Poll: What happens after the first sea ice free arctic?

[Archimid]

I open this poll with the hope of finding out what this forum thinks about the significance of the first Arctic without sea ice.

Some definitions for clarity:

Arctic changes: That includes the Arctic ocean and the atmosphere above the arctic and any/all parameters that can be given to them. Temperature, pressure, speed, wind and ocean patterns etc.

Earth Systems: That includes the world's oceans,continents and atmosphere and any/all the parameters that can be given to them.

[Buddy]

I think the most significant change will be to Greenland.  Of course...it is already being affected by the decrease in the Arctic ice.....but this will ramp up those changes.

[icy voyeur]

The global changes will continue, there may or may not be specific changes induced by reduced ice in the arctic but some arbitrary cut-off definition of what is labeled "ice free" has absolutely nothing to do with those changes.

A relatively ice free arctic will enable larger storms and larger waves with potentially significant impact on shallow methane reserves and of course coastal erosion.

There's an additional potential to disrupt oceanic currents with largely unpredictable consequences, other than that most of them will be bad by virtue of being disruptive to patterns we have adapted our economy and society to.

[Peter Ellis]

I've taken the last option, with the proviso that I do NOT mean to say there will be an irreversible transition as soon as we have one year with < 1  million km^2 of ice. That's "magic number" type thinking.

[Sterks]

Notwithstanding that nothing will happen after that year that had not happened already in the previous one, I voted for 5

[Tealight]

The question and answers are not very representative of the whole system. The Arctic changes gradually and when the first ice free year occures significant changes in the Arctic already happend. Other Earth systems like melting permafrost on continents are at least moderatly affected.

[Neven]

The question and answers are not very representative of the whole system. The Arctic changes gradually and when the first ice free year occures significant changes in the Arctic already happend. Other Earth systems like melting permafrost on continents are at least moderatly affected.

Exactly, which is why I would vote for: Some changes in the Arctic but no immediate significant changes to other Earth systems.

[jdallen]

I've taken the last option, with the proviso that I do NOT mean to say there will be an irreversible transition as soon as we have one year with < 1  million km^2 of ice. That's "magic number" type thinking.

Concur. 

My sense of our having a year with under 1 million KM2 of ice is that it will be a definitive signal of highly chaotic climate conditions having started in the northern hemisphere.

It *may* be irreversible, but whether or not that is true will depend on heat uptake and distribution, not Arctic ice coverage.

[seaicesailor]

Notwithstanding that nothing will happen after that year that had not happened already in the previous one, I voted for 5

lol
I think the same on every Election Day
Just kidding I vote 6 but not sure if it was meant summer or year-round ice free Arctic. In the second case, I'd be tempted to go for "it will not happen" or not early enough to be attributable to AGW.

[Pmt111500]

the option, "there's no marine Arctic biotope anymore, and significant changes happen to weather systems in the northern hemisphere " is missing thus not voting.

[Adam Ash]

The question and answers are not very representative of the whole system. The Arctic changes gradually and when the first ice free year occures significant changes in the Arctic already happend. Other Earth systems like melting permafrost on continents are at least moderatly affected.

Yes, the 'grand event' is just part of a continuum.  The potential for black swans like the CAA Garlic Press response to reduced ice pack particle size will persist, tho where the swan(s) will alight is likewise unknown.   

I vote for 5.

[budmantis]

I voted five, with the concession that it could become a six. Not quite ready to go that far out on a limb yet. Also, a bit of wishful thinking.

[be cause]

What happens ? .. Trump gets re-elected !

[Richard Rathbone]

People argue about whether it was actually ice free or not for the next 10 years.

[oren]

The forum software blows up from all the new readers. Nobody else cares 

[Ned W]

I'm not really sure how to interpret the options, so I'll pass on voting in the poll.  But here's a summary of my take on this:

1. I think there's a good chance that there were Arctic-sea-ice-free periods in summer during the early-mid Holocene, and certainly during previous interglacials.  So I don't  think a loss of Arctic sea ice immediately results in some massive shock to the Earth system (no catastrophic methane release or whatever). 

2. I think there may well be far-reaching impacts of a large decrease in average summer sea ice extent -- like probabilistic changes to weather patterns.  But it may be challenging to attribute those effects specifically to the loss of sea ice (causality) , because so many other aspects of the Earth system are changing as well in parallel with sea ice. 

3. There's nothing magical about 1 million or 0.5 million or 0 million km2 of ice as a threshold -- going from 1.1 to 1.0 million, or 0.1 to 0.0 million, doesn't particularly matter (well, those thresholds might be interesting to people, but as far as the Earth system is concerned they're arbitrary and irrelevant).

4. Insofar as there have been ice-free episodes in past summers, the loss of ice is obviously not irreversible.  But reversing the loss of ice depends on reversing the warming trend, which in turn depends on reversing the rise in CO2 etc. in the atmosphere.  That won't happen soon and it won't happen quickly.

[Peter Ellis]

That's a much more accurate summary of my views than my own post :-)

[Glenn Tamblyn]

I think the bigger impacts are more likely to hit when it manages to be ice free for much of the summer. Open water plus peak insolation plus no ice limiting of surface air temperatures and suddenly evaporation from the Arctic sea itself could do some really interesting things to NH weather patterns.

[Ned W]

That's a much more accurate summary of my views than my own post :-)

Thanks for the kind words.

[anotheramethyst]

I think after the FIRST ice free summer, the large amount of open water allows more heat loss in winter, causing a recovery period of a couple years to follow.  Once the arctic transitions to an ice free state nearly every summer, (which might take about a decade after the first ice free summer) then the big changes occur.  Of course, the reduced ice already affects weather in the northern hemisphere, so I expect more significant changes as more ice is lost over time.  Just my 2 cents.

[Adam Ash]

I think after the FIRST ice free summer, the large amount of open water allows more heat loss in winter, causing a recovery period of a couple years to follow.  Once the arctic transitions to an ice free state nearly every summer, (which might take about a decade after the first ice free summer) then the big changes occur.  Of course, the reduced ice already affects weather in the northern hemisphere, so I expect more significant changes as more ice is lost over time.  Just my 2 cents.

Just thinking... (apologies in advance!)

Once the Arctic becomes 'ice free' (by the prevailing definition), is there not the potential for the free ocean surface to then become much more able to transport near-surface warmth anywhere the wind blows (or at least at 45-degrees to the right thereof)? 

At the moment the comparative immobility of the ice pack constrains surface water flows.  Even in areas with a comparatively low ice concentration the free water surface is contained in ice-bounded cells without 'access' to water from adjacent cells.  This compares with the eventual future inverse state with the water surface being continuous, and the ice populating the water-bounded cells.

So is that another change point (like grain size and the CAA Garlic Press)...  where the majority of the Arctic ocean becomes a free-moving water surface with isolated cells of ice therein?

Once that free surface gets underway transporting heat wherever, then even in the depths of winter there is no practical reason why comparatively warm Atlantic surface water does not push north thru Fram Straight etc directly towards and past the North Pole.  That could mean there is continuous production of surface ice which is then promptly transported south to warmer areas to be melted again, while warmer surface water from south pushes up in to the freezing zone to replace it. 

So the first near-ice-free event may not be an easy position from which to see a symmetrical return to ice conditions similar to today.  It may be a tipping point. 

[jai mitchell]

 



?

[seaicesailor]

I think after the FIRST ice free summer, the large amount of open water allows more heat loss in winter, causing a recovery period of a couple years to follow.  Once the arctic transitions to an ice free state nearly every summer, (which might take about a decade after the first ice free summer) then the big changes occur.  Of course, the reduced ice already affects weather in the northern hemisphere, so I expect more significant changes as more ice is lost over time.  Just my 2 cents.

Just thinking... (apologies in advance!)

Once the Arctic becomes 'ice free' (by the prevailing definition), is there not the potential for the free ocean surface to then become much more able to transport near-surface warmth anywhere the wind blows (or at least at 45-degrees to the right thereof)? 

At the moment the comparative immobility of the ice pack constrains surface water flows.  Even in areas with a comparatively low ice concentration the free water surface is contained in ice-bounded cells without 'access' to water from adjacent cells.  This compares with the eventual future inverse state with the water surface being continuous, and the ice populating the water-bounded cells.

So is that another change point (like grain size and the CAA Garlic Press)...  where the majority of the Arctic ocean becomes a free-moving water surface with isolated cells of ice therein?

Once that free surface gets underway transporting heat wherever, then even in the depths of winter there is no practical reason why comparatively warm Atlantic surface water does not push north thru Fram Straight etc directly towards and past the North Pole.  That could mean there is continuous production of surface ice which is then promptly transported south to warmer areas to be melted again, while warmer surface water from south pushes up in to the freezing zone to replace it. 

So the first near-ice-free event may not be an easy position from which to see a symmetrical return to ice conditions similar to today.  It may be a tipping point.

Consider that the slightest breeze from Greenland would initiate the freezing no matter how agitated the water was. At below freezing for months in the dark, the heat flux to prevent it is absurd and would need  completely different ocean current arrangement at planetary scale. Not in this century...

[Adam Ash]

Consider that the slightest breeze from Greenland would initiate the freezing no matter how agitated the water was. At below freezing for months in the dark, the heat flux to prevent it is absurd and would need  completely different ocean current arrangement at planetary scale. Not in this century...

I was rather thinking about 'agitation' at the molecular level viz; temperature.
But thanks for the technically detailed rebuttal anyway!  I'm sure you are right.

[seaicesailor]

Consider that the slightest breeze from Greenland would initiate the freezing no matter how agitated the water was. At below freezing for months in the dark, the heat flux to prevent it is absurd and would need  completely different ocean current arrangement at planetary scale. Not in this century...

I was rather thinking about 'agitation' at the molecular level viz; temperature.
But thanks for the technically detailed rebuttal anyway!  I'm sure you are right.

Just in case, I didn't mean to be uppish, sorry.
To substantiate this a bit, some rough numbers:
Extra energy needed by a 20C ~25C warmer Arctic in winter to stay at melting temp 271.5 K, black body Stefan-Boltzmann Law
E = 0.5 * sigma * (271.5^4 - 246.5^4) ~ 50 watt / m^2 approximately (taking emissivity of ocean water ~ 0.5 to be fair)

Heat excess per unit time and area being trapped by AGW: 0.58 ~ 1 watt / m^2 (since 0.58 w/m^2 was determined during solar minimum years).

http://www.giss.nasa.gov/research/briefs/hansen_16/

Since area of Earth is 500 M km2 and Arctic ice winter is say 10 M km2 (it is more but fine), maybe if global energy excess due to AGW could be transferred to the Arctic during the NH winter by a little demon, the resulting power might reach the 50 watt / m^2.

[Adam Ash]

Thanks SeaIce!  And sorry for my sarc too!   Those are interesting and helpful figures.

[seaicesailor]

It is an interesting exercise. My rough numbers may be wrong though.

[Archimid]

Reply to poll

Thanks to all the forum members that participated in the poll and those who commented. Some comments:
1.   To me, “ice free Arctic” means just that. No sea ice. However, judging by the comments, the “less than 1 million km2” definition of ice free arctic seems to be quite well accepted among forum members. Perhaps that’s why nobody voted for option 1. If I would have clearly defined “ice free arctic” as 0 ice, maybe the poll results would have been different. Maybe under that definition many forum members would have voted for option 1?

2.   Some of the best comments point out that the changes in the Arctic and Earth system will begin happening before a sea ice free arctic. The cause and effect relationship between an ice free Arctic and the changes on Arctic and Earth systems is not a causal one-way relationship, as the poll might suggest. I completely agree. If I do another poll about this subject, I’ll have to spend some time incorporating that concept into the poll.

I think we are starting to see the beginning of those changes. Dipole anomalies, hot and cold water blobs, wavy jet streams are all the beginning of rapid change.

3.   Ned W thank you for such insightful post. However, I disagree with some key points.

1.   I think there's a good chance that there were Arctic-sea-ice-free periods in summer during the early-mid Holocene, and certainly during previous interglacials.  So I don’t think a loss of Arctic sea ice immediately results in some massive shock to the Earth system (no catastrophic methane release or whatever). 

I think that the amount of ice present in the world during the early mid Holocene was very large. The ice sheets covered what? Canada, Siberia and Northern Europe? If the arctic did become ice free then all that extra heat generated by the higher albedo of open ocean instead of ice, would have been negated by melting glaciers. Also, all that cold water reserves from the glaciers would have cooled the oceans enough to restore the Arctic sea ice.

We no longer have those massive ice sheets on the northern hemisphere. The only remaining things to melt are Greenland and the permafrost. 

2. I think there may well be far-reaching impacts of a large decrease in average summer sea ice extent -- like probabilistic changes to weather patterns.  But it may be challenging to attribute those effects specifically to the loss of sea ice (causality), because so many other aspects of the Earth system are changing as well in parallel with sea ice. 

I think we are starting to see the beginning of those changes. Dipole anomalies, hot and cold water blobs, wavy jet streams are all the beginning of rapid change. As the surface of the arctic changes from white solid ice to choppy, salty, warm water, those changes will keep changing until they are not recognizable anymore.

         

3. There's nothing magical about 1 million or 0.5 million or 0 million km2 of ice as a threshold -- going from 1.1 to 1.0 million, or 0.1 to 0.0 million, doesn't particularly matter (well, those thresholds might be interesting to people, but as far as the Earth system is concerned they're arbitrary and irrelevant).

I’ll ask you this, how much multiyear ice will be in the arctic after the first 0 ice arctic? By definition, 0. There will also be 0 second year ice. There will only be first year ice. Now look at the melt rates of first year ice vs the melt rates of multiyear ice.  The year after the first ice free arctic there will be no CAB fortress of thick ice (>1million km2). There will be no wrangle arm (<1million km2). There will be no big block (<.1 million km2). There will only be whatever ice was formed during winter. That first year ice is likely to fully melt early in the melting season, probably august or earlier, increasing the oceans heat intake and pushing the start of the freezing season forward.

4. Insofar as there have been ice-free episodes in past summers, the loss of ice is obviously not irreversible.  But reversing the loss of ice depends on reversing the warming trend, which in turn depends on reversing the rise in CO2 etc. in the atmosphere.  That won't happen soon and it won't happen quickly.

If the arctic was ice free during the early-mid holocene, it was restored by a combination of glacier melt and favorable astronomical forcing over thousands of years. Neither of those apply to today. The only ice sheet remaining in the NH is Greenland. I don’t have to tell you how fast that is melting and how much it will speed up once there is no arctic sea ice. The other one, astronomical forcing, do not apply to our time frame. As a matter of fact, according to astronomical forcing, the Earth should be cooling. Instead it is warming and it will warm for so time to come. An ice free arctic will significally speed up that warming.  It will return however. In a few thousand years Milankovitch cycle forcings will beat out CO2 forcing and the arctic will return. But that really is not relevant to us.