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Do we know when the Arctic will be sea ice-free?

Posted on 9 September 2012 by Verity

This is a re-post from Carbon Brief

Credit: NASA Earth Observatory

Over the past week, news that sea ice extent has fallen to a new low according to satellite measurements has prompted speculation about how long it will be before the Arctic Ocean is completely free of ice in summer.

The fate of Arctic sea ice has always captured attention. The ice grows in winter and retreats in summer. Records since 1979 show Arctic sea ice losing around 3% of its area per decade. The amount of ice at the summer minimum is shrinking faster, at around 12% per decade, and the sea ice is also becoming thinner.

This long-term decline is clear. But it's not possible to confidently predict how much ice there will be in a particular year. In 2007 Arctic sea ice coverage fell to an unusual low - unprecedented in the satellite record, and well below what was expected.

This prompted widespread coverage, a suggestion from US National Snow & Ice Data Center (NSIDC) director Mark Serreze that the sea ice had entered a " death spiral", and speculation from others that the Arctic ocean might be clear of sea ice in summer sooner than expected.

But 2008 through 2011 didn't see new records broken, although sea ice levels remained consistent with the long-term downward trend:

NSIDC Sept Arctic SI2 20111004

Subsequent studies suggest that unusual weather conditions contributed to 2007's record low, prompting  more conservative predictions for when we might sea ice-free summers.

Natural variability or a 'fundamental change' in melting?

But this year has seen another dramatic sea ice low, with Arctic sea ice extent already below 2007 levels and a couple of weeks of the melt season left:

NSIDC sea ice extent 010912

Commentators are once again questioning whether this year's fall in ice cover marks a fundamental change in the pattern of Arctic sea ice melt, or whether it's the result of natural variability.  Some scientists point out that the unusual weather conditions that contributed to 2007's record low haven't happened this year. Serreze explains:

"The previous record, set in 2007, occurred because of near perfect summer weather for melting ice. Apart from one big storm in early August, weather patterns this year were unremarkable. The ice is so thin and weak now, it doesn't matter how the winds blow."

Predictions are once again being made about when the Arctic Ocean might be ice-free in summer. There's quite a range of opinions. For example, Professor Peter Wadhams, ocean physicist at the University of Cambridge, tells the Scotsman:

"The entire ice cover is now on the point of collapse [...] It is truly the case that it will be all gone by 2015."

And Mark Drinkwater, mission scientist for the European Space Agency's CryoSat satellite tells Yale Environment 360:

"If this rate of melting [in 2012] is sustained in 2013, we are staring down the barrel and looking at a summer Arctic which is potentially free of sea ice within this decade."

Other scientists offer estimates in terms of decades. Ted Scambos, NSIDC senior research scientist, suggests that Arctic sea ice-free summers aren't likely to be reached until 2030, "plus or minus a decade."

And in 2011, NSIDC director Mark Serreze wrote:

"[W]e may [...] be looking at ice-free summers only a few decades from now."

The scientific literature on the subject

Peer reviewed research in this area has developed over the last few years. In 2007, before the dramatic melt that year, the most considered scientific opinion came from the Intergovernmental Panel on Climate Change (IPCC). The worst case scenario, it said, was ice-free summer seas by the end of the century.

But a 2009 review of newer scientific literature by a group of scientists concludes:

"The observed summer-time melting of Arctic sea-ice has far exceeded the worst-case projections from climate models of IPCC AR4 … The warming commitment associated with existing atmospheric greenhouse gas levels means it is very likely that in the coming decades the summer Arctic Ocean will become ice-free, although the precise timing of this remains uncertain."

Indeed, subsequent research confirms the climate models used for IPCC's AR4 underestimate future Arctic sea ice loss.

Projections made since 2007 suggest the Arctic ocean could be seasonally free of ice sooner. A 2007 paper concludes "decreasing ice coverage might lead to an ice-free Arctic in summer sometime within the upcoming decades", whilst a 2009 paper, which uses 2007/2008 September sea ice measurments as a starting point for six IPCC climate models predicts "a nearly sea ice free Arctic in September by the year 2037."

A more recent assessment of sea ice projections using the latest generation of IPCC climate models finds that the updated models more realistically represent the present state of the sea ice cover, and projects

"[A] seasonally ice-free Arctic sooner than [the older IPCC models], leading to the conclusion that a seasonally ice-free Arctic Ocean within the next few decades is a distinct possibility."

But the paper's authors point out that the updated models have not reduced the range in model projections of when there might be a seasonally ice-free Arctic Ocean.

So there are recent climate models that project seasonal ice-free Arctic seas within the next few decades, but they cannot yet pinpoint a precise year, or even decade. Lars-Otto Reiersen, head of the Arctic Monitoring and Assessment Programme, tells Reuters most models indicate ice-free conditions in 30 to 40 years, although "there are models that indicate 2015 as an extreme."

Overall, this Reuters headline probably offers the best summary of the state of scientific opinion:

"Arctic summer sea ice might thaw by 2015 - or linger for decades"

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Comments 51 to 83 out of 83:

  1. I don't mean to be disconcerting, but I had to make a comment about those who think we should NOT rebut the Washington Times op-ed. Whilst, in our circles, I would agree with your stand, unfortunately, Joe Blow on the Street doesn't share our discussion. He gets his information from such an op-ed and he believes it to be factual. The result is he will pull his lever in November for the Romney and set climate science back 10 years because we will have to fight other ignorant people like him in order to get something done positively. We have to be careful about who we respond to, I agree, but we also have to be careful about what our silence says to the general public. They read and listen to this stuff and it influences their decisions. When crackpots get a newspaper to print their stuff, we should be ready to demand their sources, raw data, etc. and to counter with more reliable findings. I know we shouldn't have to, but the unfortunate truth is that if we don't, the public will try to ask Santa what he thinks of the loss of Arctic Ice. We can't let it come to that. Too much is at stake.
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  2. DB: Thanks for that. *thumbs up* I have a further question (if that's ok) in regards to the disappearing ice cap. In the Arctic daylight period, more heat will be absorbed by the additional open water. Does this work conversely in the Arctic darkness period where more heat will dissipate from the additional open water? And if so, has anyone looked at the ratio of change and what that could mean? For instance, I mean something like: in the daylight period, +X heat, in the darkness period -Y heat, net result is +/-Z? vrooomie @45: I say this as honest reader feedback and mean no digs, or slights or anything as such. My intent is constructive. SkS's aim is to help Joe Citizen see through the myths of climate science. Correct? The target audience (I can only assume) is the average non-scientific citizen. Using scientific academic tactics on non-scientific citizens may cause more harm. A good chunk of this site is dedicated to the psychology of climate denial and how to deal with it in the average citizen. A good post dealt with ensuring you don't push them further into climate denial. IMO (as I recognised it in me) the attacking prose taken against some of my comments in the past, made me resent the message more. However now that I recognise that I can take a different approach (hence, not arguing, just asking to learn). But you can't rely on most Joe Citizen's to recognise it. Please take that into consideration.
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  3. Hi, just a general question regarding the melting of the Arctic ice: I'm interested in why the rate of warming in the Northern Hemisphere is faster than the rate of warming in the Southern Hemisphere. Is it due to the following factors: a. The greater proportion of land to water surface in the North. b. The fast-spinning ring of air over the Arctic which affects the jet stream that helps drive the movement of winter storms. c. The localised effect of positive feedbacks such as Arctic amplification. Are these factors correct? Are there any other factors influencing this phenomenon?
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  4. MarkUS, The sooner than expected melting of the Arctic (say,if we get an ice free summer before 2020, rather than 2070 as previous models would have it) would have the biggest impact on the rate of slow feed backs, or what Hansen calls "earth system feed backs". Rates of change are interesting and complicated things when it comes to the nonlinear behavior of dynamical systems. Specifically, many natural systems exhibit and entirely different responses and set of feedbacks based purely on rates of change. When systems get overwhelmed by rates of change too fast for one set of feedbacks to kick in, their final new equilibrium point can be affected. No reason to think this might not be the case with the rapid sea ice melt. Thus, I think your question related to this is an excellent one, and certainly given that no one is quite certain what it might mean if the ice is gone sooner than later, we also can't be certain that some other feedback processes might not kick in based on this more rapid melting that otherwise might not have existed if the melting was slower.
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  5. RH - Faster warming in the Northern hemisphere is primarily due to the ratio of land to ocean differs. Oceans are much larger thermal masses than land and hence warm more slowly. Arctic amplification is higher than Antarctic due primarily to geography: The Arctic is a body of water surrounded by land, mostly covered with a few meters of ice, subject to warmer waters moving in from further south. It's also highly subject to albedo feedback - open water absorbs much more light during the Arctic summer, which provides a positive feedback leading to more open water. The Antarctic, on the other hand, is a land mass surrounded by water, coverd in ice averaging 1.6 km thick, with a roughly circular weather pattern around it that to some extent isolates the Antarctic from warmer northern air. While the Antarctic is warming, and contributing to sea level rise as a result (as per the GRACE data and surface observations), it's a huge thermal mass - and will take longer to warm than the Arctic. --- I'm of the opinion that the much faster than expected warming of the Arctic is (in part) due to poor modeling of sea transport of thinned ice - the thinner ice is far more prone to be simply washed out of the Arctic to warmer waters at lower latitudes. It's my understanding that few of the models accurately represent this change in behavior, and hence predictions from just a few years ago are startlingly incorrect about the current rate of mass loss.
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  6. Dale@52, More open water in the fall months means of course that more heat can leave the ocean, however, there is one more factor to consider in this. Some studies are showing an increase in lower clouds in the Arctic that naturally form when more water vapor is leaving all that ocean water. These lower clouds of course have the effect of increasing DWLWR (downwelling longwave radiation), and thus, it acts as to keep temperatures higher than they might have been with clear skies. Thus, it gets a bit more complicated than just thinking that all that heat is going right out into space as some might think. Overall, what we can probably expect to happen once we get our first ice-free summer in the Arctic, is that sea ice will continue to form during the ensuing winter, but it will of course all be thin first year ice that will quickly melt the next summer and it will melt earlier and earlier in the summer as well. Eventually, the maximum winter extent of even that first year ice will slowly recede until the time might come that some very small amount of first year ice forms (maybe less than 5 million sq. km.) and it will be confined to the Arctic basin and along the north shore of Greenland and the Canadian Archipelago. Within most of our lifetimes, the Arctic will be quite open to navigation 12 months a year.
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  7. Thanks R Gates. I figured the water cycle would kick in at some point. Though don't low level clouds reflect more sunlight? Do you mean high level clouds? (In the dark period this is basically irrelevant I suppose). End of you day you're right, it's a lot more complicated than I probably made out (though didn't intend). The biggest concern I think is what's been trapped under the ice for so long, will now be able to sneak out.
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  8. Dale a very simple model is that open Arctic ocean will very quickly form ice on its surface due to the lack of Sunlight in your northern winter. This insulates the greater part of the oceans water from heat loss to the atmosphere or radiation into space. There will be a gradual accumulation of heat in the Arctic oceans that is due to the radiation imbalance caused by increased CO2 in the atmosphere in the summer months. The simple proof is both the loss of volume and extent of arctic ice. Just like your drink cooler if there was not a slow accumulation of heat the ice would never melt! Water has this unique property where it has a maximum density at 4C. This means even ice formed in salt water will float on the water that produced it. RG the very large circumpolar current around Antarctica is warming. If this gets to the stage the water in the Arctic seas are at now we will be in a lot of trouble. Bert
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  9. RH, I forgot to say that sea ice forms at about -2C because of the salt content of the water. The majority of the salt actually gets excluded from the ice that does form. The thickness of ice formed is largely dependent on the differential temperature of air and water below. It is very disingenuous to say that the ice is making a recovery when it is thinner and less stable than before. By the way if it was not for this property of water to be densest at 4C all the lakes in cold climates would freeze to the bottom so killing all aquatic life in them. Bert.
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  10. 31, Dale,
    What climate impact will a summer ice-free Arctic bring to the World?
    You've gotten several answers to this, and SkS really should do a post focused on it, but (from me): First, recognize that this problem does not extend only to the sea ice. The surrounding land is also losing snow cover earlier and gaining it later. So, first and foremost, the albedo of that part of the planet -- which is in 24/7 sunlight for much of the year -- is changing. That means it is absorbing more sunlight and getting hotter. That's a positive feedback that makes it (and Earth) even warmer. Second, both the permafrost (on land) and sea (in the seabed) contain vast stores of methane, a powerful GHG that stays in the atmosphere as CH4 before "degrading" itself to CO2 (and then staying in the atmosphere in that form). That's a second positive feedback. Third, the dynamics of heat and water vapor transfer are completely changing. Once, wind and waves had no effect because the Arctic Ocean was for the most part a sheet of thick ice year round. Now low pressure areas can create cyclones that can whip the water around. That water can evaporate to form clouds. The system is changing. It is hard to predict what this will mean. It's complex. More clouds in winter that hold in the warmth? More clouds in spring or summer that help keep the albedo high? Is it even harder to form ice, because the melted ice gets mixed more thoroughly by the now active wind and waves? Do ocean currents change? Scientists have already figured out that the course of outflow of Siberian rivers has changed, dumping more freshwater into the Beaufort Sea where it used to go elsewhere. And how will these changes in weather patterns affect more civilized areas? There are strong theories that blocking patterns will become more common. This will mean that heat waves and cold snaps and droughts and the like, when they do hit, will last longer and perhaps be more severe. One of the problems with a drought, for example, is that normally, the ground cools through evaporation. But in a serious drought, all of the water has evaporated. This becomes a powerful positive feedback -- with no water to evaporate and cool the ground, the ground gets hotter, making it harder to accumulate moisture with which to cool the surface. So if blocking patterns make heat waves last longer, the chance of drought grows markedly. And who knows how ocean currents may change as a result of all of this? The earth hasn't seen a truly ice free Arctic in a very, very long time. So you can see there are very, very serious implications to the Arctic melt that we're seeing now (and what we're seeing now isn't by any means the worst -- this may be the "oh, sh*t" moment when we realize we're on course to go over a cliff, but that will be nothing compared to when we are actually on the precipice, or actually plummeting down). Bottom line: 1) Positive feedbacks that make temperatures worse, in the Arctic and globally 2) Side effects on weather patterns that have unpredictable consequences for every day life. Someone is going to go hungry, someone is going to have to move, and some things are going to have to change. I predict that within 50 years the USA may well have at least 1 if not 3 "ghost cities" -- major population centers that must be abandoned due to a combination of intractable water shortages, excessive weather dangers and difficulties generating enough food. Exactly where and when is the question.
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  11. Dale@57 If you compare the two scenarios of say a square mile with ice and a square mile without. The scenario with ice gets the energy away from the planet more efficiently than if the sea is warmed and has to radiate IR into the atmosphere. So basically, even if energy is emitted from the oceans, it is less efficient than reflecting it, which means warner conditions than if you had ice.
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  12. Unless you are a scholar and a well known scientist, no one may seriously listen to what you say, write or research. I am not a scientist but an electronic engineer with long years of interest in geology and history. This perhaps prepared me to look into multi-disciplinary branches of science, geology, history and planetary system simultaneously and address the cause behind 1) more than 10% drop in the magnetic field, 2) doubling of the number of quakes above 6 Richter in the past 5 years, 3) thermosphere increased influence on the temperature belts, 4) the planetary warming on Earth and on Mars, 5) the slowdown of the spinning speed of Venus and Saturn. Upon pulling all lines into cause and effect chain I was able to estimate the like of “Earth Changes” including the melting of the Arctic ice cap, the slowdown of Earth spin speed, the complete “Climate Exchange”; where some regions will get warmer while others will turn colder to name a few. The history records that are kept in ancient text, petroglyph and the history citation within the holy books helped to establish a timeline for the cycle of Earth Changes of 3562 years. (-Snip-) I bet that you must have guessed it already that the answer to the complete ice cap melting is 2017! I wish scholars and scientists such as Ian Allison, Nathan Bindoff, Robert Bindschadler, Peter Cox, Nathalie de Noblet-Ducoudré, Matthew England, Jane Francis, Hans Joachim Schellnhuber and many others who authored the 2009 Copenhagen Diagnosis report to come to read what I summarized on the above mentioned website but more important is to debate and raise all questions and I am glad to respond as much. I hope many of them do visit skeptical science, as I failed miserably to reach scientists through the normal email channel ! I believe in what Einstein had once said, that imagination is more important than knowledge. I add that humility brings us wings to help to rise.
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    Moderator Response: [DB] Link-snipped. Please return to your earlier comment and answer the questions put to you there.
  13. @ Dale: Luckily SkS (via Neven) answered your question here concerning the effects of an ice free Arctic.
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  14. Thank you all.
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  15. In case anyone missed it, Astrofos is trying to poe Lewendansky's survey subject.
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  16. "Unless you are a scholar and a well known scientist, no one may seriously listen to what you say, write or research. I am not a scientist but an electronic engineer with long years of interest in geology and history." Umm...did anyone *else* get hit by the low-flying Irony Horse? Astrofos, I would indeed ask you, AGAIN, to justify your earlier comments, pointed out by Daniel Bailey, plus now please explain why anything you say should be taken as authoritative from this point on. FYI: I have a bit more than an "interest" in geology: i have a degree and 14 years of experience in the field.
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  17. There often seems to be a basic disconnect occuring in discussions of future ice conditions in the Arctic. One perspective focuses on the area metrics - Sea Ice Extent/Sea Ice Area - and whether looking at the trends in the data or model projections seas a Summer Ice Free Arctic in a couple of decades. Because that is what the trends are saying. The other perspective focuses on the volume of ice in the Arctic,and what the trends say about that. And this data is throwing up figures for a Summer Ice Free Arctic in a handful of years. So how to reconcile these two perspectives? Arctic Sea Ice is relatively thin and very flat. So melt & accumulation occurs mainly on the top and bottom surfaces. Yet the areal metrics are basically measuring the sideways dimensions of the ice. And Models/Projections into the future may be looking at how these 'sideways' dimensions change. Imagine a hypothetical 'ice floe'. It is 1 meter thick and 10 metres by 10 metres. Over the course of the melt season, lets assume that it loses 0.5 meters in each dimension. It is now 9.5 * 9.5 metres in area and 0.5 metres thick. So its area has dropped by around 10% while its volume has dropped by 55% Now imagine a more severe melt season. Loss over each dimension is now 1.1 meters. So Area has now dropped by 21%. But it's thickness is now -0.1 metres. It has melted away. So in reality, its area is now zero. This is the problem with using area metrics as a basis of future projections. They only hold valid while the volume projections remain above zero. Once volume starts to approach zero, area will start to crash to zero as well, and all projections of area/extent suddenly become invalid. Without some process to reverse the decline in volume, and quickly, within a handfull of years, area/extent will crash.
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  18. To put Glenn's statement more concisely... Pretty soon the amount of ice by any measure really is going to be zero, so the question will be moot. "No ice" will mean no ice. Of course, then "skeptics" will say that "well, water is just warm ice, so really there's still lots and lots of ice in the Arctic. In fact, all of the world's ocean's are ice, which means we're going through a period of catastrophic global cooling! Global warming is a hoax!"
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  19. I spent some time looking at the Arctic currents yesterday, such as here: I'd love to know more about the models that point to the Arctic being a two state system (all ice, or no ice, year round). I'm wondering if one of the problems is that without the icepack, the warm water flowing in from the Barents Sea won't easily dive beneath the fresher water flowing in from the Siberian rivers? Or is salinity the key factor, and that won't change?. But scientists have already detected a change in those (freshwater) currents, so maybe this will happen... freshwater will flow counterclockwise around the coast, while warm, Barents sea water will flow through the pole to Greenland. We may be seeing some of this effect right now... look at what is still melting in the Cyrosphere Today maps. If so, with the ice gone, it could mean more warm water flowing through the pole to the coast of Greenland, and that alone could potentially keep ice form forming, even in the cold dark of winter. But if the two-state theory is correct, this whole "when is it zero" argument may well be a very, very short discussion.
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  20. As possible evidence of my theory, consider the following overlay of the currents onto today's Cryosphere Today image. I have circled the area that is still rapidly melting in orange. You can see the ice concentrations as magenta, red, yellow and green (magment and red are the most concentrated, then yellow, then green). This is Nasa's image for how the freshwater flow has changed:
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  21. Note that at Neven's blog (for instance this comment here) people have named that hole in the ice the Laptev Bite, and the prevailing theory there is that the warm current from the Barents Sea that is forced downward is hitting the underwater Lomonosov Ridge, deflecting upwards, and causing the hole. I would not be surprised if this September, and certainly next August and September, we don't start to see the icepack being split down the middle as the current follows that underwater ridge, dividing the ice pack in two before melting it completely away.
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  22. I'm curious, what's the average thickness of the ice cap? I heard it was around 6' but I believe it's thinner.
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  23. villabolo: Neven's sea ice blog is an obvious place to look for information, but you can also go over to Tamino's blog, where he recently did a post that looked at sea ice volume/area (which basically is thickness). His third graph is the one to look at - it shows that back around 1980, the thickness ranged from 2m (summer) to 3m (winter max), whereas now it is more like 1m summer and 2m winter. [6'=1.8m for the conversion-impaired]
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  24. villabolo, by my calculations, average thickness was 1.43 meters on day 246 (Sept. 2). Thickness declines during freezeup, and min thickness usually occurs right around mid-November, but this has been changing quite a bit. It occurred on the 29th of October last year.
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  25. DSL: Yes, that makes sense. It's not a summer minimum thickness, but a minimum when you're adding lots of thin ice in the early fall/winter. The idea of an "average thickness" is complicated by the large areas that transition from ice to no-ice. Calculating an average for the entire Arctic ocean (including ice-free areas where thickness=0 would decrease the average) would give a different number from calculating average ice thickness only for those areas covered in ice (which is what Tamino's volume/area number represents). Tamino's graph also has it at around 1.4m now. Sort of like the difference between calculating average income for everyone (GDP/population), or average income only for people that actually have an income (GDP/number of working people).
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  26. I'm trying to make a list of positive feedback loops that would affect the Arctic melt. I'll list some of the obvious ones but there are some, in this list (in bold), that I've never heard mentioned before. Please tell me if there are more of if some of the ones I’ve mentioned are too insignificant: 1) Change in ocean albedo as well as land albedo 2) Ponding. 3) Rotten ice. 4) Siberian Permafrost. a) Increased surface area and depth of permafrost melt b) Increased metabolism of Methanogens throughout the melted permafrost. Microorganisms have a highly reduced metabolism in temperatures slightly above freezing which dramatically increases with small changes in their environment. I’ve brought this up before but I haven’t received an answer. c) Another amplification of both temperature and methanogen metabolism would be the albedo effect of the numerous and (ever increasing) number of lakes. 5) Increased melt of fresh water from Greenland. 6) Rain (occasional) at the fringes of Siberia and Canada + runoff into the ocean + enhanced glacier melt from the rain. Are there models that take all of these factors into account?
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  27. A short aside before I go pick up the kids: Interestingly, and for what it's worth, the 10-yr linear trend on average thickness projected to zero intercept lands on 2021 for Aug 23rd. That date has the highest rate of decline when using a 10-year trend. When using a 30 yr trend, zero intercept is 2020 for the same date.
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  28. @villabolo (76) You forgot Release of arctic fossil carbon stores (by us)
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  29. @Mark-US (#78) We both forgot ~1F down the pipeline although that's technically not a feedback.
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  30. Sure its a feedback. Global warming is allowing an animal species to expand its range and to do things in that new range which will in turn produce more global warming. Even though we are human animals, we're still animals. Take the made-up example of caribou altering ground cover in such a way that it accelerates albedo loss.... we'd have no problem calling that made up example a "feedback", right?
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  31. Mark-US@80: "Take the made-up example of caribou altering ground cover in such a way that it accelerates albedo loss" FWIW this seems to be the opposite in reality, according to this study. Based on their measurements, the grazed area had a higher albedo than non-grazed. I would hazard a guess, that while this was done in Finland and Norway, and with reindeers, the same result is applicable to caribou too. In regards to your actual point, about what constitutes a feedback, it becomes a bit fuzzy in your example. While the increased CH4-release is very mechanistic in its nature and can be directly linked to the temperature rise*, the caribou-example has a lot of other variables involved. For example, they may move to cooler areas in order to avoid mosquitoes, which will also increase as the temp goes up. This means that the caribou-feedback becomes complicated and depends a lot on external circumstances. * Except that this may not quite be the case, Blok et al. 2010 argues that increased vegetation on top of the permafrost isolates it more efficiently from the heat.
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  32. People at The Cryosphere Today probably need to change the y-axis lower bound. And note that red line showing up in the upper-right corner here. Time for a change, a change for the worse.
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  33. an interesting visualisation of PIOMAS arctic sea ice volume data
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