tag:blogger.com,1999:blog-16612221.post4002343842815971353..comments2024-03-19T03:14:04.172-04:00Comments on Rabett Run: A Message from the UnknownEliRabetthttp://www.blogger.com/profile/07957002964638398767noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-16612221.post-22032362441080400142012-06-18T13:04:27.220-04:002012-06-18T13:04:27.220-04:00F&V12 looks back at recent changes without con...F&V12 looks back at recent changes without considering what happens as these processes continue, until the Arctic becomes a net source of water vapor (heat).<br /><br />Statistics of past weather/climate will not give a clue as to future weather/climate as the very thermodynamics of the weather machine change.Aaronhttps://www.blogger.com/profile/05150805906414546377noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-57979254772142309412012-06-17T13:51:56.685-04:002012-06-17T13:51:56.685-04:00Cohen and co-authors had this in GRL recently (dra...Cohen and co-authors had this in GRL recently (draft pdf <a href="http://web.mit.edu/jlcohen/www/papers/Cohenetal_GRL12.pdf" rel="nofollow">here</a>):<br /><br /><i>Asymmetric seasonal temperature trends<br /><br />Current consensus on global climate change predicts warming trends driven by anthropogenic forcing, with maximum temperature changes projected in the Northern Hemisphere (NH) high latitudes during winter. Yet, global temperature trends show little warming over the most recent decade or so. For longer time periods appropriate to the assessment of trends, however,<br />global temperatures have experienced significant warming for all seasons except winter, when cooling trends exist instead across large stretches of eastern North America and northern Eurasia. Hence, the most recent lapse in global warming is a seasonal phenomenon, prevalent only in boreal winter. Additionally, we show that the largest regional contributor to global temperature trends over the past two decades is land surface temperature in the NH extratropics. Therefore, proposed mechanisms explaining the fluctuations in global annual temperature trends 13 should address this apparent seasonal asymmetry.</i><br /><br />Their Fig. 3 illustrates the point very clearly. Interesting stuff. I did *not* know that DJF temperatures in the NH extratropics were doing this. <br /><br />BBDAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-16612221.post-91622033938554071062012-06-17T10:29:39.596-04:002012-06-17T10:29:39.596-04:00Thanks for pulling this up out of the comments and...Thanks for pulling this up out of the comments and for anon's comment.<br /><br />This intersection of climate and weather is a very interesting arena because people don't live in 30 year averages - and as far as I know, this kind of detail is not caught in the current generation of AOGCMs.<br /><br />Yet, it seems like this is precisely the kind of thing that can drive western US snowpack and eastern US snowstorms. And I wonder if the increased amplitude and slower phase of the Rossby waves makes a play in the recent heat wave in Russia and extended rain in Pakistan.<br /><br />In a previous post you pointed out that many people's opinion of climate science are driven by their personal experience of the degree of match between local weather and what they believe to be GCM predictions. When weather seems warmer their belief goes up. When weather seems colder and/or snowier, it goes down. <br /><br />The whole 'weighted dice' narrative is an attempt to get beyond that, to help align climate predictions to experienced weather. But it is a strained relationship since, AFAIK, GCMs are not producing the natural range of variability that can be considered weather-like. And, AFAIK, aren't showing anything like this arctic impact on the Rossby waves.<br /><br />Very interesting line of research. Thanks for the post.Ron Broberghttps://www.blogger.com/profile/00360356366869878444noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-55104817219771443482012-06-16T20:05:38.399-04:002012-06-16T20:05:38.399-04:00Here's a public-access copy of Francis & V...Here's a public-access copy of <a href="http://marine.rutgers.edu/~francis/pres/Francis_Vavrus_2012GL051000_pub.pdf" rel="nofollow">Francis & Vavrus (2012)</a>, plus see this Yale Environment 360 <a href="http://e360.yale.edu/feature/linking_weird_weather_to_rapid_warming_of_the_arctic/2501/" rel="nofollow">article</a> by Francis explaining the results.<br /><br />There's also a fresh review <a href="http://www.tos.org/oceanography/archive/25-2_greene.pdf" rel="nofollow">paper</a> on the general subject, although it puts the major emphasis on the expectation of winter polar outbreaks.Steve Bloomhttps://www.blogger.com/profile/12943109973917998380noreply@blogger.com