When we will see an ice free arctic?

[frontranger8]

Who said it was? The poll is just asking about the first such occurrence, not making a statement about the implications.

 

The poll isn't the be-all, end-all on implications of "an ice free Arctic". 

[Jonger]

ehhh. I don't think that's quite right.

 

Wanna put some money on it?

 

Do you know how difficult it will be to melt out the ice that's piled up along the Canadian archipelago? The arctic could warm another 5C and it still might take a decade or more.

[LithiaWx]

Wanna put some money on it?

Do you know how difficult it will be to melt out the ice that's piled up along the Canadian archipelago? The arctic could warm another 5C and it still might take a decade or more.

That ice can still be there with a min below 1M. That's pretty much the premise of the 1M stipulation.

[Jonger]

That ice can still be there with a min below 1M. That's pretty much the premise of the 1M stipulation.

 

Possibly. 1M isn't really a meltout though. 

 

I'm guessing that's why 1M was listed as the threshold, because that last 1M will be TOUGH. It could linger for 50 years, assuming we don't suck the CO2 out.

[LithiaWx]

Possibly. 1M isn't really a meltout though.

I'm guessing that's why 1M was listed as the threshold, because that last 1M will be TOUGH. It could linger for 50 years, assuming we don't suck the CO2 out.

I didn't pull 1M out of thin air. I can't remember the exact group who first used it but the 1M is a commonly accepted definition of an ice free arctic.

[Jonger]

I didn't pull 1M out of thin air. I can't remember the exact group who first used it but the 1M is a commonly accepted definition of an ice free arctic.

 

I have heard that before, it's most likely because that last 1M will linger for decades longer than the easy ice.

 

On the bright side, if we ever do co2 sequestration, it might not take more than a decade or so to rebuild the ice back up.... There are paleo records that show meltouts and rebuilds in short timeframes.

[CAD_Wedge_NC]

I am 50 years old....If I live a normal life expectancy, I don't believe I will live to see it. There will be something to off-set the decline. Perhaps a volcano. Perhaps some other negative feed-back that we have not considered. Just my opinion.

[nflwxman]

Wanna put some money on it?

 

Do you know how difficult it will be to melt out the ice that's piled up along the Canadian archipelago? The arctic could warm another 5C and it still might take a decade or more.

 

I didn't say it was likely.  Just a hunch it will be in the mid-late 2020s.  I wouldn't put money on it as arctic sea ice is not really my area of most knowledge.

[StudentOfClimatology]

I don't think a 2020s melt is likely either, but using a one decade trend for that isn't exactly how I would've argued against it. The 30-year trend is +1C/decade.

I agree with everything but the bolded. The trend is nowhere close to 1C/decade. This holds true for both the surface station data and the satellite data:

[StudentOfClimatology]

The definitive predictions Re: melt out date(s) are a pure crapshoot. The paleo data depicts an Arctic climate that is very unstable and subject to large internal variability. The ice could disappear in 20 years, or it could take a over a century.

[PhillipS]

My recollection of the discussion several years ago about the 1M km2 threshold was that satellite observations will never go to 0 km2 because satellites can't distinguish between sea ice and the bergy ice debris from glacial calving, and because there will always be sheltered coves or fiords with some ice left.  There is also the issue of the margin of error.  Lots of room for argument.  So the thought was that specifying a threshold for the value, and the source to be used, would eliminate much of the potential disputes.  The value of 1,000,000 km2 was chosen because we shoe-wearing monkees like round numbers.  Any other value greater than, say, 100K km2 would have made equal sense IMO.

[csnavywx]

I agree with everything but the bolded. The trend is nowhere close to 1C/decade. This holds true for both the surface station data and the satellite data:

Yeah, I'm sorry, I was looking at NCEP reanalysis for the 1C/dec. GISS shows 0.6C/dec, RSS 0.4C/dec, etc.

 

I perhaps missed the crux of the point with that sentence though. Winter temps (and resultant freezing degree days) are very important for thickening. Winter warming has been ridiculously fast. Once we can't reliably get above 1.7-1.8m or so of thickness over most of the basin, most simulations show that summer ice survival chances crash.