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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 29351 to 29400:

  1. Ask Me Anything about Climate Science Denial

    An intriguing case study in denialism is climate scientist Cynthia Nevison complaining about global warming deniers, but vigorously promoting anti-vaccine crankerism and even being a leader in that "field."  Respectful Insolence has details.  I truly am intrigued by her case, from a psychological standpoint; John Cook, do you have any thoughts on how she maintains those two contradictory positions? 

  2. Tom Harris' Carleton University Climate Misinformation Class

    Vancouver Province is definetly biased against climate science. I was mildly suprised to see my letter made it in at all.

  3. Ask Me Anything about Climate Science Denial

    An interesting list of denialist tactics is on SkepticalRaptor.com.

  4. anticorncob6 at 10:00 AM on 14 May 2015
    It's not urgent

    You said here that carbon concentrations will peak at 400 ppm in 2025 under the ideal situation, but it's only 2015 and we're already at 400 ppm, and I see no signs of global emission reductions happening soon. Is this evidence that we will pass the point of no return?

  5. What do volcanic eruptions mean for the climate?

    That's a very useful little diagram Howard.

  6. Antarctica is gaining ice

    UW/bozzza - Perhaps this is a canonical example?

    https://dohumanscauseglobalwarming.wordpress.com/

  7. Antarctica is gaining ice

    UW - Perhaps I'm being naive. but it seems bozzza understands all that. I ultimately understood his question to be "how might one wrap all that up neatly in a catchy headline", or at most a sentence or two.

    "Real-politik" rather than "Rignot et al."?

  8. UltimateWarrior at 04:42 AM on 14 May 2015
    Antarctica is gaining ice

    bozzza,  Re the data you reference regarding 2D ice extent increases in Antarctica, the 3D ice mass budget studies indicate large accelarations in the rate of 3D ice loss (mass not 2D measurment).

    See the article SOTC: Ice Sheets, which refernces these studies (Rignot et al. 2008).

    The 2D ice extent in the Arctic (north pole) indicates a downward trend.

  9. 2015 SkS Weekly Digest #19

    Black humor for today at the New Yorker:

    Scientists: Earth Endangered by New Strain of Fact-Resistant Humans.

  10. What do volcanic eruptions mean for the climate?

    Just to note that this article relates to 'normal' volcanic eruptions. Regular visitors to this site will recall there have been several articles on Large Igneous Provinces that have occurred rarely in Earth's past, were colossal, and which generated dire environmental consequences including global warming. Some article links: here  and here and here.

    LIPs are an altogether different phenomenon than normal volcanic eruptions.

    There have also been Supervolcano eruptions much larger than 'normal' volcanic eruptions (but much smaller than LIPs) as summarised by the USGS here.

    I put together this handy dandy graphic so people can get an idea of the relative scale of these things. The area of each circle represents the volume of lava erupted.

    LIPs compared to supervolcanoes and normal volcanoes

    Moderator Response:

    [RH] Resized image. Remember to keep images down to 500px.

  11. What do volcanic eruptions mean for the climate?

    Nitpick: Maybe change the first sentence of the post to indicate that Calbuco erupted on April 22, 2015, rathe than last night. 

  12. 2015 SkS Weekly Digest #19

    Follow-up to HK on GISS L-OTI for April:

    — 2nd warmest April (2010 - .85)

    — 14th warmest month (tied)

    — 2nd warmest 12-month period

    — The last five 12-month periods have been top five warmest

    — 2nd warmest 6-month period (last four are top four)

    — Warmest 36-month period (last four are top four)

  13. 2015 SkS Weekly Digest #19

    GISS has released their April data: +0.75°C.

    The average so far this year has been +0.79°C (record!), and the last 12 months +0.73°C (also record!).

    Most forecasts predict a strengthening of the ongoing El Niño, so 2015 will almost certainly become the first year warmer than +0.7°C, and maybe even warmer than +0.8°C. The following months will be very interesting!

  14. Climate's changed before

    skeptic1223's over-enthusiasm for linking present-day CO2 levels to some threashold CO2 level which allowed the era of ice-ages to kick off appears to have run its course. Yet he did present one aspect of climate that seldom gets discussed.
    skeptic1223 began his input way up @420 with the observation that orbital forcing had become a bigger feature of climate since the inception of the Arctic glaciation by creating higher ampitude oscillations in the global temperature record. The graphic below (derived from Lisiecki & Raymo (2005) Fig 4) was presented @423 by way of illustration.
    tempeature 5Mybp
    Such apparent increases in ampitude do support the idea of an increase in climate sensitivity in some manner as in the long run orbital forcing cycles are constant in size. Such forcing is large at specific latitudes while small globally. To suggest this increased ampitude (and thus increased sensitivity) is somehow a function of CO2 levels is of course wrong. But it does beg the question - why doesn't this increased ampitude in oscillation make ECS vary with temperature/Arctic glaciation?
    My view of this is that to calculate the sensitivity of climate to orbital forcing from what appears a hysteresis loop could be used to show big sensitivity changes but these would not be very helpful for our purpose of finding ECS under AGW. Thus the slow feedbacks of albedo, CO2, methane, etc. are considered as forcings rather than feedbacks to allow a meaningful ECS to be calculated.
    The reference cited by AR5 in this matter is PALAEOSENS Project Members (2012) which states:-

    "Astronomical (orbital) forcing is a key driver of climate change. In global annual mean calculations of radiative change, astronomical forcing is very small and often ignored. Although this obscures its importance, mainly concerning seasonal changes in the spatial distribution of insolation over the planet, we propose that the contribution of the astronomical forcing to (the climate forcing) may be neglected initially. When other components of the system respond to the seasonal aspects of forcing, such as Quaternary ice-sheet variations, these may be accounted for as forcings themselves."

    This accounting of slow feedbacks as forcings is a reason for ECS only accounting for fast feedbacks.

  15. Monthly global carbon dioxide tops 400ppm for first time

    Phil Plait has a very clear message about this topic here.

  16. 2015 SkS Weekly Digest #19

    Is it just me that gets some amusement/bemusement from the fact that Newsel did not bother to post to the moderator suggested links?  I seems that one statement of misinformation is much better than actually educating ones-self.

  17. Monthly global carbon dioxide tops 400ppm for first time

    CBDunkerson @5,

    in another year or so we'll hit 400 ppm as the annual average

    Note the trend column in the monthly data, which just topped 399 in March. So, at current rate of over 2ppm/y, the trend will hit 400 in jsut 5-6months, very likely sooner than in a year.

    As for your FF future assessment, unfortunately, there are big areas where FF cannot be replaced by renewables yet, e.g. transport, esp. aviation. That's why oil and gas still have future beyond your decadal limit. I agree with you with respect to coal: it's use as the source of energy should've already been superceded by cheper and cleaner renewables, political will being the biggest barrier at the moment.

  18. Tom Harris' Carleton University Climate Misinformation Class

    Newspapers are biased: it's hard not to be when all human relations is tribal.

    Saying that a well worded short letter to the editor is hardly ever published because it can't be easily edited: hence the success of online forums and the associated troll phenomenon! Saying that well worded short letters than can't be easily edited into non-meaningful blather have real bite but only over time.. go democracy! 

  19. Tom Harris' Carleton University Climate Misinformation Class

    Tom wrote a letter to the editor of the local paper where I live. It was an anti Earth day piece. He made secveal common denialist points. I wrote a rebuttal refuting each point he made (very easy) but only about half of my short letter made it into the paper. It was the Vancouver Province.

  20. GHG emission mitigation solutions - a challenge for the Right?

    Interesting article http://www.vox.com/2015/5/12/8588273/the-arguments-that-convinced-this-libertarian-to-support-a-carbon-tax

    on what convinced a liberatarian and his solution.

  21. 2015 SkS Weekly Digest #19

    Good points, utr. If events alone could sway people's minds, states like Oklahoma and Texas, which have been through harrowing droughts recently, should be in the forefront of climate awareness.

    But as it is, they host some of the most backward thinking people and senators in the Union.

  22. Ice loss in west Antarctica is speeding up


    Also => Sea Level Rising Faster. Ice Loss Speeding Up.

    Moderator Response:

    [RH] Resized video. Please try to keep the image width to 500px as anything above that breaks the page formatting for this website.

  23. Climate's changed before

    skeptic123 @463, looking at the Vostock data another way, I examined in detail each of the four transitions from inter-glacial to glacial in the Vostock data.  From each such transition, I determined the minimum interval for the transition, calculated as the time from the most recent relevant datapoint above -2 C to the time of the first datapoint following which was below -4 C.  The relevant intervals were, from oldest to newest:

    3426 years (average rate of decline = -0.006 C per decade)

    4399 years (average rate of decline = -0.005 C per decade)

    2654 years (average rate of decline = - 0.008 C per decade)

    2028 years (average rate of decline = -0.01 C per decade)

    (Note: the rates of decline are for a regional temperature value.  Global values would be about half that.)

    No matter how many times you repeat the quote, the data does not support it.  Further, science proceeds by evidence, not by out of context quotation (which is rather the mark of pseudoscience).

    Now, it is possible that the scientists who made that claim define an "ice age" as any period with a temperature anomaly less than x, where x is -0.5, or -0.1, or some other arbitrary value.  It is also possible that they consider temperatures of x + 0.5 C as "a warm climate".  In that case, what they say is true, trivial, and so vague without the specification that that is how they interpret their words, and a specification of x as to be useless.  If you want to use the quote, it is therefore incumbent on you to find out the exact interpretation the authors give to the words.

    Absent that effort, however, it remains that the data directly contradicts the claim supposedly based upon it.  So, if you are not prepared to make the effort to provide the context of the quote on whose authority you rest, it is incumbent on you to follow the data.  Failure to do so simply demonstrates that you accept data only if you think it supports your position.  Worse, it shows that you present data that in fact falsifies your position as supporting it, and refuse to acknowledge the detailed examination that shows that the data refutes your position.  Again, those are the hallmarks of pseudoscience.

    Long experience has shown that debating with pseudoscientists is completely unprofitable in that their positions are not based on reason and evidence, and therefore cannot be altered by either reason or evidence.  I also think that the complete divorce of your opinions from actual data is sufficiently evident to any interested readers that I do not need to spell it out again.  Consequently I will ignore your responses in future until such time that you start correcting your position based in the actual data.

    Moderator Response:

    [JH] Your above comment is actually directed at skeptic1223.

  24. Antarctica is gaining ice

    I am saying it makes the fight to have climate science recognised by the trolls more difficult, yes!

  25. Antarctica is gaining ice

    bozzza@391 - So you're seeking a punchy "elevator pitch" that addresses the misleading headlines of Nova et al.?

    And/or suggesting that this article needs updating to include the 2014/15 numbers?

  26. Rob Painting at 19:47 PM on 12 May 2015
    The Carbon Bubble - Unburnable Fossil Fuels - Seminar and Discussion

    Rolf - oxygen makes up about 21% of Earth's atmosphere and CO2 about 0.039%. Furthermore, we know life has flourished prior to the addition of fossil fuel CO2 to the atmosphere by humans so, if we could bring back to a pre-industrial level, there would be ample oxygen available for plant and animal life.

    There's no need to worry about CCS other than that it is so far as useful as the tooth fairy and unicorns.

  27. 2015 SkS Weekly Digest #19

    @ Will.  It will be interesting to see how "natural variabilty" (eg El Nino) is viewed in western Queensland which is already suffering a drought.  My - admittedly limited with some friends who live in Roma - experience is that their political leanings prevent any discussion that the climate is changing and that these extended droughts may become the norm.  I certainly feel their pain as their livelyhoods are destroyed, but dissociating politics from science is a hard one in a tough, unforgiving (climate wise) region.

  28. 2015 SkS Weekly Digest #19

    BoM just called it: "the Bureau's ENSO Tracker has been raised to El Niño status"

    www.bom.gov.au/climate/enso/

  29. Antarctica is gaining ice

    Ok, I was just saying the numbers look weird and I think that is worthy of considered comment as to why.. I haven't understood the meaning of statistical significance but as far as sea-ice area graphs of Antarctica are concerned the last few results seems to be worth talking about.

     

    I get the mechanisms discussed but the real-politik of statistics and publicly inspired meaningful thresholds cannot go unanswered.

  30. The Carbon Bubble - Unburnable Fossil Fuels - Seminar and Discussion

    CCS worries me because CO2 is two thirds oxgen. CO2 in the air could eventually be used by plants and the oxygen returned to us. If it is locked away forever we have lost that oxygen and reduced the atmosphere as a whole. Let's just focused on reducing the production of co2.

  31. Antarctica is gaining ice

    I not entirely sure I understand your concern. As far as I can see, the article is comparing Winter Antarctica seaice (no climaticalogical effect because it happens when the sun isnt shining), versus Summer Arctic sea ice (where the loss is significant due to reduce albedo). The skeptic narrative is that northern hemisphere warming is more than matched by southern hemisphere cooling (sea ice as evidence). However the narrative fails because sea ice increase isnt due to SH cooling - the Antarctic is warming too. Its just that real situation is more complicated.

    A better comparison is to compare the climatological effect from sea ice albedo between hemispheres. Tamino did that here - compare that with the rather deceptive approach at Nova.

  32. 2015 SkS Weekly Digest #19

    Climatologists are obtaining copious amounts of evidence of unusual events such as icebergs melting, ocean currents changing, etc, etc. to be taken into account in models and in the logical arguments to arrive at a sound view of what is almost certainly happening, global atmospheric warming with associated ocean heating and acidification.

    The unsubstantiated beliefs of deniers of irreversible, rapid climate change caused largely by the emissions from the combsution of fossil fuels are not making a contribution to the understanding that would help society to adopt mitigation measures. Are they proud of their malfeasance?

  33. Antarctica is gaining ice

    I'm not denying the article is helpful in explaining that ozone depletion is causing wind increases and melting of land ice plus rain increases are freshening the Southern ocean changing the layers so that warm and cold waters don't mix like they once did... I'm simply saying the numbers look curious.

  34. Climate's changed before

    skeptic1223@470.
    "It doesn't directly," you write. Indeed it doesn't make that assertion at all.
    Now you are asserting that "we know that 3 million years ago CO2 concentrations were the same as today's." You provide a quote from a livescience blog but is your assertion supported by this livescience blog? The answer is "no".
    If you could be bothered to examine the Scripps posting referenced by your livescience blog, you will see that it talks of "The Pliocene is the geologic era between five million and three million years ago. ... It is trickier to estimate carbon dioxide levels before then(800kybp), but in 2009, one research team reported finding evidence of carbon dioxide levels ranging between 365 and 415 ppm roughly 4.5 million years ago." So this citation is actually a little early for our purpose and the range of CO2 level has mostly been left behind by today's anthropogenic emissions.
    Perhaps you can find some support for your assertion elsewhere. But then do bear in mind the actual age we are interested in is the point that Arctic glaciation kicked off which I believe was 2.7Mybp.

  35. Antarctica is gaining ice

    In which case doesn't this very article answer your question in great detail?

    If not you will need to elucidate in much greater detail!

  36. 2015 SkS Weekly Digest #19

    I find it amusing that deniers (recently) admit the climate is changing but claim it has "always changed".  Of course, the climate has changed in the past, but it has not "always changed" in the sense that there have been long periods of relative stability/very slow change in the recent and distant past.  But the really telling thing about this argument is the implicit acceptance of the paleoclimate research that identified dramatic climate change events going back as far as hundreds of millions of years.  Of course, these are bona fide research results which should be accepted in the absence of convincing evidence to the contrary.  But these same deniers will scoff at paleoclimate reconstructions going back only a few thousand years and showing that the recent onset of global warming is highly unusual, unexpected and unexplainable in the absence of AGW theory.

    So I put the question to Newsel:  Is paleoclimatology a legitimate science or not?  If not, quit claiming that the climate "has always changed" because there is no evidence for that outside of paleoclimatology.  If it is legitimate, then you must accept the work of Mann, Marcott and many others who have proven that the recent GW event does not look like a natural event and can only be explained by human GHG emissions.

  37. michael sweet at 01:43 AM on 12 May 2015
    2015 SkS Weekly Digest #19

    It might be interesting to open a thread where people can post old quotes from deniers claiming that the climate is not changing.  They used to argue that climate was not changing.  Now they claim that:

    "The reality is that the climate changes and that no one on either side of the debate argues otherwise."

    It might not be necessary to have an OP, just a place where people can put links to old quotes.  I recall that Lindzen testified to congress in 1989 that the climate would stay the same.  WUWT claimed the climate was not changing until a few years ago.  Singer still claims that change is natural and the climate is not changing at the same time.

  38. Climate's changed before

    skeptic1223 - As numerous posters have pointed out, there is really no evidence supporting a risk of sudden glaciation right now. The ice age cycles have in the past been driven by Milankovitch forcings, orbital changes, episodes like the Younger Dryas cooling event were as far as we can tell due to conditions (giant ice dams releasing) that simply don't exist today, and were regional, not global. 

    Our emissions have essentially removed any chance of a glaciation for the next Milankovitch cycle - we're just not at risk of an ice age. On the other hand, the warming we've already committed to points toward mass extinctions (as climate change exceeds the speed of species movement to keep up with their environments), considerable impacts on agriculture, disease, weather, and many many other impacts

    You've presented no evidence whatsoever supporting your hypothesis, and therefore your suggestion that we need another 100-200ppm of CO2 is just absurd. There's no risk of sudden cooling, and multiplying the impacts of warming seems just foolish. 

  39. 2015 SkS Weekly Digest #19

    Kolbert, not "Kobert"

  40. 2015 SkS Weekly Digest #19

    Typo: 

  41. PhilippeChantreau at 01:23 AM on 12 May 2015
    2015 SkS Weekly Digest #19

    Newsel,

    What scientific sources argue that the projected levels will lead to a "runaway temperature increase"? I'm sure that scientific litterature treating of such an idea would have defined too, so I won't ask you what you mean by that.

    Which predictions from scientific sources has not materialized within the time frame you seem to be considering (i.e. to present day)? Sources for these predictions are necessary.

    When was it proposed and who has seriously advocated the redistribution of developed nations wealth under "UN guidance"? What exactly would that consist of?

    I'm not asking here for blog posts or newspaper editorials but substantive sources. 

  42. Climate's changed before

    skeptic1223 @468.

    Advocating increasing C02 to prevent a future ice age sounds like someone saying "Let's burn our house down today to prevent the possibility of flooding due to rising sea levels next year."

  43. Antarctica is gaining ice

    "climate change advocate" = a non-denier of climate change 

  44. 2015 SkS Weekly Digest #19

    Talk is cheap, Newsel.  How about supporting your claims with evidence?  

  45. 2015 SkS Weekly Digest #19

    To the “message” in the cartoon and other similar comment: They are factually incorrect but now that the discussion has changed from AGW to CC or GW allows for this disinformation.

    The reality is that the climate changes and that no one on either side of the debate argues otherwise.

    What is challenged is that the climate changes due anthropogenic (AGW) causes rather than natural variability. Given that the runaway temperature increases ascribed to increasing levels of CO2 within the IPCC models (since 1995) has not materialized and the multitudes of dire predictions (also since 1995) have not materialized has to give one cause to wonder why?

    It is clear that the science is not settled and to waste precious resources and to advocate the redistribution of developed nations wealth under the guidance of the UN while trying to pretend to be able to control Mother Nature makes zero sense. It is at best a futile exercise and worst case a politically driven fraud.

    Moderator Response:

    [TD] Welcome to Skeptical Science.  Among the commenting rules here is the requirement to comment on the appropriate posts, to keep the discussion organized.  You have listed several topics, so please read the posts rebutting these myths, and then if you desire comment on those posts:

  46. Antarctica is gaining ice

    bozzza@385 - As the self same "Arctic Nerd" mentioned by Glenn above I'm afraid that I don't understand your question in this context. Is there any chance that you can rephrase it? What precisely is "a climate change advocate" in your terminology?

  47. Climate's changed before

    @469, it doesn't directly, however it states that the reason for the glaciation were atmospheric and oceanic conditions plus a tilt in the Earth's axis, it doesn't say anything about a sudden drop in CO2 and we know that 3 million years ago CO2 concentrations were the same as today's, so.

    "Scientists believe that the most recent period with a 400 ppm level of carbon dioxide in the atmosphere was the Pliocene, between five million and three million years ago, according to the Scripps Institution of Oceanography, which keeps track of the Keeling Curve."

    www.livescience.com/29437-carbon-dioxide-record-broken.html

  48. Climate's changed before

    skeptic1223@467.

    You write "So, according to the article the ice ages started at levels of CO2 close to today's..."

    Where exactly does the article make this assertion?

  49. Monthly global carbon dioxide tops 400ppm for first time

    I'm glad this article specified that we are talking about 400 ppm as the monthly average. Too many media reports have just said 'first time ever'... which might cause confusion amongst those who remember readings hitting 400 ppm a couple years ago... as a daily total.

    No doubt in another year or so we'll hit 400 ppm as the annual average.

    As to the fossil fuel vs renewables and 'economics' debates. The victory of renewables is inevitable at this point. Today even the nominal price is cheaper than fossil fuels for more than 50% of the people on the planet, and if the difference in health, environmental, national security, and/or direct subsidy costs is factored in then fossil fuels aren't even close to competitive. All they've got going for them at this point is inertia... the existing infrastructure and vested interests will continue to prop up the facade of a fossil fuel future for a few more years. However, for anyone paying attention it is already clear that they are on the way out. It's really just a question of how many more years (decades are off the table) before they peak. I doubt we'll be able to stay under 2C, but 3C is now a real possibility.

  50. Climate's changed before

    @465, 1-200ppm from now, that number is just an example, when the ice ages started CO2 concentration was similar to today's, before that the climate was relatively stable, so some level of CO2 above today's should make matters safe

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