Every year the sea ice that covers the northern part of the Earth expands and contracts though the winter and the summer. The minimum extent of the sea ice is usually reached some time in September, after which it starts to reform.
Human caused greenhouse gas pollution has increased the surface temperatures of the earth, as measured on the land at about heat height with thermometers, and on the sea at the surface, mainly with satellites. Warming of the surface has continued apace for several decades, though with some expected squiggling up and down in how fast that is happening.
Greenhouse gas, mainly CO2, causes warming because of its heat trapping properties, and this warming (and the CO2 itself) set in motion a number of feedback systems that either push against warming or increase warming. Most of these feedback systems, unfortunately, are what we call "positive" feedbacks, though they are not "positive" in a good way. They are effects that increase the amount of warming beyond what would happen from just the CO2. One of the biggest global effects is an increase in the amount of water vapor carried by the atmosphere. Since water vapor is also a greenhouse gas, more CO2 -> more greenhouse effect -> more water vapor -> more greenhouse effect.
One of the bad effects of greenhouse warming is the melting of more ice in the Arctic during the summer. On average, less and less ice is left by the end of the melt season in September. Again, this amount squiggles up and down a bit, but it is a persistent downward trend. Since ice reflects sunlight away from the earth, a decrease in ice cover in the Arctic means more warming. This has both regional effects (such as an increase in melting of land-based Greenland glaciers) and a global effect. The regional effect is very important, because this has resulted in a phenomenon known as Arctic Amplification. This refers to the fact that of all the different regions of the earth, the Arctic is warming more than most other regions. The large scale systems of air movement that make up much of our climate, and thus control much of our weather, are shaped and driven in large part by the redistribution of heat form tropical areas (where the sun has a stronger warming effect) outward towards the poles. This redistribution shapes trade wind patterns and determines the location and strength of the jet streams. The relatively warmer Arctic has changed the basic shape and pattern of these major climatic features in ways that have caused significant changes in weather. The drought in California is caused in part by the persistence of a large jet stream meander caused, almost certainly, by Arctic Amplification and other changes in heat distribution in the northern latitudes. Another change is the increase in large scale precipitation events. Here in the twin cities, for example, the frequency of 3" plus rainstorm over the year has changed from about one every two years to one every year, on average. Rainfall events of between 1 and 2 inches, and between 2 and 3 inches, have also increased.
There are two major properties of Arctic ice that should be considered. One, just discussed, is extent. Extent matters because of its direct effect on albedo, the reflection of sunlight back into space. Less ice extent, caused by warming, means even more warming. The other property is ice volume. Ice volume builds up over time. Thick ice includes ice from previous years that didn't melt. The system is complex and dynamic, but a healthy Arctic ice ecosystem has a good amount of thick high-volume ice that persists through the melt season and forms the anchor against which annually re-freezing surface ice forms. The less ice volume, the less stable the Arctic Sea ice is, and the more difficult it becomes to reform. Exactly how this effect works depends on exactly which part of the Arctic one is in.
Over the last several decades, the volume of Arctic Sea ice has reduced by something like 80%. This is not good.
Andy Lee Robinson has made an amazing and highly instructive graphic showing the decline in Arctic Sea ice volume over the years. Here is the most updated version showing data up through this year, based on these data:
From Andy's YouTube page:
Published on Oct 4, 2015
This is an animated visualization of the startling decline of Arctic Sea Ice, showing the minimum volume reached every September since 1979, set on a map of New York with a 10km grid to give an idea of scale. It is clear that the trend of Arctic sea ice decline indicates that it'll be ice-free for an increasingly large part of the year, with consequences for the climate.
The rate of ice loss in the Arctic is staggering. Since 1979, the volume of Summer Arctic sea ice has declined by more than 80% and accelerating faster than scientists believed it would, or even could melt.
Based on the rate of change of volume over the last 30 years, I expect the first ice-free summer day in the Arctic Ocean (defined as having less than 1 million km² of sea ice) to happen between 2016 and 2022, and thereafter occur more regularly with the trend of ice-free duration extending into August and October.
(The music for the graphic was also composed and played by Andy.)
By the way, those interested in computer technology will note that Andy's graphic is produced on the most powerful and stable operating system, Linux, using OpenSource tools.
I produced the animation using hand-written perl and php code to create povray scripts, and scheduling task distribution using MySQL between 7 linux servers working in parallel to render 810 frames at 1920 x 1080 resolution. The "farm" renders 22 frames simultaneously taking between 1-2 hours per frame. On completion, ffmpeg combines the individual frames and music into a high quality mp4 video.
So, that's cool.
Anyway, Andy has also created the now famous Sea Ice Death Spiral graphic, showing Arctic Sea ice volume since 1979, in a particularly helpful graphic style. Notice that the sea ice volume is fairly stable for several years, then starts to decline rapidly and continues to do so thereafter.
Sea ice extent has followed a similar pattern. Let's have a look at this year in relation to the last several decades. First, this graphic made using the interactive graphing tool at the National Snow and Ice Data Center shows this year's ice in relation to the average and standard deviation since 1979. Here we see that the ice extent has been following the lowest end of the two standard deviation spread. The lowest extent shown here is the fourth lowest since records began:
To add even more perspective, the next to graphics show the first ten years in the NSIDC data set, followed by the last ten years. In both cases, the thick black line is the average for the entire data set. This comparison clearly indicates that things have changed in the Arctic:
One of the things that people who wish to deny climate science usually start whinging about at this point in the discussion is that the Antarctic has had an increase in sea ice, and that somehow this all evens out. Let me briefly explain why this is incorrect.
There has been an increase in the extent of sea ice in the Antarctic, but there are at least two (maybe three) reasons for this. First, there has been a major increase in winds in the southern hemisphere caused by climate change. This includes winds coming off the Antarctic continent. These winds break up the sea ice and blow it around, opening areas between blocks of floating ice, which then freeze quickly. This causes an increase in extent of the ice. The other is the increase in fresh water entering the sea around Antarctic because the glaciers are melting. This fresh water allows the sea to freeze at a higher temperature, causing more ice. There may be other reasons having to do with currents of both air and water, and rainfall, also caused by climate change. So, climate change causes these changes in sea ice at both poles.
The increase in maximum sea ice in the Antarctic does not increase albedo because it happens in the dark. So the decreased global albedo in the Arctic is not offset by changes in the Antarctic. All of the regional ecological changes affecting sea life and so on can not be offset between the Arctic and Antarctic, because they are on opposite ends of the planet. Also, note, that this year we did not see an increase in Antarctic sea ice. Overall it is expected that global warming will turn around the Antarctic sea ice amount, and also, we are expecting Antarctic glaciers to begin melting at a higher rate over the next decade or so. It will be interesting to see what eventually happens. In any event, keep in mind that the Arctic and Antarctic are very different geographical regions. The Arctic is a sea surrounded by continents. The Antarctic is a continent surrounded by sea. We could not possibly expect the same things to happen in these two areas. The comparison often made by climate science contrarians is absurd.
Arctic Sea Ice Extent Second Highest For The Date Since 2005
Posted on October 5, 2015 by stevengoddard
After the shortest melt season on record, and record growth of sea ice in September, Arctic sea ice extent is now the second highest in the DMI record for the date.
psd, you have to be up to something to look at the data and think what you seem to be thinking.
Also, referencing Steven Goddard in a comment on this blog is grounds for permanent life in the dungeon for your future posts. You can comment, but your comments will be monitored. No links to denialist sites. That's the rule.
Heller may have been referring to the earlier plot, which has been replaced but linked-to, with the following note:
"The plot above replaces an earlier sea ice extent plot, that was based on data with the coastal zones masked out. This coastal mask implied that the previous sea ice extent estimates were underestimated. The new plot displays absolute sea ice extent estimates. The old plot can still be viewed here for a while."
Innocent mistake, no doubt.
A back of the envelope calculation for the Arctic sea ice volume anomaly trend of -300 km³/year from PIOMAS (1979-2015) shows that the average annual net heat flux required to cause it is only 0.3 W/m².
Fortunately the denizens at Watts Up With That and similar sites have the greenhouse gas theory on the run and will slay it the moment they catch it.
If you are writing to show the inability of "stevegoddard" to be able to distinguish between weather and climate, good on you!
If on the other hand, you are implying that the serious long term trend of loss of Arctic ice illustrated in Greg Laden's blog is no longer a problem, that the problem is all over now and everything is right with the world, that everything is AOK because of "stevegoddard" 's "extra special" interpretation of weather noise, then I would like to suggest to you that there really are no French fries. And you should go elsewhere to get some.
And have a nice day.
These are powerful graphics. Shared thanks.
@ 4 Magma : These aren't back of the envelope calculatiosn they are real observations (well graphic presentations of real empiricial data.) and WUWT is NOT exactly a credible source or able to catch anything much. Except maybe undeserved publicity and possibly fossil fuel funds?
I meant that was *my* back of the envelope calculation for the energy imbalance leading to long-term Arctic ice loss.
For the second paragraph, please check the batteries in your sarcasm meter.
Hi Greg Laden, SteveP
Thanks for the cordial replies. Usually the two sides in this debate hurl mud and scream insults.
I'm deeply interested and concerned. I really do want to find the truth.
By the way, I have a bachelor's degree in Environmental Science from UEA, the leading promulgator of AGW.
So, I'm not stupid.
The debate has become 99% political and the reason for that is also interesting.
^ Okay. Fair enough.
If Anthony Watts and Bil McGibbon can have a congenial face-to-face conversation (as they recently did) then I guess anyone can .... all of us should be able to at least communicate decently online.
(Recall that the McKibben social took place shortly after Anthony tossed-off that accusatory email to Dr. Tom Peterson about Karl(2015), causing even Revkin to blush. There's bound to be a moral there.)
"I’m deeply interested and concerned. I really do want to find the truth."
I propose that you are grappling with acceptance of the consensus position because of your political ideology. Hint: Watts and Heller aren't going to help you come to terms with the overwhelming evidence.
psd, apart from the odd description of UEA as "the leading promulgator of AGW", could you explain to us why you select the website of a known incompetent climate commenter (Goddard, real name Heller) for your news?
I mean, it isn't even true what he claims:
Both 2013 and 2014 were higher.
Of course Goddard immediately jumped on this...
Not to mention that Heller/Goddard insists that it snows solid CO2 in Antarctica.
PSD: if you want to learn climate science, study climate science. There are online courses available for free from a couple of different universities. Since you've got a BS from UEA and "aren't stupid" I don't think you'd have any problem taking the courses.
D'oh! My comment #9 here was in response to #7 magma of course. Not my thread here, sigh.
(It's a confusing thread, what with Magma/Marco and SteveP/StevoR and a misinformer-cum-concern troll. I, for one, appreciate the clarification.)
psd, unfortunately, we are accustomed to the varying attacks from the spectrum you are trying to represent and sometimes it is hard to keep patience with this nonsense. For example, the McKibben-Watts meeting turns out to have been polite only on the surface, since McKibben felt ambushed when he made the effort to show goodwill under false premises.
I treasure Goddard giving me my 15 minutes of fame for suggesting my old friend now deceased, Richard Feynman, would make very short work of the misrepresentations of his structures on truth and science appropriated by unskeptical climate "skeptics". Their assumption that I could not have known him (Cambridge, Thinking Machines, MIT, about 1985, association through drawing group) allows them to mount a cackle of insults, which would be funny if you all didn't take it seriously. They also think Galileo and Einstein would side with them.
You can see why people lose patience with the ongoing reassertion of false information. If you think these comments are rude, check the comments there. The term CAGW, for example, comes entirely from the denialosphere, and "settled science" is pretty much from there as well. So is the idea that global warming and climate change were separated for effect (well, there was an effort, but it came from Republican strategist Frank Luntz), but in fact warming has to do with increased heat trapping and results in disrupted circulation and more energy in the system, climate change. We have to use words, which are imperfect.
In any case, starting the melt record at 2005 is mildly dishonest. In the climate record, you want to go back as far as you can, not truncate for effect.
the sea ice exent data are noisy.
the sea ice trend since 2006 is greater than the trend before 2006.
the sea ice trend for summer minimum, when the albedo feedback which increases global warming is greatest, is larger than the winter trend.
the sea ice trend is much larger than models predicted - http://neven1.typepad.com/.a/6a0133f03a1e37970b017d3da64b2b970c-pi
If models are underestimating melt, why are denialists so confident that the uncertainty in model sensitivity means that the temperature increase will be smaller than projected?
Either Steve Goddard doesn't know the difference between signal and (cherrypicked) noise, or he's hoping you don't know the difference - but now you do.