Arctic Sea Ice Extent, Area, and Volume

[bluewave]

57 minutes ago, snowlover91 said:

Try reading my post where I explained it.. you seem to have a reading comprehension issue. I said the past 11 years have demonstrated stable ice extent numbers and if anything they've increased slightly.

It's perfectly normal to have both up and down bounces within a long term downward trend of the Arctic sea ice. Ed Hawkins had a great post on this. Unfortunately, nothing has changed the long term downward trajectory of the sea ice. We are on track for our first technically ice free September sometime during this century.

People such as yourself incorrectly take short term fluctuations and try to extrapolate them into the future. This is the reason so many people stop posting in this forum when the global temperatures set new records in the last few years. They tried to interpret a short term fluctuation in global temperatures during the last decade as some kind of deviation from the long term warming trend. My bet is posters like you will eventually abandon this thread at some point in the future when you figure out the same with the Arctic sea ice.There is still hope that you will eventually figure out what everyone else knows and stop making these uninformed posts. 

 

 

[snowlover91]

11 minutes ago, bluewave said:

It's perfectly normal to have both up and down bounces within a long term downward trend of the Arctic sea ice. Ed Hawkins had a great post on this. Unfortunately, nothing has changed the long term downward trajectory of the sea ice. We are on track for our first technically ice free September sometime during this century.

People such as yourself incorrectly take short term fluctuations and try to extrapolate them into the future. This is the reason so many people stop posting in this forum when the global temperatures set new records in the last few years. They tried to interpret a short term fluctuation in global temperatures during the last decade as some kind of deviation from the long term warming trend. My bet is posters like you will eventually abandon this thread at some point in the future when you figure out the same with the Arctic sea ice. But I know that the learning curve can be slow for you guys. There is still hope that you will eventually figure out what everyone else knows and stop making these uninformed posts.

There is plenty of research out there that suggests the arctic ice extent we see today is something that is cyclical and was also seen in the 1920-1950 period. My original statement was also correct; 2007-2018 has seen no discernible changes/trend in ice extent and recent years have seen slight increases compared to the 2007-2012 averages. People such as yourself take 30-40 years of data and assume that CO2 is responsible for everything we see without acknowledging or engaging in intelligent discussion of alternative possibilities that could explain some or all of the changes being seen. You said my 11 years of data is too short term and yet you want to take 38 years of data as sufficiently long enough? Ok then, double standard much?

Here's a VERY detailed article listing an abundance of information that indicates the ice levels in this period (1920-1950) were probably similar to what we see today (but not as low as 2007 and 2012). In other words, historically we may have seen ice levels nearly identical to what we are seeing now when the CO2 levels were much lower. This certainly indicates there are natural cycles and variations ongoing, contrary to your flawed assumption that CO2 must be the only possible explanation. https://judithcurry.com/2013/04/10/historic-variations-in-arctic-sea-ice-part-ii-1920-1950/

Reconstructions of the Arctic ice levels indicate some interesting details as well... but sure go ahead and ignore this scientific research since it obviously must be wrong since it disagrees with "consensus science" as you would say.

According to this new dataset, the recent period of Arctic sea ice retreat since the 1970s followed a period of sea ice growth after the mid 1940s, which in turn followed a period of sea ice retreat after the 1910s. Our reconstructions agree with previous studies that have noted a general decrease in Arctic sea ice extent (for all four seasons) since the start of the satellite era (1979). However, the timing of the start of the satellite era is unfortunate in that it coincided with the end of several decades during which Arctic sea ice extent was generally increasing. This late-1970s reversal in sea ice trends was not captured by the hindcasts of the recent CMIP5 climate models used for the latest IPCC reports, which suggests that current climate models are still quite poor at modelling past sea ice trends. Nor is it described in previous Arctic sea ice reconstructions such as the Walsh dataset or the widely used HadISST sea ice dataset, although some recent studies have noted similar reversals, e.g. Pirón and Pasalodos (2016) and Alekseev et al. (2016)." https://www.tandfonline.com/doi/pdf/10.1080/02626667.2017.1324974

 

[forkyfork]

crackpot

[forkyfork]

i will not "debate" people who think co2 isn't causing climate change. you're wrong. the end.

[fountainguy97]

2 minutes ago, forkyfork said:

i will not "debate" people who think differently than me.  you're wrong. the end.

  

There I fixed your post.   What a sad debate. You would certainly fail in a debate class. Keep up the wonderful and informative posts. 

[forkyfork]

4 minutes ago, fountainguy97 said:

  

There I fixed your post.   What a sad debate. You would certainly fail in a debate class. Keep up the wonderful and informative posts. 

yup. the deniers do think differently than me. they're hellbent on not accepting mad made climate change because of emotional reasons 

[snowlover91]

32 minutes ago, forkyfork said:

yup. the deniers do think differently than me. they're hellbent on not accepting mad made climate change because of emotional reasons 

 

Last I checked I was the one posting peer reviewed and scientific articles concerning the subject and you weren't... so who is really posting based off "emotion" right now? You're just like all the rest, you blindly accept AGW and then when challenged to defend your belief you use commonly used, logically fallacious reasons for not debating the topic rather than providing the scientific data to assert your view. I can respect someone who disagrees with me and provides scientific articles to read concerning why they believe what they do but I have no respect for someone who has nothing to go on except the news media reports they hear and what they consider the scientific consensus and fails to do any deep digging on their own.

[chubbs]

Below is the daily sea ice anomaly and a one-year running average. Autumn, winter and spring have been leading the way down recently.

[bluewave]

2 hours ago, snowlover91 said:

There is plenty of research out there that suggests the arctic ice extent we see today is something that is cyclical and was also seen in the 1920-1950 period. 

Here's a VERY detailed article listing an abundance of information that indicates the ice levels in this period (1920-1950) were probably similar to what we see today (but not as low as 2007 and 2012). 

Not even close.

https://nsidc.org/arcticseaicenews/2018/01/

Using a compilation of maps, ship reports, and other records, NOAA has published monthly estimates of Arctic sea ice extent spanning 1850 to 2013. While data in the earlier part of the record is limited, the carefully constructed time series helps to put the more recent satellite record in a longer-term context. Figure 5a shows the decline in extent over the period of satellite observations standing out prominently in comparison with the rest of the record, especially in late summer and early autumn. An earlier period of unusually low summer sea ice extent around 1937 to 1943 (as compared to the 1850 to 2013 average) did not extend to the winter season, and was followed by a few years of significantly higher-than-average summer ice extents. Early in the record (1850 to 1900), winter ice extent was not particularly elevated relative to the 1850 to 2013 average, but summer sea ice extent was quite a bit higher higher than the average. As another way to place recent conditions into a longer context using this data set, we show the years of the lowest September extent recorded within the 50-year periods 1850 to 1900, 1901 to 1950, 1951 to 2000, along with the lowest over the period 2000 to 2013 (Figure 5b). The decline in extent is apparent.

https://www.carbonbrief.org/guest-post-piecing-together-arctic-sea-ice-history-1850

Most fundamentally of all, the new dataset allows us to answer the three questions we posed at the beginning of this article.

First, there is no point in the past 150 years where sea ice extent is as small as it has been in recent years. Second, the rate of sea ice retreat in recent years is also unprecedented in the historical record. 

[snowlover91]

7 minutes ago, bluewave said:

Not even close.

https://nsidc.org/arcticseaicenews/2018/01/

Using a compilation of maps, ship reports, and other records, NOAA has published monthly estimates of Arctic sea ice extent spanning 1850 to 2013. While data in the earlier part of the record is limited, the carefully constructed time series helps to put the more recent satellite record in a longer-term context. Figure 5a shows the decline in extent over the period of satellite observations standing out prominently in comparison with the rest of the record, especially in late summer and early autumn. An earlier period of unusually low summer sea ice extent around 1937 to 1943 (as compared to the 1850 to 2013 average) did not extend to the winter season, and was followed by a few years of significantly higher-than-average summer ice extents. Early in the record (1850 to 1900), winter ice extent was not particularly elevated relative to the 1850 to 2013 average, but summer sea ice extent was quite a bit higher higher than the average. As another way to place recent conditions into a longer context using this data set, we show the years of the lowest September extent recorded within the 50-year periods 1850 to 1900, 1901 to 1950, 1951 to 2000, along with the lowest over the period 2000 to 2013 (Figure 5b). The decline in extent is apparent.

 

 

Moving the goal posts again I see. You do realize anything prior to the 1970s is going to be much less reliable and a very rough estimate right? You obviously did not even bother to read the article by Judith Curry I posted which addressed issues with ice data prior to the 70s. There have been a wide variety of studies conducted using the same data as NOAA did in theirs with different results and conclusions that conflict with them based on the same data. You should read the link I posted. It goes through exhaustively a wide range of reports, graphs, data sets, their flaws and strengths, etc and analyzes them in detail. To make it easy for you I'll post part of the abstract and let you decide if you're going to do any digging into the details... so far you refuse to do so.

"In trying to determine the true extent of sea ice during the period we run the risk of comparing apples-physical observations, and oranges- satellite altimetry, and the different methods employed over the years creates uncertainties over whether each accurately picked up what is ice, what is water covered ice and what is open water. This makes it difficult to determine how modern ice extent compares to the past with any certainty.

This paper provides evidence that supports a conclusion that the official sea ice data bases covering 1920-1945/50 appear to very substantially overstate the ice area extent. Some of the thinning of the ice and reduction of glaciers noted today appears to have had their genesis in the period." https://judithcurry.com/2013/04/10/historic-variations-in-arctic-sea-ice-part-ii-1920-1950/

[forkyfork]

blah blah blah blah

[snowlover91]

33 minutes ago, chubbs said:

Below is the daily sea ice anomaly and a one-year running average. Autumn, winter and spring have been leading the way down recently.

And here's a longer term reconstruction. It's interesting that the satellite era happened to occur right around a peak according to this study. Also note that anything pre-satellite era is prone to large errors but it gives an idea of the possibilities based on various reconstruction proxies which are the best we have to work since satellites weren't around prior to the 70s.

 

[DaculaWeather]

6 minutes ago, forkyfork said:

blah blah blah blah

And now I remember why I quit coming here. 

[snowlover91]

6 minutes ago, DaculaWeather said:

And now I remember why I quit coming here. 

Yeah forky’s stuff belongs in banter but mods won’t do anything about it. Hard to have intelligent debate and discussion with things like that going on. 

[bdgwx]

17 hours ago, snowlover91 said:

I think it’s relevent here since the CO2 relationship is an important aspect of the discussion and no one really is posting much about sea ice right now since it’s about on pace with recent years so far. I’m not really a fan of starting new threads personally. 

I get that, but this thread is focused on Arctic sea ice. Judith Curry makes several points in her blog and none of them were directly related to sea ice. Don't get me wrong. They're good talking points, but they deserve their own thread. That way we can address each talking point via several posts without taking this thread too far off course. That's what the climate change subforum is for afterall. Post another thread and I'll participate as I get time.

[bdgwx]

7 hours ago, BillT said:

when a person mentions "consensus science" as evidence they are admitting they know NOTHING about the most basic concepts of science......

Let me clarify something. Consensus is not itself a form of evidence. Rather it is born out of the abundance of evidence. Specifically it is the consilience of evidence from which a consensus is born.

In other words the reality tends to land in the spot where there is the best overlap of available evidence. What I find often in the blogosphere is that they are brainwashing people into believing that consensus is bad and outlier is good. They do this in a variety of guises but the main issue is that they simply don't tell you about the abundance of evidence from which the consensus came and instead focus solely on outlier lines of evidence. Of course it doesn't help that evidence supporting the consensus is often misrepresented or misinterpreted and that the outlier evidence often has significant issues which is also not presented to you. This is actually a big problem with the internet today in general but specifically with climate science.

The fact is that the Earth is going to experience a persistent net positive radiative forcing as a result of human activities (including but not limited to CO2). And baring any significant and unpredictable events like significant volcanic eruptions or other cataclysms the entire geosphere will respond with an increase in heat uptake and an increase in temperature. This will put longterm downward pressure on sea ice (especially in the Arctic region) resulting in ice-free conditions in the summer months with the most likely timing being around mid century assuming a business-as-usual representative climate pathway. Different RCPs yield different amounts of warming at different times. Dismissing the abundance of evidence (a mountain of evidence in fact) that has been collected over the last 150+ years isn't going to stop CO2 from producing a positive radiative forcing on the planet or stop the declining trend of Arctic sea ice extents.

 

[bluewave]

1 hour ago, snowlover91 said:

 

Moving the goal posts again I see. You do realize anything prior to the 1970s is going to be much less reliable and a very rough estimate right? You obviously did not even bother to read the article by Judith Curry I posted which addressed issues with ice data prior to the 70s. There have been a wide variety of studies conducted using the same data as NOAA did in theirs with different results and conclusions that conflict with them based on the same data. You should read the link I posted. It goes through exhaustively a wide range of reports, graphs, data sets, their flaws and strengths, etc and analyzes them in detail. To make it easy for you I'll post part of the abstract and let you decide if you're going to do any digging into the details... so far you refuse to do so.

"In trying to determine the true extent of sea ice during the period we run the risk of comparing apples-physical observations, and oranges- satellite altimetry, and the different methods employed over the years creates uncertainties over whether each accurately picked up what is ice, what is water covered ice and what is open water. This makes it difficult to determine how modern ice extent compares to the past with any certainty.

This paper provides evidence that supports a conclusion that the official sea ice data bases covering 1920-1945/50 appear to very substantially overstate the ice area extent. Some of the thinning of the ice and reduction of glaciers noted today appears to have had their genesis in the period." https://judithcurry.com/2013/04/10/historic-variations-in-arctic-sea-ice-part-ii-1920-1950/

You should research the sources that you get your material from. The authors you cited aren't even qualified in the field of climate science. That's why the graph is so inaccurate compared to the legitimate study in the NSIDC link that I posted.

 

[BillT]

since there was more ice this past summer than in 2007 where is this continuing decline in the arctic sea ice please?????....also the greenhouse effect is an insulating effect, please name one insulator than adds extra heat to any system????? i ask because seems to me co2 in no way adds to the total heat in our atmosphere.

[snowlover91]

2 hours ago, bluewave said:

You should research the sources that you get your material from. The authors you cited aren't even qualified in the field of climate science. That's why the graph is so inaccurate compared to the legitimate study in the NSIDC link that I posted.

 

Which specific authors are you referencing? You do realize who Judith Curry is right? You also realize the incredible difficulties in amassing anything remotely accurate pre-satellite especially since most of the old ice maps use climo or the gaps are filled in right so there will be significant differences in how this data is assimilated even among various climate scientists? I’m sure you’re aware of a possible critical flaw that was made in the data set you referenced regarding the use of DMI and other maps or did you just blindly accept it?  You also realize what even the IPCC has to say regarding this in AR5 chapter 10?

[LithiaWx]

Deniers luz

[bdgwx]

14 hours ago, BillT said:

since there was more ice this past summer than in 2007 where is this continuing decline in the arctic sea ice please?????....also the greenhouse effect is an insulating effect, please name one insulator than adds extra heat to any system????? i ask because seems to me co2 in no way adds to the total heat in our atmosphere.

It's true. The 2007 summer minimum was lower than in 2018. However, if you integrate the sea ice extents over the entire year and assuming 2018 follows the 2017 trajectory the remainder of the year (a reasonable assumption) you'll find that 2018 results in less ice than in 2007. Except that's really moot anyway. Keep in mind that when we say "decline" we are talking about a longterm secular decrease in sea ice extents. We are not in any way implying that every year will necessarily be lower than the previous. Natural variation is still very much in play. And we aren't necessarily even focused on just the summer minimum. The winter maximum and, of course, the yearly mean are equally important metrics.

Regarding your second point there may be some confusion as to what a greenhouse gas does.  CO2 and other polyatomic molecules (like H20, CH4, and CFCs) aren't sources of heat. What they do is disrupt the balance between Qin (the incoming shortwave radiation) and Qout (the outgoing longwave radiation). This imbalance creates a net positive gain in heat uptake in the geosphere (90% goes into the hydrosphere) until a new equilibrium is achieved such that Qin = Qout once again. It's really not much different at a conceptual level with the insulation in your home. All other things being equal your house will achieve an equilibrium at a lower temperature if there is no insulation. Again, CO2 is not a source of heat. What it does is impede the transmission of heat.

[aperson]

6 hours ago, snowlover91 said:

There is plenty of research out there that suggests the arctic ice extent we see today is something that is cyclical and was also seen in the 1920-1950 period. My original statement was also correct; 2007-2018 has seen no discernible changes/trend in ice extent and recent years have seen slight increases compared to the 2007-2012 averages. People such as yourself take 30-40 years of data and assume that CO2 is responsible for everything we see without acknowledging or engaging in intelligent discussion of alternative possibilities that could explain some or all of the changes being seen. You said my 11 years of data is too short term and yet you want to take 38 years of data as sufficiently long enough? Ok then, double standard much?

Here's a VERY detailed article listing an abundance of information that indicates the ice levels in this period (1920-1950) were probably similar to what we see today (but not as low as 2007 and 2012). In other words, historically we may have seen ice levels nearly identical to what we are seeing now when the CO2 levels were much lower. This certainly indicates there are natural cycles and variations ongoing, contrary to your flawed assumption that CO2 must be the only possible explanation. https://judithcurry.com/2013/04/10/historic-variations-in-arctic-sea-ice-part-ii-1920-1950/

Reconstructions of the Arctic ice levels indicate some interesting details as well... but sure go ahead and ignore this scientific research since it obviously must be wrong since it disagrees with "consensus science" as you would say.

According to this new dataset, the recent period of Arctic sea ice retreat since the 1970s followed a period of sea ice growth after the mid 1940s, which in turn followed a period of sea ice retreat after the 1910s. Our reconstructions agree with previous studies that have noted a general decrease in Arctic sea ice extent (for all four seasons) since the start of the satellite era (1979). However, the timing of the start of the satellite era is unfortunate in that it coincided with the end of several decades during which Arctic sea ice extent was generally increasing. This late-1970s reversal in sea ice trends was not captured by the hindcasts of the recent CMIP5 climate models used for the latest IPCC reports, which suggests that current climate models are still quite poor at modelling past sea ice trends. Nor is it described in previous Arctic sea ice reconstructions such as the Walsh dataset or the widely used HadISST sea ice dataset, although some recent studies have noted similar reversals, e.g. Pirón and Pasalodos (2016) and Alekseev et al. (2016)." https://www.tandfonline.com/doi/pdf/10.1080/02626667.2017.1324974

 

 

Connolly et al., 2017: https://www.tandfonline.com/doi/full/10.1080/02626667.2017.1324974

Quote

Indeed, Alekseev et al. (2016) recently used Arctic summer surface air temperatures as a direct (inverse) proxy for September Arctic sea ice extent by applying a simple linear regression relationship. Alekseev et al.’s approach bypasses the problems from the multiple data sources described above. It therefore offers a useful approximate estimate of Arctic September sea ice extent trends for the 1900–2013 period. However, because the Alekseev et al. (2016) reconstruction is essentially an inverse Arctic summer temperature index, it cannot be used for studying the relationship between Arctic sea ice extent and surface air temperatures outside the satellite era (as that would lead to circular logic). Also, it discards all of the pre-satellite era direct observations of Arctic sea ice incorporated in the Walsh and Zakharov datasets.

Emphasis mine.

Thus the Alekseev et al. 2016 data set cannot be used to refute the CO2 hypothesis impact on SIE, that is CO2 -> increased temperature -> decreased SIE, because doing so is a circular argument.

The rest of your posting career is a similar abuse of scientific literature. People don't engage you because you're correct (you're delusional), they don't engage you because of the Bull**** Asymmetry Principle.

[BillT]

2 minutes ago, bdgwx said:

It's true. The 2007 summer minimum was lower than in 2018. However, if you integrate the sea ice extents over the entire year and assuming 2018 follows the 2017 trajectory the remainder of the year (a reasonable assumption) you'll find that 2018 results in less ice than in 2007. Except that's really moot anyway. Keep in mind that when we say "decline" we are talking about a longterm secular decrease in sea ice extents. We are not in any way implying that every year will necessarily be lower than the previous. Natural variation is still very much in play. And we aren't necessarily even focused on just the summer minimum. The winter maximum and, of course, the yearly mean are equally important metrics.

Regarding your second point there may be some confusion as to what a greenhouse does.  CO2 and other polyatomic molecules (like H20, CH4, and CFCs) aren't sources of heat. What they do is disrupt the balance between Qin (the incoming shortwave radiation) and Qout (the outgoing longwave radiation). This imbalance creates a net positive gain in heat uptake in the geosphere (90% goes into the hydrosphere) until a new equilibrium is achieved such that Qin = Qout once again. It's really not much different at a conceptual level with the insulation in your home. All other things being equal your house will achieve an equilibrium at a lower temperature if there is no insulation. Again, CO2 is not a source of heat. What it does is impede the transmission of heat.

the incoming is both short and long wave radiation, and there is NO balance never has been, thermodynamics means the system seeks to find balance but because factors constantly change that balance is never found.......

[snowlover91]

29 minutes ago, aperson said:

 

Connolly et al., 2017: https://www.tandfonline.com/doi/full/10.1080/02626667.2017.1324974

Emphasis mine.

Thus the Alekseev et al. 2016 data set cannot be used to refute the CO2 hypothesis impact on SIE, that is CO2 -> increased temperature -> decreased SIE, because doing so is a circular argument.

The rest of your posting career is a similar abuse of scientific literature. People don't engage you because you're correct (you're delusional), they don't engage you because of the Bull**** Asymmetry Principle.

Yes, set in the context of the paper, the author does a good job picking out the difficulties in using various pre-satellite data sets and I have made that clear in my posts. Read the article I linked from Judith Curry’s site, you’ll find some fascinating information about the various data sets and methods used and the issues with them all. Having said that there is evidence from various reconstructions, proxy sets and other studies that indicates the Arctic was quite warm in the 1920-1950 period and that significant ice loss was noticed. How much we will never know since data was so sparse and the war made things even more difficult but the point remains. Here’s another article discussing the difficulties involved with various data sets as well as some proxy data. https://judithcurry.com/2017/08/16/what-do-we-know-about-arctic-sea-ice-trends/

[bdgwx]

10 hours ago, BillT said:

the incoming is both short and long wave radiation, and there is NO balance never has been, thermodynamics means the system seeks to find balance but because factors constantly change that balance is never found.......

I only mean that CO2 is adjusting the overall energy budget by perturbing some of the longwave channels as opposed to the other channels. As a result its effect is more pronounced on the Qout side than the Qin side due to its spectral behavior in relation to the precise nature of the Earth/Sun radiation fluxes. I'm not sure what your point was about "there is NO balance never". Anyway, we're starting to digress here as the physical process behind polyatomic molecule's propensity to trap heat isn't directly related to the subject of this thread. We're trying to discuss Arctic sea ice extents here. If you have questions or comments regarding other topics of climate change maybe it would be better to post them in another thread? There's a whole forum dedicated to this.

[bluewave]

11 hours ago, bdgwx said:

It's true. The 2007 summer minimum was lower than in 2018. However, if you integrate the sea ice extents over the entire year and assuming 2018 follows the 2017 trajectory the remainder of the year (a reasonable assumption) you'll find that 2018 results in less ice than in 2007. Except that's really moot anyway. Keep in mind that when we say "decline" we are talking about a longterm secular decrease in sea ice extents. We are not in any way implying that every year will necessarily be lower than the previous. Natural variation is still very much in play. And we aren't necessarily even focused on just the summer minimum. The winter maximum and, of course, the yearly mean are equally important metrics.

You make an excellent point about the importance of looking at annual sea ice metrics. Luckily, Zack Labe has a fantastic site that includes these types of graphs. 2016 was the lowest annual extent on record. The lowest annual volume was recorded in 2017.

 

 

[snowlover91]

2018 ice volume finished above 2016 and 2017, passed 2015 and was just below 2014.

 

Here's some interesting stats from another forum. If you like reading up on stats about the ice and other scientific details they post some pretty cool stuff here. https://forum.arctic-sea-ice.net/index.php/topic,2223.2050.html

NSIDC stats for 11-12-18. Currently 2018 is 8th lowest, now surpassing 2017, 2016, 2012, 2011, 2010, 2009, and 2006. If current trends continue 2018 can "drop" to 11th lowest because 2015, 2013 and 2007 are stalling the next few days.

2018 - 9.559 km2 (8th)
2017 - 9.326 km2 (4th)
2016 - 8.649 km2 (1st)
2015 - 9.650 km2 (stalling next few days)
2014 - 9.827 km2
2013 - 9.575 km2 (stalling next few days)
2012 - 9.002 km2 (2nd)
2011 - 9.458 km2 (5th)
2010 - 9.521 km2 (7th)
2009 - 9.283 km2 (3rd)
2008 - 10.090 km2
2007 - 9.660 km2 (stalling next few days)
2006 - 9.500 km2 (6th)

 

[chubbs]

Below is the best discussion of the available data for the past 1500 years. The current warming is unprecedented.

Year-to-year variation in sea ice is expected. We get the sea ice is recovering story periodically in this forum: 2008/9, 2013/14, etc. Sea ice is not crashing and its not recovering, just a steady long-term decline with large year-to-year variability.

https://www.nature.com/articles/nature10581

[donsutherland1]

17 hours ago, bluewave said:

Not even close.

https://nsidc.org/arcticseaicenews/2018/01/

Using a compilation of maps, ship reports, and other records, NOAA has published monthly estimates of Arctic sea ice extent spanning 1850 to 2013. While data in the earlier part of the record is limited, the carefully constructed time series helps to put the more recent satellite record in a longer-term context. Figure 5a shows the decline in extent over the period of satellite observations standing out prominently in comparison with the rest of the record, especially in late summer and early autumn. An earlier period of unusually low summer sea ice extent around 1937 to 1943 (as compared to the 1850 to 2013 average) did not extend to the winter season, and was followed by a few years of significantly higher-than-average summer ice extents. Early in the record (1850 to 1900), winter ice extent was not particularly elevated relative to the 1850 to 2013 average, but summer sea ice extent was quite a bit higher higher than the average. As another way to place recent conditions into a longer context using this data set, we show the years of the lowest September extent recorded within the 50-year periods 1850 to 1900, 1901 to 1950, 1951 to 2000, along with the lowest over the period 2000 to 2013 (Figure 5b). The decline in extent is apparent.

https://www.carbonbrief.org/guest-post-piecing-together-arctic-sea-ice-history-1850

Most fundamentally of all, the new dataset allows us to answer the three questions we posed at the beginning of this article.

First, there is no point in the past 150 years where sea ice extent is as small as it has been in recent years. Second, the rate of sea ice retreat in recent years is also unprecedented in the historical record. 

Thanks for posting Dr. Stroeve's Arctic sea ice extent data. I hadn't seen this paper and it really reinforces the dramatic changes that have been taking place in the Arctic region.

[snowlover91]

Some interesting ice core results from various parts of the Arctic over the long term show interesting results. The Fram strait has seen a significant drop but the 3 other regions are within the norms for the long term climate if one accepts these results as valid.  https://onlinelibrary.wiley.com/doi/abs/10.1002/jqs.2929