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Websites for Watching the Arctic Sea Ice Melt

Posted on 8 June 2011 by michael sweet

The Arctic Sea Ice collapse is one of the most obvious changes caused by Global Warming.  Last winter's minimum was the third-lowest ever recorded.  The rapid melt of the sea ice has led to scientific predictions of an ice-free Arctic Ocean in summer as early as 2013 (though most mainstream predictions range from 2030 to 2050). Every northern hemisphere summer, some bloggers watch the ice melt and try to guess what will happen.  Others claim it is like watching paint dry.  I think the situation is similar to watching a season of sport.  The individual games are interesting to watch, and difficult to predict, but the final season record is what really matters.  This article will give some web sites to check if you want to be informed about what is happening this season, but do not want to follow the day to day action.  I posted a similar thread with links to more websites last year on Skeptical Science.

My favorite place to find out what is really happening in the Arctic is the National Snow and Ice Data Center (NSIDC) web site.  This site has a sea ice extent graph that is updated daily.

 

It compares the ice to 2007 (the record low year) and also to the average from 1979 through 2000.  The sea ice extent is defined as the area of ocean that is covered by at least 15% sea ice.  In addition they have a very nice FAQ section that answers many sea ice questions.  This FAQ section is a good place to find out the basics in one place that you can trust.  NSIDC has a monthly commentary on the sea ice conditions.  It is usually issued around the fifth of the month.  This commentary discusses current sea ice conditions, relevant weather and whatever else the scientists at NSIDC think fits the situation.  If you read only the NSIDC summary every month you will be well informed about the sea ice this summer.  NSIDC also issues reports when something special happens, like if a new record low is set.  These comments happen less often.  Hopefully they will expand their commentary this summer.

Cryosphere Today is a good site to look at data.  They offer no commentary on the data.  They have a daily graph of the sea ice (from the University of Bremen) to follow the daily action. 

 They have a graph of the sea ice area from the past two years that gives you an idea of what has been happening for the entire melt season. 

The sea ice area is defined as the total area of the ocean covered by ice.  They take the sea ice extent and subtract the open ocean portions.  There is a little more error in the sea ice area than the sea ice extent; that is why NSIDC and IJIS use the sea ice extent.  In general, it is best to compare one site's graphs with their own graphs.  Cryosphere Today has about 10 local area maps that are interesting. 

They also have a comparison app that allows you to compare any two days of ice in the satellite record. 

test

Notice above how much more ice there was in 1980.  The snow data is only present for the past few years.

Cryosphere Today also has data from the Antarctic.

IJIS has a good site to check on the sea ice extent on a daily basis.  Their graph is similar to the NSIDC graph, but they include all the years from 2002 to the present (they do not show the long term average).  You can quickly compare the current extent to previous years.  

AMSR-E Sea Ice Extent

Lately 2011 has been running near the record low.

If you check these sites occasionally and read Skeptical Science posts on sea ice during the summer, you will be able to keep up with what is going on.  If you are interested in learning more about sea ice, Nevin’s Arctic Sea Ice Blog is a good place to read.  Amateurs test their predictive powers against the ice.  Nevin has a very complete daily graphs page which includes much more data than I have described here.  If you want to watch the daily struggle of the ice against warming, this is the place to go.  Nevin has links to all of the arctic web sites that I visit.  Please attach links in the comments to other interesting sites. 

If you want to keep up with the "skeptics", WUWT and Steve Goddard have a lot of commentaries on sea ice.   Somehow they can look are a new record low and tell you the ice is recovering.

Any discussion of skeptics and sea ice would be incomplete without this graph from Denial Depot:

DD

This graph is a little dated, but great skeptic data can be reused forever.

Have a good time following the Arctic Ice this summer.


Addendum

Regular Skeptical Science contributor Sphaerica has kindly made available the following graphics, which add clarity to the discussion:

NHSeaIce

Note that the areas of increased melt indicated by the yellow boxes are all at lower latitudes around the edges (warmer temps, warmer water).

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Comments 101 to 150 out of 208:

  1. Eric the Red wrote : "My comments were to counter michael's claims that if we stopped emitting CO2 today that temperatures would continue to rise dramatically, resulting in several meters of sea level rise." Are you referring to michael sweet's comment at 91 ? If so, I can see no use of any form of the word 'drama' and he links to a paper by Hansen et al which predicts a sea-level rise of up to 5m. What would you call 5m, if not 'several' ? Can you specify where your use of the word 'dramatically' comes from (or withdraw it, if you can't), and show how your argument against Hansen et al is backed by peer-reviewed research.
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  2. #92, moderator, if went to zero tomorrow CO2 would immediately exponentially decay to half way back to 280 in less than 48 years. There is simply no other possibility considering how much we have put in the atmosphere and how much remains. I posted a simple spreadsheet showing this here: https://www.iwork.com/document/en/?a=p1415598010&d=CO2growth.numbers
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    Moderator Response: [Dikran Marsupial] You would indeed get a fairly swift reduction half way back to the pre-industrial level (although 48 years would be an optimistic estimate IIRC), however the decay would not be a simple exponential and the reduction to a quater of the way to the pre-industrial equilibrium would take very much longer.
  3. JMurphy, I find no one in the Hansen report were he says that the amount of CO2 added to the atmosphere today is enough to raise sea levels 5m.
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  4. Eric, is the trend in sea ice volume or in minimum sea ice extent linear or nonlinear? And please do not insult everyone's intelligence by suggesting that the trends are based on 'one or two points'! These things can and indeed have been assessed properly, and we do not need to rely on your 'anticipation' to evaluate the shape of the current trend.
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  5. Eric, What about my questions about reversibility here?? You have chosen one of my comments and ignored the rest. You claimed that nothing is irreversible. What will reverse the flooding, drought, fires and ocean acidification that already exist? Your claim that all is reversible is not supported by showing that it is not yet known how much sea level will rise in the next few decades. It may just as well be true that sea level will rise more than 2 meters by 2100 as that it will be less than 1 meter, uncertainty cuts both ways. Your choice of only the most optimistic models is unlikely to hold up.
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  6. EricR @96, "The IPCC predicted that it would take a 5.5C temperature rise to melt Greenland, and it would take several centuries. Recent studies show that the melt rate is significantly less." That statement is demonstrably wrong. Your biased interpretation of the papers (which you don't seem to really understand) have been addressed by Michael and Skywatcher, and you did not recognize your error, ignored their insights and just tried to re-frame your argument and shift the goal posts @100. Doing so is incredibly ungrateful, people are trying to help you understand this better, but you appear to have too many mental hurdles/blocks (and no I am not saying you are dim or anything like that) in the way I doubt you even followed the link to Tamino's statistical analysis of Arctic sea-ice volume. Monthly Arctic sea-ice volume anomalies: September Arctic sea-ice volume anomalies with quadratic fit: Source]
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  7. Eric the Red wrote : "I find no one in the Hansen report were he says that the amount of CO2 added to the atmosphere today is enough to raise sea levels 5m." Why were you looking for such a scenario in that report ?
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  8. michael sweet @105, given sufficient low entropy energy, in principle everything is reversible (except perhaps plate tectonics). We could even resurrect the dinosaurs in principle, although it would probably take fifty years research to develop the correct techniques. We would certainly be able to resurrect all of the many species expected to go extinct over the next century - if we where prepared to devote enough resources to it. Should we desire, we could even spray sulfates in the upper troposphere above greenland, and "crop dust" the surface with fresh water to recreate the ice sheet and glaciers. What we can't do is reverse anything except the smallest changes cheaply. We can't reverse anything significant except at a far greater cost than the cost of preserving it in the first place. And what is more, given the likely impacts of BAU, in fifty years we won't have the spare resources to even think about reversing anything. Contrary to Eric's claim that he was responding to you when he made his comment about reversibility, it was actually a response to my claim that effective action had a used by date of 2020 @86 (see his 87). As such, it was an empty rhetorical sally to divert attention from my point and should be allowed to die a quiet death.
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  9. Eric (Skeptic) @102, David Archer has studied this issue extensively. He shows that if we release 2000 Gigtonnes of CO2 into the atmosphere, then in a thousand years, atmospheric concentrations will still be elevated by 29% of that value, and by 14% after 10,000 years. He also shows an interesting graph correlating global temperatures with sea levels from geological records: (As adapted here)
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  10. JMurphy, I was looking for it in the Hansen report because michael stated that the report made such a claim, which resulted in the subsequent posts. michael, If you claim that all these effects are the result of rising temperature (resulting from a CO2 increase), then a reduction in temperature (CO2) will reverse all the effects. Which of these effects will not be reduced? We cannot undo a flood that already happened, but future flooding would be reduced. sky, The trend in maximum sea ice extent shows considerable linearity. The trend in minimum sea ice show more linearity than not, but may be skewed by the high value in 1996 and low value in 2007. It is entirely possible that it could be non-linear, or a shift in the linear trend starting in 1996. There are other possibility that exist with such a small dataset. Some people here seem to prefer the volume calculations over the area measurements. I have a differences of opinion on the topic which I will not pursue. Tom, Yes, it was an initial response to your post, which has been blown out of proportion, and should be put to rest.
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  11. Eric the Red wrote : "I was looking for it in the Hansen report because michael stated that the report made such a claim, which resulted in the subsequent posts." Where did michael make the claim that "the Hansen report...says that the amount of CO2 added to the atmosphere today is enough to raise sea levels 5m" ?
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  12. Post #91, and your post #101.
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    Response:

    [DB] Point to Eric.  But while we're playing silly schoolboy games. let the record show that it was you who misquoted Michael Sweet & introduced the "drama" into the discussion.  And it was also you that introduced the red herring about the Hansen report @ CO2 levels, not Michael.

    Prithee, let us all return to the subject of the OP with civility and flank speed.

  13. 112, Eric et al, If I may, Michael probably merely misremembered which Hansen paper to reference. Hansen and Sato 2011 (which in turn is referenced by the paper to which Michael linked) contains the following (which is only part... it really should be read in its entirety, not in snippets):
    Alley (2010) reviewed projections of sea level rise by 2100, showing several clustered around 1 m and one outlier at 5 m, all of which he approximated as linear. The 5 m estimate is what Hansen (2007) suggested was possible, given the assumption of a typical IPCC's BAU climate forcing scenario. Alley's graph is comforting, making the suggestion of a possible 5 m sea level rise seem to be an improbable outlier, because, in addition to disagreeing with all other projections, a half-meter sea level rise in the next 10 years is preposterous. However, the fundamental issue is linearity versus non-linearity. Hansen (2005, 2007) argues that amplifying feedbacks make ice sheet disintegration necessarily highly non-linear. In a non-linear problem, the most relevant number for projecting sea level rise is the doubling time for the rate of mass loss. Hansen (2007) suggested that a 10-year doubling time was plausible,pointing out that such a doubling time from a base of 1 mm per year ice sheet contribution to sea level in the decade 2005-2015 would lead to a cumulative 5 m sea level rise by 2095.
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  14. Eric, You are presuming that your personal (amateur) estimate of decline of CO2 is what will happen. Leaving aside the fact that you estimate is not reviewed at all (and you have provided no peer reviewed link that supports your extraordinary claim), there is no possibility that CO2 will stop tomorrow. If the decision to reduce CO2 as much as possible was made today, it would take decades to replace current carbon sources. Can you do your calculation over with a more realistic estimation of 2050 before carbon release is zero? Calculate temperatures with resonable feedbacks for the loss of the Arctic sea ice, which you agree will be gone by 2050. If it is 200 years before temperature returns to current temperature, that is forever for me and my children. You also completely ignore natural sources of carbon. It is clear that in the next two decades much carbon will begin to be released from thawing permafrost and sea floor methane clathrates. Does your naieve estimation include release of carbon from these sources? It is at least as likely that natural carbon sources will become larger than current sinks as it is for the sinks to absorb carbon at the rates you estimate. Where do you think the carbon came from in the PETM? You pick only the most optimistic projections to consider, and then you insist they are the only possible option. We all hope that the optimistic projections are correct, but prudence suggests we should plan for some downside. Since the 2007 IPCC report the changes in nature have exceeded many of the IPCC projections (for example: sea ice loss, ice loss from Greenland and WAIS). You insist that the most optimistic projections of ice melt are now correct. Why do you expect these changes to suddenly drop from above the maximium to the minimum of the projections? The Earth has been permanently altered by mankind. If we take strong action immediatley we hope to keep the change to a minimum so that life can continue with little disruption. You advocate taking no action until the problem is much worse and argue that if action is taken at some uncertain future time the damage will be easily reversed. The longer we delay before action is taken the more likely the changes will spin out of our control. Waiting to reduce carbon emissions seems to me to be a receipt for disaster.
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  15. michael, I answered you here: /argument.php?p=2&t=94&&a=80#55874
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  16. Michael, If you remember, this all started when you stated that if CO2 were stopped today, that temperatures would continue to rise for several decades, and sea level would increase several meters. I agree that CO2 emissions will not end today, tomorrow, or this decade. I made no estimate of the decline of atmospheric CO2 after that point, but merely stated that would - others have provided links to various decline rates. With regards to the sea ice trends, using the volume graph provided by Albatross in 106 and corresponding reference, the accelerating decline would reach zero by about 2015. The trend based on the sea ice area, even using the steeper decline since 1996, would take 30 years. Unless an infintely thin 5 million square km sheet of ice forms in the intervening decades, one of those proejections will have to be wrong. (mathematically a large area with zero height will result in zero volume, but physically, it is impossible). I have never advocated taking no action. I do not know were you get these ideas. I simply stated that if we waited, action will be harder, and that effects thus far (not sometime in the future) are reversible (I also never said easily). While I will admit to presenting what amounts to optimistic forecasts, oftentimes, they are a counter to those who are using the more pessimistic. For most forecasts, there is a wide range of possibilities, due to large uncertainties, which have not been resolved yet.
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  17. Eric, I find it difficult to respond to your posts. In one you appear to say all effects are reversible, we should wait and see what happens before we do anything, and in another you claim to be concerned about change in climate. I think regular readers will understand your position through your various claims. While you have made an argument that you believe that the sea ice will recover if CO2 is controlled, you have not addressed many other issues like ocean acidification (since that is where you claim all the CO2 will go) and flooding. See my post 105 which you ignored. While it is of course possible that only the most optomistic possibilities wil be realized, so far changes are proceeding faster than the IPCC has predicted. There is at least an equal chance that the worst projections will be realized. Prudence requires that we take action to prevent the chance of the worst. As has been repeatedly pointed out, if we implement sustainable energy and it turns out we didn't need to, we can always burn the coal when it is clear it is safe. The economidc and health beneifts of shifting to sustainable energy are desirable in their own right. If we do not take action and we should have, it will be impossible to unwind the problems.
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  18. michael, When did I ever say that we should wait and see what happens before we do anything? Also, when did I claim that all the CO2 will go into the oceans? If you want me to respond, do not invent statements and attribute them to me. Sea ice, precipitation, glaciers are all based on temperature, and therefore, should recover if temperature increases are reversed. You have not presented any reason to dispute this. I have not addressed ocean acidification because I believe that it is a non-issue. What changes are proceeding faster than predicted, certaintly not temperature increases, which have not risen as predicted.
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    Response:

    [DB] "certaintly not temperature increases, which have not risen as predicted."

    Simply incorrect, but thoroughly off-topic here.  Much of the remainder of your comment is either incorrect (ocean acidification a non-issue, also off-topic here) or simply unsupported assertions and thus, hand-waving.

    As constituted, most of your comment could be described as trolling.  As I'm certain that is not your intent, you may wish to take greater care when formulating your comments.

  19. Eric, your assertion is blithely simplistic. Glaciers, for example depend not only on temperature/precipitation, but on the elevation of the ice surface, which is obviously dependent on the thickness of the glacier. Melt a bit of a glacier, whether it is a small valley glacier or a large ice sheet, and it is harder to grow it back to it's previous state, because the surface elevation where the snow falls is lower. 'Reversible', the melt may be, but not simply by returning temperatures to 'normal', whatever that is. I can't honestly believe you asked "What changes are proceeding faster than predicted?" on a thread about Arctic sea ice. Seriously!
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  20. Eric the Red, Could I ask you to quantify, with a time frame, temperatures, ice extent, and any other variables that you feel relevant, the scenario that would make you 100% confident that climate change is not happening, and that we are safe, and this is all just a natural blip in the climate system? Could I also ask you to bound, in the same way, the hypothetical situation which would force you to abandon your skepticism, and to agree that we have a serious problem... to the extent that you would begin arguing the other side, and telling people that you know that something needs to be done about it?
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  21. Arctic sea ice decline, Greenland ice loss, Antarctic ice loss, sea level rise, and ocean acidification are all progressing faster than most past projections showed. I'd include other less directly measurable factors such as 'extreme weather events' and 'species impacts' as also proceeding faster than most predicted, but as these can't be shown on a simple graph they aren't as clear cut.
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  22. sky, While I agree that the assertions are over-simplistic, the question was what changes would not be reversible if temperatures decreased? Alpine glaciers, sea ice, etc. has advanced and receded many times during the past millenia as temperatures have increased and decreased. The issue is what changes that have happened to date (not sometime in the future) are not reversible. Sphaerica, That is a tough question to quantify, but I will try. Since some predictions of solar minimum and cold PDO claim that temperatures will decrease until 2030, I will use that timeframe. If temperatures and Arctic sea ice revert to 1980 levels by then, then I would be fairly confident that the changes are all natural. Conversely, if temperature rise significantly prior to then, and is accompanied by acceleration in sea ice decline, sea level rise, glacial loss, flooding, etc..., then I would gladly abandon all skepticism. The timeframe would depend upon how fast the previous effects are changing - acceleration, or lack thereof would be the key. Arguing the "other side" is a matter of perception. Since I argue for both natural and manmade cause, I am on the "other side" of those who argue for one or the other. Remember, I have taken neither of the two aforementioned positions.
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  23. You're looking for an acceleration of Arctic sea ice melt, Eric? It's in the data, see Polyak et al or whatever data source that goes back 30 years or more! And it's not just due to extreme years in 1996 and 2007 either. So there's no need to wait and see if 2011 continues the acceleration...
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  24. Sky, That is one parameter. I agree that the calculated September Arctic sea ice volume does show accelerated loss since 1979. That has not been shown in either Septmeber or March sea ice area, which are displaying linear trends (see above). Based on the most recent observations, there is no reason to believe that 2011 will not fall on or near that trendline.
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  25. 122, Eric the Red, I guess I'd still ask you to quantify... set a precise boundary, for how much of a temperature rise, by what year, accompanied by continued other factors, that would define your "enough is enough" point. As far as your statement about being in the middle... you are entitled to your own perspective, and we've been down this road before, but my perception of you, and I believe most others will agree, is that you constantly argue against climate change. Maybe you think you are providing balance and moving the argument to the middle of the road, but that's not how it comes across. Every single point you make is in contradiction to the AGW perspective. Every comment appears to look for the silver lining that lets us delay serious consideration of the problem for just a little longer. That's why I'd like you to quantify, unequivocally, your limits. I'd like a line that I know you won't cross, and that won't move, so we know when enough is enough by your own standards.
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  26. Sphaerica, Let me get back to you on precise boundaries, if I can even set up such a thing. Regarding the middle, yes that is perspective. On this site, I am definitely on the skeptic side (or denier by your standards). However, you must remember that this site is highly biased towards those you believe that climate sensitivity is high and warming is imminent. There are others who think that the temperature record is a sham, and that no warming has occurred at all. To them, I look like an alarmist (their term). I am not saying that I am dead center, but there is a rather long continuum.
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  27. #126 Eric, this site, so far as I can see it, is highly biased towards the science! The sham is that some think there is some kind of 'balance', some kind of middle point between the scientists and the deniers where the truth sits. It's the trap that media organisations everywhere fall into, the 'two sides to every story' trap. It works quite well for politics, but fails miserably for science. The truth, as supported by the evidence, almost certainly lies with the science, and whether the true answer is 2C per doubling or 4.5C per doubling, or somewhere in between, the true answer is very very far from denier positions. And that's not based on belief, but evidence. To lighten the tone, this quote from the ever-brilliant Hitchhiker's Guide seems appropriate somehow: "It occurred to him almost instantly, with the instinctive correctness that self-preservation instils in the mind, that he mustn't try to think about it, that if he did, the law of gravity would suddenly glance sharply in his direction and demand to know what the hell he thought he was doing up there, and all would suddenly be lost." I like the idea of Arthur thinking of almost anything he possibly can (such as the pleasing firm roundness of the bottom of tulips!), to deny the possibility that gravity might look sharply in his direction. Seems appropriate, somehow...
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  28. 126, Eric, That's a cop out. You seemed to give a pretty clear description, but by leaving it unquantified, it gives you all the wriggle room that you want to claim "that's not what I meant." Set things high if you want, but set some numbers. There has to be some point where you'd say really, this isn't right, no matter what. On the whole middle thing... science doesn't have a middle. There are a few fine points where you can argue one way or the other, and there are some other points where you can appear to argue it two ways (like climate sensitivity), but overall, the facts are the facts. The two sides of the road are "people who understand, and are concerned" and "people who are confused, and don't realize that they should be concerned." People who stand in the middle of the road, unable to choose, have either fooled themselves into thinking they understand when they don't, and they belong on the ignorance side of the road, or else the do understand and they are being disingenuous for some unknown reason, and are misleading people into thinking there is some reason to hesitate before picking a lane. There is no middle of the road. There's the side that's trying to steer the car around an upcoming, deadly obstacle, and there are the people on the other side, driving backwards, laughing, drinking beer, and guffawing at the frantic looks on the faces of the people in the other lane, shouting "Look out behind you! You're going to crash! Look out!"
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  29. Eric, which kind of event(s)/data in the future will convince you that you are wrong?
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  30. Sphaerica, I said give me time, that is not a cop out by any stretch of the imagination. Here is my response: Using CRU data, the 10-yr centered moving average increased 0.59C from a low in 1967 to a high in 2002. Therefore, if temperatures decreased by a similar magnitude over a similar time period, then I would say it was all natural, -0.6C by 2037. Using the same data, the calculated climate sensitivity over the 35 years is 2.8. Therefore, based on an expected CO2 increase of 17.5% by 2037, the temperature should rise another 0.65C. Then I would say it is all CO2. Obviously any changes of similar magnitude in shorter timeframes would yield a similar result. The other number to watch is a temperature decrease of 0.2C by 2028. That is the average of the last two cooling periods, and would indicate that both natural and CO2 forces are impacting temperatures. The resulting climate sensitivity would be ~1. I think that I have set some fairly solid bounds for you. Your middle analogy is woefully inaccurate, as you imply it results from indecision and apathy, rather than scientific inquiry. In reality, there is only one answer, and it lies somewhere between the left and right shoulder of the road.
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  31. 130, Eric the Red, You're kidding, right? You need to wait for 26 years before you'll see enough evidence to support climate change theory? Except by then the cumulative change that you need to see to convince you is 1.3C, with more warming in the pipeline, and presumably more CO2 to be added to the atmosphere after that because our infrastructure will still be unchanged. So you are basically saying that we have to be committed to a very dangerous 2˚C of warming before you'll even admit that climate scientists have it right. How can you not label that as complete and total denial? As far as the middle of the road goes, I see no evidence of scientific inquiry on your part. I see clear evidence of you reading every single piece of evidence presented as just not enough in your opinion, so you have to wait until what might as well be the end of time until you're sure that anything is true. Sorry, Eric, but your position is completely unsupportable and irrational. You try to speak rationally and act like you are in the middle of the road, except outside of the window dressing of the calm, reasonable words themselves, your position is far, far, far from scientific.
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  32. Spaerica, When is this committed warming expected to kick in? You keep mentioning that it will occur sometime in the future, but without giving a time table (sounds like your abovementioned cop out). At least I am presenting hard numbers. My presentation was totally scientific, and without denial. Let me turn the tables. What would it take to convince you that the observed warming is not all attributable to CO2?
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  33. Eric the Red. Look at the projections of climate models. The committed warming is already happening, it is gradual and doesn't "kick in". The second paragraph is specious, without specifying a minimum proportion that is not attributable to CO2, the question is meaningless. Has anyone said that 100% of the warming is due to CO2?
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  34. Eric the Red - This is discussed in some detail on Has Earth warmed as much as expected. This committed warming is primarily driven by the time for the oceans to warm given the current imbalance. Long story short, we're right about we we should expect for a sensitivity of 3C/doubling of CO2, with an inertial deficit of about 0.6 W/m^2 ocean energy absorption, or roughly another 0.4-0.5 C that we're committed to with the current radiative imbalance (once the oceans catch up). If we were to stop GHG's today, and somehow maintained the current aerosol level, mind you - that's negative 1.2-1.3 W/m^2, and if we suddenly stopped emitting aerosols we would have another >1C warming over 2-10 years.
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  35. KR: How can you say the aerosol level is negative? What are you basing that assumption on? Dikran Marsupial: What percentage of the warming is from natural cycles if not from co2?
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  36. camburn You are missing the point, the question as phrased was a straw man, it is widely known that CO2 is not the only driver of climate; I don't think anybody is claiming that all of the warming is unambiguously attributable to CO2 radiative forcing. The direct answer to Eric's question as posed is "very little, as I didn't think it was in the first place". Now Eric can make it an interesting question by specifying a ratio, but that is his job not mine. Personally, I am a mainstream science kind of guy, and to find an answer to your question I would probably get my copy of the IPCC WG1 report down from my bookshelf and look it up. However, I should have gone home hours ago. As a conservative estimate, I'd say that CO2 radiative forcing has been the dominant driver of climate since, say 1970, so that would be > 50%. BTW, not all natural variability is cyclical.
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  37. Camburn - Read the link in my post, look at Figure 1. Aerosols increase cloudiness, reduce sunlight reaching the ground, and are a major reason for the 1940-1975 cooling period mid-century, with the temperature anomaly slope reversing around the time of the Clean Air act and similar measures enacted in Europe. In other words, read the references. It's becoming even more clear that you have not.
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  38. ( -Snip-). Just to keep this on topic, under such a scenario, the Arctic sea ice would increase.
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    Response:

    [DB] Off-topic portion snipped.

  39. Eric, you love to set goals far into the future, don't you? Just like in the comments for this thread, you want us to sit back and wait over two decades before you'll decide the evidence is sufficient. You're picking numbers out of thin air and calling them 'hard'. That's not too scientific. I agree with Dikran - the second para is particularly woeful - every climate projection includes contributions from all major forcings, not just CO2. The continuing CO2 trend is clearly visible in every temperature dataset when the other forcings are removed, and is right in line with what the physics tells us. It's not about to start, it's already here and continuing. Pretending that there is some kind of middle ground is just another form of denial, and not in agreement with physics.
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  40. "...under such a scenario, the Arctic sea ice would increase." But that's just the atmospheric temperature! Have a look at accumulated ocean heat shown in that graphic. Do you really think that ice would not continue melting from beneath while that amount of heat is still circulating?
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  41. 132, Eric the Red, As far as your comment on the "committed warming," it is clear that the thermal inertia of the oceans is a factor, as well as the fact that many feedbacks are slow acting, such as changes in albedo due to ice melt, and natural carbon sources that result from ecosystem changes (Amazon to savanna, prairie/grassland to desert, shrinking forests), not to mention potential methane release and other sources. So there is no reason to think for one moment that stopping at 1.3C is going to mean stopping at 1.3C. Indeed, a change to 1.3C in a period of a mere 75 years may have frightening implications, because I'm not sure the temperature of the planet has ever changed at that rate -- ever. As far as your "scientific" label for yourself -- hard numbers, pulled at random from your gut aren't scientific just because they're numbers. I appreciate you thinking that you answered the question, but you really dodged it by setting a time frame that is so distant that your answer is effectively meaningless. As far as what it would take to convince me that warming is not attributable to CO2, the answer is a something amazing, because that would mean that our understanding of the physics is completely wrong, and that there is some element of the physics that we've completely failed to identify. Really, the fact is that the evidence is currently so strong that there is no chance that warming is not caused by CO2. The only viable argument, as you know, is related to overall climate sensitivity, and if thoughtful, well-founded studies were produced that put climate sensitivity at or below 1.5˚C per doubling, and if further studies lent support to and buttressed that conclusion, then I would start to relax. To be more direct about your question about attribution to CO2, I would need to see studies on some utterly silly nonsense like GCRs that actually bear fruit, providing both a viable mechanism and a correlation between temperatures and some measurable values to demonstrate that there is another factor at work in place of CO2. Even if the globe started to cool, that would not be evidence to me that CO2 does not operate as science believes. It would be evidence that there are in fact mysterious and unexpected forces at work that need to be identified and unraveled (and which therefore might then, once understood and quantified, be hoped to mitigate the impact of CO2). This is very unlikely to happen, since by this point in time we seem to have most of the factors pretty well nailed down, everything adds up and the ledger balances. But without an understanding and firm theory of atmospheric physics to support any change in temperature, observations that contradict expected warming point to a puzzle, not to a reason to out of hand dismiss existing theory.
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  42. Eric the Red - I have to agree with Sphaerica. In order for your apparently random numbers to work out, two things would have to be true. (1) Another cause for current warming, that fits the various fingerprints, would have to be found. So far, nothing. Not the sun, not GCR's, not reptoids... (2) CO2 would have to not behave as physics predicts, because it's doing just what we expect based on spectroscopy and other measurements. You appear, for some reason, to be hunting for alternatives. I don't know why, and quite frankly it doesn't matter. If they don't have physics and measurements behind them, they are just wishful thinking, and you're wasting folks time.
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  43. Sky, These are not numbers "out of the air," but hard data. I know you modelers do not like to look at real data becasue it upsets your thinking, but sometimes you have to face the facts. It is also much more scientific that mathematical models, as it includes real scientific measurements. The ocean temperatures have been following the land temperatures for the past decade, no heat accumulation. Ice would discontinue melting under such a scenario. Waiting for two decades are your words, not mine.
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    Response:

    [DB] First off, cease with your baiting.  That is simply trolling and you know it.

    "The ocean temperatures have been following the land temperatures for the past decade, no heat accumulation."

    Factually incorrect.  See the Oceans are cooling thread.

    Backing up your handwaving assertions with citations to peer-reviewed published sources would bring your credibility out of the negative range.  That would be the scientific thing to do.

  44. Dikran: Thank you for the response. I personally don't think it is responsable for >50%. One of the main reasons for this is the sine components within the measured and proxy temp record. But i am getting off topic. KR: I know the theory, but there was no practicle way of measureing the Aerosols during that time frame. I wasn't sure if you had found something new to verify them. Thank you for your response.
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  45. Camburn - The difficulties in measuring aerosols are part of the reason aerosol uncertainties (how much negative feedback) are so high. There have been some proposed satellites that could more directly measure aerosols, but they just haven't been launched. However, aerosols do appear to be directly implicated in the mid-century cooling that ended ~1975.
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  46. KR: A bit off topic again, but I talked to the NSIDC center today in realation to Aqua data on earth brightness. They seem very confident that the product they are presenting concerning is credible. They are fairly confident on the ice area as that is actually quit hard to measure even with a satillite. They look forward to sharing data from Cryosat. We live in exciting times. Prob in 100 years someone will look back and think we were in the dark ages, but the tech advances even in the last 10 years are quit marvelous and provide for a contining reliable data set. Another thing I learned that I was not aware off is that the NSIDC has a solar arm to it. The fellow I talked to, his grandfather was one of the designers of SOHO. Thank you for pricking my interest again moreso in earth brightness. It produced a very interesting and worthwhile telephone conversation.
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  47. Eric: A long term sine wave shows hamronics in the temperature of the planet. As solar research is getting going, there are not only hints, but the beginning of a credible data base that TSI is constant, but magnetic fields, solar winds, GCR, and it even seems events such as the Carrington, while not pointed at earth still play some type of roll in climate. But that is off topic. I still predict sea ice decline to 3.5 this year. From old Canadian Ice data it would seem that this year "should" be the lowest for quit some time. IF the trend continues as it has, then cycles, as we know them, have been over ridden.
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  48. Camburn, Based on the slowdown in Arctic melt compared to 2007 and 2010, and the cold North Atlantic, I so not share your sentiments. I do agree with your harmonics however. The next few years should be telling (not necessarily 26 Sphaerica).
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  49. There is no "slowdown." 2007 saw a sharp acceleration of melt in late june, which is not happening this year. There is plenty of weather yet to come that will determine what the minimum extent of September will be. Whereas the next few years might indeed be telling, I'm hard pressed to see how the past few weren't quite telling as well. "I know you modelers do not like to look at real data becasue it upsets your thinking." Gratuitous, baseless and insulting. You should refrain from such, the usual tone of your posts is much better.
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  50. Camburn, are you suggesting that "a long term sine wave shows hamronics" indicates that the sea ice low this summer will be less than 50% of the lowest level recorded before 1940 (see Cryosphere Today) and you think that is normal? Please explain how a sine wave harmonic could result in 50% of the ice melting when the trend was flat for decades prior to that time. Please refer to scientific sources for your data. Please support your reasoning with more analysis than your eyecrometer. Please stop poisoning the scientific discussion on this site with your wild, unsupported speculations.
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    Response:

    [DB] "wild, unsupported speculations"

    The technical term, I believe, is "gibberish".

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