Antarctic Sea Ice Extent

[Hambone]

Volcanoes!!

 

http://www.pnas.org/content/early/2014/06/04/1405184111.full.pdf+html?sid=5859c342-ec49-4de6-a82a-9b2c2c826b3e

 

In May 2014:  "The thinning of the ice in recent decades is most likely related to climate change, Joughin said. More emissions would lead to more melting and faster collapse, but other factors make it hard to predict how much time we could buy under different scenarios."

 

Think again muchacho.

 

http://www.sciencedaily.com/releases/2014/05/140515090934.htm

[PhillipS]

Volcanoes!!

 

http://www.pnas.org/content/early/2014/06/04/1405184111.full.pdf+html?sid=5859c342-ec49-4de6-a82a-9b2c2c826b3e

 

In May 2014:  "The thinning of the ice in recent decades is most likely related to climate change, Joughin said. More emissions would lead to more melting and faster collapse, but other factors make it hard to predict how much time we could buy under different scenarios."

 

Think again muchacho.

 

http://www.sciencedaily.com/releases/2014/05/140515090934.htm

 

Just wanted to point out a few things you probably are already aware of.  First, the West Antarctic Ice Sheet (WAIS) in not sea ice - it originated on land and then flowed to where portions are over water.   The WAIS is typcally around 1,000 meters thick.  Sea ice is usually less than 10 meters thick.

 

Second, are you seriously suggesting that geothermal heat is responsible for the observed thinning and acceleration of the WAIS?  The PNAS article you linked to gives values for the geothermal heat flux of 114 - 200 milliwatts per m2.  That's about an eigth to a fifth of a watt of heat for every square meter of ice sheet.  Or, to put it in terms you might understand better, that's equivalent to heating a cubic kilometer (1 km2 area by 1 km thick) of ice with between 114 to 200 1,000 watt hair dryers.  It's gonna take a while to melt the ice - orders of magnitude longer than the observed melting rate.

 

Certainly the geothermal heat contributes to the observed melting, but it's a pretty small contribution.  There is no getting around the fact that AGW is the primary cause of the melting.

[Snow_Miser]

This does not disprove Global Warming or Anthropogenic Global Warming. However, I'm very surprised this wasn't posted. Antarctic Sea Ice is at the highest anomaly ever recorded. 

 

[AvantHiatus]

We need to find an accurate method to discover how much melt water actually flows into the Southern Ocean each year. I think there would be a correlation between this and sea ice extent.

[Jonger]

I dont buy the melt water theory. We are talking about peripheral ice that's probably a thousand miles from the continent that's freezing anomalously. Plus, the storms are so violent down there, they would mix up the salt into fresh water quite quickly.

[FPizz]

This does not disprove Global Warming or Anthropogenic Global Warming. However, I'm very surprised this wasn't posted. Antarctic Sea Ice is at the highest anomaly ever recorded.

highest anomaly ever.png

it is not as sexy for the news or people to talk about. That is the main reason. That is really high!

[CAD_Wedge_NC]

This does not disprove Global Warming or Anthropogenic Global Warming. However, I'm very surprised this wasn't posted. Antarctic Sea Ice is at the highest anomaly ever recorded. 

 

highest anomaly ever.png

 

Wow, absolutely incredible.

[Jonger]

Wow, absolutely incredible.

 

It will be interesting to see how expansive it can get over the next few years, it appears to be trending up at an accelerating rate.

[PisgahNCWeather]

Wow, this is noteworthy. Why is Antarctica downplayed so much? Not understanding the lack of emphasis on the South Pole.

[AvantHiatus]

Wow, this is noteworthy. Why is Antarctica downplayed so much? Not understanding the lack of emphasis on the South Pole.

The winds surrounding Antarctica have accelerated greatly, reducing the surface heat exchange between the mid-laditudes and the poles. The major mechanism for melting glaciers down there comes from warm sea surface temperatures, which flow under the ice.

 

It's basically an isolated micro-climate.

[Snow_Miser]

The winds surrounding Antarctica have accelerated greatly, reducing the surface heat exchange between the mid-laditudes and the poles. The major mechanism for melting glaciers down there comes from warm sea surface temperatures, which flow under the ice.

 

It's basically an isolated micro-climate.

 

Antarctica itself has warmed for the most part, with the Antarctic Peninsula being one of the fastest warming regions on the planet aside from the Arctic. The thickness increases in the Antarctic are also not statistically significant, and the southern ocean continues to gain heat content. Thus it makes sense that winds are responsible for the Antarctic Sea Ice increase, in combination with natural variability from the Bipolar Seesaw.

 

http://onlinelibrary.wiley.com/doi/10.1029/2009GL037524/abstract

 

http://onlinelibrary.wiley.com/doi/10.1029/2010GL042793/abstract

[nflwxman]

Antarctica itself has warmed for the most part, with the Antarctic Peninsula being one of the fastest warming regions on the planet aside from the Arctic. The thickness increases in the Antarctic are also not statistically significant, and the southern ocean continues to gain heat content. Thus it makes sense that winds are responsible for the Antarctic Sea Ice increase, in combination with natural variability from the Bipolar Seesaw.

 

http://onlinelibrary.wiley.com/doi/10.1029/2009GL037524/abstract

 

http://onlinelibrary.wiley.com/doi/10.1029/2010GL042793/abstract

Yeah, a standard deviation of extent in the antarctic is far less area than a standard deviation in arctic.  It's important to put that in perspective. In addition, it seems like the majority of Antarctic increase has occurred in the winter. 

[PisgahNCWeather]

The theme for Antarctica's increases seem to be that it is isolated and insignificant. At what point either it be gains or losses does It have relevance? Not understanding as it is larger than the Arctic and I was under the assumption that it is considered part of our globe. Is it then thrown out of the equation then as far as global warming is concerned?

[FloridaJohn]

The theme for Antarctica's increases seem to be that it is isolated and insignificant. At what point either it be gains or losses does It have relevance? Not understanding as it is larger than the Arctic and I was under the assumption that it is considered part of our globe. Is it then thrown out of the equation then as far as global warming is concerned?

 

My understanding is that antarctic sea ice is not really "the thing" like it is in the arctic. The land ice in antarctica is overall more important than the sea ice. The main reason is that the antarctic sea ice is not much of a factor is that it almost completely melts out each summer, where the arctic has a remaining "core" that survives the summer melt (at least so far). That remaining core helps to lower the temperature of the earth because it is available to reflect the sun during the summer when there is sunlight on the arctic. In the antarctic, the land ice is there in the summer to reflect the sunlight, so the net variation from a "good" year to a "bad" year during the summer is very small in the antarctic, but very large in the arctic.

 

The relavance of the antarctic to climate change is when the land ice starts to melt, which will have a large impact on sea level, unlike the arctic, which won't change the sea level much regardless of how much melts out each summer.

 

 

More info here.

[FPizz]

Yeah, a standard deviation of extent in the antarctic is far less area than a standard deviation in arctic.  It's important to put that in perspective. In addition, it seems like the majority of Antarctic increase has occurred in the winter. 

Seems like the majority of the Arctic decrease has occurred in the summer.

[nflwxman]

Seems like the majority of the Arctic decrease has occurred in the summer.

It's their cold season.  Since the increase in antarctic ice occurs mostly when there is little radiation available, it probably does not offer much offset to the planet's current forcing.  

[ORH_wxman]

It's their cold season.  Since the increase in antarctic ice occurs mostly when there is little radiation available, it probably does not offer much offset to the planet's current forcing.  

 

Neither the arctic or antarctic provide much forcing. The arctic albedo is usually over-estimated in this forum. I can't remember what the exact number is, but I think skierinVT ran the numbers once to show that even if the entire arctic ocean melted out, the albedo change would only produce a few hundreths of a degree celsius increase as a feedback. It ended up being quite small.

 

 

The land ice is definitely of more interest since it could contirubte to large sea level increase.

[nflwxman]

Neither the arctic or antarctic provide much forcing. The arctic albedo is usually over-estimated in this forum. I can't remember what the exact number is, but I think skierinVT ran the numbers once to show that even if the entire arctic ocean melted out, the albedo change would only produce a few hundreths of a degree celsius increase as a feedback. It ended up being quite small.

 

 

The land ice is definitely of more interest since it could contirubte to large sea level increase.

Exactly.  Arguably the methane hydrate feedback is more important (in the arctic) over the long term versus albedo declines.

[StudentOfClimatology]

Exactly. Arguably the methane hydrate feedback is more important (in the arctic) over the long term versus albedo declines.

On a global scale, I agree. But the albedo loss would significantly affect the climate in the Arctic itself...radiative transfer laws would suggest an ice free arctic (during the summer) should lead to a 5-8K warming over the Arctic Ocean.

[Jonger]

On a global scale, I agree. But the albedo loss would significantly affect the climate in the Arctic itself...radiative transfer laws would suggest an ice free arctic (during the summer) should lead to a 5-8K warming over the Arctic Ocean.

You are completely within your right to try and predict this, but like most of this science, the verification will probably fall well short. The climate system has been stubbornly slow to respond.

[Snow_Miser]

New paper published on future trends in the wind field around Antarctica. The changes in winds lead to rapid warming at the grounding lines of glaciers, which have potential implications for future changes in Sea Level Rise.

 

http://onlinelibrary.wiley.com/doi/10.1002/2014GL060613/abstract

[nflwxman]

You are completely within your right to try and predict this, but like most of this science, the verification will probably fall well short. The climate system has been stubbornly slow to respond.

Stubborn because, what?  This is not all happening within a decade?  What other predictions have fallen short, out of curiosity?

[ORH_wxman]

Stubborn because, what?  This is not all happening within a decade?  What other predictions have fallen short, out of curiosity?

 

I would argue that temperature is falling short of predictions. Perhaps that won't be the case 30 or 40 years from now...that is conjecture at this point....but for now, the climate models that predictions are based on have proven to be too warm. Even when hindcasting back to the early 1990s.

 

Regional predictions are obviously all over the place. Models didn't see the big fall in arctic sea ice 2007-2012, and didn't see the antarctic increase (or lack of decrease). They also didn't see the big cooldown in central/northwestern parts of North America or Siberia...or the magnitude of the warmup in the arctic over the past decade.

 

Invalidating predictions that span decades is a tricky business.

 

A lot of this talk sort of reminds me of people trying to say whether a 5 day forecast has busted or not with 48 hours to go until verification time. We can use trends in the models to evaluate our forecast from a few days earlier...but we can't actually say the forecast is busted until verification time.

[nflwxman]

I would argue that temperature is falling short of predictions. Perhaps that won't be the case 30 or 40 years from now...that is conjecture at this point....but for now, the climate models that predictions are based on have proven to be too warm. Even when hindcasting back to the early 1990s.

 

Regional predictions are obviously all over the place. Models didn't see the big fall in arctic sea ice 2007-2012, and didn't see the antarctic increase (or lack of decrease). They also didn't see the big cooldown in central/northwestern parts of North America or Siberia...or the magnitude of the warmup in the arctic over the past decade.

 

Invalidating predictions that span decades is a tricky business.

 

A lot of this talk sort of reminds me of people trying to say whether a 5 day forecast has busted or not with 48 hours to go until verification time. We can use trends in the models to evaluate our forecast from a few days earlier...but we can't actually say the forecast is busted until verification time.

Yeah, I know we disagree about how global temperature projections should be used/validated.  The regional projections have been hit or miss in my opinion.  The hydrology changes modeled have been decent, while temperature has been more spotty.  This is a very slow moving experiment where a decade means little to nothing in the grand scheme of validation.  Jongers' point was not a good one, in that he stated unequivocally that climate predictions have generally overestimated change, which I believe is generally either 1) incorrect 2) too early to tell 3) rare instances true  

[Jonger]

Yeah, I know we disagree about how global temperature projections should be used/validated.  The regional projections have been hit or miss in my opinion.  The hydrology changes modeled have been decent, while temperature has been more spotty.  This is a very slow moving experiment where a decade means little to nothing in the grand scheme of validation.  Jongers' point was not a good one, in that he stated unequivocally that climate predictions have generally overestimated change, which I believe is generally either 1) incorrect 2) too early to tell 3) rare instances true  

 

I never stated HOW overestimated they were, but most would agree that we are falling into the lower tier of confidence ranges.

[ORH_wxman]

Yeah, I know we disagree about how global temperature projections should be used/validated.  The regional projections have been hit or miss in my opinion.  The hydrology changes modeled have been decent, while temperature has been more spotty.  This is a very slow moving experiment where a decade means little to nothing in the grand scheme of validation.  Jongers' point was not a good one, in that he stated unequivocally that climate predictions have generally overestimated change, which I believe is generally either 1) incorrect 2) too early to tell 3) rare instances true  

 

 

If models have correctly incorporated a fair assessment of the background GHG warming with natural variability imposed on it...then error bars should be plenty large enough to incorporate a slowdown in global temps.

 

The "20 years is too short for climate models" should already be accounted for in their error bars and spread of solutions. So when we run statistical tests, observations that fall outside of 2 sigma generally say there is something wrong with the models.

 

That is where my argument comes from with climate modeling. There was actually a paper that was published last year that criticized the latest generation of GCMs:

 

http://onlinelibrary.wiley.com/doi/10.1002/grl.50562/abstract

 

 

 

Though despite this, I generally agree that for many other aspects of climate change, 20 years is too small...especially when discussing variables like extreme weather.

[PisgahNCWeather]

Coldest June ever which would coincide with the record setting ice.  Is it still to be ignored?

[nflwxman]

Coldest June ever which would coincide with the record setting ice.  Is it still to be ignored?

The "record setting ice" in Antarctica at it's max is approximately ~1.2 million sq kilometers over the mean.  At the same token, the record low sea ice in the arctic was ~4 million sq kilometers under it's mean.  The trend on antarctic sea ice over the sat record is statistical insignificant.  When there is significance to the trend, scientists may pay more attention, but unfortunately, this is considered "noise" at this point and nothing more.  As you can see below (record in 2013), it's not a terribly compelling story yet (the orange line is the mean).

 

 

[Jonger]

The "record setting ice" in Antarctica at it's max is approximately ~1.2 million sq kilometers over the mean.  At the same token, the record low sea ice in the arctic was ~4 million sq kilometers under it's mean.  The trend on antarctic sea ice over the sat record is statistical insignificant.  When there is significance to the trend, scientists may pay more attention, but unfortunately, this is considered "noise" at this point and nothing more.

 

I'm not sure if it was the entire antarctic continent, but if the record cold was true... This is 1.2mil sq kilometers of additional ice and the land inside the continent that was below normal... adding those together, its a massive area and a significant event.

[nflwxman]

I'm not sure if it was the entire antarctic continent, but if the record cold was true... This is 1.2mil sq kilometers of additional ice and the land inside the continent that was below normal... adding those together, its a massive area and a significant event.

In the middle of the cold season, it's really not.  If anything, the colder it is, the more dry it is and the less mass is added to the ice sheet.