Comments

1. #1 Eachran

   2010/01/04

   What do you think the discount rate should be for adaptation to and mitigation of global warming?

   The article here makes some good criticisms but in my view makes the issue far too complicated :

   http://www.springerlink.com/content/633517qw4j526470/?p=714a39e0638d4ec5895510ee283df4a1&pi=1

2. #2 Magnus W

   2010/01/04

   Well you I presume quite recently where responsible for this “A researcher in the network took it upon himself to clear the articles from anything that might interfere with the description of a unique and catastrophic global warming. Among other things, wiping out his Medieval Warm Period from history.”

   any comments on that? :)

   http://translate.google.com/translate?hl=sv&sl=sv&tl=en&u=http%3A%2F%2Fwww.dn.se%2Fopinion%2Fsignerat%2Fefter-fn-fiaskot-kolumnen-hans-bergstrom-om-behovet-att-tanka-nytt-i-klimatfragan-1.1021445

3. #3 carrot eater

   2010/01/04

   Given your interest in the cryosphere and the history of the literature, can you point out when people started realising that wind or ocean circulation patterns and the ozone hole would somewhat obscure polar amplification at the Antarctic?

4. #4 CIP

   2010/01/04

   Climate doomsayers tend to focus on worse storms (kinda bad), drowning of low lying land (pretty bad), worse draught (potentially very bad). What do you see as the worst case scenario? Is a Venusian style runaway even slightly plausible? A PETM style mass extinction?

5. #5 Steve Bloom

   2010/01/04

   OK then, I’ll repeat my request from the previous thread for you to have a look at this new paper. It’s even got sea ice! Speaking of which, I haven’t read the papers discussed in this DKos diary, but they sound interesting with regard to current trends.

6. #6 Boris

   2010/01/04

   What do you think would be a profitable price on the Intrade market 2010 to be hottest year on record (in GISS). I’m thinking anything below 35 should be +EV, and if you can buy at below 50 now, you should be able to sell for a profit after the first couple of months of El Nino.

   Lowest current ask price is 26.

7. #7 Anna Haynes

   2010/01/04

   What’s causing the observed decline in Sierra snowpack & ski conditions – what are the relative contributions of climate change, vs the Pacific Decadal “Oscillation”? (“…in the sense that it’s a variation, but …[no] firm evidence of periodicity”)

   This Q came up yesterday – a coal-suckered Tahoe-area skier said that the ski conditions are worse than they were 20 yrs ago, but believed it’s from the PDO. I said I’d check, & did some quick googling but didn’t run across anything from this millennium that directly addresses the issue.
   (FWIW, the #1 PDO site, with up to date graph, seems to be jisao.washington.edu/pdo )

   He also said that the 2 ski resorts he visited encouraged personal-footprint “drive a Prius” greenness, but didn’t try to educate their customers about the threat (including to the sport) & how best to fight it.

8. #8 Brian Schmidt

   2010/01/04

   1. What’s the protocol, if any, for IPCC use of non-peer reviewed material?

   2. What do you think of Working Group II?

   3. Want to try your hand at explaining stratospheric cooling? I still don’t have a good handle on it.

9. #9 Anna Haynes

   2010/01/04

   Any fMRI studies of contrarians making climate claims? especially of professionals vs amateurs.
   (perhaps we should we should ask Dano – “… friend who is working on his PhD in cognitive science, studying confirmation bias with fMRI” – link)

10. #10 Hank Roberts

    2010/01/04

    Here’s one, though the ‘ask’ is pretty much ‘will someone fix this’ –

    http://www.realclimate.org/index.php/archives/2010/01/the-carbon-dioxide-theory-of-gilbert-plass/comment-page-1/#comment-152977

    “… Dufresne corrected the French page of Wikipedia on Pouillet ( http://fr.wikipedia.org/wiki/Pouillet ). Unfortunately the English pages are still erroneous …”

11. #11 Vinny Burgoo

    2010/01/04

    Michael Tobis reckons the consensus (IPCC) position on the potential impact of business-as-usual AGW is on the sceptic/denialist side of ‘most informed opinion’. His chart is here:

    http://img22.imageshack.us/img22/5162/picture20n.jpg

    Where would you put it?

12. #12 Steve Bloom

    2010/01/04

    Re #7: Anna, if you search the KQED Climate Watch posts for PDO, you’ll find one (from about a year ago IIRC) from a Univ. of Santa Clara scientist demonstrating that the PDO doesn’t drive much of anything. Given what it is, that’s no surprise.

    Re the Sierra snowpack, IIRC that’s down to the observed slight warming trend (but like so many things it’s too soon for formal attribution). It’s not a large effect as yet, but recalling that our (CA) climate future is linked to what’s happening in the Arctic, go look at the mid-Pliocene SST map in the new paper I linked in #5 and note the two most prominent features. If we then compare that map with the corresponding CO2 results of Tripati et al’s Fig. 2, we see that it took only a very brief (relatively speaking and noting that the forthcoming high-res studies will add important detail) spike of CO2 to levels no greater and perhaps a bit less than current to run Arctic temps and sea levels up to the noted levels. The brief spike implies a relatively fast climate response, which given all that lovely frozen carbon up in the Arctic is really not good news.

13. #13 Steve Bloom

    2010/01/04

    Tripati et al link.

14. #14 Steve Bloom

    2010/01/04

    Re #10: Michael says that, Vinny, because climate scientists understand the implications of papers like the two I linked above. Do you recall hearing much about either in the media or from politicians? As Wally Broecker says, climate is an angry beast and we are poking it with a stick.

15. #15 Eachran

    2010/01/05

    I hope that I am allowed more than one question, so here goes.

    1. This is a numbers question. What is your guess for SLR by the end of the century. Is it still 1m? I will not hold you to your answer I just want your best judgement. What would you bet on?

    2. Do you think that now that IPCC has done its job it should be dissolved?

16. #16 PeteB

    2010/01/05

    just been rereading AR4 and saw this

    8.6.2.3 What Explains the Current Spread in Models’
    Climate Sensitivity Estimates?

    http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch08.pdf

    ‘…In the idealised situation that the climate response to a doubling of atmospheric CO2 consisted of a uniform temperature change only, with no feedbacks operating (but allowing for the enhanced radiative cooling resulting from the temperature increase), the global warming from GCMs would be around 1.2°C (Hansen et al., 1984; Bony et al., 2006).
    The water vapour feedback, operating alone on top of this, would at least double the response.6 The water vapour feedback is, however, closely related to the lapse rate feedback (see above), and the two combined result in a feedback parameter of approximately 1 W m–2 °C–1, corresponding to an amplification of the basic temperature response by approximately 50%. The surface albedo feedback amplifi es the basic response by about 10%, and the cloud feedback does so by 10 to 50% depending on the GCM. Note, however, that because of the inherently nonlinear nature of the response to feedbacks, the fi nal impact on sensitivity is not simply the sum of these responses. The effect of multiple positive feedbacks is that they mutually amplify each other’s impact on climate sensitivity.
    Using feedback parameters from Figure 8.14, it can be estimated that in the presence of water vapour, lapse rate and surface albedo feedbacks, but in the absence of cloud feedbacks, current GCMs would predict a climate sensitivity (±1 standard deviation) of roughly 1.9°C ± 0.15°C (ignoring spread from radiative forcing differences). The mean and standard deviation of climate sensitivity estimates derived from current GCMs are larger (3.2°C ± 0.7°C) essentially because the GCMs all predict a positive cloud feedback (Figure 8.14) but strongly disagree on its magnitude.
    The large spread in cloud radiative feedbacks leads to the
    conclusion that differences in cloud response are the primary source of inter-model differences in climate sensitivity (see discussion in Section 8.6.3.2.2). However, the contributions of water vapour/lapse rate and surface albedo feedbacks to sensitivity spread are non-negligible, particularly since their impact is reinforced by the mean model cloud feedback being positive and quite strong….’

    I found this interesting that without a strong positive cloud feedback the models will give an unrealistically low climate sensitivity (compared with observations). Any insights ?

17. #17 Steve Bloom

    2010/01/05

    Re #7: Anna , further to my #11, see this up-to-date review. It appears to be exactly what you want.

18. #18 Tony O'Brien

    2010/01/05

    I had a theory: Global warming plus global dimming plus the pan evaporation paradox equals greater than expected melt ponding. With most of the action happening at the micro level within in the highly reflective glaciers, we get melting instead of sublimation.

    While it still may be a factor, a recently published article in Science Daily would suggest that irradiance in fact causes quicker glacial collapse. Would this be due to light energy penetrating further than heat energy due to the insulative effect of ice and snow.

    Question 2) When looking at year of first melt and melt days I was struck by how the melt ponding often occurs at the internal edge of an ice shelf. On a thinner shelf warm water circulation may be a factor but on a thicker shelf such as the Ross I doubt this could be. The only other suggestion is that is in fact a version of Termination Melt (Sun low in sky vertical edge of shelf receives more energy than flat areas) but in this case it is the slopes of the Trans Antarctic Mountains that provide the slope. Any ideas?

    Question 3) In the 2003,4,6,7,8 Arctic sea ice area figures there is an upwards blip in the first few days in June. Is this a real phenomena or just a data glitch? If it is real it is sort of curious.

    I know I am greedy but the questions are sort of related.

19. #19 Anna Haynes

    2010/01/06

    Thank you Steve!
    - for #16, A to my Q about Sierra skiing, linking to:

    http://tenaya.ucsd.edu/~dettinge/Lundquist_UUPress09.pdf
    Variability and Trends in Spring Runoff in the Western United States – Jessica D. Lundquist, Michael D. Dettinger, Iris T. Stewart, and Daniel R. Cayan

    Content appearing in Wagner, F. (ed.), 2009, Climate warming in western North America—Evidence and environmental effects, University of Utah Press, 63-76.

20. #20 samspade10

    2010/01/06

    All right I’ll play nicely. Can someone explain this to me from realclimate.org:

    “The confusion in the denialosphere is based on a misunderstanding between ‘airborne fraction of CO2 emissions’ (not changing very much) and ‘CO2 fraction in the air’ (changing very rapidly)”

    How are these two different?

21. #21 PeteB

    2010/01/06

    Sam – I think this explains it well

    http://www.skepticalscience.com/Is-the-airborne-fraction-of-anthropogenic-CO2-emissions-increasing.html

22. #22 carrot eater

    2010/01/06

    The reaction to the Knorr/airborne fraction paper exposes a lot of these sceptics for a simple inability to read and understand a paper. It’s somewhat amusing.

23. #23 Eachran

    2010/01/06

    Dr Connolley, your e.g. link didnt work for me for the discount rate. But if any are interested it works if you go through RC to Real Climate Economics.

    [It was your link. I think somehow a pi -> "pi" got confused -W]

    Incidentally happy to do the discount rate bit myself but I would prefer that you have a shot first. Then we can compare notes. It’s really a difficult problem conceptually and ripe for people to make mischief.

    I saw that your colleague/friend Dr Annan ducked the issue on his sensitivity paper : wise man.

24. #24 crandles

    2010/01/06

    Do I recall that you have said that modelling works better at just below the Courant, Friedrichs, and Lewy (CFL) criterion rather than a lot below it?

    [No, not me -W]

    Could CFL criterion being (mildly/not quite?) exceeded be responsible for the weird pressure patterns in http://climateprediction.net/board/viewtopic.php?f=4&t=9191

    [I somewhat doubt it - exceeding CFL usually crashes things, as I recall. But it looks bad (is that a snapshot or an average?). Throw that run away. Also, find someone to ask about it - some of the Hadley folk (or Reading?) ought to either know, or be interested in finding out -W]

    There is also that what you would bet on for 2010 arctic minimum sea ice that you promised shortly a few months ago.

    [Yeah, I'm still thinking about that -W]

25. #25 crandles

    2010/01/06

    Boris,

    I hold 4 at an average cost of 24.3. Should I continue to wait to see if my lower priced buy orders get taken up or should I grab the 10 at 25 before you get involved, grab them and push the price up?

    Regards ;)

26. #26 crandles

    2010/01/06

    >”[I somewhat doubt it - exceeding CFL usually crashes things, as I recall. But it looks bad (is that a snapshot or an average?). Throw that run away. Also, find someone to ask about it - some of the Hadley folk (or Reading?) ought to either know, or be interested in finding out -W]”

    They are snapshots – much easier to grab and show. However it has been reported that the ‘riddles’ come and go from time to time though I doubt in the same place so they could easily be averaged away despite some persistence. “That run” hmmmm, if other people have found similar when they have gone and looked it seems unlikely to be the odd very rare case. This would make asking someone about it more important. Sue Rosier, the project co-ordinator, has commented on that thread (as moderators have requested) so the core team know about it and they will have a much better idea of who and what to ask than we will. Nevertheless, if you or anyone has any suggestions of who to ask, suggestions would be gratefully received.

27. #27 Anna Haynes

    2010/01/06

    Re skiing, today’s
    Can U.S. skiing be saved?
    http://climateprogress.org/2010/01/06/skiing-global-warming-science
    (a CAP repost, on Climate Progress)

28. #28 James Annan

    2010/01/07

    Chris,

    Looks like bog-standard numerical instability to me, many (all?) GCMs control this with filtering, especially near the poles where the grid spacing and thus CFL threshold is smaller. Running close to the CFL threshold is often most accurate at least for simple advection schemes, but the main reason people do it is just for computational speed!

    [Casting my mind back, I recall that HadxM3 is grid-point not gaussian and there is extra stuff to deal with this (i.e. filtering, as James says) as you go polewards. Since winds aer much larger higher up, it would be worth looking at what is happening at 200 hPa, if you have full dumps -W]

29. #29 Oliver

    2010/01/07

    How do you think the arctic oscillation extreme state at the moment will effect next year’s arctic sea ice?

30. #30 samspade10

    2010/01/07

    Thank you PeteB.

31. #31 Andy Wickert

    2010/01/11

    Do modeled reconstructions of past climate show a global increase in temperatures during the Medieval Warm Period, or simply an increase in Europe/Scandinavia (with constant or decreasing temperatures elsewhere)?

32. #32 crandles

    2010/01/12

    On the CFL query/Ripple riddle, there is now a better response from Sue, the project co-ordinator, in the thread linked in comment 23. There is also more pics, an animation etc.

33. #33 Phil Hays

    2010/02/09

    How did the Arctic get so warm during the Tertiary?

    Fossil forests show that the northern part of Ellesmere Island was very warm, freezing level even in the winter was ~1000 meters, complete with alligators, tortoises and such what. Ellesmere Island was high Arctic then, as the fossil wood allows sunlight cycle to be reconstructed: the trees grew well above the Arctic Circle.

    Is there any climate model that can produce such warmth in the Arctic without heating the tropics to levels where vertebrate life could not survive, which contradicts the fossil record?

34. #34 carrot eater

    2010/02/10

    How long will the current interglacial last?

35. #35 dhogaza

    2010/02/10

    Carrot eater, wikipedia’s not the best resource, but this seems reasonable:

    The Earth has been in an interglacial period known as the Holocene for more than 11,000 years. It was conventional wisdom that “the typical interglacial period lasts about 12,000 years,” but this has been called into question recently. For example, an article in Nature[29] argues that the current interglacial might be most analogous to a previous interglacial that lasted 28,000 years. Predicted changes in orbital forcing suggest that the next glacial period would begin at least 50,000 years from now, even in absence of human-made global warming [30] (see Milankovitch cycles).

36. #36 dhogaza

    2010/02/10

    Except when our host edits it, I mean :)

    (fast recovery there, eh?)

    (except I forgot to click “post” for about a half-hour!)

37. #37 carrot eater

    2010/02/11

    dhogaza: I’d seen numbers like that, and thought it was a pretty wide spread. Given the predictable periodicity of the various orbital cycles, I was hoping for better precision. I’m hoping for a review paper that looks at it all in context.

38. #38 Simon

    2010/02/13

    Hi Stoat, and others! Nice of you to have a Q&A area. Here is my question.

    After the CRU hack and the Himalaya glacier error, we’ve seen a lot of supposed “-gates”, many of them debunked. One of these on which I haven’t been able to find any commentary from the more serious writers is “Africagate“, the claim that “global warming could cut rain-fed north African crop production by up to 50% by 2020″ is reported in WGII and SYR and that this is entirely unfounded.

    Do you have a comment on that? Or just a link to someone that does. Thanks!

    [I never replied. How impolite - sorry. But only because my answer was:I don't really know. Poking around in the WGII report for what it actually says is probably your best resource -W]