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Messages - Juan C. García

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You are confusing yourself by thinking that the NSIDC monthly extent is an average. It isn't. Its the monthly extent. NSIDC say things like "Arctic sea ice extent for May 2013 was 13.10 million square kilometers". No mention of "average" there. Its the extent for May, not the average daily extent during May.
Extent varies depending on the grid scale used, both in space and time. Daily extent isn't an average of hourly extent, and monthly extent isn't an average of daily extent.
A year ago I was confusing myself by thinking that the NSIDC monthly extent was an average of the daily values (and I believe that I am not the only one making that mistake). Now I am maybe wrong by using the term “Official NSIDC monthly average” and I should use the term “Official NSIDC Monthly Extent”. But anyway, what I am looking to highlight is precisely the difference between the “Official NSIDC Monthly Extent” and an average of NSIDC daily values on a given month.
NSIDC defines a daily extent as grids that have 15% or more of ice in a given day. If this grid has 15% or more of ice, then the grid counts as if it has 100% of ice. I believe that this criteria was good in the XX Century, but can overvalue the sea ice extent now, that we can have a lots of grids with 15% or a little more of ice. So I tend to be concern about the concept of daily extent.
But I find more misleading the concept of monthly extent. NSIDC defines monthly extent as the sum of grids that have 15% or more of ice in a month. But especially in July, October and November, the ice at the start of the month is very different of the ice at the end of the month. On July, the ice is melting quickly and on October and November, the water of the ocean is freezing quickly. So in July, the NSIDC monthly extent is close to the daily values that we have on July 5-12th. It doesn’t matter if afterwards we have a strong melt on the month. An in October and November, the NSIDC monthly extent is also close to the daily values that we have on October 18-25th and November 18-25th, respectively.  Especially in October, it doesn’t matter if the first week of October we have values similar to those close to the minimum of the year and then we have a strong freeze-up. The Official NSIDC October value will reflect the strong freeze-up, not the slow start of freeze.
As a conclusion, what I mean is that if a daily extent could be overvalue now that the Arctic Sea Ice is melting, as never before in the history of the human being, the Official Monthly Extent is worst because it is overvalue against an average of the daily extent values.
So for me it is better to follow area or volume, instead of extent, and if I follow extent, I look at the daily values but I find very misleading the concept of monthly extent. And that is a concern when I see that a lot of models using monthly extent.

Is there any probability that this years melt will drift into October, even if just for a few days or a week??
I made a study looking for the difference between the official NSIDC monthly average and what should be the statistical monthly average (that is, average of the daily values). I had interesting results, but I stop writing the Assay because I’m working on another field. I have several graphs and I will look to put them on this Forum.
One of the conclusions is that the Official NSIDC October monthly average is overvalue against the statistical monthly average. So from my point of view, the answer is that if there is a September ice-free Arctic Ocean, then we can have an ice-free on the first week of October. It is just that the Ocean is warm at the beginning of October and the NSIDC monthly average tends to give a value that corresponds to October 18-25.

On Neven’s Arctic Sea Ice blog, he formally invited everybody to this Forum on February 20, 2013 at 17:38.

Arctic sea ice / Re: Bottom melt in Central Arctic ?
« on: June 26, 2013, 07:03:45 PM »
Maybe your 2013 "North Hole" post will mean something totally different...
Hi Rob:
The link that wanderer put made me see the possibility of a 2013 bottom melt on Central Arctic, so I recommend seeing this link. 

I was expecting a drop in CT SIA today. I understand that it hasn’t drop in 3 or 4 days, but I see important changes on Bremen AMSR2 ASI concentration. I don´t see the same changes on the CT image.
I don´t expect to see this melt on NSIDC or Bremen values, because they use extent on their images (not area). But why CT SIA is not dropping? Which satellite does CT uses? Does it have some time lag? Can anybody give me a link to know how CT makes their SIA calculation?

Past couple of days CT SIA: Century break - small uptick - century break - small uptick - century break - small uptick...
Those clouds, holes and melt ponds are making the sensors sweat.  :)
Yesterday I saw an important melt on Hudson Bay and Baffin/Newfoundland Seas, but it was offset by more ice on East Siberian Sea, Canadian Archipelago and Arctic Basin.
Today seems that Arctic sea ice was waiting to melt after the speech of President Obama. Now I see weakness on Hudson Bay, Canadian Archipelago, Arctic Basin and the seas of Kara, Greenland, Baffin and Newfoundland.
I will wait for the possible drop on CT SIA this week.
Or maybe Century break - small uptick - century break - small uptick...? 

I didn´t see this voting poll until now, so I will vote for June 30, knowing that yesterday (June 24) the Forum had a new record of 13683 page views in a single day! Congratulations for the success!

Arctic sea ice / Re: When will we see open ocean at the north pole?
« on: June 24, 2013, 08:06:46 PM »
Let's put aside the arbitrary figure of > 1 million km2 for a virtually ice free summer arctic and lets talk about open ocean at 90 degrees N.
Last September satellites showed large ice free areas around 87 degrees N in the Laptev Sea. that's approx. 200 miles from the North Pole. 
The question is when will we see open ocean at 90N and more importantly, from what direction and how?
Not sure about when, but as for direction, I reckon from the south  :P Sorry.
Maybe your 2013 "North Hole" post will mean something totally different...
Impressive images! They made me believe that the ice free will not come from the south: it will just appear at the North Pole!  ;)

Hi, Ghoti and Wanderer.
I prefer to see Bremen AMSR2 as a first view of ASI. Just want to express that I do not trust NSIDC SIE graphs to have a good feeling of what is happening on.

....well, well - judging by the ice area and extent figures this year, I wasn't too concerned about the ice breaking any records, but then I had a look at the ice thickness maps here at HYCOM/CICE and compared to the same time last year, it looks pretty bad!
Just eyeballing the images, the extent and area are above last year but the 'interior' looks pretty rotten. There appears to be less thick, old ice and the rest looks considerably thinner, than last year. So, given a bit of prolonged irradiance, things could get decidedly dodgy by late August/September  :P
What do you guys think - are these thickness images reliable? Are they a good indicator of things to come?
Hi Jim:
  • Last year we had less ice on Hudson Bay and Baffin/Newfoundland Seas, but it is this important? It is not. I expect this ice to disappear anyway.
  • Last year we had less ice on the Kara Sea. Does someone expect to have some of this ice at the end of the melt season? I don´t expect so.
  • Last year we had some MYI blocking the entrance of warm water to the Chukchi Sea. Now we don´t. Will this factor be important on the following months? Yes, it could be.
  • Last year we had more ice on the east coast of Greenland. This year there is some talking that the tail on Fram Strait could disappear. Would this mean that we can have some MYI export from Fram Strait, when there is not too much MYI left? Yes, it could.
  • And last but not least, the ice at the Arctic Basin seems weak. Are these thickness images reliable? I have several reasons to believe in them. We know that we had a persistent Arctic cyclone (PAC 2013) that made some damage to the ice and several sources (AMSR2 Bremen and NSIDC concentration Images) have being showing us the weakness for at least a week. So why not believe in this weakness? We know that SIE images can be misleading, so it is better to trust concentration images.
So anything can happen. The September SIA can end being above 2012 value or under it. But the true is that the SIE and SIA values that are measured right now can be very misleading when we are evaluating the real weakness of the actual Arctic sea ice.

According to NSIDC, there is much more SIE at 2013 that it was at 2012

According to NSIDC, the 2013 Arctic sea ice looks stonger than 2012 and almost like 1979-2000 average.

But are we able to see Arctic sea ice weakness in their concentration map?

Policy and solutions / Re: crazy idea: block Fram Strait
« on: June 21, 2013, 11:37:10 PM »
The best ideas could look crazy at the beginning. I don´t know what the pressure will be, but I think that could be good to investigate more about what can be done. A dam with the water pump in winter? Maybe a combinations of several ideas will work.

Arctic sea ice / Re: Arctic sea ice free (extent)
« on: June 20, 2013, 06:51:51 PM »

However, when you know the climate is changing showing 3 decadal averages does seem a lot more useful than one 30 year average.

I totally agree. Maybe the best way to see it is to see the IJIS/JAXA SIE graph. Right now NSIDC is giving the approximated average (discarding 1979 and 1980 or 2000) of the first two lines (80´s and 90´s). With the new standard, NSIDC is going to give the approximated average of the first three lines (80´s, 90´s and 2000´s). The graphs of 2007, 2011 and 2012 are too low in values, so it doesn`t matter if you use standard 1979-2000 or 1981-2010. The differences are clear.
But the true is that you can see AGW better if you have the three decadal lines, instead of just one.

Arctic sea ice / Re: Arctic sea ice free (extent)
« on: June 20, 2013, 12:14:20 AM »
That's right. The new standard will have lower values. But I believe that the difference will not be so much, in regards to the lower values of 2005-2012.

Arctic sea ice / Re: Arctic sea ice free (extent)
« on: June 19, 2013, 09:12:01 PM »
NSIDC announces a change on the baseline climatological period for Arctic Sea Ice News and Analysis: from 1979-2000 to a 30-year reference period, from 1981 to 2010:

This July, NSIDC plans to change the baseline climatological period for Arctic Sea Ice News and Analysis and the Sea Ice Index, the data set we use for our sea ice analysis. We are making this change to match the comparison time frames used by other climate research.

Until now, we have used the 22-year period 1979 to 2000 when comparing current sea ice extent to past conditions. When NSIDC first began to monitor and analyze sea ice extent, a longer period was not available. Since the satellite record is now extended, we are choosing to move to a more standard 30-year reference period, from 1981 to 2010.

I am going to stay in the range 1.75-2 million km2 of SIA, that I voted in April and May. I believe that the ice is weak, and even that the melt is having a low start, I believe that we could have a great melt in the following months.

I must ask; is it possible for this upcoming cyclone to melt the vast majority of the pack and leave very little of it for the rest of June, July and August?

fishmahboi, the cyclone is already there and no, it will not melt the vast majority of the pack. I think it will weaken it somewhat.

When I see the NSIDC and Bremen SIE graphs, I think that we are not going to have a new record this year. Even when I see the Chryosphere Today SIA graph, I believe that we will keep 2012 records. It seems that at 2013 the Arctic has more sea ice than any of the years from 2007 to 2012.

But when I see the new AMSR2 Bremen image, I believe that at the end, the 2013 persistent cyclone is going to affect (or it has affected) an important part of the Arctic sea ice, at least the one that is between Asia and the North Pole.

So I am going to wait a few days, to think if I will keep the forecast of 1.75-2 million km2 on CT SIA, or lower it even more.


¿Are there 25 polynyas? ¿Would these 25 polynyas be a normal scenario on May 21? If it is true that they capture the heat and they melt their surroundings, then it seems that we are in trouble. It is just starting the melting season.

We can have as many options as we like, but how about I keep the gap 0.25 and add the options all the way to zero?

I agree.

A month seems a long time when a lot can happen so it might be hard to know whether differences arise from different views or different information. So, would it be better to shorten the poll period to half a month?
It might be better, but doing just one a month is enough of a job for me (which I mustn't forget)

Instead of making several polls on the same topic in a month, the SIA and SIE polls can start the 10th of the month (or the 15th the latest) and end the last day of the month. By example, I am waiting for the May 20th to give my vote on Cryosphere SIA.

The forum / Re: Thanks for setting up the forum
« on: May 05, 2013, 07:11:59 AM »
In the previous post, I was talking about reaching a new record of 10,000+ page views on a single day. I wrongly saw the 8,250 page figure of May 1st, instead of looking at the number of May 4th. So I apologize for the mistake. The April 9th stat of 9,951 page views will continue to be the daily record.
Of the other hand, on the Arctic Sea Ice blog, Neven formally invited us to this forum on February 20th. So, in just two and a half months, the Forum was able to have 260 topics with a total of half million page views. I am sure that this statistics is a good example of the success of the Forum. Congratulations!

The forum / Re: Thanks for setting up the forum
« on: May 04, 2013, 04:53:41 PM »
Today (May 4th, 2013) the Forum reached half a million page views! Congrats to Neven, DungeonMaster and the others that had intensively participated of this Forum for the success!
Also, at 4:44 PM, we have 8,250 page views in a day, that could be compared with the 5,584.47 average page views per day. Could be possible that the Forum will reach a new record of 10,000+ page views today? Well, we will just wait and see!

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: April 22, 2013, 07:42:59 AM »
I usually don't like to say "I said it" but this time I will:

After six years, having new 2007 and 2012 SIE records, they are developing new models but they continue to underestimate the actual melt. From my point of view, it is unacceptable that almost all the models put the Arctic sea ice free after 2100. Only the worst scenario has a sea ice free at 2060 (according to the definition of Arctic sea ice free happens when NSIDC SIE average is less than one million km2)

From the NOAA's News "Arctic nearly free of summer sea ice during first half of 21st century"

We can jump to the following article abstract made by James Overland of NOAA’s Pacific Marine Environmental Laboratory and Muyin Wang of the NOAA Joint Institute for the Study of Atmosphere and Ocean at the University of Washington:

[1] The observed rapid loss of thick, multi-year sea ice over the last seven years and September 2012 Arctic sea ice extent reduction of 49 % relative to the 1979-2000 climatology are inconsistent with projections of a nearly sea ice free summer Arctic from model estimates of 2070 and beyond made just a few years ago. Three recent approaches to predictions in the scientific literature are: 1) extrapolation of sea ice volume data, 2) assuming several more rapid loss events such as 2007 and 2012, and 3) climate model projections. Time horizons for a nearly sea ice free summer for these three approaches are roughly 2020 or earlier, 2030± 10 yrs, and 2040 or later. Loss estimates from models are based on a subset of the most rapid ensemble members. It is not possible to clearly choose one approach over another as this depends on the relative weights given to data versus models. Observations and citations support the conclusion that most Global Climate Models results in the CMIP5 archive are too conservative in their sea ice projections. Recent data and expert opinion should be considered in addition to model results to advance the very likely timing for future sea ice loss to the first half of the 21st century, with a possibility of major loss within a decade or two.
doi: 10.1002/grl.50316

Thanks Wanderer, Jim, Vergent and Cris from your answers.
I think that we will have to wait a couple of weeks to see how the crack will develop, but at this moment, I believe that the fragmentation event will be a topic on April/May and it will have an important impact in this melting season.

This area has a crack that has stayed for the whole April. From my point of view is growing, becoming wider than before. I don’t remember seeing something like this in the past. The Arctic sea ice is very weak.

Arctic sea ice / Re: Historic Predictions of an Ice Free Arctic
« on: April 09, 2013, 06:21:59 AM »
NSIDC, October 1st, 2007:
NSIDC scientists monitor and study Arctic sea ice year round, analyzing satellite data and seeking to understand the regional changes and complex feedbacks that we are seeing. Serreze said, “The sea ice cover is in a downward spiral and may have passed the point of no return. As the years go by, we are losing more and more ice in summer, and growing back less and less ice in winter. We may well see an ice-free Arctic Ocean in summer within our lifetimes.” The scientists agree that this could occur by 2030. Serreze concluded, “The implications for global climate, as well as Arctic animals and people, are disturbing."

It seem too early when it was said at 2007. Five years later, I am convinced that it is going to happen before 2020.

After seeing how the sea ice concentration is changing at Bering Sea, Okhotsk Sea, Barents Sea and the exit of Hudson Bay, I want to keep record of the status of the poll at this moment, because I bet that the percentages are going to change in the following days (to ranges with less value). Let’s wait and see.

It seems incredible that the perception of the status of the Arctic could change only 8+ days after this poll has started.

I want to use the occasion of Neven’s question to ask if it is ok to write: “Arctic sea ice free” or would be better an expression like: “Arctic free of sea ice”?
On the other hand, I already voted for 1.75-2.00 million km2. I agree with Reynolds about the concern of FYI, but from my point of view, it is more important to highlight the actual weakness of the ASI. I  believe that the cracks are the evidence of this weakness. Also, there are starting to appear polynyas that are another evidence of weakness and show the possibility of an early melt during April-May. So FYI is the cause, but cracks and polynyas are two consequences that we can see right now.
I concern that could be a strong melt at 2013, but for now, I will keep my vote on the 1.75-2.00.

I think Neven should say more prominently that this is daily minimum not a monthly average.

Agree that the bin sizes changing from .2 to 1, a factor of 5, seems a large sudden change.

What would I set? Perhaps:

so have to go below 1.5 or above 3 to get larger bins. Bins then double the size and continue to do that or more with each bin as they move further from most peoples expected range. Just 50% larger bins has been suggested which also looks sensible; perhaps should also apply at high end?
I believe that Crandles made a good recomendation (so forget mine, too many options).

Well, I thought to wait and see how Arctic sea ice will perform during April, but then, I prefer to start this poll. From my point of view, there should be more ranges between 1 and 2 million km2, if 2012 minimum was 2.234 million km2. So I invite Neven to make more ranges and I will vote again. Given the ranges that are right now, I chose from 1 to 2 km2 as the minimum.
I suggest making the following new ranges: from 1 to 1.3, from 1.3 to 1.6, from 1.6 to 1.8 and from 1.8 to 2 million km2. With the cracks that the ice had on February-March 2013, I expect to have a new record on September 2013. At this moment, I will bet for the 1.8 to 2 million km2, but I could change my mind during April.

Arctic sea ice / Re: Arctic sea ice free (extent)
« on: April 01, 2013, 06:58:16 AM »
Last day to vote...  ;)

Arctic sea ice / Re: Arctic sea ice free (extent)
« on: March 28, 2013, 05:10:45 AM »
Well, if you haven’t vote, there are only three days left, so I invite you to do it.
On the other hand, I thank the votes and replies to this topic. I find very interesting that almost 90% (at this moment) expect an Arctic Sea ice free before or at 2020, even that the question was with NSIDC extent monthly average, that is a tricky way to measure the Arctic sea ice.
So thanks for your participation and we will continue following the 2013 melting season, which seems that will have an early and strong start.

Some polynyas that are showed from AMSR2 (Bremen):

It is too early, isn't it? And at several places of the Arctic...

Arctic sea ice / Re: Vote with your guts - And if... ?
« on: March 22, 2013, 05:16:01 AM »
This doesn’t sound like a poll
More like an official bet
Are the cracks so bad?
I choose “not really, but…” I hope it won’t.

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: March 21, 2013, 08:02:25 AM »

Difference between NSIDC Official Monthly Averages and the Daily Value Averages by month (2012)

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: March 21, 2013, 07:09:49 AM »
On their November 2012 analysis, NSIDC made public:
Average ice extent for October was 7.00 million square kilometers (2.70 million square miles). This is the second lowest in the satellite record, 230,000 square kilometers (88,800 square miles) above the 2007 record for the month.

(Green and red straight lines added by myself)
Quote and Graph:

I couldn’t understand the 7 million km2 assigned as October 2012 average by NSIDC, for two reasons:
  • NSIDC official October 2012 average was above October 2007 average, but the first fifteen days of October 2012 where substantially below 2007, while the second part of the month where just slightly above 2007 (and not for all of the fifteen days).
  • If we analyze 2012 alone, the October values where substantially lower than 7 million km2 for the most part of the month, so how can it be that the average was 7 million km2?
I was wrong in my conclusion, but I thought that the October average was 6 million km2 and someone at NSIDC, by mistake, made it 7 million km2. I wrote comments at Neven’s Arctic Sea Ice Blog and I also wrote to NSIDC. Thanks for the answers of Wipneus (1), NLPatents (2) Piotr Djaków (3) and NSIDC (4), I found that NSIDC was not using the statistical monthly average, that is, the NSIDC monthly average is not the sum of the daily values of a month, divided by the days with value on that particular month.


Instead, NSIDC calculates the monthly average and makes a graph of the monthly sea ice extent, according to the following criteria:
2. Overview of Sea Ice Index Processing

Mean Concentration Fields and Median Ice Edge Position
On monthly extent images, ice ends and water begins where the concentration estimates of grid cells in the gridded average, or mean, concentration field for that month drop below 15 percent.

As I understand now the NSIDC monthly average, in a 30-days month the 15% is 4.5 days, in a 31-days month the 15% is 4.65 days and in a 28-days month the 15% is 4.2 days. To explain it with rounded numbers, if a grid cell is with 100% of ice during 5 days, that grid is going to count as 100% ice for the entering month. It can also have 50% of sea ice for 10 days or 15% for the whole month. Both will also count as 100% for the entering month. If it is 4 days or less, then the grid cell will count as 0% of sea ice for the entire month.
Finally, if a grid cell on October 22nd has 10% of sea ice, on October 23rd has 20%, and so on until October 30th with 90% and October 31st with 100% of sea ice, then this grid cell will also count as 100% with sea ice for the whole month. More or less, that is what happens on October 2012. Even that it was just slightly above 2007 for a few days, these days where on October 20th – 26th and it meant that several 2012 grid cells qualify as 100% sea ice for the month, but this didn’t happen in the same magnitude on 2007.   

Basically, the rule that NSIDC uses to calculate what I will be calling the “Official NSIDC Monthly Average” tends to over valuate the average, if it is compared with what I will be calling “The Daily Values Average” that will be the statistical average based on the sum of the daily values divided by the numbers of days with a value.
The overvaluation is especially true during the months where there is a fast freeze up or a fast melt, as it happens in October and July, respectively.

Arctic sea ice / Re: Arctic sea ice free (extent)
« on: March 16, 2013, 08:15:04 PM »
I will be writing about the characteristics of NSIDC SIE monthly averages and the difficulty of reaching sea ice extent less than one million km2. So I just want to show how it is the poll right now, before I start to talk about it.

The discussion will be held at the Forum topic: Models of projected Arctic sea ice decline:
With “https”:,83.0.html
With “http”:,83.0.html

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: March 16, 2013, 07:26:39 PM »
I will be writing about the characteristics of NSIDC SIE monthly averages and the difficulty of reaching less than one million km2 of sea ice extent. So I just want to show how it is the poll right now, before I start to talk about it.,80.50.html

The forum / Re: [Solved] How to post an image?
« on: March 16, 2013, 07:07:08 PM »
Let's make a test:

and the result is great!

The forum / Re: Insert an image
« on: March 14, 2013, 04:07:13 PM »
For those who are entering the Forum as Guests (not registered as Users), seems that you are not able to see the attachments, so you are not able to see the graphs that I have put on this blog. I will look to put the next graphs as “images” instead of attachments. Seems that images work better and you will be able to see them.
But anyway, other users can put attachments (that are simpler to put on), so I invite you to register to the Forum.

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: March 14, 2013, 04:05:05 PM »
For those who are entering the Forum as Guests (not registered as Users), seems that you are not able to see the attachments, so you are not able to see the graphs that I have put on this blog. I will look to put the next graphs as “images” instead of attachments. Seems that images work better and you will be able to see them.
But anyway, other users can put attachments (that are simpler to put on), so I invite you to register to the Forum.

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: March 14, 2013, 07:48:44 AM »
Do the models are based on Arctic sea ice extent or are based on Arctic sea ice volume?
This image is a suggestion to the Slogan contest and I surely believe it is important to highlight that we have lost more than 50% of Arctic sea ice.
I invite you to participate in the Slogan contest that is ending at March 15th, 2013.
More information on Neven’s Arctic Sea Ice Blog:

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: March 14, 2013, 07:15:09 AM »
At the NSIDC August 6, 2012 Analysis, the NSIDC showed a graph with the SRESA1B models (that are part of the CMIP3 Models used in the IPCC 4th Assessment Report of 2007) and with the RCP 4.5 models (that are part of the CMIP5 models and could be use in the 5th Assessment Report to be published at 2013-14).
In this NSIDC August Analysis, the NSIDC said:
Previous research at NSIDC documented that September Arctic ice extent has declined faster than models predicted it would. The comparison was between observations and simulated trends from models participating in the World Climate Research Programme Coupled Model Intercomparison Project Phase 3 (CMIP3). These climate models were used in the 2007 4th Assessment report of the Intergovernmental Panel on Climate Change (IPCC). In a new paper, Stroeve et al. (2012) compared the observed 1979-2011 September trend for the Arctic against trends over the same period from the next generation of models in the CMIP5 archive. While the newer CMIP5 models do a better job of simulating the observed trend, most of the modeled ice extent trends are still smaller than the observed downward trend. NSIDC is working with researchers to further improve the models, which help extend and refine our understanding of the climate system.
Credit: National Snow and Ice Data Center courtesy Stroeve et al. 2012

On the other hand, on Stroeve et al. 2012 we have (4. Discussion and Conclusions):
If we constrain the analysis to models that (based on criteria described earlier) can reproduce the observed climatological mean September ice extent, the spread in projected ice extent throughout the 21st century from the CMIP5 and CMIP3 models is similar. This holds despite the overall better match of the CMIP5 models with the observed seasonal cycle and trend. Furthermore, a similar number of these ensemble members reach nearly icefree conditions (less than 1.0 x 106 km2) before the end of the 21st century. Viewed in this context, conclusions drawn from CMIP5 are not much different than those from CMIP3.

On this regard, I included the graph published in the NSIDC August Analysis, but with the following changes made by myself:
  • The graph is updated with the new 2012 SIE record (yellow line)
  • I made explicit that the new 2012 record is ahead 50 years of the CMIP3 SRESA1B (2007) models, but also 20 years of the CMIP5 RCP 4.5 models.
  • Finally, I highlight that roughly at 2030, the difference between the two types of models is around 2.25 million km2, while at 2100 this difference decreases to only 0.5 million km2.
Would that be reasonable? Or are the models being forced so that they follow the real values that we are having on the last ten years, but then they are also being force so that they do not have an ice-free at 2100?

Permafrost / Re: Northern Hemisphere snow cover
« on: March 12, 2013, 03:16:36 AM »
It will be interesting to see if we will have a new snow cover anomaly record at June/2013. The last five years were of impresive anomalies and of course, it has a relation with the permafrost and methane emissions, even that I would say that there is not good measurement of methane emssions related to the thawing of the permafrost.

(image also from Rutgers University Global Snow Lab:

The forum / Re: Thanks for setting up the forum
« on: March 08, 2013, 03:00:02 AM »
Hi, Neven.

I didn’t thank you for setting up the Forum (that I should…), but I want to be the first one to congratulate you for reaching the 100,000 views in only 16 days.
Thank you for the work and the ideas that are making the Forum, the Blog and  the Arctic Sea Ice Graphs page so successful. Also thanks to DungeonMaster that surely is helping you.

Arctic sea ice / Re: Records and oddities
« on: March 05, 2013, 03:23:45 PM »
The cracks that you are showing and the forecast of the HYCOM CICE are very impressive.
I don’t believe that there will be a recovery before the start of the melting season, so this year the sea ice will be very weak and I would expect an early melt.
Do you agree?

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: March 05, 2013, 02:48:43 PM »
Results of the Poll Arctic sea ice free at March 5, 2013 2:36 PM

(Don't forget to give your vote),80.0.html
(without "https")

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: March 05, 2013, 05:45:33 AM »
I am not an expert in IPCC Arctic sea ice models, but let me know if I understood them correctly:

According to the table information, foot note 2, at 2005 we were at 375 ppm CO2-eq. So, if we assume that we increased 2 ppm CO2-eq each year, roundly we should be at 390 CO2-eq at 2012. Also, it is known that if we stop emitting GHG today, the world will continue warming. There is a time lag between the emissions and the complete effect that the GHG will have on our planet.
  • Nevertheless, on the RCP 2.6 scenario, we can jump to 450 CO2-eq approximately at 2040, but the graph of the IPCC models shows (on average) that we will not significantly go under the Arctic SIE record establish at 2012.
  • On the RCP 4.5 and on the RCP 6 we will increase to 650 and 850 ppm CO2-eq, respectively. That is, on the RCP 6 we more than double the CO2-eq that we have right now. But in both models the graph shows that we will not have (on average) an Arctic sea free of ice at 2090.
  • Finally, in the RCP 8.5 we continue to build up GHG without any control. So in this scenario, the graph shows that we will have an Arctic sea free of ice (extent less than 1 million km2) at 2060 (almost half a century from now).
On the other hand, there is the possibility that we could have an Arctic sea free of ice in only eight years, that is, before 2021, if the 80% of the poll answers are right.,80.0.html
If I am wrong about this analysis, I will be happy if you let me know. But if I am right (and the forum members that are voting are also right), I would like to know if you share the concern that institutions -like the IPCC- are failing to accomplish their mission for which they were created (like making models that are credible).

Arctic sea ice / Re: Arctic sea ice free (extent)
« on: March 05, 2013, 01:54:36 AM »
John Mann:
I read a comment over the main articles about acoustic/seismic monitoring of ice sheet cracking. Can anyone elaborate on this?

Maybe they will help you on the topic: Arctic sea ice - Records and oddities.,35.50.html

Arctic sea ice / Re: Records and oddities
« on: March 04, 2013, 10:13:46 PM »
PS - where have the first two pages of this thread gone?
I understand that there were 25  posts/page before and now there are 50 posts/page, so the posts are the same but in less pages.

Arctic sea ice / Re: Models of projected Arctic sea ice decline.
« on: March 04, 2013, 04:56:39 AM »

Jim Williams:

I agree that it is a waste of time to try to correct IPCC models and my proposal is not trying to correct them. What I am proposing is, as a group, to pursue  to include a PIOMAS volume graph -showing the historic values and the possible tendency- on the following publications:
  • Third Climate Assessment Report of the USA National Climate Assessment and Development Advisory Committee (NCADAC) (in review until April 12).
  • The IPCC Fifth Assessment Report
  • The UNEP year Book 2014
  • Any official publication that will cover the Arctic sea ice melt on the following years
On the other hand, I agree that this topic could be changed to the category AGW, group Policy and Solutions.

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