Arctic sea ice could completely melt away by the summer of 2015

[skierinvermont]

Friv, I may have busted on extent but only because we got that huge storm where we lost like 180k every night. I said we couldn't break the record with the Pacific remaining robust, but the storm sapped away the robustness of the Pacific ice pack. That was an unforeseen event that no one could have predicted: a 970mb low over the Arctic in summer is nearly unprecedented, and having 200k losses in August is unusual. So I admit I was wrong, but it wasn't a bad forecast until the storm caused the huge declines.

I am relatively confident that we won't be ice free by 2015 or 2020. That's a much easier prediction to make than an individual year because the weather in the Arctic varies so greatly during any given summer, like the storm. You can't just follow the curve of PIOMAS because the inner ice core is more difficult to melt, and the Arctic amplification is out of step with generally stable global temperatures.

Disagree strongly. That tongue of ice extending towards/into the ESB would have melted out anyways. It was thin ice surrounded by open water that melted out very early and has been warming through peak insolation. The ice was simply too thin and too exposed from too early in the melt season.

When you and I others entertained the possibility back in early July that this ice could last through September it was too early in the melt season. There was simply too much time for this ice to melt out barring some very ideal conditions.

You and others even thought that the arctic storm would be favorable for the ice. It might have even been favorable in a normal year. But cooler 850s didn't help much when the ice was being sloshed around in warm salt water that had been heating up since July.

We also had been losing ice at 100k/day for a week before the storm started. This was because of the large amount over very thin, very low concentration ice sitting in warm water. The reason for the large losses in late july through mid august was fairly weather-independent. We had ridiculous amounts of thin low concentration ice surrounded by warm SSTs. This ice would melt in almost any weather pattern.

It was inevitable that this ice would melt out. Low concentration, thin ice, surrounded by warm SSTs in early-mid July is not going to survive until the end of September.

[Vergent]

JAXA 8/23

4,333,281 -123k

NSIDC

2012, 08, 22, 4,290,620 -41

CT bounced +51

2,792,791

1,540k water in the extent

[nzucker]

Disagree strongly. That tongue of ice extending towards/into the ESB would have melted out anyways. It was thin ice surrounded by open water that melted out very early and has been warming through peak insolation. The ice was simply too thin and too exposed from too early in the melt season.

When you and I others entertained the possibility back in early July that this ice could last through September it was too early in the melt season. There was simply too much time for this ice to melt out barring some very ideal conditions.

You and others even thought that the arctic storm would be favorable for the ice. It might have even been favorable in a normal year. But cooler 850s didn't help much when the ice was being sloshed around in warm salt water that had been heating up since July.

We also had been losing ice at 100k/day for a week before the storm started. This was because of the large amount over very thin, very low concentration ice sitting in warm water. The reason for the large losses in late july through mid august was fairly weather-independent. We had ridiculous amounts of thin low concentration ice surrounded by warm SSTs. This ice would melt in almost any weather pattern.

It was inevitable that this ice would melt out. Low concentration, thin ice, surrounded by warm SSTs in early-mid July is not going to survive until the end of September.

I'll post more later when I have access to the maps, at work right now. I think the strong winds associated with a 970mb low definitely had a large influence in JAXA falling below 2007 as that was basically the turning point when we went from being slightly above 2007 to being now in a 400k km sq deficit. We fall well below 2007 in the 1st and 2nd weeks of August, and that was the time at which the storm was hitting the Arctic.

I also think what the summer proved was that weather is still the largest factor. We still had a predominate dipole anomaly with low heights on the Asian side, as well as the anomalous storm that caused the very large drops in extent including the melt-out of the tongue of ice in the East Siberian Sea. We had much higher minimums in 2008 and 2009, with those years not having as large of a dipole anomaly, especially 2009.

This might be better for responding to your other post, but I don't think the optimistic predictions were necessarily ill-founded. Global temperatures have been stable since 2002, and July 2012 was actually the third coldest of the decade on GISS. All this while the Arctic has seen warming of nearly 1C per decade and record melt-out...so we obviously have a disconnect between what's happening with global temperatures, with the Southern Hemisphere sea ice, versus the Arctic. If you take the Arctic out of the picture, global temperatures are actually cooling at around 0.08C/decade on GISS since 2002 (what a difference!) so this is obviously an isolated region in terms of warming/ice loss that people are inappropriately using as a sign of the coming doom of a warming planet.

[skierinvermont]

I'll post more later when I have access to the maps, at work right now. I think the strong winds associated with a 970mb low definitely had a large influence in JAXA falling below 2007 as that was basically the turning point when we went from being slightly above 2007 to being now in a 400k km sq deficit. We fall well below 2007 in the 1st and 2nd weeks of August, and that was the time at which the storm was hitting the Arctic.

I also think what the summer proved was that weather is still the largest factor. We still had a predominate dipole anomaly with low heights on the Asian side, as well as the anomalous storm that caused the very large drops in extent including the melt-out of the tongue of ice in the East Siberian Sea. We had much higher minimums in 2008 and 2009, with those years not having as large of a dipole anomaly, especially 2009.

This might be better for responding to your other post, but I don't think the optimistic predictions were necessarily ill-founded. Global temperatures have been stable since 2002, and July 2012 was actually the third coldest of the decade on GISS. All this while the Arctic has seen warming of nearly 1C per decade and record melt-out...so we obviously have a disconnect between what's happening with global temperatures, with the Southern Hemisphere sea ice, versus the Arctic. If you take the Arctic out of the picture, global temperatures are actually cooling at around 0.08C/decade on GISS since 2002 (what a difference!) so this is obviously an isolated region in terms of warming/ice loss that people are inappropriately using as a sign of the coming doom of a warming planet.

It is true that we crossed 2007 around the time of the storm. But the large losses began well before that. The large losses occurred because of the large amounts of very low concentration very thin ice surrounded by warm SSTs. The melting of this ice was inevitable. By the end of July I believe it was fairly predictable we would see a 2007-esque minimum or lower due to the massive amounts of low concentration thin ice surrounded by warm SSTs.

Moreover a 970mb low and cooler 850mb temperatures at the NP is far from an ideal melt pattern. You and others insisted it was in fact a favorable pattern for preservation of ice. As others correctly pointed out, due to the amount of low concentration thin ice surrounded by warms SSTs created by the weather in June and July, this ice was going to melt one way or another.

Finally, if you watch the CT loops, it is clear the ice melted in place due to thermodynamics, not the wind pattern from the low causing compaction.

[dabize]

It is true that we crossed 2007 around the time of the storm. But the large losses began well before that. The large losses occurred because of the large amounts of very low concentration very thin ice surrounded by warm SSTs. The melting of this ice was inevitable. By the end of July I believe it was fairly predictable we would see a 2007-esque minimum or lower due to the massive amounts of low concentration thin ice surrounded by warm SSTs.

Moreover a 970mb low and cooler 850mb temperatures at the NP is far from an ideal melt pattern. You and others insisted it was in fact a favorable pattern for preservation of ice. As others correctly pointed out, due to the amount of low concentration thin ice surrounded by warms SSTs created by the weather in June and July, this ice was going to melt one way or another.

Finally, if you watch the CT loops, it is clear the ice melted in place due to thermodynamics, not the wind pattern from the low causing compaction.

All really good points, especially the in situ melt pattern.

I found this to be extremely striking.

Cross posting this from the SIE thread because it is appropriate re the modeling of sea ice loss (and its deficiencies) by Dr. Maslowski himself

http://www.oc.nps.ed...tic Sea Ice.pdf

[tacoman25]

It is true that we crossed 2007 around the time of the storm. But the large losses began well before that. The large losses occurred because of the large amounts of very low concentration very thin ice surrounded by warm SSTs. The melting of this ice was inevitable. By the end of July I believe it was fairly predictable we would see a 2007-esque minimum or lower due to the massive amounts of low concentration thin ice surrounded by warm SSTs.

Moreover a 970mb low and cooler 850mb temperatures at the NP is far from an ideal melt pattern. You and others insisted it was in fact a favorable pattern for preservation of ice. As others correctly pointed out, due to the amount of low concentration thin ice surrounded by warms SSTs created by the weather in June and July, this ice was going to melt one way or another.

Finally, if you watch the CT loops, it is clear the ice melted in place due to thermodynamics, not the wind pattern from the low causing compaction.

Sure, there is no doubt that most if not all of that ice on the Pacific side would have melted out eventually this summer. But there is also no doubt that the huge storm damaged/broke up the thin ice pack in an expedited way. Which then cleared the way for more melting sooner. So I think it's fair to say with some certainty that we probably would not have seen such massive ice melt the second half of August if it hadn't been for that storm weakening an already thin ice pack.

[dabize]

Sure, there is no doubt that most if not all of that ice on the Pacific side would have melted out eventually this summer. But there is also no doubt that the huge storm damaged/broke up the thin ice pack in an expedited way. Which then cleared the way for more melting sooner. So I think it's fair to say with some certainty that we probably would not have seen such massive ice melt the second half of August if it hadn't been for that storm weakening an already thin ice pack.

I don't

Even if what you say about breaking up the pack is qualitatively true, nothing needed to be cleared away.

The image I posted shows that the ice was melting out in place, and the melting was occurring everywhere. It was melting in parallel, no waiting for serial melting needed.

The storm might have speeded it up a few days, that is all.

[Alpha5]

The weekly doomer - EC composite

Terry has a point, something is progressively eating away at the ice on the Pacific side, and it doesn't care about bathymetry

pacific ice hit a record high extent earlier this year

[Vergent]

I don't

Even if what you say about breaking up the pack is qualitatively true, nothing needed to be cleared away.

The image I posted shows that the ice was melting out in place, and the melting was occurring everywhere. It was melting in parallel, no waiting for serial melting needed.

The storm might have speeded it up a few days, that is all.

Its a chicken and egg argument. impossible to answer the hypotheticals.

A more interesting question is How much ice area will be left in the arctic ocean at the min.?

[TerryM]

pacific ice hit a record high extent earlier this year

A perfect example of why extent is the least meaningful measurement.

Area takes melt ponds and leads out of the equation. Since melt pond albedo approximates open ocean albedo it gives us a much clearer picture of what lies ahead during spring and summer. In fall, as melt ponds freeze more rapidly than sea water SIA bottoms out sooner, again giving a cleared picture of how much ice surface has survived the melt.

Extent I believe was the earliest and easiest metric to come up with, and has a place in historic comparison - as well as a use when compared to area to determine how loose the pack is. This was the measure used by deniers when predicting a large recovery for this year. Those of us more concerned with volume and MYI saw a different picture.

Terry

[PhillipS]

Here is an interesting chart of the record of arctic SIA I came across [source]

The 2012 melt season isn't offically over, of course, but it should be close to finished. Several things I found interesting - an obvious one being that the 2012 minimum SIA is well below half of what the minimums were early in the observational record. Also, the 2012 SIA minimum broke the old record by more than 600,000 km2. And in the past decade the minimum has dropped by more than 1,700,000 km2. That's a lot of ice.

Since the definition of an 'ice free' arctic is a SIA value less than 1,000,000 km2, additional losses to the SIA minimums of 1,300,000 km2 are needed to reach that milestone. Is that likely to happen over the next three years? In my opinion - no. Is it impossible for that to happen in the next three years? No.

[Vergent]

Here is an interesting chart of the record of arctic SIA I came across [source]

The 2012 melt season isn't offically over, of course, but it should be close to finished. Several things I found interesting - an obvious one being that the 2012 minimum SIA is well below half of what the minimums were early in the observational record. Also, the 2012 SIA minimum broke the old record by more than 600,000 km2. And in the past decade the minimum has dropped by more than 1,700,000 km2. That's a lot of ice.

Since the definition of an 'ice free' arctic is a SIA value less than 1,000,000 km2, additional losses to the SIA minimums of 1,300,000 km2 are needed to reach that milestone. Is that likely to happen over the next three years? In my opinion - no. Is it impossible for that to happen in the next three years? No.

Is it possible to lose 1,300,000 km^2 in the next month?

Edit:

http://www.weatherbellmodels.com/weather/gfs/2012091112/arctic/gfs_mslp_uv900_arctic_stamp.php

[SVT450R]

Is it possible to lose 1,300,000 km^2 in the next month?

Edit:

http://www.weatherbe...rctic_stamp.php

[DarthDoppler]

I just voted. Despite this years huge losses, I still voted later. I am thinking later only because it has basically melted down to a point in an area I would consider a "stronghold". While I expect a continued downward trend, I do think that trend will slow a bit for awhile, before a tipping point is reached. I do expect it gone in my lifetime though, just not this decade. (I'm 41 now.)

[TerryM]

I think it's more interesting to consider the position of the ice rather than the amount at this stage. It seems to me that given the right weather pattern we could loose large amounts through Fram prior to melt season starting up. A question has to remain about thickness in the Beaufort Sea as well as in the Laptev Bite area. If these remain thin through the winter & melt out while there is still strong insolation it's not impossible that we would have an unanchored pack drifting toward Fram on the Trans Arctic Current through the next summer season, with nothing but the CAA tethering it atop of Greenland.

I can't picture much more melt this season, but do see a very slight possibility that we could lose enough through advection next year to basically end up ice free. My WAG is still 2016 +_ 2 yrs.

Terry

[PhillipS]

As an old fart who was taught to use words instead of pictographs and runes - could you please explain the meaning of Hector Elizondo shading his eyes?

[SVT450R]

As an old fart who was taught to use words instead of pictographs and runes - could you please explain the meaning of Hector Elizondo shading his eyes?

It's called a facepalm basically used when someone makes a stupid statement or your in disbelief of what one is saying.

[PhillipS]

It's called a facepalm basically used when someone makes a stupid statement or your in disbelief of what one is saying.

Ah.

[tacoman25]

Is it possible to lose 1,300,000 km^2 in the next month?

Edit:

http://www.weatherbe...rctic_stamp.php

Don't worry, even with this melt season ending, you will have another one to root on in 2013!

[Mallow]

~2030ish

[Amped]

Is it possible to lose 1,300,000 km^2 in the next month?

Edit:

http://www.weatherbe...rctic_stamp.php

If It does I called it.

[csnavywx]

SWAG: 2020 or earlier.

Reasoning: It appears to me that the Arctic region's climate is unstable and in the midst of a non-linear response due to multiple feedbacks (some of which are actually "second order" feedbacks). Systems in linear decay don't behave in the manner we're observing. The result thus far has been rather ruthless in its speed.

One major player showing up to the scene seems to be changes in synoptic patterns brought on by altered surface heat and vapor fluxes, as well as a reduction in jet stream speeds.

This year shouldn't be all that terribly shocking, though. We have paleoclimate data that suggests changes can be significantly more rapid than they are today, even with gradual increases in GHGs. We are playing with fire in this scenario and I'm afraid little good can come of it. The multi-meter rises per century in sea level the paleo-record shows should be a caution flag that we still don't comprehend the scale and rapidity of the changes that could come, given the rate we've increased GHGs compared to the past (very rapidly on geological time scales).

[ORH_wxman]

SWAG: 2020 or earlier.

Reasoning: It appears to me that the Arctic region's climate is unstable and in the midst of a non-linear response due to multiple feedbacks (some of which are actually "second order" feedbacks). Systems in linear decay don't behave in the manner we're observing. The result thus far has been rather ruthless in its speed.

One major player showing up to the scene seems to be changes in synoptic patterns brought on by altered surface heat and vapor fluxes, as well as a reduction in jet stream speeds.

This year shouldn't be all that terribly shocking, though. We have paleoclimate data that suggests changes can be significantly more rapid than they are today, even with gradual increases in GHGs. We are playing with fire in this scenario and I'm afraid little good can come of it. The multi-meter rises per century in sea level the paleo-record shows should be a caution flag that we still don't comprehend the scale and rapidity of the changes that could come, given the rate we've increased GHGs compared to the past (very rapidly on geological time scales).

In the past, the GHGs lagged temperature though...so its not really comparable. Sea level rise has not been accelerating to alarming levels despite the loss of ice in Greenland. It is still unclear whether Antarctica is contributing to sea level rise or not despite the GRACE measurements. There is contradicting literature there. The IPCC's AR4 in 2007 projected Antarctica to gain ice mass as the temperature warmed during the 21st century due to increased snowfall which is likely what drives their fairly unalarming sea level rise projection through 2100....actually matching up closely with the current rate that would yield about 10 inches of sea level rise by 2100. Their projection was 7-23 inches.

Greenland is losing ice at a faster rate, but not at a rate that is drastically affecting sea level rise. It would have to accelerate exponentially to become a huge factor in the next several decades. Greenland is an interesting case though. I've seen some literature that suggests it could contribute to several inches of sea level rise by 2050. I find this extremely unlikely, but we will absolutely no doubt be able to see it very quickly in the next several years if it is going to do that.

[The_Global_Warmer]

In the past, the GHGs lagged temperature though...so its not really comparable. Sea level rise has not been accelerating to alarming levels despite the loss of ice in Greenland. It is still unclear whether Antarctica is contributing to sea level rise or not despite the GRACE measurements. There is contradicting literature there. The IPCC's AR4 in 2007 projected Antarctica to gain ice mass as the temperature warmed during the 21st century due to increased snowfall which is likely what drives their fairly unalarming sea level rise projection through 2100....actually matching up closely with the current rate that would yield about 10 inches of sea level rise by 2100. Their projection was 7-23 inches.

Greenland is losing ice at a faster rate, but not at a rate that is drastically affecting sea level rise. It would have to accelerate exponentially to become a huge factor in the next several decades. Greenland is an interesting case though. I've seen some literature that suggests it could contribute to several inches of sea level rise by 2050. I find this extremely unlikely, but we will absolutely no doubt be able to see it very quickly in the next several years if it is going to do that.

Thermal expansion has come to a standstill the last 7 years. How long do you expect that to last? Did the literature not say anything about the abrupt stop in thermal expansion, yet the sea level rise is not effected?

Let's assume several inches means 3-4" by 2050. Greenland would need to lose 900-1000km3 of ice mass per year to add this. You think that is extremely unlikely, so you think over the next 38 years Greenland will basically melt at 2000-2006 rates? Albedo will magically fix it self?

I guess you think Grace is wrong in Antarctica? Literature? Why not just figure it out yourself, if Antarctica has lost -1400km3 of volume then it's contributing to sea level rise, even if it's small. Unless they are calculating floating ice into this? I would assume not.

[GaWx]

Here is a link to an article put out by JB today:

http://patriotpost.us/opinion/14736

Comments are welcome. I'm neither taking his side nor siding against him. I'm pretty neutral on all of this although I admittedly have a concern about the grand solar min. we entered in 2008 and how that may or may not exert a sig. cooling influence soon. Anyway, I'd like to see some discussion about a view that differs from many here and elsewhere. i think that it at least deserves to be discussed.

Excerpts:

"The Atlantic is in its warm stage now, so the ice cap is being attacked from the ocean also. Once the Atlantic comes out of its warm phase in 10 to 15 years, the ice cap will rebound."

"But is the lack of ice at times that unusual? Apparently not as photographic evidence shows. Here is a picture of a submarine surfacing at the North Pole in August of 1959 -- another period of known warmth similar to the cycle we are in now.

More startling to me was this picture that shows large amounts of open water at the North Pole in May of 1987 with three subs surfacing."

"Wind and storminess can also have an effect on the Arctic ice, which is what recently happened. A fierce storm broke up a lot of the ice and shoved much of it southeast into the center of the ice cap"

"The reason we are seeing all this is because we have seen a distortion of the global temperature pattern the past 30 years brought about by the warm phase of the Pacific, which started the warming of the northern hemisphere, followed by the Atlantic warming. The response was greater over land where air is dry and can be easily warmed! How can we test this theory, besides waiting for it to simply recover once the Atlantic turns colder? Well we have a hint, and it's in the southern hemisphere. After all, we have to think globally, right? That is what we hear: GLOBAL warming. So we should also have the southern hemisphere shrinking if they are correct and my hypothesis is wrong."

[ORH_wxman]

Thermal expansion has come to a standstill the last 7 years. How long do you expect that to last? Did the literature not say anything about the abrupt stop in thermal expansion, yet the sea level rise is not effected?

Let's assume several inches means 3-4" by 2050. Greenland would need to lose 900-1000km3 of ice mass per year to add this. You think that is extremely unlikely, so you think over the next 38 years Greenland will basically melt at 2000-2006 rates? Albedo will magically fix it self?

I guess you think Grace is wrong in Antarctica? Literature? Why not just figure it out yourself, if Antarctica has lost -1400km3 of volume then it's contributing to sea level rise, even if it's small. Unless they are calculating floating ice into this? I would assume not.

The peer review on GRACE estimate is +50 to -200 gigatons...so the uncertainty lies within both sides.

The recent presentation by Zwally calls into question the GRACE measurements due to many assumptions that GRACE was going by and comes to the conclusion that Antarctica is gaining mass via ICESAT...it should be a full paper soon, but here was the abstract:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120013495_2012013235.pdf

As for thermal expansion...that will continue of course as long as we are adding heat to the ocean...but this is offset somewhat by mass gain in Antarctica as we warm which again, results in the relatively benign sea level rise projected by IPCC.

Greenland has been accelerating ice loss and yet we have not seen an acceleration in sea level rise during the post-2000 period. The greatest sea level rise since we had the good data in the early 1990s was definitely during that 1990s decade.

Therefore, by deductive reasoning, something is offsetting the Greenland melt at the moment. What do you suppose that would be if you are certain Antarctica is losing mass? (I'm not certain at all, and think that it is probably gaining mass)

[donsutherland1]

Here is a link to an article put out by JB today:

http://patriotpost.us/opinion/14736

Comments are welcome. I'm neither taking his side nor siding against him. I'd like to see some discussion about a view that differs from many here and elsewhere.

Excerpts:

"The Atlantic is in its warm stage now, so the ice cap is being attacked from the ocean also. Once the Atlantic comes out of its warm phase in 10 to 15 years, the ice cap will rebound."

"But is the lack of ice at times that unusual? Apparently not as photographic evidence shows. Here is a picture of a submarine surfacing at the North Pole in August of 1959 -- another period of known warmth similar to the cycle we are in now.

More startling to me was this picture that shows large amounts of open water at the North Pole in May of 1987 with three subs surfacing."

"Wind and storminess can also have an effect on the Arctic ice, which is what recently happened. A fierce storm broke up a lot of the ice and shoved much of it southeast into the center of the ice cap"

"The reason we are seeing all this is because we have seen a distortion of the global temperature pattern the past 30 years brought about by the warm phase of the Pacific, which started the warming of the northern hemisphere, followed by the Atlantic warming. The response was greater over land where air is dry and can be easily warmed! How can we test this theory, besides waiting for it to simply recover once the Atlantic turns colder? Well we have a hint, and it's in the southern hemisphere. After all, we have to think globally, right? That is what we hear: GLOBAL warming. So we should also have the southern hemisphere shrinking if they are correct and my hypothesis is wrong."

A number of points:

1. The thick ice pack can periodically rupture with holes or fissures. That a sub surfaced through a hole--and the U.S. Naval Institute's Naval History blog's entry makes clear that the area was surrounded by thick ice--does not necessarily mean that Arctic sea ice extent, area, or volume rivaled today's figures.

2. Natural variability (mainly the AMO) plays a significant role in influencing Arctic sea ice trends, but the role of natural variability has been declining.

3. Recent scientific papers e.g., Stroeve et al., (2012) suggest that the anthropogenic contribution explains about 60% of the Arctic sea ice extent trend since 1979.

4. The decline in summer sea ice cover has also coincided with a rapid disappearance of very thick multi-year ice. Although winter ice maxima have declined less than the summer ice minima, the ice coming into the summer is, on average, thinner. That is setting the stage for further reductions in summer ice coverage (with some temporary fluctuations).

5. The decline in summer ice coverage has not been linear. There have now been two abrupt steps down (2007 and 2012). Research from Antarctica might have some relevance, as such developments were found to occur with respect to marine ice cover as opposed to land ice cover. If so, additional abrupt declines in summer ice might lie ahead down the road. Whether or not this is a transition from perennial sea ice cover to seasonal sea ice cover remains to be seen, but the modeling suggests that such a transition is underway, though the timing is uncertain.

Taking this information into consideration, I suspect two plausible scenarios stand out:

1. The shift in the AMO could lead to a partial but temporary recovery in summer sea ice coverage. The recovery would be partial, because the AMO still has influence. The recovery would be temporary, as greenhouse gas forcing continues to increase relative to natural forcings and oceanic cycles.

2. The shift in the AMO would slow the rate of decline for a time, but abrupt declines would continue to occur. Greenhouse gas forcing coupled with amplifying feedbacks would preclude a meaningful recovery and the transition toward seasonal ice coverage would continue.

If I had to venture a guess, the second scenario would probably be the more likely one. First, if one examines the Arctic temperature data, the last peak-to-trough decline in annual Arctic readings was 1.91°C (1943 peak anomaly of +1.22°C to 1964 anomaly of -0.69°C). For 2011, the annual anomaly was +2.15°C. For 2012, a figure approaching +2.50°C is not out of the question. That data would suggest that even if the Arctic cools at the rate it did last time, Arctic readings would remain warmer than normal. Considering that greenhouse gas forcing is greater than it was during the 1943-64 period, one can expect less cooling than during the last flip of the AMO. Second, summer ice extent is lower than it was during the last "warm cycle" and almost certainly, thinner, as well. Amplifying feedbacks associated with that situation could also impede any ability to recover. Overall, greater warmth coupled with reduced capacity for recovery suggest a continuation of the decline in summer ice coverage, though possibly at a slower rate for a time, is probably more likely than a partial recovery. If that's correct, the kind of rebound Bastardi is anticipating is very unlikely.

[dabize]

The peer review on GRACE estimate is +50 to -200 gigatons...so the uncertainty lies within both sides.

The recent presentation by Zwally calls into question the GRACE measurements due to many assumptions that GRACE was going by and comes to the conclusion that Antarctica is gaining mass via ICESAT...it should be a full paper soon, but here was the abstract:

http://ntrs.nasa.gov..._2012013235.pdf

As for thermal expansion...that will continue of course as long as we are adding heat to the ocean...but this is offset somewhat by mass gain in Antarctica as we warm which again, results in the relatively benign sea level rise projected by IPCC.

Greenland has been accelerating ice loss and yet we have not seen an acceleration in sea level rise during the post-2000 period. The greatest sea level rise since we had the good data in the early 1990s was definitely during that 1990s decade.

Therefore, by deductive reasoning, something is offsetting the Greenland melt at the moment. What do you suppose that would be if you are certain Antarctica is losing mass? (I'm not certain at all, and think that it is probably gaining mass)

Thermal expansion is negated when all of the heat absorbed goes into latent heat needed to melt SI.

Sea level is not affected by the phase change itself, since ice floats and net expansion is not affected.

However, liquid water actually contracts as it is heated from freezing to 4 degrees C, where it reaches its highest density.

If most of the oceanic heating is devoted to heating water that is below 4C up toward 4C, then this will serve to negate thermal expansion somewhat. Almost all of the Arctic energy absorption this year probably went into either such warming of very cold seawater or sea ice melting.

Don't know if this is enough to offset GIS contributions (which should be a directly positive contribution to SLR whatever the temperature), but it should be considered. The ocean is a big place, and an awful lot of ice was lost.

Edit: This is relevant to Don's post as well - I'd like to get his impression as to whether this 0 to 4C contraction is likely to make a significant contribution as well.

Latest EC composite:

[Entropy]

Here is an interesting chart of the record of arctic SIA I came across [source]

The 2012 melt season isn't offically over, of course, but it should be close to finished. Several things I found interesting - an obvious one being that the 2012 minimum SIA is well below half of what the minimums were early in the observational record. Also, the 2012 SIA minimum broke the old record by more than 600,000 km2. And in the past decade the minimum has dropped by more than 1,700,000 km2. That's a lot of ice.

Since the definition of an 'ice free' arctic is a SIA value less than 1,000,000 km2, additional losses to the SIA minimums of 1,300,000 km2 are needed to reach that milestone. Is that likely to happen over the next three years? In my opinion - no. Is it impossible for that to happen in the next three years? No.

Interesting graph. Probably not the best way to communicate the loss of sea ice to a lay audience, but it definitely manages to convey a lot of information in a single graph. You can easily see that the area lost has been increasing much faster than the winter maximum in recent years. Of course, when the two lines finally meet, we'll be at zero ice.

[Vergent]

Thermal expansion is negated when all of the heat absorbed goes into latent heat needed to melt SI.

Sea level is not affected by the phase change itself, since ice floats and net expansion is not affected.

However, liquid water actually contracts as it is heated from freezing to 4 degrees C, where it reaches its highest density.

If most of the oceanic heating is devoted to heating water that is below 4C up toward 4C, then this will serve to negate thermal expansion somewhat. Almost all of the Arctic energy absorption this year probably went into either such warming of very cold seawater or sea ice melting.

Don't know if this is enough to offset GIS contributions (which should be a directly positive contribution to SLR whatever the temperature), but it should be considered. The ocean is a big place, and an awful lot of ice was lost.

Edit: This is relevant to Don's post as well - I'd like to get his impression as to whether this 0 to 4C contraction is likely to make a significant contribution as well.

Latest EC composite:

Don, dabize,

You are describing the thermal expansion properties of fresh water. Sea water does not expand as it cools from 4C to 0C.

http://www.kayelaby..../2_7/2_7_9.html

Verg