Poster on Uncertainty at the American Geophysical Union Meeting in San Francisco

By Stephan Lewandowsky
Professor, School of Experimental Psychology and Cabot Institute, University of Bristol
Posted on 28 November 2012
Filed under Adaption & Mitigation, Carbon Reduction

This post relates to a poster at the American Geophysical Union Meeting in San Francisco in December 2012 that summarizes our work on uncertainty in climate science. (Thursday, 6 December, 1:40 PM - 6:00 PM, Poster Hall, Moscone South).

There is also an oral session on Uncertainty organized by the same team: Wednesday, 5 December, 2:30-3:30, 3003 (Moscone West).

The abstract of the poster is shown below, and it is followed by links to earlier posts on Shapingtomorrowsworld that present the arguments in greater detail:

TITLE: Uncertainty as Knowledge: Constraints on Policy Choices Provided by Analysis of Uncertainty

AUTHORS: Stephan Lewandowsky1, James Risbey2, Michael Smithson3, Ben R Newell4


1. University Western Australia, Crawley, WA, Australia.
2. CSIRO Marine and Atmospheric Research, Hobart, TAS, Australia.
3. Australian National University, Canberra, ACT, Australia.
4. University of New South Wales, Sydney, NSW, Australia.


Uncertainty forms an integral part of climate science, and it is often cited in connection with arguments against mitigative action. We argue that an analysis of uncertainty must consider existing knowledge as well as uncertainty, and the two must be evaluated with respect to the outcomes and risks associated with possible policy options. Although risk judgments are inherently subjective, an analysis of the role of uncertainty within the climate system yields two constraints that are robust to a broad range of assumptions. Those constraints are that (a) greater uncertainty about the climate system is necessarily associated with greater expected damages from warming, and (b) greater uncertainty translates into a greater risk of the failure of mitigation efforts. These ordinal constraints are unaffected by subjective or cultural risk-perception factors, they are independent of the discount rate, and they are independent of the magnitude of the estimate for climate sensitivity. The constraints mean that any appeal to uncertainty must imply a stronger, rather than weaker, need to cut greenhouse gas emissions than in the absence of uncertainty.


The poster summarizes the points made on this blog over the last 6 months or so. There are several arguments that are worth drawing attention to:

Uncertainty is not your friend. Uncertainty about the evolution of the climate system (operationalized as the variance of the sensitivity distribution) means that things could be worse than anticipated, rather than better. And in the case of the climate system, there is an inherent asymmetry such that uncertainty is more likely to cause nasty surprises than positive outcomes.

There is another aspect of uncertainty that is not altogether comforting: greater uncertainty inescapably means that the damages from unabated climate change are likely to increase. That is, all other variables being equal, greater uncertainty translates into greater expected risk. This fact rests on a single assumption, namely that the function relating global warming to damages is convex (i.e., accelerating), and all extant economic models agree on that point.

We can even relax the convexity assumption when we consider sea level rise. It turns out that for some fairly straightforward and inescapable mathematicaly reasons, the risk of inundation increases with the uncertainty of future sea level rises. Once again, all other things being equal, greater uncertainty implies greater risk.

Finally, uncertainty is also not a friend when it comes to mitigation. All other things being equal, greater uncertainty means a greater risk that mitigation might fail. A mitigation failure is said to occur when the carbon budget that would limit temperature increases to any agreed maximum is already exhausted by the time mitigation commences. This represents a failure because emissions cannot cease over night—by definition, therefore, mitigation will fail because we will necessarily exceed our budget. It is the probability of such failure that increases with greater uncertainty.

The bottomline of all those strands of argument is that greater uncertainty means greater risk. Greater risk of damages and greater risk of mitigation failure. Any appeal to uncertainty therefore implies a greater need to cut emissions than if uncertainty were smaller.

Bookmark and Share


Comments 1 to 31:

  1. Great knowledge, do anyone mind merely reference back to it
    free facebook likes
    free youtube views
  2. This is highly informatics, crisp and clear. I think that everything has been described in systematic manner so that reader could get maximum information and learn many things.
    dj und hochzeit
  3. japan.comp234 at 20:26 PM on 6 October, 2015
    hello!! Very interesting discussion glad that I came across such informative post. Keep up the good work friend. Glad to be part of your net community.
    where to eat in phuket
  4. japan.comp234 at 21:13 PM on 16 October, 2015
    I really loved reading your blog. It was very well authored and easy to understand. Unlike other blogs I have read which are really not that good.Thanks alot!
    free twitter followers
    youtube subscribers
  5. I really enjoyed reading this post, big fan. Keep up the good work andplease tell me when can you publish more articles or where can I read more on the subject?
    The Venus Factor Review
  6. I read that Post and got it fine and informative. Please share more like that...
  7. The information you have posted is very useful. The sites you have referred was good. Thanks for sharing..
    best online marketing companies
  8. brad.haddon234 at 17:18 PM on 28 November, 2015
    A debt of gratitude is in order for the significant data and bits of knowledge you have so given here... such a good point
  9. japan.comp234 at 19:47 PM on 3 December, 2015
    If it's not too much trouble let me know in case you're searching for an article essayist for your site. You have some truly extraordinary posts and I feel I would be a decent resource. In the event that you ever need to take a percentage of the heap off, I'd completely love to compose some material for your web journal in return for a connection back to mine. If it's not too much trouble send me an email if intrigued. Much obliged to you! discount deal
  10. The meeting should happen more often as that will increase the communication between the people, how to gain followers on instagram.
  11. japan.comp234 at 19:51 PM on 8 January, 2016
    Very useful info. Hope to see more posts soon!. Tang Group
  12. japan.comp234 at 00:49 AM on 12 January, 2016
    You have a real ability for writing unique content. I like how you think and the way you represent your views in this article. I agree with your way of thinking. Thank you for sharing. Online Casino seriös
  13. japan.comp234 at 16:31 PM on 12 January, 2016
    It is a great website.. The Design looks very good.. Keep working like that!. Tree Injections
  14. japan.comp234 at 19:17 PM on 18 January, 2016
    This blog is so nice to me. I will keep on coming here again and again. Visit my link as well.. buy instagram followers
  15. japan.comp234 at 17:40 PM on 29 January, 2016
    I was surfing net and fortunately came across this site and found very interesting stuff here. Its really fun to read. I enjoyed a lot. Thanks for sharing this wonderful information. marketing proposal
  16. Imagine you’ve come across a great instagram app for followers tweet on marketing automation and visit the company’s twitter page to learn more – the equivalent of jumping on the elevator and hearing their instagram pay for followers pitch.
  17. You’re going to can you really buy followers on instagram spend 20 seconds, then decide whether to follow them. In that scenario, who will you find more compelling Ad2action or Marketo?The majority of you will opt is buying instagram followers legit to follow Marketo.
  18. Their digital elevator free followers app for instagram pitch is visually interesting and they’ve used their 160 characters to tell you the benefits and breadth of what instagram likes and followers free they do.
  19. Imagine fast free followers on instagram the sales rep pacing his office rehearsing his elevator pitch, prepping for the moment he finds himself face-to-face with the CEO of his key free fast followers on instagram target.
  20. That’s you perfecting your social media how to earn more followers on instagram bio. It takes work to get it right.Share your value proposition. Remember, you’re trying to convince prospects and influencers to engage what can i do to get more followers on instagram with you – follow, circle, like and comment on your social media activity.
  21. japan.comp234 at 18:13 PM on 2 February, 2016
    I discovered your this post while hunting down some related data on website search...Its a decent post..keep posting and upgrade the data. hi8 sur dvd
  22. japan.comp234 at 16:44 PM on 4 February, 2016
    I am definitely enjoying your website. You definitely have some great insight and great stories. discount
  23. japan.comp234 at 19:00 PM on 6 April, 2016
    You know your projects stand out of the herd. There is something special about them. It seems to me all of them are really brilliant! mihran kalaydjian
  24. japan.comp234 at 16:28 PM on 12 April, 2016
    Just admiring your work and wondering how you managed this blog so well. It’s so remarkable that I can't afford to not go through this valuable information whenever I surf the internet!
  25. you have post the best articles till now,thanks for goal the perfect achievements and i am so delighted to be here and to discover this awesome post.
    Escorts in Dwarka
  26. You have a real ability for writing unique content. I like how you think and the way you represent your views in this article
    Call Girls in jaipur
  27. Just admiring your work and wondering how you managed this blog so well. It’s so remarkable that I can't afford to not go through this valuable information.
    Escorts in Gurgaon
  28. We have been managing Sexy, Young and High Class Call Girls from most recent 15 years and giving 100% acceptable call girl service to our customers.
    Escorts in Jaipur
  29. brad.haddon234 at 19:20 PM on 15 April, 2016
    This is highly informatics, crisp and clear. I think that everything has been described in systematic manner so that reader could get maximum information and learn many things. seo marketing tools
  30. japan.comp234 at 15:54 PM on 21 April, 2016
    thanks for the tips and information..i really appreciate it..
  31. Wow amazing, i like this, this is really awesome.

    Escorts in Delhi
    Dehradun Call Girls
    Delhi Escorts
    Call Girls In Gurgaon
    Escorts in Delhi
    Escorts in Jaipur
    Call girls service in Gurgaon
    Escorts in Gurgaon
    Escorts Delhi
    Escorts service in Delhi
    Escorts in Bangalore
    Escorts in South Delhi
    Gurgaon Escorts
    Delhi call Girls
    Call Girls in Gurgaon
Comments Policy

Post a Comment

You need to be logged in to post a comment. Login via the left margin or register a new account.