures in the range of 15-20+ degrees C above average cover about 1/3 of the high Arctic region above 80 degrees North Latitude. Laptev, Kara, Barents and the Arctic Ocean proper are all included in the heat bulge. Temperatures in this zone today spiked to near or above the point at which sea ice melts at the surface (-2.5 C) with temperatures in the Kara in the 0 to -2 C range, temperatures in the Laptev in the -2 to -4 C range and temperatures within 100 miles of the pole hitting around -3.8 C. For this region, these are readings more typical to June or even July."
 
Don't buy hyped bits of text! "sea ice melts at the surface (-2.5°C)"? Really? Explain it to me.

I've got little time, let's state some things:

  • Maximum Arctic sea ice extent depends on peripheral regions like Arctic Pacific or the Gulf of Bothnia. Don't extrapolate these conditions to the Arctic Ocean.
  • Temperatures above 80°N are much higher than normal, like each year during the last two decades. In fact, not such high. Compare this season with 2012's.
  • There are still some 1,000 km3 of extra multi-year ice when compared to the values for the same dates during 2012.
  • Niño season with Pacific Decadal Oscillation near its 1998 record, so it's logical there's little ice in N. Pacific during March and warmer weather North of Alaska and Eastern Siberia April to July. It has no much bearing on the ice extent but it affects its distribution.
 
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