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Comments 28201 to 28250:

28201. scaddenp at 06:34 AM on 27 July 2015
       Arctic sea ice loss is matched by Antarctic sea ice gain
       

       The really big factor is height. The south pole is at 2700m - making it a much colder place than North pole. Raising the summer temperature from current -29C to say -9C still wouldnt do much melting. Furthermore, arctic ice is constantly moving with combination of wind and currents. Moving ice from somewhere cold to somewhere warm is much more effective at melting than inplace melting. In the antarctic, ice movement is at literrally glacial pace. The oceans also bring in warmer water which thins arctic ice but so far only affects the antarctic margin.

28202. CBDunkerson at 06:30 AM on 27 July 2015
       Arctic sea ice loss is matched by Antarctic sea ice gain
       

       Rovinpiper, Arctic sea ice averages less than two meters thick. Antarctic land ice averages more than 1800 meters thick. See the problem?

28203. Rovinpiper at 06:15 AM on 27 July 2015
       Arctic sea ice loss is matched by Antarctic sea ice gain
       

       Ok, so why is the fact that there is land at the South Pole so important? Ice can melt on land, too. Open ocean absorbs heat very well, but what is the rock of Antarctica like? How well will it absorb heat?

28204. Tom Curtis at 22:05 PM on 26 July 2015
       Arctic sea ice loss is matched by Antarctic sea ice gain
       

       bozza @13, there are three different things that could be meant by a claim that the NH is 'warmer than' the SH.

       First, it might be a claim that the annual variation is surface temperature is greater in the NH than in the SH, as shown in this chart:

       

       This greater variation results in the seasonal variation in global mean temperatures being in phase with the NH variation, even though the SH in fact recieves more sunlight over the year.  The reason for this difference is the relatively low thermal inertia of the NH (which is 39% land) compared to the SH (which is only 19% land).

       The same factor is the dominant factor in the more rapid rise in mean hemispheric temperatures in the NH since 1950 (the second possible interpretation), shown here:

       

       Neither implies that the NH is actually warmer than the SH in absolute terms, as a more rapid warming response also implies a more rapid cooling response.  In fact, it appears that in absolute terms, the SH is warmer than the NH:

       "Data from a large number of stations suggest that the annual mean temperature is around 27^o C within 20^o S - 16^o N degrees and then falls by about 0.85 K/degree latitude in the northern hemisphere and 0.63 K/^o lat in the south (Fig 2). This implies that on average the southern hemisphere is warmer than the northern hemisphere (17^oC vs 11^oC, respectively), which is true, if the Antarctic plateau stations are excluded, as in Fig 2. These stations are 30-40K colder than the curve in Fig 2 suggests, on account of their altitude and their isolation within the circumpolar vortex."

       

       It may be that the very cold Antarctic temperatures more than compensate for the greater extent of tropical warmth in the SH, and the slower loss of temperature with higher latitude.  But I have no evidence showing that to be the case.

       Regardless, the cause of these differences are complex, including the effect of the positions of landmasses and currents on the location of the Inter Tropical Convergence Zone (which would govern the latitudinal extent of the tropical zone) and the relative ease of heat transport towards the poles in the two cases.  Part of the explanation may lie in the circumpolar vortex around Anarctica, which by limitting heat transport to the pole may allow that heat to remain in mid-latitudes in the SH rather than being transported to the pole (or at least above the arctic circle) in the NH.

28205. bozzza at 21:09 PM on 26 July 2015
       New Zealand Snow No Show = No Jobs
       

       Not sure where to ask about global snowlines but is the data available for say 50 years of global snowlines to establish trends?

28206. bozzza at 17:38 PM on 26 July 2015
       Scientific consensus and arguments from authority
       

       Science is done by consensus and it starts with nomenclature!

28207. Jim Hunt at 17:34 PM on 26 July 2015
       2015 SkS Weekly News Roundup #30C
       

       Regarding the "Tory attacks on green policies", Tony Juniper was good enough to "retweet" a recent message of mine on this very topic:

       https://twitter.com/jim_hunt/status/624483364679061504

       Might I suggest that any UK citizens reading this follow my example and Lord Deben's suggestion and write to their own Member of Parliament about the issue at their earliest possible convenience?

28208. bozzza at 16:54 PM on 26 July 2015
       Arctic sea ice loss is matched by Antarctic sea ice gain
       

       Tom @ 12, in a nutshell is this why the Northen Hemisphere is warmer than the Southern Hemisphere?

        

       I've been looking for the simple explanation as to why this is because apparently it was theorised many moons ago but the mechanism for it being so was not quite understood.

28209. Tom Curtis at 15:38 PM on 26 July 2015
       It's the sun
       

       Just a small extension to MA Rodger's analysis of Dan Pangburn's 'model' @1149.  What I did was obtain the sunspot numbers and annual average TSI figures from SORCE for the years 1979-2013 (ie, the satellite record).  I calculated the equilibrium temperature response for each sunspot number as:

       T(eq) = 286.2*(S(i)/34)^0.25

       At that value, S(i) = 34 * (T(i)/286.2)^4, and hence S(i) - 34 * (T(i)/286.2)^4  = 0, ie, there is no temperature change using Pangburn's model.

       Using the equilibrium temperature for the sunspot number of a given year, and the forcing (=0.7*TSI/4) for each year from SORCE, I calculated the linear trend of temperature relative to forcing, a value which give the ECS.  It turns out to be 1447 +/- 194 K/Wm^-2.

       This differs from MA Rodger's estimate because, his upper bound on the forcing massively overestimates the forcing differential.  In particular, in 1987 the sunspot number was 33.9, with an insolation of 238.19 W/m^2, a value that differs by only 0.015 W/m^2 from the average over the period.  Ergo Rodger's overestimated the forcing differential by a factor of 66.67.

28210. LarryM at 06:59 AM on 26 July 2015
       2015 SkS Weekly News Roundup #30C
       

       Links in article "How this El Nino..." are missing above and on homepage.

       [feel free to delete this comment once dealt with]

       Moderator Response:

       [JH] Glitch fixed. Thank you for bringing this to our attention.

28211. Tom Curtis at 05:58 AM on 26 July 2015
       It's the sun
       

       MA Rodger @1149, 0.003503/17 = (approx) 0.0002.  You have misplaced a decimal point.  Further, the temperature term takes the fouth power of the ratio between T(i) and T_(o), not ratio between T_(i) and T_(i-1).  Consequently it is not always negligible, and is certainly not negligble at T(i) = T_(o) + 60.  Of course, you did not neglect that in calculating the equilibrium temperature.  Neglecting the temperature ratio changes the time to equilibrium but not the equilibrium temperature.  That, as you know, is determined solely by the requirement that at equilibrium (T_(i)/T_(o))⁴ = s(i)/34, resulting in the integrated term in Pangburn's formula equalling zero.  I estimate the increase in temperature at equilibrium to be  +62.59 C, or given the baseline temperature, at 75.6 C.  Ignoring the misplaced decimal point, a neat analysis, and "lunatic value" is exactly correct.

28212. MA Rodger at 04:19 AM on 26 July 2015
       It's the sun
       

       Tom Dayton @1147/1148.

       I think the two previous excursions of Dan Pangburn here @SkS do not provide a clear explanation of Pangburn's proposition, possibly even less clear than Pangburn's explanation linked to by APT @1146.

        

       APT @1146.

       The graphs you link to are simple nonsensical curve-fitting with zero basis in physics. The guts of Pangburn's sunspot equation can be much simplified and still produce the same-shaped resulting graph. That simple equation is:-

       • T_(i+1) = T_(i)+0.00002(S_(i)-34)

       where T is temperature and S is sunspot number for year i.

       For the last 75 years, the average sunspot number has been about 75, way above the average 34 used in the equation which is why the graphed temperature soars despite the heavily lagging terms employed. Indeed, it is only during the Manuder Minimum & the Dalton Minimum that the average sunspot number drops below 34 allowing Pangburn's graph to dip downward. Including SSN data to 2014 shows that even weak Sunspot Cycle 24 is averaging above 34 and showing a further increase in temperature.

       Heavy lagging is used by Pangburn because the T⁴ term is far too weak to define an equilibrium temperature. If the ~75 average sunspot number of recent decades persisted, the equation tells us global temperatures would rise by over 60ºC before equilibrium appears. Given the forcing involved will be less than 1Wm^-2, this means this equation of Pangburn's is suggesting an Equilibrium Climate Sensitivity ECS > 240ºC, an entirely lunatic value.

28213. Jim Hunt at 00:50 AM on 26 July 2015
       The importance of good climate communication: a recent Arctic example
       

       Thanks for your kind words John!

       I've now "Storified" recent Twitter conversations with the likes of David Rose and Andrew Neil, and added the result to the article you just linked to. Here's how it looks just at the moment, but I cannot help but feel that this particular story still has (long!) legs:

       Inconvenient Truths for the Daily Mail and The Spectator

       It's interesting that two right-wing publications in the UK simultaneously attack climate policy by throwing jabs at climate science.

28214. Tom Dayton at 00:48 AM on 26 July 2015
       It's the sun
       

       APT: Dan Pangburn re-appeared in a recent comment. Read the responses there.

28215. Tom Dayton at 00:46 AM on 26 July 2015
       It's the sun
       

       APT: Dan Pangburn, the author of those claims, commented here on SkS several years ago. Please read the responses.

       Also, the cooling stratosphere is incompatible with increased energy from the Sun.

28216. APT at 23:08 PM on 25 July 2015
       It's the sun
       

       Hello,
       I'm curious about the graphs shown here: http://hockeyschtick.blogspot.com.es/2014/08/its-sun_9.html
       and here:
       http://hockeyschtick.blogspot.com.es/2013/11/the-sun-explains-95-of-climate-change.html
       Clearly this isn't published, peer-reviewed science, but I'd like to know if there's any sense to it, and if not, to understand what the problems with it are. I know a little about climate change, particularly regarding reconstructions of past environments, but I'm out of my depth trying to understand these sunspot calculations.
       Many thanks.

       Moderator Response:

       [TD] Hotlinked the URLs. In future please do that yourself with the link button in the comment editing controls.

28217. Tom Curtis at 20:37 PM on 25 July 2015
       Arctic sea ice loss is matched by Antarctic sea ice gain
       

       Rovinpiper @11, not it is not.  That is because the Arctic is an ocean surrounded by land, while the Antarctic is land surrounded by ocean.  The important effect of that is that while in principle summer sea ice in the Arctic can shrink to zero, thereby exposing the entire Arctic ocean with its much lower albedo than sea ice; the Antarctic sea ice shrinking to zero still effectively left the entire polar region above 70 degrees south covered by land ice, and hence maintaining the same albedo.  As the Arctic sea ice shrinks will within that 70 degree circle, the consequence is a much larger Arctic impact on seasonal albedo.

       This is discussed in the intermediate version of the original post.

28218. Harry Twinotter at 20:14 PM on 25 July 2015
       An experiment into science blogging
       

       Is this the "experiment" the conspiracy types are currently going on about?
       
       Never let the truth get in the way of a good story :-)

28219. Rovinpiper at 19:54 PM on 25 July 2015
       Arctic sea ice loss is matched by Antarctic sea ice gain
       

       dcpetterson,

       Isn't the situation just the reverse six months later, when it is Southern hemisphere summer? I would think, that if the ice gain in the South were equal to the ice loss in the North there would be no change in albedo fo Earth as a whole over the year.

28220. John Mason at 19:01 PM on 25 July 2015
       The importance of good climate communication: a recent Arctic example
       

       Neat work Jim and Phil and I note that a scan of the print version with "decades" is there on your blog. I've updated the post to mention your efforts with a link to the blog.

28221. Rovinpiper at 18:39 PM on 25 July 2015
       Arctic sea ice has recovered
       

       Interesting. Looking at this figure:

       arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.area.arctic.png

       Northern sea ice is down about 2 million square kilometers since 1979....

       Okay, this post just went completely off of the rails. I read in Forbes that total polar ice extent has decreased by less than 10% since 1979. Of course, we are talking about Arctic ice here, and the Antarctic is completely different. 

       I guess it is correct to say that sea ice area and extent are far less sensitive to changes in temperature than is sea ice volume. That sets up an insidious tipping point, doesn't it?  We've lost maybe half of the Arctic's ice volume, but that change in albedo has hardly begun to take effect. 
       
       Then again, Antarctica is gaining ice which will make it more reflective. How does that affect the overall balance?
       
       If we have a much less reflective Arctic, but a more reflective antarctic, what are the implications of the uneven heating of the planet?

28222. dvaytw at 15:10 PM on 25 July 2015
       Scientific consensus and arguments from authority
       

       I'm a big fan of Potholer.  That said, I'm less than crazy about this one.  I don't like this point at all:
       
       "We don't know if there's a consensus on ~any~ scientific theory"
       
       This is just the kind of out-of-context quote that denialists love to grab at, and in this case, it wouldn't even be too much of an egregious cherry pick, because, while Potholer goes on to say you ~could~ count citations and so forth, he doesn't actually come out and explain that, yes, in fact, this has essentially been done in John Cook et al and others.  Nor does he mention the IPCC assessments, which to me already seem the most explicit statements of a consensus opinion on Earth.  

       Maybe I'm missing subtlety here, but trust me: if I missed it, fence-sitters without much opinion missed it more, and denialists, ten times as much.

       Also, he goes on rather a lot about the "Conspiray Theory" Tim Ball episode.  It is really funny and incredible - but a bit trivial.  

       What I was hoping to hear more about was denialist canards about appeals to consensus... things like "Science isn't done by consenus" or "The consenus has been wrong before", "That's just an Argumentum ad Populum" etc.  I realize some of these aspects have been addressed well by Orac, Steven Novella and others, but it would be nice to hear them addressed in Potholer's particular style in a video format.  

        

28223. ryland at 14:21 PM on 25 July 2015
       2015 SkS Weekly News Roundup #30B
       

       Oh sorry I should have stated I was replying to comment 1.  I didn't think to as it was the only comment on the thread .  

       Moderator Response:

       [JH] No problem. I read your comment in isolation so I didn't see the connection to the prior comment. 

28224. dvaytw at 13:56 PM on 25 July 2015
       In charts: how a revenue neutral carbon tax cuts emissions, creates jobs, grows the economy
       

       Thank you, Tom.  Just from the tables I posted above, I was already getting the sense that the BI chart had serious issues.  How can that guy get away with publishing that... it appears to be a blatant fabrication.

       As far as the Murray and Rivers article, great stuff.  It's clear from this though (among other things) that the collective action problem renders such measures much less effective than they otherwise could be.  

       There seems to be some momentum going now, parly thanks probably to clear indicators of current AGW impacts and a very obvious end to the so-called Pause (not that there ever was such a pause, but the average person needs to see it reflected clearly in the year-to-year surface temperature charts, apparently).  Let's hope it carries through to a real effect in Paris.

28225. ryland at 13:46 PM on 25 July 2015
       2015 SkS Weekly News Roundup #30B
       

       Sorry JH but I don't know what you mean by OP.  My comment was made in response to a piece on BBC news a couple of days ago commenting on the UK government's plans to scale back subsidies to renewables. Roger Harrabin was interviewed and was, as you might imagine, not entirely enamoured of the plan. One of the links above was to a UK government website.   I also read a piece on the plan in the Guardian and gave a link to their comments. I hope this answers your query.

       Moderator Response:

       [JH] OP=Original Post 

       BTW, comments need context if they are to be meaningful to the reader.

28226. wili at 12:13 PM on 25 July 2015
       2015 SkS Weekly News Roundup #30B
       

       Any plans to post any response to or summary of the Hansen et al. paper on sea level rise and related issues that just became public?

       
       rs has a nice summary on his blog: robertscribbler.com/2015/07/24/warning-from-scientists-halt-fossil-fuel-burning-fast-or-age-of-superstorms-3-20-feet-of-sea-level-rise-is-coming-soon/

       Moderator Response:

       [JH] It's a draft paper subject to open review. If individual members of the SkS all-volunteer author team want to comment on it, they are certainly free to do so. 

28227. bozzza at 11:59 AM on 25 July 2015
       The importance of good climate communication: a recent Arctic example
       

       @12, all quibbles are welcome here. Seeing as I've been telling the internet for quite a long time now that 'Science is consensus and it starts with nomenclature' I'd better get my nomenclature right... it might give me half a chance, cheers!

28228. mancan18 at 10:19 AM on 25 July 2015
       Global warming deniers are an endangered species
       

       In Australia, Climate Change denial does pay. Australia is one of the world's largest coal exporters, a significant proportion of it's power generation comes from coal, and coal products are an important component the national income that underpins Australia's wealth. As a result, attitudes towards climate change follows party lines, with one party, Labor, promoting it as a serious issue and the other, Liberal/National Party, while giving it token support, take a "lukewarmer" position. This is the reason that the Government has implemented it's clayton's climate change policy, "Direct Action" and has attacked the climate advisory bodies, climate change funding arrangements for developing needed technologies, and promoted many climate change deniers to important positions upon it's economic advisory bodies.

       The reason for this is actually quite simple. One of the main Liberal/National party policy think tanks is the Institute of Public Affairs (the IPA). It is Australia's equivalent of the George C Marshall Institute. The IPA, along with other Liberal Party policy think tanks like the Menzies Research Centre and the H. R. Nicholls Society, all actively promote Climate Change denial. Scientists like climate change deniers, Ian Plimer and Bob Carter are attached to the IPA, providing advice related to climate change policy. Plimer is also an important member of the Mining Council of Australia, having been it's chairman, and he influences it's political stance. Gina Reinhart, Australia's wealthiest person, who made her money from huge mining projects, is also related to the IPA. She funded a Christopher Monkton speaking tour of Australia, at the height of the ETS/Carbon Tax debate when Labor tried to introduce an ETS. The IPA is also an important source of climate change denial material and underpins the political stance of Murdoch media outlets who reach around 83% of the Australian population, where right wing commentators like Andrew Bolt, Miranda Devine, and Piers Ackereman, and right wing shock jocks like Alan Jones and Ray Hadley, disseminate IPA inspired climate change denial material to their readers and listeners.

       Also, the IPA, through it's journal, provides climate change material to its readers, and it's latest effort comes in the form of a book called "Climate Change - the Facts 2014" with contributions from Ian Plimer, Richard Lindzen, Bob Carter, Nigel Lawson, Bill Kininmonth, Willie Soon, Christopher Monckton, Garth Paltridge, Richard Tol, Brian Fisher, Bob Carter, Donna Laframboise, Anthony Watts, Alan Moran amongst others and other climate change deniers. Also, this book seems to form the basis of Matt Ridley's latest essay in June's Quadrant magazine "How the Climate Wars Undermine Science", where John Cook's Consensus Project is discredited, (in their eyes), by referring to it as being biased and unrepresentative.

       Now I don't know about you, but, I don't think that climate change deniers are being marginalised in Australia. If anything, they are still pre-eminent due to the IPA's political and media reach. Trying to take effective action to tackle climate change in Australia has already seen the toppling of two prime minsters and a leader of the Liberal Party who did think that the issue was important. It will be a significant issue in the next election but whether the electorate will embrace it, after a fear campaign related to the hip pocket nerve and xenophobic fears related to asylum seekers, is questionable.

       While it is easier to have a debate with like minded people; what is happening in Australia, while the Sydney Morning Herald and the Guardian do present material properly conveying the 97% consensus; demonstrates why climate change advocates need to be more engaged with the climate change deniers from the IPA, the Murdoch press, and the right wing shock jock community, because, at the moment the denier/lukewarmer argument is still pre-eminent and not getting it's proper voice with Australia's public.

28229. The_Debtor at 07:07 AM on 25 July 2015
       It cooled mid-century
       

       Here's an updated version of the 'Radiative Forcing since 1750' chart. There is even a section that shows the forcing in 1950 relative to 1750. It is NOT negative. Though I strongly suspect that since reconstruction of past aerosol concentrations and their effects on radiative forcing going back to 1750 is highly controversial and involves a lot of errors.

       Either way, the IPCC's AR5 version of that chart does not seem to support the notion that aerosols exerted enoguh negative forcing to contribute to a slight cooling trend.

28230. Phil at 05:29 AM on 25 July 2015
       The importance of good climate communication: a recent Arctic example
       

       Just to say that I managed to get the Mail to change the wording of the article from "decades" to "years". You can see some of my correspondence on Jim Hunts blog. A small victory perhaps!

28231. Jim Hunt at 05:00 AM on 25 July 2015
       The importance of good climate communication: a recent Arctic example
       

       Tom/Bozzza - There are so many areas of apparent misunderstanding on the Mail's part it's hard to know where to begin when demanding a correction.
       
       A simple "letter to the editor" most certainly won't cut the mustard! Perhaps a set of graphs in print plus Andy's video online might go some way towards setting the bitterly twisted record straight?
       
       After listening to Radio 4 last night it seemed sensible to try and set the record straight for the BBC as well:

       Inside the BBC’s Arctic Sea Ice Science

       Not as far off track as the Mail, but far too much emphasis on a "WHOPPING 41% [increase] on the previous year!" for my taste, I'm afraid.

28232. Tom Dayton at 01:40 AM on 25 July 2015
       Models are unreliable
       

       dvaytw: Climate Lab Book has a comparison that is updated frequently.

28233. dvaytw at 01:09 AM on 25 July 2015
       Models are unreliable
       

       I'm looking for a good graphic showing where the surface temperature models with the latest observed temperatures added.   Anyone know of one?

28234. ryland at 00:59 AM on 25 July 2015
       2015 SkS Weekly News Roundup #30B
       

       It seems the UK is moving in the opposite direction by reducing subsidies on renewables Perhaps this is a reflection on David Cameron's comment  that "polices that increased household bills are green crap

       Moderator Response:

       [JH] I presume your comment is in response to one of the articles listed in the OP. Which one?

28235. CBDunkerson at 00:35 AM on 25 July 2015
       2015 SkS Weekly News Roundup #30B
       

       I've been saying for a few years now that US coal was being killed off by economic forces. A Washington Post article seems to confirm this. New Obama administration EPA regulations which would sharply cut back on coal power are about to go into effect and the GOP had been promising all out war to block them... only to discover that most states are already on track to meet the requirements without any regulatory pressure at all. Natural gas, wind, and solar have been decimating US coal. Coal plants are being shut down en masse... years before end of life. That has changed investments in those plants into losses... which in turn has virtually eliminated investment in and development of new coal plants. More than 70% of the new US electricity deployed so far this year has been renewable.

       Natural gas isn't as cheap for the rest of the world, but wind and solar are and will soon be having a similar impact world wide. Even China and India are now looking at reducing their plans for coal, and that change will only accelerate as wind and solar costs continue to fall. Coal is dying.

28236. chriskoz at 00:24 AM on 25 July 2015
       Lomborg: a detailed citation analysis
       

       Huh! The LNP govs did not give up on this pathetic effort and they want to place Lomborg in Flinders Uni now. Hold your breath about the "Australian pride". Will see if FU (or yet another education institution before the project collapses) accepts the lure of $4m govt grant...

28237. Jutland at 00:15 AM on 25 July 2015
       Climate's changed before
       

       Tom @490, ah that's helpful, thank you. I had not realised that albedo changes had such substantial historic effects on past climates. I will read Hansen's paper. 

       It is reassuring to know that we need to reach c 950 ppm before Antarctica warms by 10C above pre-industrial, because that's about 183 years away (assuming a linear 3 ppm annual rise in CO2) and human energy use will presumably have moved off fossil fuels sometime well before then. At least I hope so.

28238. chriskoz at 00:14 AM on 25 July 2015
       The importance of good climate communication: a recent Arctic example
       

       bozzza@10,

       This thread (where, interestingly in your comment therein, you've coiled a term 'clever country') is the appropriate place to talk about Lomborg. Your upbringing of Lomborg & 'clever country' here does not make any sense & I would not be surprised if it was deleted.

28239. Tom Curtis at 22:43 PM on 24 July 2015
       Climate's changed before
       

       Jutland @488, you are correct that orbital forcings only kick of the variation between glacial and interglacial; and also that CO2 forcing is a major driver of the temperature change.  It is, however, not the major driver.  Rather, albedo effects from changes in sea ice extent, growth of ice sheets and reduction in forest cover.  Hansen quantifies the differences in his well known paper, Target Atmospheric CO2, saying:

       "Climate forcing in the LGM equilibrium state due to the slow-feedback ice age surface properties, i.e., increased ice area, different vegetation distribution, and continental shelf exposure, was -3.5 ± 1 W/m²relative to the Holocene. Additional forcing due to reduced amounts of long-lived GHGs (CO2, CH4, N2O), including the indirect effects of CH4 on tropospheric ozone and stratospheric water vapor (fig. S1) was -3 ± 0.5 W/m². Global forcing due to slight changes in the Earth’s orbit is a negligible fraction of 1 W/m²(fig. S2). The total 6.5 W/m²forcing and global surface temperature change of 5 ± 1°C relative to the Holocene yield an empirical sensitivity ~¾ ± ¼ °C per W/m²forcing, i.e., a Charney sensitivity of 3 ± 1 °C for the 4 W/m²forcing of doubled CO2. This empirical fast-feedback climate sensitivity allows water vapor, clouds, aerosols, sea ice, and all other fast feedbacks that exist in the real world to respond naturally to global climate change."

       6.5 W/m^2 is the equivalent to the forcing of a 3.4-fold increase in CO2 concentration.  In otherwords, we should expect a 10 C increase in Antarctic temperatures with an increase of CO2 from 280 ppmv to 952 ppmv.  That, of course, is just the Equilibrium Climate Sensitivity (ECS) which does not include the impacts of long term feedbacks such as the melting of ice sheets.  Including those will result in higher temperatures, but only after the course of many centuries.  What is more, if we are sensible and end all CO2 emissions, CO2 concentrations will fall significantly so that we will never experience the Earth System response to the peak CO2 levels. 

28240. Jutland at 21:44 PM on 24 July 2015
       Climate's changed before
       

       

       Apologies, here's the image correctly linked

       Jutland

28241. CBDunkerson at 21:33 PM on 24 July 2015
       Global warming deniers are an endangered species
       

       anticorncon6, yes the article is suggesting that global warming deniers are getting less common. This is backed up by surveys. There is an old saying that new scientific paradigms are never 'accepted'... it's just that all of their detractors eventually die out. We're seeing the same thing with global warming... disbelief of the physics is disproportionately found amongst the elderly.

       As to when they will finally die out completely... I'd say that we will continue to have global warming deniers until the fossil fuel interests funding the disinformation campaign lose their financial clout. Then the new moneyed interests will tell the deniers that they all believed in global warming all along, and so shall it be. Should be less than twenty years before the start of the 'great conversion'.

28242. MA Rodger at 21:32 PM on 24 July 2015
       NOAA State of the Climate report: Which seven records were broken in 2014?
       

       The graphic discussed @1 to 3 came from this NOAA web page and, as the caption there now reads, the graphic's datum should have read (and now does read) "1993 average" not the un-corrected "1993-2013 average" as in the post above.

28243. Jutland at 21:32 PM on 24 July 2015
       Climate's changed before
       

       I find this particular image in AR5 WG1, figure 5.03 about climate over the past 800,000 years, a bit scary:

       

       Its purpose is to demonstrate the correlation between past climates and insolation changes, which is why it shows precession, obliquity and eccentricity. But these orbital factors only kick off each period of heating, it's clear that CO2 does most of the work in raising temperatures, and it is the correlation between CO2 and temperatue in the diagram which is what interests me.

       CO2 has each time risen from about 200 ppm to about 280 ppm, or thereabouts, which is roughly a 40% rise. What I find worrying is that this 40% CO2 rise seems to correlate consistently with a rise in Antarctic temperature of about 10C. That is a large effect. (And it's just 40%; a doubling of CO2 would be even larger.)

       Anthopogenic CO2 is now 40% above pre-industrial levels (280 ppm up to 400 ppm) so does that mean we already have 10C locked in for the polar regions?

28244. CBDunkerson at 21:24 PM on 24 July 2015
       The importance of good climate communication: a recent Arctic example
       

       bozza @8, just a quibble. Technically, volume = area x thickness... and area = extent x concentration.

       There usually isn't a big difference between area and extent because the average concentration is relatively near 100%. However, sometimes, such as right now, you get large swaths of ocean covered with low concentration broken up ice and thus the actual surface area of the ice is significantly less than the extent of ocean with ice.

28245. Tom Curtis at 20:08 PM on 24 July 2015
       The importance of good climate communication: a recent Arctic example
       

       Jim Hunt @2, perhaps you need to say it with pictures, given that the lawyer is so mathematically challenged.  Ie, sea ice volume anomaly (what the article should have been talking about):

       

        

       And sea ice extent anomaly (what the article in fact talked about):

       

       From these it is clear that the 2014 arctic sea ice volume is lower than that of any year prior to 2008, and the 2013 sea ice extent lower than that of any year prior to 2007.

       Put another way, for the daily mail "decades" means nine years or less.

       Of course, that particular mathematical incompetence may well pass muster with a fact checker who does not know (apparently) that 1/x * x = 1, or that the final value in a time series does not always lie on the trend line.

28246. bozzza at 18:28 PM on 24 July 2015
       Global warming deniers are an endangered species
       

       The global warming denier hides as the global warming negotiator,... hence Bjorn Lomborg still being offered University status at Flinders University to spruik his idea that fossil fuels should be allowed to warm our kids earth by 3 degrees instead of 2... 

       He doesn't deny global warming, you must understand, ..just asks why fossil fuels shouldn't be allowed a bit more breathing room to continue making profits for a little bit more!

       (Like an ear worm he will make you sing along if given airplay!!)

       The global warming denier is Abbott hiding as, of course- this is politics, the negotiator! Wow, strategy and stuff.... just watch Holloywood and vote for whatever...cool, yeh! Beer is in the fridge and we've got hotdogs yay!

28247. bozzza at 18:12 PM on 24 July 2015
       The importance of good climate communication: a recent Arctic example
       

       If Lomborg gets the gig at Flinders University will that increase or decrease the good communication of climate science?

       More to the point, if Lomborg gets the gig at Flinders University will that be the last straw for the once allegedly 'clever country',... ?

28248. bozzza at 18:06 PM on 24 July 2015
       The importance of good climate communication: a recent Arctic example
       

       First, yes, extent decreased since 1979, but the paper is about volume (which is extent x thickness). Second, the 41% increase is with regards to the 2012 mega-record low, which was 80% lower than 1979, off the top of my head. Third, this is a pure lie: “the northern ice-cap INCREASED by a staggering 41 per cent in 2013 and, despite a modest shortage last year, is bigger than at any time for decades.” It’s not an ice cap, and the Arctic sea ice pack isn’t bigger than at any time for decades.

28249. Jim Hunt at 17:41 PM on 24 July 2015
       The importance of good climate communication: a recent Arctic example
       

       bozzza @7. Have you followed the link and read the comments? If so, what do you fail to understand?

28250. anticorncob6 at 14:22 PM on 24 July 2015
       Global warming deniers are an endangered species
       

       Is this article actually suggesting that global warming deniers are getting less common? I find that difficult to believe. I've always believed that, until global warming gets so bad that nobody can ignore it or dismiss it as a natural cycle or an illusion, we will always have global warming deniers.

       With all the recent news about climate change, I'd say that AGW deniers are getting angrier and more aggresive because of it, and are not struggling to stay in denial at all.

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