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  1. I'd guess it might be pretty dangerous - getting people to agree on the level of dimming would be an awful challenge in itself. Add to that the problem that the energy imbalance caused by increased GHGs is not the same as the energy imbalance caused by a brighter Sun, namely that opposite effects occur for day versus nighttime temperature, winter versus summer, stratospheric temperature, and high latitude temperature, so your treatment is not most effective where the impacts of AGW are most dramatic. To me it wouold be an exercise in treating the symptoms, not the causes, and surely only a last resort if things got really bad...
  2. I agree wholly with most of what you say there VP. I stated that it is an hypothesis that heat being released from exposed Arctic water in the autumn is affecting our weather patterns - it is not elevated to theory or any higher degree of scientific acceptance than 'hypothesis'. It is some way from that hypothesis being verified by the evidence, though as most of these papers were written before the last two winters, the evidence is growing. Still it is far too short a time for significance, while the alternative hypothesis I mentioned, that low solar activity leads to cooler winters at least in the UK/North Atlantic region, is much more established and supported by longer term data. The indicator for me would be if these conditions persist, either repeating over too many years for it even to be solar-related (few occasions even in the LIA had long unbroken streches of cold winter years), or if the conditions repeat even when solar activity rises to a peak. Additionally, if we see truly unprecedented synoptic patterns, especially if repeated, alarm bells may ring. For this particular hypothesis, I wouold suggest that the years 2012-2016 may be key, around the next solar maximum, which although not a strong one, should be strong enough to negate the solar-driven cold winter weather pattern and we may be able to determine the strength of this hypothesised new driver of Northern Hemisphere weather. As yet, I remain open-minded, as I cannot forget shivering through the coldest nights on record in December 1995, and that probably had a 'low solar' component to the blocking! I read a 1999 paper discussing how we might see climate change expressed in the dominance of one or other weatehr pattern - ie the anthropogenic signal forces the pattern, rather than being altered by it, link below: http://www.nature.co...s/398799a0.html While not quite exactly relevant here, particularly as this is perhaps the emergence of an almost unprecedented pattern, I think the general comment would be that with a warming atmosphere, and modified parts of the land-ocean-atmosphere linkages such as reduced sea ice, we might expect to see unusual weather patterns emerging (or the increased frequency of particular patterns). The result is that any one region may see sharp changes in local climate by comparison to what is thought of as 'normal' rather than a difficult-to-spot gradual 0.17C/decade warming trend. You'd be hard-pressed to clearly identify the gradual trend, but you'll notice if there are events happening that have never happened before (2 feet of snow in Edinburgh)! Some regions see large warmings, others even coolings (seasonal or overall), yet others see large changes in prevailing wind direction or precipitation. But as you say, too early to call it a trend yet - I remember the long period of +ve NAO, but the next few years will provide interesting weather watching... It will be very interesting to see if we get a full repeat of the Warm Arctic - Cold Continents pattern - at the moment, the November temperature anomaly plot shows the UK and Scandinavia alone as a patch of blue in a sea of red warm anomalies above ~45deg N. Places like China and the US that were affected last winter were dominantly above average in November's record global warmth. Edit: Interesting blog post too - well worth a read!
  3. Recent winter weather patterns make fascinating viewing, especially as one who loves a snowy and cold winter! There will likely be a grerat many people who will be desperate to equate a snowy winter on these shores to global cooling of some form, but the below papers are well worth bearing in mind: Petoukhov and Semenov (2010): A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents. JGR: http://www.agu.org/p...9JD013568.shtml ScienceDaily version here: http://www.scienceda...01117114028.htm Note the date - it was published before this year's recent cold spells began, and the initial paper was received in Nov 2009, before last year's cold spells began. At present, I remain open-minded about whether the current anomalous patterns (including remarkable NAO values) are at least partly due to low solar activity, which has been flagged frequently as a possible cause (for example: Lockwood et al (2010): Are cold winters in Europe associated with low solar activity? http://www.nature.co...s.2010.184.html) But I find it intriguing that we are having a series of remarkable cold winters while the rest of the world has high temperatures. Check out http://data.giss.nas...vs2005+1998.pdf (record high Nov temperature despite strong La Nina) and http://climateprogre...-solar-minimum/ - note that the only NH mid-high latitude region with anomalous cold is UK/Scandinavia! To me, you have to ask the question - are we seeing the first strong impact on our weather due to reduced Autumn sea ice? It is still clouded by the remarkable low solar activity, but if we see these kinds of patterns persisting through the coming solar max, then we may have to adapt to them as a consequence of AGW, namely hot globe, cold UK winters. Perhaps the Arctic can't hold in it's winter cold anymore. If I was to bet, I'd go for a combination of the two, strengthening the signal to produce extreme remarkable synoptics, but where we go from here with continuing losses in the Barents-Kara Seas and elsewhere, yet rising solar activity till 2014, I have no idea. Other (reasonably) recent sea ice-winter climate papers, some published before even last year's winter: Francis, J. A., W. Chan, D. J. Leathers, J. R. Miller, and D. E. Veron, 2009: Winter northern hemisphere weather patterns remember summer Arctic sea-ice extent. Geophys. Res. Lett., 36, L07503, doi:10.1029/2009GL037274. Honda, M., J. Inoue, and S. Yamane, 2009: Influence of low Arctic sea-ice minima on anomalously cold Eurasian winters. Geophys. Res. Lett., 36, L08707, doi:10.1029/2008GL037079. Overland, J. E., and M. Wang, 2010: Large-scale atmospheric circulation changes associated with the recent loss of Arctic sea ice. Tellus, 62A, 1–9. Warm Arctic-cold continents... our future? "In December 2009 (Fig. A7b) and February 2010 (Fig. A7c) we actually had a reversal of this climate pattern, with higher heights and pressures over the Arctic that eliminated the normal west-to-east jet stream winds. This allowed cold air from the Arctic to penetrate all the way into Europe, eastern China, and Washington DC. As a result, December 2009 and February 2010 exhibited extremes in both warm and cold temperatures with record-setting snow across lower latitudes. Northern Eurasia (north of 50° latitude to the Arctic coast) and North America (south of 55° latitude) were particularly cold (monthly anomalies of -2°C to -10°C). Arctic regions, on the other hand, had anomalies of +4°C to +12°C. This change in wind directions is called the Warm Arctic-Cold Continents climate pattern and has happened previously only three times before in the last 160 years." http://www.arctic.no...atmosphere.html Would I be right in saying that this pattern is repeating/has repeated this year, making it twice in consecutive years? Whatever the cause, this Edinburgh resident knows the conditions are truly remarkable!
  4. Looks like a coincidence. They seem to suggest a significant reason being that in some areas evapotranspiration slows down because there is no more water to evaporate once everything's dried out. Also, specific humidity continues to rise in neat agreement with temperature rise, which has of course continued through the past decade despite the 1998 anomalous year. Se the below post from Tamino at Open Mind, with data from the State of the Climate 2009 report: http://tamino.wordpress.com/2010/08/08/urban-wet-island/
  5. Two excellent points. If we can actually have some corroborated evidence of cloud cover changes driving temperature, then there would be something interesting to talk about. It is interesting how some people repeat falsehoods about Mann and Hansen and others despite exonerations (I think, by now, their methods are the most public of all!). Spencer hasn't had any enquiries go after him because to date his cloud results haven't been that important, or very good. Jethro, you're right about clouds being highlighted by the IPCC - they are of course crucial, and your excerpt shows this is not a topic the scientific community are ducking. But holding a senior position and having awards etc does not give you a free ride to the truth - you are still judged on the quality of what you produce. On that score (to use the above examples), to date Hansen and Mann have scored much more highly than Spencer, despite blogosphere attempts to muddy reputations. If Spencer comes up with the goods and shows the necessary changes in cloud cover, then all well and good, but so far he hasn't. Why are people so quick to accept the word of Spencer, yet equally quick to dismiss the results of thousands of other scientists that happen to point to a single alternative conclusion?
  6. So Spencer still believes that scientists are naughty and he's repeating debunked rubbish in suggesting there was any substance to the climategate allegations. Of course all the subsequent exonerations by multiple independent panels mean nothing... Other cloud research has not shown the same links Spencer claims, so it seems he's the one out on a limb, and with a track record of producing ropey results. I'd still be intersted to know how, if clouds are such a powerful negative feedback, we get large palaeoclimatic shifts from small initial orbital forcings. CO2 explains that well, quite apart from all the other direct evidence for CO2 operating as expected today... Lets see what the professionals have to say, if they care a jot about Spencer's claims these days. The last few times out Spencer's claims were torn to shreds, so I hope he's got his sums, and graphs, in order and not cooked up this time.
  7. Hope it's better than Spencer and Braswell's last effort.... http://www.realclima...e-easy-lessons/ The section on Spencer's rather bizarre "internal radiative forcing" [weather] is worth a re-read as that concept rears it's head again in Spencer's new paper. I'll await the professional responses to this paper, but I wonder if Spencer has the wrong end of the stick (yet) again? Also worth noting is that the feedbacks are a product of the physics in the models, not specifically coded in - from the above RealClimate post: "the concept of feedbacks is just something used to try to make sense of what a model does, and does not actually enter into the formulation of the model itself." Spencer's unfounded accusations against climate modellers do him no favours in the world of real science, and his failure to understand where the feedbacks come from gives me rather serious concerns about the validity of his latest paper. Some might have already made their minds up about the validity of the paper, but I'd prefer to see some independent corroboration, and see how it stands up to criticism.
  8. Hi Jethro, I agree with you - this study is indeed good news, if verified. I'd certainly be happier in a world where the ice caps were shrinking at a slower rate. I think such a revision would still have us at the high end of current IPCC sea level projections (given that they have been seen as too low by most recent studies), and is not an excuse for us to delay action, but it might give us more time to avoid the worst effects of warming.
  9. Not really, as you then have to show what natural cycle(s) drove such a past change. There is no evidence for natural cycles that can force present climate and past climate in the observed pattern... unless you are arguing that somehow the natural cycles operated in a different way in the past?? [or suggest that half a dozen different proxy types are all wrong in the same direction of wrongness]. You cannot base any hypothesis, or course of action, on an unknown that might be imaginarily the case - you have to show why it is the case. And present a compelling suite of evidence that not only shows your unknown process is consistent with the observed and proxy data, but shows why we can largely disregard CO2 variations which, coincidentally, already explain the observed and proxy data variations. So far, climate skeptics have failed this crucial test. An while the match between temperature and CO2 over the past 1000 years is quite appealing if the 'swiss horn' is closest to the mark, it does not provide direct evidence for a human imprint on climate. Direct evidence of temperature forcing includes outgoing and downward longwave radiation measurements showing the CO2 signature, and observations of increasing nighttime and winter temperatures, stratospheric cooling etc that show a signature in the forcing pattern of the atmosphere that is neatly consistent with GHGs, but not consistent with other forcings. They, to me, are the most important pieces of evidence. 'Swiss horns' tell us about sensitivity, and indicate a lower sensitivity to forcing than otherwise.
  10. I'll call such reconstructions 'Swiss Horns' from now on, shall I?
  11. Jethro, those are exactly the two points I've been making all along. Thankyou. I'm happy not to discuss with YS anymore, as the concept of a rational discussion seems to disappear when the words 'hockey stick' appear in relation to research. It's not even that important in connecting humans to climate change - other lines of evidence are far more important (radiation measurements, changing patterns of temperature etc).
  12. Funny how you keep saying the hockey stick is dead, yet it appears in numerous different proxies and numerous different reconstructions. Far from being dead, it's actually one of the most validated graphs in science. It does not just refer to tree rings (as you seem so obsessed by), but to a multitude of other proxies from flowering dates to borehole temperatures, via glaciers on the way. Quite what is 'cherry picking' about finding mutually consistent evidence from a great diversity of sources, while there is no scientifically valid evidence to suggest otherwise? http://www.skepticalscience.com/broken-hockey-stick.htm On Wegman among other things - it is well worth slandering as I would not use it even as toilet paper: http://www.desmogblog.com/crescendo-climategate-cacophony http://deepclimate.org/2010/04/22/wegman-and-saids-social-network-sources-more-dubious-scholarship/ [and links within] As for the NAS report which you persist in suggesating that it wrecked Mann's early hockey stick, maybe you should read the report and the discussion here: http://www.realclimate.org/index.php/archives/2006/06/national-academies-synthesis-report/ From the NAS summary: "The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. This conclusion has subsequently been supported by an array of evidence that includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators, such as melting on ice caps and the retreat of glaciers around the world, which in many cases appear to be unprecedented during at least the last 2,000 years. Not all individual proxy records indicate that the recent warmth is unprecedented, although a larger fraction of geographically diverse sites experienced exceptional warmth during the late 20th century than during any other extended period from A.D. 900 onward." Hardly demolishing the paper, is it? http://www.nap.edu/catalog.php?record_id=11676 Climate science moved on, past Mann et al (1998,1999), and confirmed the hockey stick. Only those people like MacIntyre and cronies (Montford, Monckton) still claim it's "broken", failing to realise there are many sticks made of different materials. The hockey stick is dead... in the eyes of a very few.
  13. I linked to discussions with plenty of very serious criticisms of the M&W paper. Y.S., instead of insulting me for my views, why don't you head over to Deep Climate and see if you can come up with reasons why those criticisms are invalid, ditto for the criticisms at RealClimate. There's no point in having a debate with you here as all you do is throw insults when anybody suggests that MacIntyre might be wrong, Wegman might be a politicised and plagiarised report, or that the latest paper purporting to raise doubts about anthropogenic global warming turns out to have a number of critical flaws. When was the last time you were truly sceptical of claims made by MacIntyre, Spencer or that ilk? I'm sceptical of every scientific claim I see, whatever side of the fence it's from - some of those claims stand up to scrutiny, others don't. And I'll consider a claim rubbish if it is not supported by evidence. M&W's claims about reconstructive ability appears not to be supported by evidence. http://deepclimate.org/2010/08/19/mcshane-and-wyner-2010/ Though I do think M&W's statement is rather funny, for a skeptic paper: "Using our model, we calculate that there is a 36% posterior probability that 1998 was the warmest year over the past thousand. If we consider rolling decades, 1997-2006 is the warmest on record; our model gives an 80% chance that it was the warmest in the past thousand years." I just don't think the stats they did look likely to stand up to scrutiny, and their background reading falls very flat.
  14. I agree completely with that last post VP! The hard part is that it's very difficult to convince people that they are able to do something when they have convinced themselves they can't... It's a pity that the M&W paper fails so badly. It would have seemed to me an opportunity for statisticians to collaborate with relevant climate scientists and do the best possible job. Unless of course McShane and Wyner didn't want to come to the same conclusions as the climatologists... I find it amusing, in a way, that they can do such a poor job of reviewing the literature or understanding the methodology applied by Mann, Wahl and others, yet claim to overthrow a raft of independently verified climate reconstructions. And from what I can see, and from what others better qualified than me can see, they do an awful job of the actual statistics in the process. The only place they then get it published is of course a journal that clearly has no idea about why the paper is bad - which raises questions about how that particular journal is screening papers! And the only people who of course see it as flawless statistics perfectly applied to the topic are... Watts, MacIntyre and their acolytes, who will be horrendously critical of every piece of climate science , except something that happens to say what they believe, however bad a piece of science it is. Confirmation bias? Of course. Denial? Written all over their faces. When will they learn that to be truly sceptical you have to be sceptical of every piece of science, including the ones you initially think ought to be right?
  15. The paper is certainly not a vindication of Wegman's plagiarised political rubbish, nor does it appear to be a successful vindication of McKitrcik or MacIntyre's so far failed attempts to discredit one of the many 'hockey sticks' in existence. The NAS (infinitely superior to the Wegman garbage) critcised Mann's statistics but vindicated his results. Others subsequently reproduced his results several times over with different methodologies, and Mann addressed the NAS criticisms in the 2008 paper. Those who think that McShane and Wyner have demonstrated anything more than the fact that statisticians really ought to consult with climate scientists before attempting to publish on climate science should read carefully the criticisms outlined at Deep Climate: http://deepclimate.o...and-wyner-2010/ "So there you have it. McShane and Wyner’s background exposition of the scientific history of the “hockey stick†relies excessively on “grey†literature and is replete with errors, some of which appear to be have been introduced through a misreading of secondary sources, without direct consultation of the cited sources. And the authors’ claims concerning the performance of “null†proxies are clearly contradicted by findings in two key studies cited at length, Mann et al 2008 and Ammann and Wahl 2007.These contradictions are not even mentioned, let alone explained, by the authors." [Deep Climate] I'm not qualified to comment on all the details of the statistical reconstructions, but I can comment that the choice of favoured review literature was awful to the point of being deliberately awful. It would not pass muster for an undergraduate essay. Lots of serious statistical issues raised by Deep Climate - anyone defending the paper in detail might have their work cut out it would appear. RealClimate also has a passing nod at it, with hints that there may be more to come: http://www.realclima...-it-yourselves/ I like Deltoid's take on it, here: http://scienceblogs....mcshane_and.php The most interesting part there is Martin Vermeer's early comment - one of the many errors in the paper is a failure to adjust for high latitude skewing of results - hence the slanting shaft of their hockey stick. But seeing as they purport to discredit palaeoclimate temperature reconstruction altogether, much more serious are the statistical failings pointed out at Deep Climate and RealClimate - it looks very much like this paper will be added to the list of those that fails to dislodge even one of the many hockey sticks on the rack from it's place. EDIT: Interesting second paper there VP - though it's 13 years old. Any sign of those problems being remedied? But the main issues with software such as those you pointed out are resolved by replication of results by different methodoloiges. In the case of 'Hockey sticks', tree rings, boreholes, lake sediments, glaciers, ice cores, corals and stalagmites all provide independent evidence, as do the reconstructions using different combinations of these sources and different methodologies. Computing issues then don't come into it IMHO.
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