parmenides3

When TV shows glaciers calving during reports about climate change it is doing so for 'dramatic effect'. Lots of ice melts every year, lots of water freezes every year (in quantities which are hard to comprehend, they are so vast). The important thing to look for is the difference between the average amount which is recorded as coming and going, and the current situation; the anomaly. The anomaly can be positive or negative, meaning more or less ice than average is melting/freezing. A big anomaly (two or more standard deviations from the 'norm') is a cause for concern if it is part of a trend; in reality, the range of variability every year is so vast that one 'extreme' year may or may not carry a larger signal. What is unusual about the Arctic sea ice is that there has been a consistent trend of decline for a long time now, that this trend appears to be accelerating, and that there hasn't been a positive anomaly in ice area or extent since 2003, which is unusual in itself. These are indicators that the pattern of things is changing. The pattern of things changing is, in other words, a 'climate change'. What is worrying to a lot of scientists is that many of the world's natural systems exist in fine balances, which are vulnerable to even small changes. Long term, large scale changes are a source of concern for two main reasons; firstly, they will have a knock-on effect, wherein the disruption to one part of a system will have an impact on another, and secondly, that the process of change may have a 'quantum' element, ie, at certain 'tipping points', a change may become more or less permanent, or a trend of decline or growth becomes 'fixed' and irrecoverable. In such a case, it is clear that there will be substantial consequences, but how long they will take to manifest, and what they will mean for the infrastructure of human societies, is very unclear, and, if you don't like the idea of mass extinctions or population crises, somewhat alarming. Try to ignore the 'scary' stuff the TV/papers show and say; this is not science and it is often barely even based on fact; worry about what the evidence and observations show; this is less spectacular but more important. P Don't confuse the measurement of sea ice area with the rate of melting; they are not the same thing. We use such terms as shorthand, but what the data shows is sea ice area/extent, which can be seen and measured, to a degree. Sea ice depth has been measured occasionally over recent years but this is much harder to do for such a large area, so inferences have to be made from whatever measurements are taken. Again, look at the pattern rather than the detail; it is the trend which matters, which is why the measurers work on the basis of five or seven day averages, or even longer ones; statistically, the accuracy of a longer pattern is more reliable than the accuracy of a subset. P

Hi CJWRC & welcome. No, it's mostly the ice being shifted around. Sometimes, given the weather up there, there might some surface ice formed during the melt season, but generally, once it starts melting, it carries on melting till the end of the season (roughly, September). There are lots of things to know about arctic sea ice, so simple snapshots can be confusing. I'm not sure how it can be propaganda-like to post pictures showing what is; this is simple observation of fact. What the image means, and how it is interpreted, can be subject to bias in the person doing the interpreting, but generally, if there's not much ice there, then it's not there. Is it propaganda-like to show a long-term trend? Surely, propaganda is manipulation of fact ( or disinformation, or straight-out lying) for political purposes. Do you believe that the images shown, or the graphics/facts, are inaccurate? If so, do you have a basis for this belief? P

NADS: apparently, the Fram outflux is more a function of the Dipole Anomaly. This was supposed to produce Northerlies during July but current suggestions are that there more of an Easterly element than expected. The Russian sea ice service has good short-term current and wind flow forecast maps, if you're interested. The perennial problem of the Arctic is its immense natural variability, which makes fools of forecasters. Its generally safer to make use of trends and tendencies over periods than look at synoptics, but the best you can do is gather the evidence on current and recent conditions from every possible source and then make inferences about what they might be indicating. Current indication seem to be that the seasonal sea ice level is about three-four weeks ahead on long term average. Impossible to talk about records, really, but it's a surefire bet that the Summer low point will be very low, and the trend of long-term decline will be fortified, if not slightly worse than anticipated. P Are thos ehtr Rapidfire images, GW ? http://rapidfire.sci.gsfc.nasa.gov/

Cheers J. Hi GW. Check out this forecast: FECN16 CWIS 011800 THIRTY DAY ICE FORECASTS FOR THE EASTERN AND NORTHERN ARCTIC FOR JULY ISSUED BY ENVIRONMENT CANADA ON 01 JULY 2010. THE NEXT 30 DAY FORECAST WILL BE ISSUED ON 15 JULY 2010. Air temperatures in the Eastern and Northern Arctic were above normal during the second half of June, except in Committee Bay where they were below normal. As a result, the retreat and melt of the ice along the eastern margin of the pack ice in Davis Strait and Baffin Bay is proceeding at a faster pace than normal and ice concentrations are currently below normal in this area. The eastern margin of this pack ice lies approximately 150 nautical miles further west than its normal position at the end of June. Ice concentrations over most of Cumberland Sound are also currently below normal. However, as a result of the Arctic sea ice influx through Nares Strait, which did not consolidate this past winter, and due to a recent period of easterly winds over Lancaster Sound, ice concentrations in parts of northwestern Baffin Bay and in Lancaster Sound are currently greater than normal. Old ice concentrations in Nares Strait, Baffin Bay, the mouth of Lancaster Sound and in Davis Strait are also greater than normal. Because of the above, the "open drift or less" and the bergy water routes across northern Baffin Bay, which were forecast to develop in mid-June, have not yet developed. The "open drift or less" and bergy water routes to Thule, however, did develop by the end of June (1 week later than forecast but still approximately 3 weeks ahead of normal). Small openings in the sea ice have developed in Eureka Sound and in Belcher Channel on the southwest side of Norwegian Bay and ice melt in these areas is proceeding normally. Forecast ice conditions for July 1st to July 15th. Air temperatures for the first half of July are forecast to be above normal over the Eastern and Northern Arctic and no significant storms are forecast to affect the region during this period. As a result, ice across the region is expected to continue melting at a greater rate than normal. A brief period of moderate westerly winds associated with a low pressure system crossing northern Ellesmere Island is forecast to affect Jones Sound and Lancaster Sound on the 5th and 6th of July. This event will cause some flushing of areas of fractured fast ice from Jones Sound into northwest Baffin Bay and also cause flushing of the mobile pack ice in Lancaster Sound towards Baffin Bay during this time. As a result of this, as well as due to the continued influx of sea ice from the Arctic Ocean through Nares Strait, ice concentrations in northwest Baffin Bay are expected to remain greater than normal during the first half of July, delaying the development of the bergy water route across northern Baffin Bay by another 1 to 2 weeks. At the same time, these winds will help fracture the fast ice in Jones Sound by mid-July, in keeping with the forecast date for this event. Fracture of the fast ice in Norwegian Bay, Pond Inlet, the northern half of Admiralty Inlet, Wellington Channel and in McDougall Sound is still expected to occur near mid-July, 2 to 3 weeks ahead of normal. In southern regions, ice concentrations along the southern edge of the ice pack in Davis Strait will continue to decrease and the remaining ice in Cumberland Sound will flush out of the region. In Nares Strait, fast ice in adjacent bays and fiords will continue to break off, adding to the old ice floes descending from the Arctic Ocean and to the bergy water in the area. Forecast ice conditions for July 15th to July 31st. While air temperatures over southwestern and western Baffin Island, the Gulf of Boothia and eastern Barrow Strait are forecast to remain above normal during the period, air temperatures over the Northern Arctic, Jones Sound, eastern Lancaster Sound and along eastern Baffin Island are forecast to drop to below normal towards the end of July. This may impact the fast ice fracture in Eureka Sound, the clearing of Pond Inlet and the development of the "open drift or less" route to Cape Dyer, all of which are forecast to occur by the end of the month. However, due to the rapid melt and retreat of the ice that will take place during the first half of July in these areas, fast ice fracturing and clearing in these areas will likely still occur as forecast. The main ice pack in east-central Baffin Bay will continue to shrink and by the end of the period, the ice concentrations in that area will resemble conditions normally seen in the first or second week of August. END GW, if my links aren't working, Google the Canadian Ice Service and navigate through the extensive products. Or try this link: http://www.ec.gc.ca/glaces-ice/default.asp?lang=En&n=D32C361E-1

Useful reference tool: http://www.ec.gc.ca/glaces-ice/default.asp?lang=En&n=4CE72415-1 or: http://www.ec.gc.ca/glaces-ice/4CE72415-E22F-4872-9C3E-8DC170BBFB3D/ar_breakup.gif Context is everything. Check out what is happening at the Fram Strait; if there is a lot of North-South flow there, then older ice can be flushed out of the Arctic and lost, which is bad. P Oh, and this... http://ice-glaces.ec.gc.ca/prods/WIS56DPTCT/20100705180000_WIS56DPTCT_0005069498.gif

Well, it can have existed, perhaps at a relatively stable level, for a long time, but then an increase or decrease over an extended period would have to come in to alter the response of the system to said forcing. Volcanoes are an interesting short-term example; Pinatubo changed several elements of the system, resulting in short term fluctuations which would not have other happened. There is also a degree of hysteresis in the system response, but, once it stopped erupting, the system was eventually allowed to restabilise at close to its previous state. We have to find a mechanism to account for the persistent trend. Actually, we have found a lot of mechanisms, with various degrees of influence; the question still remains which mechanisms matter, and which if any we (humans) can do anything about. Without the change to the system, your solar hysteresis idea would suggest that, over time, the earth would warm indefinitely (I think) P

Yes. Here we need to find something which is/has changed which has led to an observed trend; a long-term positive forcing which did not previously exist. P

Neatly explained, Songster. http://polar.ncep.noaa.gov/seaice/Analyses.html contains some good explanations (scroll down the page. Bob Grumbine is also a good egg and has recently started blogging, to cover some of the enquiries he gets about science and GW: http://moregrumbinescience.blogspot.com/ if you have technical questions about the Arctic, he may well address them for you... P

'As I have said before (though you may have missed it since you've been away, P3) the temperature increase over the last 100 years or so would require the Earth to retain no more than an extra 1/1000th of a degree Celsius every month, which is not a great deal.' If the System retains 'extra' heat, this suggests that something has changed, either to the system, or the external forces working on it. But consider a tropical desert at night, or a temperate location through the seasons; to what extent do these places exhibit hysteresis? If I recall rightly, for example, temperatures in the UK respond to our relationship to the Sun with an approximate six-week lag (variable), so that we get our warmest months after the period of greatest insolation, and vice versa. Where the global surface temperature may well exhibit hysteresis is in the case of our old friend the Arctic, sea ice and sea surface temperature. This has to do with the way in which the measurements works today compared to 30 years ago. The reason why the lower Arctic waters show such a high anomaly is at least partly because, 30 years ago, areas which were perennially ice-covered are no longer; therefore there is a large anomaly recorded. It is also important to understand how much of the long-term global trend is affected by these anomalies (though also important to recognise that models account for the phenomenon to some degree). So, is the sea ice reducing at 8% per decade because of warming oceans, or are the oceans showing warming because the sea ice is reduced? The two are obviously demonstrating the same overall pattern - one of warming - but establishing cause and effect is less obvious. So, a suggestion here might be that the leaky integrator model could work quite effectively in relation to the Arctic Ice; think of single-year and multi-year ice as the 'new' and 'carried over' elements of the system. For a year like 2007 to happen, there has to be a loss of multi-year ice as well as the expected seasonal variation in the single year ice. This is, in part, what happened on 07; because of the currents, the winds and the Summer synoptics, multi year ice was pushed out of the 'bowl' of the Arctic Ocean, via the Fram Strait, out into the warmer Greenland Sea, whence it melted. If the system is 'in balance', then, over time and allowing for variability, the proportion of multi-year and single year ice remains broadly similar. This is because the steady build-up of the hysteretic element is countered by the occasional 'burst' of the system, leaking what has been gained out into the oceans surrounding. Is this suggesting anything?...

Blast, why would NOAA scientists conspire to falsify data? :)P

Question: have we accumulated enough information to confidently state that a trend does or does not exist? next: if a person is not satisfied with the information that is currently available or used, given its incredible quantity and variety, then said person is not going be satisifed with the addition of further data. It's not the input, it's the result which some people find unpalatable, so, in order to avoid the result, the easiest thing to do is deny the validity of the evidence. we have several hundred years worth of measurements, and several hundred thousand years worth of proxy-based estimates. But it would make no difference if we had sizteen zillion signed affidavits by Saint Joan; if you want to deny scientific results, you will. This is not the same as refuting scientific hypotheses, or demonstrating errors in research work; these are rational and methodological practices. If you feel uncertain about GW, it should ideally be because you have a reason to doubt the science, not a need to run away from it. P

I'd have to spend some time hounding out the latest papers to give a proper answer to what's been happening since the AR4, it's really more my sense of 'what's been discussed' rather than hard theory. In 2007, thought was as you suggest; I think it may have modified a bit since then. P

Ah, but how much of a 'blip' was it, and did it have an impact which makes long-term reversal more difficult in future? I don't know, but my suspicion is that 2008 and 2009 might have been less extreme, given the conditions, if 2007 hadn't happened. Finally, is it likely that we'll get another 2007 soon, and what would the impact of that be? P

Hi J. Does this mean you've forgiven me? P

Hi Shandiman; there is still uncertainty about whether changes in oceanic currents will result in considerable cooling in N Europe in the decades to come. Recently. the feeling seemed to be that the odds of a consistent slowdown in the THC, effecting our local climate, were about 1/4 for this century, and perhaps 50/50 for the next. But the uncertainties are very large, and various measurements and research seem increasingly to suggest that the THC is a lot more variable than we used to think, and that it is already exhibiting possible signs of long-term changes. I don't think anybody, even the top scientists, are really comfortable that we have got to grips with this yet. Small side point; best guess is that, even if there is a general THC slowdown and a localised cooling, GW will still continue globally, and temps. in 2080 in the UK are still more likely to be higher on average than they are now. P weathereater; ta mate.

This is one of the most important issues that need to be addressed, both with respect to climate change and biodiversity loss, water balance, drought, exploitation, political will, loads of reasons. It should be at the tope end of any program which attempts to address the possible future problems and issues for our planet. P

There's interesting debate in the science blogs about how significant 2007 was; was this a 'freak' year, or 'the shape of things to come', or 'the sign of a step-change in the sea-ice metric'? Even the scientists aren't agreed about this. As I have suggested elsewhere, though, it is the larger picture which is the cause for concern. Have you read the ICARP materials? You can imagine that the past 2 years represent a 'minor reversal', but if 2007 hadn't happened, how would 2008 and 2009 look compared to 2000, or 2005, or any other years? There's still a lot less ice in the Arctic now than there used to be. P

be right with you... sorry if there are delays; i don't have the time i once had... :unsure: P

Beng; there is a lot of blog action going on these days discussing the likely numbers, including a number of gambles. This is partly because opinions even among specialists vary, but mainly because the Cryosphere, particularly the Arctic, is so strongly affected by natural variability that any one season's metrics are almost impossible to anticipate. So the discussions are about the likelihoods, and the significance of events like 2005 and 2007. You seem to be making the classic mistake of thinking of a climate trend as a linear progression, and seeing a short-term reversal of that trend as significant, whereas it is not a linear progression, and the significance of short-term results is effectively zero, unless they happen to fall into the category of 'unprecedented', in which case, their significance needs to be considered. Time has told. there is 25% less sea ice in the Arctic this Summer than there was, on average, between 1979-2000. I encourage you and everyone to consider not the moment, but the pattern, the trend; in climate terms, this is what matters. I would say the same if the ice extent had been a new record low this year. Look at the trend. How much ice is there likely to be in 20 years time, compared to 1979-2000? P

There's a whole load I've missed since yesterday; sorry to go missing when it all starts off. Can I clear up a couple of points which seem to pop up regularly? 1. The 'general scientific opinion' and motives for having such opinions. Either there is a large general opinion within the relevant sciences that AGW is happening, or there isn't. You can't both claim that there is no consensus and at the same time claim that the majority of scientists are self-interested lackeys of the system; this is inconsistent. I asked 3600 scientists with track records in climate related sciences what they thought, and about 1/4 thought the effect of AGW might be less extreme than the 'IPCC standard'; another 1/4 -1/3 thought the IPCC underestimated the problem, and the rest though the IPCC standard was there or thereabouts. In other words, whilst not all scientists agree with the detail, it does seem to represent the 'mean' opinion reasonably well. Not one scientist who responded said they did not think AGW was happening. (This was nearly two years ago; opinions may have changed since then. 2. Climate models. Just about everyone wants climate models to be better than they are, and to remove any inaccuracy or false assumptions. But the sheer size and compexity of the modelling makes this a slow and difficult process. these are huge computers with thousands of interdependent variable equations running hundreds of millions of calculations a second; and even then, it takes months to run a single 'projection' run, for example. Nobody thinks climate models are perfect, and nobody in the scientific community is suggesting that their output is 'gospel' as far as the future is concerned. But; there is considerable consistency between different models in different places; none of them is projecting a long-term cool down or return to historic conditions, and between them the range of possible future warming is quite a broad range, but all are positive. This is a source of great concern in climate science, because it appears likely that the differences between +1.5C in 100 years, and +5C, are huge, and the actual total anticipated warming is very important socially, politically, and practically. 3. Extreme views. It doesn't really matter what the subject is, whether it is climate science, or politics, or religion, or art, the range of individual views always contains the extremes as well as the broad middle ground. Personally, I worry about extreme views, because I have a sense that they are by their nature unbalanced, and because their proponents are often polemical, aggressive and violent about them, none of which characteristics appeal to me personally. The history of our world is littered with the corpses of the victims of extremism. We don't need it in climate discussions. But there are people who will differ in their opinion to me, and I respect their right to have these views, but I will spend my time willingly working to try to encourage these people to moderate the extremity of their views, beccause to do so seems to me right. 4. Pro and anti. Black and white. Righteous or heretic. This is to place all discussion into a context of contradiction, opposition and antipathy; the consequences are inevitable; conflict. If you want to pick a fight, fine, but AGW is not an issue which lends itself readily to absolutes or pointless labelling, and dialogue which is based on confrontation gives little benefit or value to anyone. Enough for now, P

VP; starting from the start: what do you mean by (i)? Hysteresis; are we presuming this refers to rate-independent ('memory') hysteresis? I can understand how GSTs can exhibit hysteresis - in the sense that the present state is (partially) past-state dependent, and for this, the application of a leaky integrator might be fun. But how can the temperature record be affected? Surely it merely measures the consequences of the hysteresis, rather than being subject to hysteresis itself? Is the leaky integrator another way of expressing the non-linear nature of climate? Once we've sorted this out, we'll move to the next item... C-Bob: As I said on another thread, I am leaning towards the idea that the mechanism that is being sought is nothing more than the long-established greenhouse effect - no need to change the basic principles there. The change to AGW theory would be that the greenhouse effect is not significantly altered by small changes in CO2 concentration - rather, the greenhouse effect's basic ability to retain heat, and how it reacts to changes in incoming energy, is sufficient to explain global warming in conjunction with the sun's varying output. we need to be much clearer about this; 'greenhouse effect' is no more than a (dodgy) name used to provide a convenient analogy to the global climate system. You seem to be suggesting that the system's record of temperature change might be disconnected from the CO2 content - to a greater or lesser degree - if it can be shown that 'heat memory' from the Sun is in some way the cause of changes to the temperature record. But why would this phenomenon suddenly come into being since the 1950's, and not before? If the system is retaining more heat than it used to, and the rate of retention is increasing, there must be some physical cause. Thermometers measure current conditions (+/- some short-term hysteresis); other than that, there is no 'memory' in the measurement tools, surely? P

Go on... give me a questionable 'myth' :lol: P BTW; heartfelt congrats on getting into UEA. P

Let's see then if my brief perusal has got this right... 'Solar activity has been at a higher level over the past fifty years than previously'. Is this the case? 'There is a strong relationship between Solar activity and global surface temperature'. Seems reasonable. 'There is a physical mechanism which allows a proportion of the suface temperature of the Earth to be retained around the Earth rather than radiated out into space'. Yep. 'In the past thirty-odd years, though there is no measured correlative increase in solar activity, there has been a (positive) change in the balance of temperature retained in the earth's atmosphere and at the surface'. fine. 'A physical mechanism exists, which has not previously been apparent, which accounts for the change in temperature'. Yes... 'It is possible to mathematically model a number of variables into a system such that it replicates the change in global average temperature'. This is easy... This is by no means meant to be read as a hostile or aggressive response to what is clearly a serious attempt to understand what is going on with our climate, but if C-Bob's summary elsewhere is accurate, the hope is to establish that it is mathematically possible that GW is a consequence of an unspecified Solar forcing, and not something else; is this correct? As I understand it,whether or not there is a lag in the relationship between Solar activity and global temp., there would still need to be some physical mechanism or process which accounts for the change in the global temperature balance. There has been some very interesting work done on the idea that the oceans, soaking up the majority of the solar energy, have a lag associated with release of the energy absorbed from the Sun(which, BTW, is different for NH and SH), but the bad news is that this lag implies that the change in global temps has been constrained, not exaggerated, so far, and that the future release of the energy, combined with the heightened temps. in situ, is likely to result in an acceleration of GW. Just having fun... :lol: P

Calm down, Solar... I think you'll find it was me who said that Svensmark is a respected scientist in the first place. No, he isn't on his own, but the number of actual scientists (ignore Morano's ridiculous 'list') who contend that AGW is not happening is miniscule. I know this, because I asked them. Try to get away from the idea of 'proAGW' and 'antiAGW'; this suggests that there is a debate (there isn't), that this debate is based on opinions (it wouldn't be), and that everyone who works in science must have an 'agenda' - by which I presume you mean a policical intent - which is simply false. It is possible to study the facts, read the science, consider the options, and reach a conclusion, without having any kind of 'agenda'; this is what searching for truth and understanding is about. If you are contending yourself that AGW is not happening, give me a reason for this opinion and I can address that. Peace. :lol: P RC isn't unbiased, but it is rational. Again, show me an example from RC of a discussion or subject which you think has been handled in an unbalanced manner. I don't disagree with you about us all having prejudices, but surely, the point of science is to remove such things from the equation? And the point of reason (as opposed to polemic) is to test propositions, not to presume their truth or falsity? P

We clearly have a different sense of what 'balanced' means. I will suggest that one site contains rational discussion of facts and findings, whilst the other contains nonsense got up in someone's elses clothes. I am happy for you to give me an example of a 'valid point' from Watts' site if you can find one, and discuss it with you. I haven't found one yet, but I don't bother with the site that often these days. On the basis of what you have said here, I'll comment on the LI thread at some point.