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Arctic Sea Ice Extent, Area, and Volume


ORH_wxman
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23 minutes ago, Mallow said:

 

Wow... that has to be an error, doesn't it? That would be like if NYC's record high and low for a date were 80°F and 40°F respectively, and then they go and record an 18°F.

Not an error.  Something is going on...

http://www.independent.co.uk/environment/arctic-antarctic-sea-ice-polar-global-warming-climate-change-india-alaska-a7458881.html

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Just now, pazzo83 said:

Yeah, it's definitely not an error. Something rather odd going on down there this year, including the sudden reappearance of the Weddell Polynya.

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3 minutes ago, pazzo83 said:

Is it possible that there those record levels in the Antarctic over the past couple years were only in coverage and not necessarily volume (as in, the ice was more widespread but demonstrably thinner)?

I think that was the general consensus. It's just so strange to me that it would seem so steady, and then suddenly collapse. Perhaps feedbacks are more important down there than I realized.

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8 minutes ago, pazzo83 said:

Some of what I read suggests some changes in circumpolar winds, but to cause an almost 6SD drop?

The SAM went negative, so that's helped, but it doesn't explain everything.

Pure speculation mode:

I was wondering if there was a link with the Super Nino earlier this year. However, we didn't see this kind of response in 1998, so I'm having a hard time reconciling that.

The big coastal polynyas this year might hold a clue. More warm CDW being directed at the continental margins would explain that.

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11 minutes ago, csnavywx said:

The SAM went negative, so that's helped, but it doesn't explain everything.

Pure speculation mode:

I was wondering if there was a link with the Super Nino earlier this year. However, we didn't see this kind of response in 1998, so I'm having a hard time reconciling that.

The big coastal polynyas this year might hold a clue. More warm CDW being directed at the continental margins would explain that.

But why would that show up as polynyas in all the basins at once this year, and not in any previous year? Not even a hint...

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1 hour ago, pazzo83 said:

Holy sh*t - that end of year max is just not there this year for global sea ice:

 

Yep. As far as I could tell, this is the only year on record that the NH summer peak in global sea ice was higher than the NH autumn peak. I couldn't find one in the past that was even close.

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He's right, here is very little evidence of these "tipping points" that cause "runaway" melting. This is probably even more true for southern ice. In the Arctic, where ice is thicker, a big volume loss event like 2007 can cause a step-down, but that isn't possible in Antarctic sea ice since most of the ice there melts out every year. And even as the Arctic has gone to a higher percentage of first year ice since 2007, we've seen very little correlation from year to year of values. The Tietsche et al 2011 paper went into depth on this issue when there was a lot of speculation about ice free arctics by 2014 or 2015 due to "runaway melting" after the 2007 min. The paper concluded that you wouldn't see this due to negative feedback in the form of volume regeneration in winter months. This is exactly what we have seen and why those early ice free predictions busted and haven't really come close. They said you needed to blunt the volume regeneration in the form of much much warmer winter temps...and we actually saw a glimpse of this last winter. It was so warm that it probably helped in not allowing some first year ice to survive the past summer that might have normally done so...so we had a pretty low minimum despite the summer weather not being all that hostile. So once we get winter temps regularly surpassing last winter, then there is more physical mechanism for ice free Arctic at the min. 

The southern sea ice is less well understood and is pretty sensitive to surface wind. The huge Weddell sea polynya was actually a regular feature in the 1970s and has reappeared smaller a few times in the 1980s too. But this recent occurance is the biggest since then. 

Gordon et al 2007 hypothesizes that the southern annular mode contributed to it in the past. 

http://journals.ametsoc.org/doi/abs/10.1175/JCLI4046.1

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S Hemi ice is highly variable and gets a reset every year since most of the ice melts so we will need to see several years to confirm any change in the sea ice trend. Biggest concern is surface melt on ice shelves that are already under pressure from bottom melting. One unusually warm year could speed things up.

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I posted some rough numbers on another blog. S Hemi sea ice has been running 2500000 sq km lower than last year. That is roughly 0.7% of earth's surface. Sea ice albedo impact vs open water is roughly 0.2 after accounting for clouds. Insolation at 70S is 50% above the global average on the Dec solstice. So currently there is roughly 0.2% more solar being absorbed at the earth's surface due to the change in SHemi sea ice vs. last year. Of course the impact decreases off the solstice and disappears completely once the sun sets. Integrating over a season the impact is about the same magnitude as going from peak to bottom of a solar cycle.

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Arctic sea ice likely has been low and declining because of the warm phase of the AMO which started in the 1990s and is still peaking. Notice
from the diagram below that the cold phase of the AMO was in the 1970s when satellites began measuring sea ice accurately

Amo_timeseries_1856-present.png

Hence waters going into the Arctic Basin from the north Atlantic have been warmer than normal. Thus sea ice is affected and Arctic temperatures are higher, sea ice lower. Once this reverses sea ice will recover in the Arctic Basin and Arctic temperatures will fall off again. This is strong evidence that the sea ice is cyclical and related to the AMO. This years warmth as seen from the reanalysis data and even the more accurate satellite data is related to the very strong El Nino we just had and there is a lag effect. Land temperatures have fallen about 1C since peaking from this El Nino. So its all downhill from here.  Also remember that reanalysis data, especially in the Arctic regions is unreliable, and even the satellite data is not as good for the Arctic because of the skewed angle of the satellite at our high latitudes.   

 

 

 

 

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6 hours ago, blizzard1024 said:

Arctic sea ice likely has been low and declining because of the warm phase of the AMO which started in the 1990s and is still peaking. Notice
from the diagram below that the cold phase of the AMO was in the 1970s when satellites began measuring sea ice accurately

Amo_timeseries_1856-present.png

Hence waters going into the Arctic Basin from the north Atlantic have been warmer than normal. Thus sea ice is affected and Arctic temperatures are higher, sea ice lower. Once this reverses sea ice will recover in the Arctic Basin and Arctic temperatures will fall off again. This is strong evidence that the sea ice is cyclical and related to the AMO. This years warmth as seen from the reanalysis data and even the more accurate satellite data is related to the very strong El Nino we just had and there is a lag effect. Land temperatures have fallen about 1C since peaking from this El Nino. So its all downhill from here.  Also remember that reanalysis data, especially in the Arctic regions is unreliable, and even the satellite data is not as good for the Arctic because of the skewed angle of the satellite at our high latitudes.   

 

 

 

 

How do these fluctuations explain what is only a recent sharp decrease in sea ice coverage?

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8 hours ago, pazzo83 said:

How do these fluctuations explain what is only a recent sharp decrease in sea ice coverage?

The AMO has been in the warm phase since the late 1990s so little by little sea ice coverage shrinks. Then this year we had a strong El Nino and hence a low sea ice year. We only have about 40 years worth of reliable sea ice coverage data and the satellite monitoring began during a known cool period in the 20th century when sea ice likely was at a maximum in coverage. So we are seeing the downward trend of a cyclical process.  And the Vize, Russia observation is just weather, not climate. There has been tremendous cold in Asia this fall. The average global temperature from the satellites is around +.4C which is not that big of a deal and we are in a cooling trend as the effects of the strong El Nino fade. There is nothing unusual about our current climate.  CO2 may be leadling to some of the observed warming but climate scientists, in my opinion, underestimate the natural variability of our climate system.   

 

 

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