This post contains an error in data interpretation. The NSIDC provides the data in a continuous time series, in their well documented site they describe an upgrade in satellite at 1987 which resulted in an upward offset in the data prior to 1987. Despite hours reading the website I somehow missed this offset which makes my analysis incorrect. Sea ice totals have decreased as advertised although the trend is less than we hear. Sorry for the confusion.
Jeff Id
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I calculated a true global sea ice anomaly in this post using the National Snow Ice Data Center data. What would you say if I told you that over the last 30 years the sea ice area has stayed flat or even trended — Up!!!???
This isn’t a small deal. We have been told, well screamed at really, that CO2 is causing unprecedented rise of temperature on a global scale. We hear constantly that the ice is melting and the result will be dramatic flooding of the earth; movies have even been made. Those of us who pay attention to the scientists have heard that the most significant warming will be at the poles (according to the computer models). We also hear that the Antarctic has added ice during the same time the Arctic lost sea ice. This is explained in that the Antarctic ice increase is a local situation and the Arctic ice loss is a result of global warming. A unique form of cherry picking but should be treated with an open mind.
If you’ve been paying attention, you have heard that the net ice level is going down. The Antarctic gain cannot compensate for the Arctic loss. Well, I set out to see how bad the situation is.
First, anthropogenic global warming scientists use two measures, extent and area.
Extent looks at all the square Kilometers (Km^2) with more than 15% ice in them and adds them up.
Area looks at all the square Kilometers (Km^2) with more than 15% ice in them and adds them up but multiplies the Km^2 by the amount of ice in the square kilometer. i.e -(if you have 1 Km^2 of sea filled 15%, ice- extent counts it as 1Km^2 while area counts it as 15% of 1Km^2 or 0.15Km^2)
This post deals with the amount of sea ice so I used Area. In the future Iwill do it with extent. The NSIDC uses two algorithms for calculation of sea ice, nasateam and bootstrap. We will look at both here.
Without modification the NSIDC data for bootstrap runs from 1978-Dec. 2006 and the nasateam runs from 1978-Dec 2007, these near 30 year trends comply close enough with current science which states (conveniently) that climate requires a 30 year trend to see the result.
This is a graph of the global sea ice area from the nasateam algorithm.
The red line is the slope of the global sea ice data from nasateam in its raw format. The slope is negative by only 6803 Km^2/year and the mean is 18,290,000 km^2.
We should look at sea ice anomaly to be the most accurate for trend. To calculate sea ice anomaly I took the average shape of the annual signal and subtracted it from the curve above.
The average ice variation globally looks like this on an annual basis.
I subtracted this curve above to get the sea ice anomaly.
The downward slope of this graph is more extreme but the scale is highly magnified. The net downslope in 30 years of global warming is – 10173Km^2/year. Over 29 years of data this means that we have lost 302025 Km^2 of ice. This is a 1.65 percent drop in global ice level in 30 years. Remember though that this data ended on an extraordinary high melt year of 2007, the ice level can be seen recovering in dec 07 leading into 2008. This shows as a slight change in slope of the very tip of the first graph (a subtle, difficult to see effect).
Well NSIDC recommends using the Bootstrap algorithm for research instead of Nasateam because of certain errors which have been corrected for.
The bootstrap algorithm plot for global data looks like this.
The red line is slope again, and this time it is positive, indicating an increase in ice level from 1978-Dec 2006. The slope of the red line is plus 6341 km^2 per year indicating that the earth in 28 years has added 177,000 sq kilometers of ice with a mean ice level of 20.42 million Km^2.
The anomaly is better for calculating trends because it cleans up the end points making the slope insensitive to the start and stop point of the annual cycle.
The up trend for the anomaly in sea ice from 1978 to end 2006 is 804Km^2 per year. Which in our timeframe the preferred bootstrap algorithm says the earth ADDED 22,000 Km^2 of ice area!!
Here are the anomalies rescaled to actual by adding the mean of the original data back in.
Obviously people cannot make the claim that sea ice is being lost. It isn’t. The data shows that our trend is basically flat during this time of unprecedented temperatures. It’s clear that there has been no significant change in sea ice area.
This is almost enough to make me turn in my Skeptic union card, but increased CO2 warming the earth makes some sense to me, the magnitude is in question. The fact that polar sea ice not melting is not an insignificant point. It is also important to realize that the changes are too small to fit with IPCC statements about the trend. Unlike trees, ice does make a good thermometer. I can’t say this strongly enough— This is a strong indication of substantial errors in the computer models and temperature data which needs to be addressed before we throw what’s left of our global economy to the wind. How would Earth’s total sea ice ignore such substantial warming? It’s a good question which deserves an answer.
I will update this when new data becomes available and will also attempt to demonstrate that the net slopes we see are within the margin of error for the measurement in a future post. In the meantime, lets let the world know the truth. We aren’t going to drown any time soon!
————————
I had a request for description of the difference between the bootstrap and nasateam algorithms. It is a bit complex but it seems well documented on the NSIDC here are a few links and descriptions from that site. From FAQ section.
2. What is the difference between the NASA Team algorithm and the Bootstrap algorithm?
For general analyses or creation of simple images, either algorithm will suffice. The Bootstrap sea ice concentration data set is believed to be more useful for modeling and process studies in the polar regions because it is generally free of residual errors that could not be removed by conventional techniques. A temporally more consistent time series of sea ice concentrations is provided, offering improved accuracy over the ice concentration maps created from the original Bootstrap algorithm.
More interesting to me was the table provided which shows the strenghts and weaknesses of each process. The original table is at the link above.
For more details and complete descriptions NSIDC provides two links Bootstrap and Nasateam
HERE is a link to the R code to make the above graphs.
the Air Vent 
I posted the R code for the Global sea ice area here.
https://noconsensus.wordpress.com/2008/12/14/code-for-global-sea-ice-calcs/
This is the same code (with titles changed) used to calc hemispherical trends.
Congrats on yet another post getting picked up by Watts!
This is an irrelevant statistic.
Sea Ice in the Antarctic is one year ice. It all melts in the summer.
Winter ice is irrelevant to global warming because the sun doesn’t shine on it, so loss or gain of reflectivity has no influence on climate.
The Arctic summer sea ice is the important factor to future climate, and this decline is a positive feedback mechanism for temperature.
This blog has the effect of diverting attention from the important statistic, the Arctic summer sea ice area, which has what appears to be an accelerated downward trend.
#3
Now that’s serious cherry pickin. If the summer ice is downward trending in the arctic, other ice must be compensating for it right, or the net would be downward????
Don’t pay attention to the man behind the curtain.
#3, You posted at Watts: “The summer ice area is the thing to look at, and it is decreasing in the Arctic and more and more ice is one year ice. ”
More correctly, it “was” decreasing, and more and more ice “was” one year ice. The pesky summer of 2008 didn’t go as planned, and thus there is now more 2+ year ice this winter than last winter. When we see 2009 ice increase from 2008, then that will mean there is more 2+ year ice than in the previous couple years.
Just like the cooling trend in place at the moment that gets dismissed as a short-term aberration, I wonder how many years if increasing levels on the summer trough will have to now occur before AGW proponents will move on to the next argument and ignore the trend reversal.
And yes, despite the one data point, I do believe we’ve seen a reversal. The temps in the Arctic have declined now for a few years and it had warmed enough that it makes perfect sense that we would see a lag in the reformation of ice.
Now, you post “The Arctic summer sea ice is the important factor to future climate, and this decline is a positive feedback mechanism for temperature.”
Please provide support for both points of this statement: (1) The Arctic summer ice is the important factor to future climate [I contend that this is simply an irrefutably silly statement], and (2) this decline is a positive feedback mechanism for temperature. [There are countless examples of both positive and negative feedbacks that are simply missed, misapplied, and misunderstood by climate models. Melting ice reduces ice surface area, but also cools water. Colder water absorbs CO2 while ice doesn’t. Melting ice can increase cloud cover. I think you’re simply repeating talking points.]
Not to mention wrong. The Antarctic sea ice doesn’t all melt in the summer. Most of it melts, but there’s still 1 to 2 Mm2 left at the minimum. My preferred statistic is the annual average or a 365 day moving average. That will really tell you, IMO, the status of the ice and the overall energy balance. In the Arctic, the 365 day moving average reached a minimum in 2007 and has been increasing ever since. It’s now back to 2005 level.
Direct satellite measurements say otherwise.
http://www.nsidc.org/news/press/2007_seaiceminimum/20071001_pressrelease.html
http://www.nsidc.org/arcticseaicenews/
See animations here:
http://arctic.atmos.uiuc.edu/cryosphere/
Anyone can write some code and cook some data. When you get satellite photos, let us know.
CMB,
This is the exact same data from the exact same satellites as you showed just a longer trend taking into account the much denigrated south pole. My post is therefore in full agreement with your graphs just not the articles extremist conclusions.
“Anyone can write some code and cook some data.” — I used a friggin’ plus sign and linked to the code. I know I’m no brilliant IPCC climatologist but I think as an aeronautical engineer I am licensed for the plus sign. If you want to accuse me of cooking things, read the code first.
tamino
Your entire analysis is invalid. You should have read the documentation more closely.
There’s a discontinuity in area data in 1987 because there’s a “hole” in the observed area which is smaller for the SSM/I satellite than for SMMR, hence area data after the switch from one satellite to another are larger — not because ice area was greater, but simply because the area which is “not counted” is smaller:
Sea ice concentrations are assumed to be 100 percent around a circular sector centered over the Northern Hemisphere pole (known as the pole hole) which is never measured due to orbit inclination. The Southern Hemisphere also has a pole hole; however, it does not affect this sea ice data set; since only land is under this hole. For SMMR, the hole is 611 km in radius and is located poleward of 84.5 degrees north. For SSM/I, the hole is 310 km in radius and is located poleward of 87 degrees north.
This is better explained in the documentation given for monthly averages:
Important Note: The “extent” column includes the area near the pole not imaged by the sensor. It is assumed to be entirely ice covered with at least 15% concentration. However, the “area” column excludes the area not imaged by the sensor. This area is 1.19 million square kilometers for SMMR (from the beginning of the series through June 1987) and 0.31 million square kilometers for SSM/I (from July 1987 to present). Therefore, there is a discontinuity in the “area” data values in this file at the June/July 1987 boundary.
Hence there’s an artificial “jump” in sea ice area data of about 0.88 million km^2. Without compensating for that discontinuity, any trend analysis of the data (including this one) has no validity.
If you correct for the discontinuity in the way area is measured, it’s undeniable that global sea ice has trended down over the time span monitored by satellites.
I got the above link through Anthony Watts from of all people Tamino. Well you know he’s reading anyway.
It looks unfortunately like he’s right. It is completely my fault and I will issue a corrected post tonight. I think adding .88 million km ^2 of trend will give a slight but noticeable downtrend in the curve.
I’m not a climate scientist (or any kind of scientist) at all, so bear with me here.
If there is a non-measured hole in the data and more recent measurements have a smaller hole, shouldn’t charts/graphs remove/ignore an area equal to the largest unmeasured hole? This would help make the SMM/I data more comparable with the SMMR data. While it is assumed that this entire area is ice extent, our measurements have not showed this yet because they don’t cover it.
I posted this comment and apology on Watts up with that.
To my readers, Anthony Watts received a comment from our friend Tamino on the ice data I used for the area analysis. Unfortunately for me he is right this time. It appears that a correction to the data is required prior to 1987 which will create an approximate negative trend of 0.88 million sq kilometers per 30 years. It is a fairly small trend in the scheme of a 20million sq kilometer signal, but understand this mistake is entirely mine and is unrelated to Anthony Watts excellent blog.
Unfortunately the change makes the Area signal difficult to determine prior to 1988 because the percent fill is unknown. Anthony cannot check every detail of a post which took me days of research and he simply requested if he could copy it here.
The link to my corrections is:
https://noconsensus.wordpress.com/2008/12/16/sea-ice-decreases-despite-the-air-vent/
My apologies.
Jeff Id
And this one on tamino – my posts don’t pass moderation so I put it here
[Response: The analyst (Jeff Id) failed to notice in the documentation that there’s a discontinuity in the northern hemisphere ice area data, caused by the fact that there’s a “hole” in the observed area which is smaller for the SSM/I satellite than for SMMR. Hence area data after the switch from one satellite to another are larger — not because ice area was greater, but simply because the area which is “not counted” is smaller.
You were correct Tamino, I have posted your comment and a correction to my post. It is more in line with my original expectation. Anthony has asked me to do the same for him and was waiting for me.
The net change in ice and downslope are exaggerated in this analysis because the %fill inside the hole prior to the satellite switch is assumed to be %100.
https://noconsensus.wordpress.com/2008/12/16/sea-ice-decreases-despite-the-air-vent/
You could consider letting this one through moderation.
Your comment is awaiting moderation.
Jeff,
The missing hole area is going to make the adjustment to the data regarding the 1978 to 1987 offset that I was talking about.
I noticed in looking at the CT images that there is a difference in the size of the land features (islands and bays are most obvious) for the images before vs after (about) 2003. Is there a correction factor applied for those differences as well?
Thanks for treating my comments/questions so professionally/politely/respectfully.
You’re right. I hadn’t got back to that yet. Pretty crappy day considering that Tamino found my mistake.
I’m sitting here thinking of how to do an accurate plot. I haven’t got anything except elimination of the pre 87 data or an approximation of ice concentration based on today’s more complete data (sound’s tough)
Also, I really want to include all the years up to 2008 so I am working on that.
Jeff id:
There are actually people out here that appreciate your attempts. there is a good side to this issue. Now there is not enough data to prove that the ice is responding to AGW so therefore there is no AGW. Also there is not enough accurate temperature data that has not beeb adjusted to prove AGW. What else do they have?
Thanks Mike,
I’m kinda grumpy now, I spent the weekend looking at the curves feeling completely surprised by the flatness. I wrote the post and it got very little play until I told Anthony in the comment thread on Watts Up. My blog gets about 800 views a day which isn’t huge but is appreciated. Then Watts up sent a request to post, it seemed great. Now I’m just kind of pissed off at myself for screwing it up. A good sized mistake like that affects how everything else is interpreted so I did my best to apologize but the damage is done.
I have to be more careful in the future which means slower posts. I don’t know if it would have helped this time because I read that same paragraph at least twice and somehow skipped over the important sentence in the middle.
It’s not like the end of it for me or anything, after all tamino screws up all the time.
Just out: Over 2T tons of ice melted in arctic since ’03
http://www.physorg.com/news148641631.html
(AP) — More than 2 trillion tons of land ice in Greenland, Antarctica and Alaska have melted since 2003, according to new NASA satellite data that show the latest signs of what scientists say is global warming.
“More than half of the loss of landlocked ice in the past five years has occurred in Greenland, based on measurements of ice weight by NASA’s GRACE satellite, said NASA geophysicist Scott Luthcke. The water melting from Greenland in the past five years would fill up about 11 Chesapeake Bays, he said, and the Greenland melt seems to be accelerating.
NASA scientists planned to present their findings Thursday at the American Geophysical Union conference in San Francisco. Luthcke said Greenland figures for the summer of 2008 aren’t complete yet, but this year’s ice loss, while still significant, won’t be as severe as 2007.” […]
CMB
And nearly the same amount was added in the antarctic. Just because it’s on the backside of the earth doesn’t mean we should ignore it.
CMB – I doubt even the most skeptical among us are arguing that ice hasn’t melted in the north. North Pole temperature anomalies increased quite a bit over the last 20-30 years. But what you need to understand is that this was a regional, and not a global phenomenon. I know that somehow the AGW crowd as managed to develop some nice and elaborate theories as to why the North Pole alone portends a supposedly global phenomenon, but only time will tell on that. It’s hypothetical at this point, and in my opinion simply looks to be driven by the different Oceanic Oscillations.
Since 2003, there has been a definite trending back down of temperature in the Arctic. Now, someone not thinking this through may look at ice melt since 2003 and a cooling trend as inconsistent. It’s not. When something has warmed for 20 years, then stops warming and starts cooling, those initial cooling years are still going to be warm enough to induce more melt. So there is a lag – depending on how warm it reaches – to the start of a cooling trend to the point where ice mass will be added. It would appear that we reached the point in late 2007 where the cooling started adding to sea ice extent. Only time will tell if this will continue, but if it does, it can be expected that we will start to see an increasing ice mass in both sea extent and on land over the next few years. I have read a number of stories lately about glaciers that had been retreating that have now started advancing again. This seems consistent with the Arctic cooling trend in very recent years and the increase in Sea Ice Extent.
The old saying goes: there are lies, damn lies, and statistics. Neither side is immune from mis-representing statistics. But simply taking a comparison shot of two points in time and making any sort of extrapolation without understanding what led to that, how it’s changed, and what the long-term AND short-term trends are is the worst kind of statistical analysis.
Jeff Id Says:
December 16, 2008 at 5:07 pm
CMB
And nearly the same amount was added in the antarctic. Just because it’s on the backside of the earth doesn’t mean we should ignore it.
– I’m afraid not. Did you check?
http://www.sciencedaily.com/releases/2008/01/080123181952.htm
http://www.eurekalert.org/pub_releases/2006-03/uoca-ais022806.php
http://www.nasa.gov/home/hqnews/2006/mar/HQ_06085_arctic_ice.html
The Diatribe Guy Says:
December 17, 2008 at 3:39 pm
CMB – I doubt even the most skeptical among us are arguing that ice hasn’t melted in the north. North Pole temperature anomalies increased quite a bit over the last 20-30 years. But what you need to understand is that this was a regional, and not a global phenomenon. I know that somehow the AGW crowd as managed to develop some nice and elaborate theories as to why the North Pole alone portends a supposedly global phenomenon, but only time will tell on that. It’s hypothetical at this point, and in my opinion simply looks to be driven by the different Oceanic Oscillations.
– Time has told, see cites in above comment. Incidentally, current oscillatory activity includes a cold PDO and we are just off a cold La Nina – I’m guessing that’s not really likely to generate unusual heating.
You may also want to review the effect of axial tilt on the distribution of GW effects.
Since 2003, there has been a definite trending back down of temperature in the Arctic. Now, someone not thinking this through may look at ice melt since 2003 and a cooling trend as inconsistent. It’s not. When something has warmed for 20 years, then stops warming and starts cooling, those initial cooling years are still going to be warm enough to induce more melt. So there is a lag – depending on how warm it reaches – to the start of a cooling trend to the point where ice mass will be added. It would appear that we reached the point in late 2007 where the cooling started adding to sea ice extent. Only time will tell if this will continue, but if it does, it can be expected that we will start to see an increasing ice mass in both sea extent and on land over the next few years. I have read a number of stories lately about glaciers that had been retreating that have now started advancing again. This seems consistent with the Arctic cooling trend in very recent years and the increase in Sea Ice Extent.
– Oddly enough, your facts again seem unsupported.
http://www.mcclatchydc.com/256/story/54229.html
http://www.independent.co.uk/environment/climate-change/record-22c-temperatures-in-arctic-heatwave-394196.html
http://news.bbc.co.uk/2/hi/science/nature/7786910.stm
The old saying goes: there are lies, damn lies, and statistics. Neither side is immune from mis-representing statistics. But simply taking a comparison shot of two points in time and making any sort of extrapolation without understanding what led to that, how it’s changed, and what the long-term AND short-term trends are is the worst kind of statistical analysis.
I’m surprised to see that description. What do you have that bears out that version of events?
Science daily had this paragraph,
To infer the ice sheet’s mass, the team measured ice flowing out of Antarctica’s drainage basins over 85 percent of its coastline. They used 15 years of satellite radar data from the European Earth Remote Sensing-1 and -2, Canada’s Radarsat-1 and Japan’s Advanced Land Observing satellites to reveal the pattern of ice sheet motion toward the sea. These results were compared with estimates of snowfall accumulation in Antarctica’s interior derived from a regional atmospheric climate model spanning the past quarter century.
Comparison of outgoing flow to incoming ice from a “computer model” is not acceptable.
eurekalert is a news article regarding measurements of a very localized area
The nasa article is interesting but a bit weak from an instrument standpoint. As an aeronautical engineer, there are a number of things which could affect satellite position on these scales without seeing the data I cannot comment.
Heres a quote
The Antarctic mass loss findings were enabled by the ability of the identical twin GRACE satellites to track minute changes in Earth’s gravity field resulting from regional changes in planet mass distribution. Mass movement of ice, air, water and solid earth reflect weather patterns, climate change and even earthquakes. To track these changes, GRACE measures micron-scale variations in the 220 kilometer (137 mile) separation between the two satellites, which fly in formation.
It is also an older study. I wonder if they continued the analysis?
However, I think it is unlikely that sea ice extent would expand so much without some form of interior ice expansion. There are plenty of news and pseudoscience articles which reference the expansion as well. No time now to look them up for you. Check the link below.
https://noconsensus.wordpress.com/2008/12/14/sh-sea-ice-data-and-anomaly/
Additional info:
Arctic ice thickness ‘plummets’
http://news.bbc.co.uk/2/hi/science/nature/7692963.stm
Report says Arctic temperatures at record highs
http://www.physorg.com/news143391947.html
– And for the antarctic:
New rifts have developed on the Wilkins Ice Shelf
http://www.esa.int/esaEO/SEMXK5AWYNF_index_0.html
28 November 2008
New rifts have developed on the Wilkins Ice Shelf that could lead to the opening of the ice bridge that has been preventing the ice shelf from disintegrating and breaking away from the Antarctic Peninsula. […]
In February 2008 an area of about 400 km² broke off from the ice shelf, narrowing the ice bridge down to a 6 km strip. At the end of May 2008 an area of about 160 km² broke off, reducing the ice bridge to just 2.7 km. Between 30 May and 9 July 2008, the ice shelf experienced further disintegration and lost about 1 350 km². […]
If the ice shelf breaks away from the peninsula, it will not cause a rise in sea level since it is already floating. However, ice shelves on the Antarctic Peninsula are sandwiched by extraordinarily raising surface air temperatures and a warming ocean, making them important indicators for on-going climate change. […]
In the past 20 years, seven ice shelves along the Antarctic Peninsula have retreated or disintegrated, including the most spectacular break-up of the Larsen B Ice Shelf in 2002, which Envisat captured within days of its launch… “
Jeff, it would be great if you could write a follow-up to this post, given recent developments:
As you should know by now Nevin, I don’t have a lot of time to debunk alarmist nonsense. Do you really want to see a plot of crop growth? You can find one yourself. Do you really need to see yet another proof that models are statistically separable from observation to know the doom scenario’s aren’t realistic? I don’t — it’s boring because we already know the answers. We all know we are coming off a large el-ninio – why are you surprised this time? Was it a surprise in 98?
Just another silly liberal pining away for central control of everything imo. Unfortunately, I think you will win that most important battle despite the sky-is-falling nonsense you peddle.
Trying not be too much of a troll here, but, Jeff, did you see Arctic or Global sea ice do any of the stuff it is doing now after the super El Niño of 97/98? You do know that none of the models predicted these changes, right?
Eight years ago you wrote this:
“Obviously people cannot make the claim that sea ice is being lost. It isn’t. The data shows that our trend is basically flat during this time of unprecedented temperatures. It’s clear that there has been no significant change in sea ice area.”
Perhaps at the time it was warranted, but I wonder if you would write the same thing now, especially given recent developments on the Global sea ice front. I tried to post a graph in my previous post, but it didn’t come through (here’s a link).
You also wrote:
“I will update this when new data becomes available”
So, maybe now would be interesting to do that, as there is now 8 years of new data, and these events are largely ignored by climate skeptics.
I’m not asking you to acknowledge the sky is falling or we’re all going to drown, or some such nonsense. I’m not saying that this means that solution A or B now absolutely must be implemented. All I want to hear, is from people like you that it can no longer be said that nothing is going on, that the changes are pretty spectacular, and that it doesn’t look like things are getting back to ‘normal’ any time soon.
I can’t say much unfortunately. I have to see the data. I saw your graph and am wondering where the ice was lost from! Did the NSIDC restore their series yet? How did they knit the new satellite data with the old?
Unfortunately my company has grown too large and I’m spending this weekend writing new software to help it operate. It stinks but there really isn’t any time to play in blogland.
If the ice melted, that would be kind of fun to see why. At least something interesting is going on! Is it south pole finally moving or is the north not refreezing fast enough? Maybe later tonight I will get a few minutes. Anyway, if it has gone away I will certainly admit it has gone away with no flinch whatsoever – because the ice isn’t there.
BTW, I have always, universally, with 100% certainty and perfect sincerity have said warming IS real and ‘something’ is definitely going on. Whether any particular trend we are measuring is related, or whether added energy is dangerous are all questions that are wide open and completely unanswered anywhere other than warmanista theology.
Fair enough.
Arctic sea ice and Antarctic sea ice are currently both at record lows, and have been for a while, hence the radical Global sea ice deviation. Antarctic has been extremely volatile in recent years, going from lowest minimum on record to highest to lowest again in just a few years. Arctic sea ice is consistently low, with 2013 and 2014 rebounding after the 2012 record smasher, but then 2015 and especially last year going low again. Modelled sea ice volume is currentl also lowest on record.
You can see several Arctic sea ice extent graphs (and lots of other stuff) on this website I compiled. The NSIDC data can be found in the links section at the top of the page, but here’s the link to the ftp server (data is in north and south folders).
i think that politically we would agree on many things, more than we would disagree (I’m not your average alarmist). But I truly think AGW is risky business that could cause lots of problems, and I believe that Arctic sea ice loss is the most compelling arguments for that, given its potential consequences (accelerated permafrost melt, accelerated Greenland ice sheet melt/sea level rise, changes to atmospheric patterns/Jet Stream).