Yesterday, Dr. Meier commented on PIPS -VS- PIOMAS, here is Part 2
Here are some thoughts on three other sea ice issues addressed in recent posts: (1) concentration vs. extent, (2) the causes of the 2007 record minimum, and (3) whether it is possible for the Arctic to lose all its sea ice during summer. Again, I’m speaking only for myself and not as a representative of the National Snow and Ice Data Center or the University of Colorado at Boulder.
Concentration vs. Extent as a measure of the summer ice cover
Sea ice concentration fields are difficult to interpret during summer because of the significant melt that occurs. Areas of low concentration may include open water or ice with surface melt or some combination of both.
Atmospheric moisture, which is higher in the summer, can also affect the observed concentration (e.g., concentration values can change with passing storms). Extent is a more consistent and stable measure of the amount of surface covered by ice and is more legitimate in comparing the data from different years, which is why NSIDC uses extent. Because of the melt and atmospheric effects on concentration, it can be particularly misleading to Steve’s comparison of two single days of concentration data. If one wants to compare concentration, it is better to compare monthly averages, which smoothes out at least some of the ephemeral atmospheric and surface effects. Looking at anomalies for June from 1990 and 2010, there isn’t much difference in the middle of the Arctic (the 2010 anomaly is a bit lower) with lower anomalies in 2010 in coastal areas. Again though, in the central Arctic this may indicate more open water or simply more intensive surface melt. Comparisons with other years can be made at NSIDC’s Sea Ice Index.
Monthly concentration anomaly (in percent) for June 2010 (left) and June 1990 (right). Positive anomalies (higher than average concentration) are in red, negative anomalies (lower than average concentration) are in blue. Anomalies are relative to a 1979-2000 average.
Reasons behind the record low minimum 2007 ice extent
Ice motion has been discussed as a major reason for the record 2007 minimum. While ice motion was important, it was far from the only contributor. For example, Zhang et al. (2008) attribute ~30% of the ice volume loss to ice motion, with the remaining 70% due to pre-conditioning (i.e., thinner ice cover) and more solar heating. Kwok (2008) attributes 15% of the extent loss to motion of ice from the Pacific side across the pole toward the Atlantic. Ogi et al., (2008) calculated a 37% contribution of unusual winds (and resulting ice motion) to the September extent.
So, what else played a role? Kay et al. (2008) suggest that below normal cloud cover and enhanced solar energy played a role (though another study, Schweiger et al. [2008] suggest the role may have been limited). Steele et al. (2008) found anomously high sea surface temperatures during 2007, which enhanced melt. Lindsay et al. (2009) showed that by 2007, the ice cover had thinned enough to reach a threshold where a dramatic loss in extent was possible under conditions experienced during the summer of 2007. Furthermore, the thinner ice cover allows the ice cover to be blown by winds more easily (Haas et al., 2008) – i.e., the winds contributed to the low extent, but the thin ice enhanced the effect of the winds.
In other words, the 2007 minimum was not simply the result of unusual ice motion. It was the result of ice motion, enhanced melt, warmer ocean temperatures, and a long-term thinning trend seen in a variety of observations (Maslanik et al., 2007; Nghiem et al., 2007; Kwok and Rothrock, 2009). The same atmospheric conditions would not have led to such a low extent in earlier years when the ice pack was thicker. As Ogi et al. (2008) say (with clarifying comments by me italicized in brackets): “… the precipitous decline in September SIE [sea ice extent] in recent years is mainly due to the cumulative loss of multi-year ice: summertime SLP [sea level pressure] anomalies [which control the strength and direction of the wind anomalies] have played an important role in setting the timing of record lows, but the long term trend is mainly due to preconditioning [the thinning of the ice cover].”
Can the Arctic really become sea ice-free during summer?
It has been suggested that the Arctic really can’t lose all its sea ice during summer because there isn’t enough energy to melt all of the ice in the short summer. There are a couple of reasons why this thinking is faulty.
First, we know the Arctic can potentially lose all its sea ice during summer because it has done so in the past. Examination of several proxy records (e.g., sediment cores) of sea ice indicate ice-free or near ice-free summer conditions for at least some time during the period of 15,000 to 5,000 years ago (Polyak et al., 2010) when Arctic temperatures were not much warmer than today.
Second, the primary evidence provided for the implausibility of ice-free summers is the plot of daily temperature for regions poleward of 80 degrees N from the Danish Meteorological Institute. It shows that temperatures rise only a couple degrees above freezing for a period of about 75 days throughout the entire record since 1958. So there is no warming trend of the surface air temperatures in the high Arctic. So how could one possibly melt ice near the pole with summer temperatures at most a couple degrees above freezing with no increasing trend?
North of 80 degrees, the Arctic has been continuously covered by ice, even during summer, throughout the entire record (except for a small area briefly during summer 2007). As a result, any heat energy in the vicinity will be used to melt ice and will not raise temperatures. Only after the ice melts can the ocean absorb the energy allowing the ocean surface and the air above it to warm significantly. So the summer near-freezing temperatures don’t say anything much about the energy available to melt ice, only that ice is melting. (I’ll note that it is possible to have higher air temperatures locally, for example due to a weather system bringing in warm air from the south, but the average over the entire region will stay near freezing).
However, there are still only ~75 days of melt, which isn’t much time. But one needs to think about the overall process of what happens in the Arctic, not simply the direct solar energy. As temperatures increase, summer extent decreases, which allows more absorption of solar energy. This melts more ice, decreasing the extent and thinning the ice. Heat absorbed in the ocean away from the ice edge will warm the ocean waters, which will delay freeze-up in the fall. This leads to less ice growth further thinning of the ice. With warmer temperatures, melt will begin earlier in the spring and freeze-up will start later in the fall (as has been observed, e.g., Markus et al. [2009], Serreze et al. [2009], Stroeve et al. [2006]). This is a positive feedback (the sea ice-albedo feedback). Under this feedback, the ice will eventually become thin enough to melt completely most everywhere in the Arctic during a single summer.
There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.
References
Haas , C., A. Pfaffling, S. Hendricks, L. Rabenstein, J.‐L. Etienne, and I. Rigor, 2008. Reduced ice thickness in Arctic Transpolar Drift favors rapid ice retreat, Geophys. Res. Lett., 35, L17501, doi:10.1029/2008GL034457.
Kay, J.E., T. L’Ecuyer, A. Gettelman, G. Stephens, and C. O’Dell, 2008. The contribution of cloud and radiation anomalies to the 2007 Arctic sea ice extent minimum, Geophys. Res. Lett., 35, L08503, doi:10.1029/2008GL033451.
Kwok, R., 2008. Summer sea ice motion from the 18 GHz channel of AMSR-E and the exchange of sea ice between the Pacific and Atlantic sectors. Geophys. Res. Lett., 35, L03504, doi:10.1029/2007GL032692.
Kwok , R. and D.A. Rothrock, 2009. Decline in Arctic sea ice thickness from submarine and ICESat records: 1958–2008, Geophys. Res. Lett., 36, L15501, doi:10.1029/2009GL039035.
Lindsay, R.W., J. Zhang, A. Schweiger, M. Steele, and H. Stern, 2009. Arctic sea ice retreat in 2007 follows thinning trend, J. Climate, 22, 165-176.
Markus , T., J. C. Stroeve, and J. Miller (2009), Recent changes in Arctic sea ice melt onset, freezeup, and melt season length, J. Geophys. Res., 114, C12024, doi:10.1029/2009JC005436.
Maslanik, J.A., C. Fowler, J. Stroeve, S. Drobot, J. Zwally, D. Yi, and W. Emery, 2007. A younger, thinner Arctic ice cover: Increased potential for extensive sea-ice loss, Geophys. Res. Lett., 34, L24501, doi:10.1029/2007GL032043.
Meier, W.N., 2005. Comparison of passive microwave ice concentration algorithm retrievals with AVHRR data in Arctic peripheral seas, IEEE Trans. Geosci. Remote Sens., 43(6), 1324-1337.
Nghiem, S.V., I.G. Rigor, D.K. Perovich, P. Clemente-Colon, J.W. Weatherly, and G. Neumann, 2007. Rapid reduction of Arctic perennial sea ice, Geophys. Res. Lett., 34, L19504, doi:10.1029/2007GL031138.
Ogi , M., I.G. Rigor, M.G. McPhee, and J.M. Wallace, 2008. Summer retreat of Arctic sea ice: Role of summer winds, Geophys. Res. Lett., 35, L24701, doi:10.1029/2008GL035672.
Polyak, L., and 17 others, 2010. History of sea ice in the Arctic, Quaternary Science Rev., 29, 1757-1778, doi:10.1016/j.quascirev.2010.02.010.
Schweiger , A.J., J. Zhang, R.W. Lindsay, and M. Steele, 2008. Did unusually sunny skies help drive the record sea ice minimum of 2007?, Geophys. Res. Lett., 35, L10503, doi:10.1029/2008GL033463.
Serreze, M.C., A.P. Barrett, J.C. Stroeve, D.N. Kindig, and M.M. Holland. 2009. The emergence of surface-based Arctic amplification, The Cryosphere, 3, 11–19.
Steele, M., W. Ermold, and J. Zhang, 2008. Arctic Ocean surface warming trends over the past 100 years, Geophys. Res. Lett., 35, L02614, doi:10.1029/2007GL031651.
Stroeve, J., T. Markus, W.N. Meier, and J. Miller, 2006. Recent changes in the Arctic melt season, Ann. Glaciol., 44, 367-374.
Zhang, J., R. Lindsay, M. Steele, A. Schweiger, 2008. What drove the dramatic retreat of arctic sea ice during summer 2007?, Geophys. Res. Lett., 35, L11505, doi:10.1029/2008GL034005.
So if “Examination of several proxy records (e.g., sediment cores) of sea ice indicate ice-free or near ice-free summer conditions for at least some time during the period of 15,000 to 5,000 years ago”? How come we still have polar bears?
Wow! Great analysis. But Dr. Meier, in your last 2 paragraph’s wherein you say:
As temperatures increase, summer (ice)extent decreases, which allows more absorption of solar energy.
And: With warmer temperatures, melt will begin earlier …..
And again: There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.
Could you clarify WHAT temperatures you are specifically talking about? And site, as you did so well in both this and the previous contribution (be it ocean or atmosphere), the studies/data that show the temperatures that “continue to rise”.
Michael Penny
Fantastic question!
The post is interesting. Whilst the Mid Holocene warm period did see an ice free Arctic for possibly a couple of thousand years (Norwegian research) the actual cause of that warming is a mystery – and so are what are supposed to be ‘natural’ ups and downs in the climate. Something must cause them to happen. As C02 was not involved it is equally just as likely that C02 is not involved in modern warming – and it is simply the Sun being more active (or some other factor). What cannot be denied however is that mountain glaciers in the Alps and the Andes show evidence of shrink – sometimes quite dramatic shrink. Now, the altitude of mountains might suggest that as they are closer to the Sun and less inhibited by cloud that once again the Sun has been in a more active mode over the last 100 years. However, what bothers me is the fact that one of the Andes glaciers has melted to such a degree that plants frozen over 5000 years ago have only just emerged from a frozen state. That smacks of a warming that is greater than anything in the last 5000 years – otherwise the plants would have died off. There is also a hint that at around 3000BC one section of the Andes, at least, was suddenly uplifted – taking those plants from a lower altitude position where they normally grow into a high altitude position where they were quickly frozen and preserved. That means the warming is even greater – as it has climbed through that altitude hike. Any explanations?
Likewise, archaeologists in Canada are now seeking out thawing ice patches and finding human artifacts, mainly associated with hunting, that were dropped or left behind thousands of years ago. This suggests once again that in spite of the Roman Warm Period and the Medieval Warm Period and the Little Medieval Warm Period (Tudors) that ice kept those artifacts preserved – until now. These ice patches may also be located in high places – but as far as I know are not associated with mountain tops.
Hi Anthony,
There is an interesting article (in German) about the ice melting phenomena observed this spring. Astonishing is a correlation between ice melting in the Arctic and the de Vries/Suess solar cycle. Of course other cycles have been discussed there.
http://translate.google.de/translate?js=y&prev=_t&hl=de&ie=UTF-8&layout=1&eotf=1&u=http%3A%2F%2Fwww.eike-klima-energie.eu%2Fnews-anzeige%2Farktische-sommereisschmelze-ein-menetekel-fuer-eine-bevorstehende-anthropogene-klimaerwaermung%2F&sl=de&tl=en
jakers says:
July 14, 2010 at 12:52 pm (Edit)
OK, so it’s “natural variation” then. Well, if you can’t identify the mechanism, the ‘how’ of its workings, then how is it not mystical?
Here, have a look at this:
Arctic insolation Vs Arctic temperature and Co2 Vs Arctic temperature
http://tallbloke.files.wordpress.com/2010/07/soon-arctic-tsi.jpg
I’m sorry Dr. Meier, there are entirely too many “will” “can” and other predictions of the future to suit me.
The facts are, you guys are good about hindcasting, and pretty good at figuring out what has already happened.
But you all have the worst record of predicting the future any group of people could have.
When you guys start getting lotto numbers right, let me know.
There’s a reason there are no weather or climate pools, like football pools.
carol clapham says:
July 14, 2010 at 1:23 pm
“Whilst the Mid Holocene warm period did see an ice free Arctic for possibly a couple of thousand years (Norwegian research) the actual cause of that warming is a mystery”
The cause of that warming is fairly clear. The Earth’s orbit was slightly different in the early Holocene, with greater summer insolation at high latitudes. This extra solar heating, together with feedbacks (such as reduced albedo) caused the Arctic to warm in the Early-Mid Holocene. We can be absolutely sure the same process is not happening today.
“and so are what are supposed to be ‘natural’ ups and downs in the climate. Something must cause them to happen. ”
Not necessarily. A certain amount of unforced, internal variability is expected. You can get an idea how by running a climate model without any external forcing.
I would suggest that Dr. Meier’s statement …“There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.” Is also true because the Arctic has been ice-free in the recent past — about 8,000 ybp — and will probably pass though a similar state in the future.
There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.
And conversely, the Antarctic will continue to exceed all previous ice extents due to temperatures that continue to rise!
If that doesn’t makes sense, Dr. Meier, it’s because the assumption of warming is not consistent with reality.
I see no warming trend north of 80L.
If you have some ideas about why the North warms while the South cools, now would be a good time.
Due to orbital mechanics, the Arctic was warmer than present about 7,000 years ago, allowing trees to grow to the edge of the Arctic Ocean and possibly producing brief periods in the late summer when the Arctic was ice-free. I’m not sure if any humans lived in the area, but the polar bears and other species obviously survived this experience. The Greenland Ice Cap didn’t melt. Methane may have bubbled from melting permafrost, but not enough produce a spike in methane levels in ice cores. Why should anyone – the alarmists or the skeptics – care?
I’m always glad to see posts like this from those in “the other camp” (so to speak). Generally the AGW crowd issues a series of flat statements to the media ending with “and it’s worse than we thought,” with few details of the science behind them — the science being all too complicated for our little minds to grasp. (Okay, so in my case that’s true — but still.) Then I come here where I read what seem to me to be excellent attacks on these flat statements, complete with scientific backing. However, I know that this site has a particular view-point and bias, but I also know that the people on this site can be remarkably vigilant in trying to balance that viewpoint.
So what I end up with is the AGWs on one side treating me like an idiot who must listen to whatever they say or risk being categorised as a flat-earther, and reasonable, intelligent discussions of the science by the anti-AGW crowd. (And as the AGWs moan about the problems they’re having with “communication” they might just look at that particular dynamic.)
Thank you, Dr. Meier, for coming here and talking about the science. I’ll let those with more knowledge hash out how “robust” it is, but for me, at least it’s nice to see answers from the other side that don’t involve ad hominem attacks and broad statements about the end of the world. (Seriously — that endless doomsday scenario, of which we’ve had so many over the decades, and throughout history, doesn’t inspire intelligent people to pay much attention.)
And as for whether any possible ice retreat is caused by human activity, that’s not the issue in Dr. Meier’s essay. The issue is whether or not his science is good.
I am daringly predicting a NORMAL minimum NH ice this year
Just check this out ladies and gentlemen LOL
http://ocean.dmi.dk/arctic/icecover.uk.php
The next 6 months mark the end of even the concept of AGW
After reading the article and the comments I’m wondering what the AGW skeptics would accept as a prove, that CO2 is connected to disappearing ice?
Just in case somebody thinks falsification is a good thing.
Dr. Meier continues to prove a very valuable asset to this website. It is my opinion that we can derive much integrity and strength as a community by attracting more “cross aisle” communication. This is one trend in climate science I’d like to see continue ;P. If we can’t enter their domain for open communication we CAN encourage and be receptive to them entering ours. Preaching to the choir tends to only go so far as compared to dissenting dialogue. And that applies to both sides of the AGW coin.
In other words, the 2007 minimum was not simply the result of unusual ice motion. It was the result of ice motion, enhanced melt, warmer ocean temperatures, and a long-term thinning trend seen in a variety of observations (Maslanik et al., 2007; Nghiem et al., 2007; Kwok and Rothrock, 2009). The same atmospheric conditions would not have led to such a low extent in earlier years when the ice pack was thicker. As Ogi et al. (2008) say (with clarifying comments by me italicized in brackets): “… the precipitous decline in September SIE [sea ice extent] in recent years is mainly due to the cumulative loss of multi-year ice: summertime SLP [sea level pressure] anomalies [which control the strength and direction of the wind anomalies] have played an important role in setting the timing of record lows, but the long term trend is mainly due to preconditioning [the thinning of the ice cover].”
====
Let’s compare this with what Walt Meier said then (published on Yahoo):
“This year’s record was caused by a “perfect storm” of interacting factors, Meier , said by telephone. These included a long-running high pressure system that kept skies cloudless over the Arctic, along with a circulation pattern that pushed ice out of the Arctic towards Greenland, instead of letting it circle around the Beaufort Sea north of Alaska as it usually does.”
Also quite misleading is Fig. 1 Part1 of ice age distribution: 1985 jumping to 2008, 2009 and 2010. Over the past 3 years the variability of distribution is quite significant. Therefore juxtaposing a snapshot at 1985 out of context, without showing the variability then simply occult the processes that lead to yearly transformation of the Arctic ice.
Let’s notice also that the multiyear ice on these images is considered 5y + and not 20y or 50y. Therefore, if Arctic ice was so stable in the past, where has 50y ice gone Dr. Meier? It is likely it has been melted and recycled in an ever dynamic Arctic. Thus presenting 1985 as a supposed representation of the Arctic Ice of the past -i.e. stable- and the evolution since as a abnormal situation -i.e. AGW induced changes- is misleading at best.
Very good to see this on this website, this is why I come here as a mere layman.
They cannot accuse Anthony of not presenting the other side-in a reasonable fashion.
BTW- I suspect Luis the troll has been thrown into that place before. Style and all that…
richard telford says:
July 14, 2010 at 1:45 pm
“and so are what are supposed to be ‘natural’ ups and downs in the climate. Something must cause them to happen. ”
Not necessarily. A certain amount of unforced, internal variability is expected. You can get an idea how by running a climate model without any external forcing.
But if, as has been argued here often, climate sensitivity is low, this variability with no forcing would be very very small. You can’t have it both ways.
Many thanks Dr. Walt Meier I have found both articles very interesting with a great deal of food for thought. I am trying not to get indigestion, so will keep chewing awhile.
Just one comment, at present, after the “Hockey Team”, I think references to a “Sea Ice Community” could be counterproductive. This subject is far too polarised as it is. (is that a pun?).
The “we know better than you” meme that I find attached to AGW policy could account for some of the lack of “cross fertilisation”? It typifies the “consensus science” stance, a stance that politicians may take. However if scientists call a consensus are they not actually saying “I must be correct, my community says so”? Therefore where is the motive and opportunity to look further, deeper?
Right or wrong Steve Goddard, makes his stance on his own, backs his thoughts with his predictions for all to see, somehow I don’t think he is part of the “Sea Ice Community” or is he?
For an issue as critical as AGW, having “teams and communities” held together by consensus is far too warm slipper and cosy.
In a lighter vein, like the England football team, I can’t help thinking that most teams and communities benefit from the infusion of new, young, hungry blood?
Once again many thanks for your insight, it is greatly appreciated.
Speaking of the dipole anomaly:
http://www.robertb.darkhorizons.org/seaice.anomaly.Ant_arctic.jpg
Heads or tails?
“There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.”
Which temperatures ? Where ? Could anyone clarify ?
Does he mean seasonal – The temperature will continue to rise until September ?
Does he mean -As we climb out of the Little Ice Age and revert to normality ?
Does he mean – As this ball of rock which was once molten solidifies ? (Whoops that is cooling)
Aside from my rather vulgar mocking tone – Can I seriously, humbly and genuinely ask what he means by ” as temperatures continue to rise.”
“There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.”
I have problems with this statement too.
Is Walt getting this from “The Models”? From the super-duper computers?
There are real world indications that says the temperature will decrease, not increase.
So…..
Jakers>
You seem to be making a very good case for solar-activity driven climate change. Is that your intention?
Just a note: it’s not ‘mystical’ to say that the climate must vary naturally, because we know that it *has* varied naturally. You’re right that any posited explanation without good proof is a touch ‘mystical’ by the definition you appear to be using.
Does the truncated basis period exaggerate the sea ice trends at both ends of the world?
DRr Meier,
Are you aware of the 2007 JGR arcticle that looked at arctic sea ice volume trends for the twentieth century and determined there was none.
http://www.agu.org/pubs/crossref/2007/2006JC003616.shtml