A Pielke and Pielke Special

August 8th, 2006

Posted by: Roger Pielke, Jr.

Over at my father’s blog we have collaborated on a post titled, “Big Time Gambling With Multi-Decadal Global Climate Model Predictions.” The whole thing is posted below. Feel free to comment here or there, we’ll both read comments on each other’s blog.


Big Time Gambling With Multi-Decadal Global Climate Model Predictions
Roger A. Pielke Sr. and Roger A. Pielke Jr.

Many advocates for action on climate change, including the IPCC assessments and recent documentaries have promoted a view that global warming will continue through the 21st century, with global warming defined as a steady increase in global average temperatures. This prediction of warming is based on the output of multi-decadal general circulation models and is primarily due to the radiative forcing effect of anthropogenic emissions of CO2. In such models only relatively minor year-to-year variations in global average temperatures are forecast in the upward trend, except when major volcanic eruptions cause short-term (up to a few years) of global cooling. For example, see these projections of the most recent IPCC — none of the models has an obvious multi-year (i.e., >2) decrease in global average temperatures over the next century.

Such predictions represent a huge gamble with public and policymaker opinion. If more-or-less steady global warming does not occur as forecast by these models, not only will professional reputations be at risk, but the need to reduce threats to the wide spectrum of serious and legitimate environmental concerns (including the human release of greenhouse gases) will be questioned by some as having been oversold. For better or worse, a failure to accurately predict the changes in the global average surface temperature, global average tropospheric temperature, ocean average heat content change, or Arctic sea ice coverage would raise questions on the reliance of global climate models for accurate prediction on multi-decadal time scales. Surprises or experience that evolve outside the bounds of model output would likely raise questions even among some of those who have so far accepted the IPCC reports as a balanced presentation of climate science. (for a perspective different than the IPCC on applications of climate models see this).

The National Research Council published a report in 2002 entitled “Abrupt Climate Change: Inevitable Surprises” (of which RP2 was a committee member). The report raised the issues of surprises in the climate system. One of the surprises (to many) may be that the global climate models are simply unable to accurately predict the variability and trends in the climate metrics that have been adopted to communicate human-caused climate change to policymakers. Among the climate metrics with the most public visibility are the long term trends in global average surface temperature, global average tropospheric temperature, summer arctic sea ice areal coverage, and ocean heat content.

There is some emerging empirical evidence to suggest, however, that the concerns expressed here are worth consideration. The recent dramatic cooling of the average heat content of the upper oceans, and thus a significant negative radiative imbalance of the climate system for at least a two year period, that was mentioned in the Climate Science weblog posting of July 27, 2006, should be a wake-up call to the climate community that the focus on predictive modeling as the framework to communicate to policymakers on climate policy has serious issues as to its ability to accurately predict the behavior of the climate system. No climate model that we are aware of has anticipated such a significant cooling, nor is able to reproduce such a significant negative radiative imbalance. Meaningless distinctions between “projections” and “predictions” will be unlikely to convince consumers of climate models to overlook experience that does not jibe with modeled output.

There is no greater danger to support for action on important issues of human impacts on the environment than an overselling of what climate science can provide. If the climate behaves in ways that are unexpected or surprising it will be more than just credibility that is lost. Advocates for action should think carefully when gambling with the unknown predictive abilities of climate models. The human influence on the climate system is real, but the climate may not always cooperate.

29 Responses to “A Pielke and Pielke Special”

    1
  1. David Roberts Says:

    “There is no greater danger to support for action on important issues of human impacts on the environment than an overselling of what climate science can provide.”

    This seems to perfectly capture the raison d’etre of this website. It also strikes me as plainly wrong and willfully naive.

    Here’s a greater danger: The extraordinary influence on government exercised by industries with direct financial stakes in the outcome of environmental policy discussions.

    Here’s another: A deliberate, coordinated propaganda effort to deny or distort environmental science and portray supporters of progressive environmental policy as closet communists or hysterics, waged by people with financial and/or ideological ties to polluting industries.

    If we come to a point in U.S. public dialogue where the greatest threat to support for environmental action is an overstatement of the degree of predictive power of climate models, I will celebrate. And I will join you in your obsessive quest to watchdog those who advocate for such action. Until then, there are much more immediate and obvious dangers and obstacles to overcome.

  2. 2
  3. Roger Pielke, Jr. Says:

    David-

    Thanks for your comments. A few reactions.

    Political coalitions come and go. The entire history of the environmental movement (and politics more generally) should give one optimism that the influence of industrial interests can be overcome in the political process. Witness clean air, clean water, ozone depletion, etc.

    The propaganda nonsenese is a convenient myth that we’ve busted before, but seems too convenient to let go of — I’ll say it again, a majority of US citizens (and members of Congress!) think that climate change is real and want action. The same it true in Europe with respect to citizens and their representatives. Yet emissions keep going up everywhere. Sorry, but it isn’t propaganda holding back action.

    But if the credibility of those advocating action is lost — good luck getting it back. Lesson #1 from WMDs and the Iraq war. Exaggerate the science (or stand by silently) and you are playing a high stakes game. Climate change isn’t the Spanish-American War (Remember the Maine?), it is a political battle that will have to be fought over decades not this year or next. Long-term credibility matters.

    Thanks!

  4. 3
  5. Andrew Dessler Says:

    Roger-

    I’m not sure what your point is. I agree with much of what you say, but if we don’t use models, then how do we make predictions of the future? Or is your point that we don’t need predictions? Or is your point that we need models, they just need to be improved to get short-term variability more accurately?

    Regards.

  6. 4
  7. Roger Pielke, Jr. Says:

    Andrew- Thanks. The issue isn’t whether or not we use models, it is how we use models. From another post earlier today quoting Steven Popper:

    “Too often we ask “What will happen?”, trapping us into the mug’s game of prediction, when the real question should be: “Given that we cannot predict, what is our best move today?”"

    We have fallen into the mug’s game on climate change. Climate models are being used by many as truth machines or crystal balls, and much of the justification for action is being placed upon them. Should climate models not be truth machines or crystal balls, don’t be surprised to see skepticism gain considerable traction, when in fact the reasons for action will reamin as they do today.

    For more on prediction in policy, see:

    Pielke Jr., R. A., D. Sarewitz and R. Byerly Jr., 2000: Decision Making and the Future of Nature: Understanding and Using Predictions. Chapter 18 in Sarewitz, D., R. A. Pielke Jr., and R. Byerly Jr., (eds.), Prediction: Science Decision Making and the Future of Nature. Island press: Washington, DC.
    http://sciencepolicy.colorado.edu/admin/publication_files/resource-73-2000.06.pdf

  8. 5
  9. Sylvain Says:

    First, I’m a lay person on the subject, yet I believe my opinion can help you know what the average Joe understand of the subject.

    I must admit that I usually get thrown by the way the “alarmist side” try to sell me GW. I frequently feel like they would want me to believe that extreme weather event are new phenomenon of recent years and that future one will be apocalyptic in nature.

    Yet almost any extreme weather events we faced these later year have similarities with events that happened in the past 100-125 years.

    The only thing I see that are or can be unprecedented is how unprepared people living in these extreme weather events area are. Also if these area are so risky why so many people move to these places only to complain when something bad happen.

    I’m also often left with the impression that some people prefer inaction only to be able to say that they were right to say that weather events would have catastrophic effect.

    That is why I find the “so what” question very important. What ever is bound to happen is happening right now and policy are required on land use, building code, evacuation plan, etc.

    The debate over science seems to lead to inaction when action is required whether either of “skeptics” or “alarmist” are right.

    Finally, concentrating the debate on CO2 emission doesn’t do anything to solve the problem that we face right now.

  10. 6
  11. chrisl Says:

    Hello Roger,I’ve been set a challenge by a blogger in Australia (Initials JQ)to name 10 Climate Scientists who are currently working who are sceptical about AGW who are not right wingers or funded by oil companies.
    Which leads me to ask how many working climate scientists there are?
    Regards
    Chris

  12. 7
  13. Roger Pielke, Jr. Says:

    chrisl- Thanks for your comment.

    My sense as a close observer of this community is that if by “skeptical about AGW” you mean “don’t believe in a human influence on climate” that the number is vanishingly small.

    However, if by “skeptical about AGW” you mean “outside the IPCC consensus” than I would think that the number is pretty significant, and on both sides of the IPCC perspective (i.e., smaller human influence and larger human influence).

    The only way to find out authoritatively would be to actually survey relevant scientists. Here is an example of one such study:

    http://cdmc.epp.cmu.edu/survey.htm

  14. 8
  15. Dan Hughes Says:

    Professor Pielke and chrisl. So how do we determine which persons can be counted and which are disqualified. Can left-wing persons and persons funded by taxpayers be counted? How about ’scientists’ who are very clearly driven by an agenda? And ’scientists’ who are driven by a political agenda? How about persons funded by taxpayers who might be driven by the need to keep money flowing?

  16. 9
  17. Mark Shapiro Says:

    Roger -

    1) You’re posting these thought-provokers faster than I can read and absorb them, let alone respond. What’s your secret?

    2) The distinction between “projections” and “predictions” is anything but meaningless. I made financial projections for some years, and I would insist that the difference is crucial. And yet even sophisticated consumers of models struggle to appreciate this. The piece by Mike McCracken (that you link to above) explains this very well. But at some level every adult makes projections, and knows their limits, too. Fishermen say “If you rise at x AM you’ll catch y fish; at x+1 AM, y-1 fish.” Parents say “If you look both ways, you’ll live longer (and I’ll yell less). Politicians say “If we don’t reform x, the deficit will grow y (and the bad guys win).”

    Every serious modeller knows and accepts the limits of projections. So let’s help policy makers, and all citizens, understand those limits.

    Furthermore, the models can alleviate another problem that you discuss often: the misconception that global warming (and especially hurricanes) has some magic on/off switch. A five-minute discussion of a model, simply comparing two scenarios, could dispel that better than any other tool I know of.

    Like any tool, models have limits. So let’s help people use them properly.

  18. 10
  19. Roger Pielke, Jr. Says:

    Thanks Mark for your comments.

    I agree that there is an important distinction to be made between predictions and projections. In the case of climate science such distinctions often are in fact “meaningless.”

    I agree that it is important to help policy makers understand models and use predictions. Have a look at this volume on this subject:

    http://sciencepolicy.colorado.edu/homepages/roger_pielke/prediction_book/

    Thanks again!!

  20. 11
  21. Steve Hemphill Says:

    One can talk semantics about the modeling community’s perception of projection vs. prediction all one wants, but it’s hot air. The fact is, on the inside modelers consider it “data” – Erasing all doubt of their prejudice.
    http://www-pcmdi.llnl.gov/ipcc/about_ipcc.php

    Model outputs are not “data” when it comes to complex systems we admit we do not fully understand. Sorry.

    Based on the fact there are many studies showing albedo changes from land use, black carbon, etc. and solar output changes have well over half the effect on AGW leaving CO2 way behind, and comparing what’s left to the potential gain from CO2 enhancing the bottom of the food chain: To waste quality of life on reducing CO2 now without really knowing what we’re gaining or losing is wholly irrational.

    Here’s the climate change nightmare. It’s not warming, which has proven beneficial throughout mankind’s existence. It’s cooling, when people the world over start burning anything they can, including plastics, to stay warm. Got air pollution (and albedo) now? Not likely. So, I submit to you all that the penalty for failure of modeling projections is probably much, much worse than the probable penalty for “AGW”. It’s time for another Manhattan Project. And it’s time for the Chicken Littles to start looking heavily for silver linings in the clouds (errh, at clouds anyway?). Seriously.

  22. 12
  23. Mark Bahner Says:

    Hi,

    I made several comments regarding this piece on the Climate Science blog that were never posted.

    I see there’s a Climate Science “log in” that links to the WordPress site. But that login doesn’t seem to allow new registrants.

    Any suggestions?

    Thanks,
    Mark

  24. 13
  25. Mark Bahner Says:

    “The distinction between “projections” and “predictions” is anything but meaningless. I made financial projections for some years, and I would insist that the difference is crucial. And yet even sophisticated consumers of models struggle to appreciate this. The piece by Mike McCracken (that you link to above) explains this very well.”

    I’m sorry, but I don’t see the link. What piece by Mike McCracken does Roger link to?

  26. 14
  27. Roger Pielke, Jr. Says:

    Mark- Thanks. I’m not sure how the comments work at Climate Science, best to email my father directly.

  28. 15
  29. Mark Bahner Says:

    Mark Shapiro writes, “2) The distinction between ‘projections’ and ‘predictions’ is anything but meaningless. I made financial projections for some years, and I would insist that the difference is crucial.”

    However, if one does a Google “define” for “projection,” one gets as the very first line:

    http://www.google.com/search?hl=en&lr=&rls=GGLD%2CGGLD%3A2004-32%2CGGLD%3Aen&q=define%3A+projection

    “a prediction made by extrapolating from past observations”

    And if one looks at an Encarta thesaurus for “prediction,” one sees:

    http://encarta.msn.com/thesaurus_561584188/prediction.html

    “Synonyms: forecast, guess, calculation, estimate, prophecy, expectation, likelihood, extrapolation, prognostication, projection”

  30. 16
  31. Hugh Says:

    Come on Mark B, the definitions you’re talking about are these, not Encarta

    “Climate prediction
    A climate prediction or climate forecast is the result of an attempt to produce a most likely description or estimate of the actual evolution of the climate in the future, e.g. at seasonal, interannual or long-term time scales. See also: Climate projection and Climate (change) scenario.

    Climate projection
    A projection of the response of the climate system to emission or concentration scenarios of greenhouse gases and aerosols, or radiative forcing scenarios, often based upon simulations by climate models. Climate projections are distinguished from climate predictions in order to emphasise that climate projections depend upon the emission/concentration/ radiative forcing scenario used, which are based on assumptions, concerning, e.g., future socio-economic and technological developments, that may or may not be realised, and are therefore subject to substantial uncertainty.

    Climate scenario
    A plausible and often simplified representation of the future climate, based on an internally consistent set of climatological relationships, that has been constructed for explicit use in investigating the potential consequences of anthropogenic climate change, often serving as input to impact models. Climate projections often serve as the raw material for constructing climate scenarios, but climate scenarios usually require additional information such as about the observed current climate. A climate change scenario is the difference between a climate scenario and the current climate.”

    IPCC TAR Glossary

    There is I would suggest a technical rather than semantic difference in their meanings which is acknowledged in this document.

  32. 17
  33. Roger Pielke Sr. Says:

    Mark B. – I do not know why your comments were not posted on the Climate Science weblog. You do not need to login. You only need to write your comments in the “Comment” section. Please try again.

    On the MacCracken paper,

    MacCracken, M., 2002: Do the uncertainty ranges in the IPCC and U.S. National Assessments account adequately for possibly overlooked climatic influences. Climatic Change, 52, 13-23.

    it can be obtained from

    http://blue.atmos.colostate.edu/publications/pdf/maccracken2002.pdf

  34. 18
  35. Mark Bahner Says:

    Hugh Deeming (August 10, 3:41 PM) quotes from the IPCC TAR glossary, attempting to show that the IPCC makes clear the difference between “climate prediction” and “climate projection.”

    OK, based on those definitions, what does this IPCC TAR statement mean?

    “The globally averaged surface temperature is projected to increase by 1.4 to 5.8°C (Figure 5d) over the period 1990 to 2100.”

    http://www.grida.no/climate/ipcc_tar/wg1/008.htm

    Is that a projection, or a prediction?

    And if it is NOT a “prediction,” what is the IPCC’s “prediction” for temperature rise?

  36. 19
  37. Mark Bahner Says:

    Darn it!

    I forgot to log in, and sent in some comments to Hugh Deeming. (Without copy/pasting them to my email, so I’d have a record.)

    Could someone at Prometheus recover the comments for me? I don’t want to try to recreate them.

    Thanks,
    Mark

    P.S. I don’t know if this is something that’s easy to do, programming-wise, but if the “comments” section was yellow or red until a person signs in, that would be really helpful to people like me who frequently forget that Prometheus now requires a sign-in for each session. Or it would even help if the font was raised to much larger, saying, “YOU ARE NOT SIGNED IN!” As it is, there is not much visual difference between when a person is signed in or not signed in.

  38. 20
  39. Mark Bahner Says:

    Hi,

    Many thanks for recovering my comments to Hugh Deeming.

    Best wishes,
    Mark

  40. 21
  41. Steve Hemphill Says:

    The MacCracken paper indicates Mike’s subtle paradigms have not changed. For him, there is nothing outside the direction he wants to take the conceptualization. His insinuation that there is no way biospheric response to increased CO2 could overcome CO2’s physical effect on heat retention is typical of his support of the dogma.

    Also, his discussion of strictly albedo changes of land use changes without considering the effects on transpiration is interesting. How valuable is an assessment of -0.02 deg per century based on land use changes without considering transpiration? I suggest it is wholly irrelevant to the big picture.

    While he touches on the differences between forcings and feedbacks, his analysis has a strictly anthrocentric view, dismissing the fact that CO2 follows temperature.

    The possibility that land use changes from our current burgeoning population (not to mention black carbon) are decreasing transpiration leading to decreased cloudiness is outside his paradigm, therefore beyond his comprehension.

    Then again, this is an old paper. 4 years is a long time in climate science – although not so long considering the entrenchment from the inbreeding, strengthening the alarmists’ credo.

  42. 22
  43. Hugh Says:

    Mark

    Okay, I’m biting my lip here a bit because I seem to be walking headlong into one of your booby traps…but…

    In my (very) humble opinion the statement:

    “The globally averaged surface temperature is projected to increase by 1.4 to 5.8°C (Figure 5d) over the period 1990 to 2100.”

    Means that, dependent on the emissions scenario applied, global…blah blah..will rise to a point where the mean temperature will end up at a point somewhere within the range of 1.4-5.8°C. i.e. a low emissions scenario will result in mean temp being in the bottom end of the range and a high emissions scenario will result in the mean being in the upper end.
    This makes these *projections*

    A *prediction*, again IMHO, would require the analysis of current global energy policies (to identify current and planned levels of capital expenditure on emitting /non-emitting power sources), and various business plans/trends (e.g. automobile manufacturers) to assess how such businesses’ emissions are being planned to increase decrease in the future.

    I understand the issue about the investigation of such plans stepping across the divide into *projections* but major infrastructure (e.g. a power plant)does have a design lifetime and I therefore suggest that *predictions* can at least be guided up until the end of this period.

    As I read it *projections* are there to *guide* energy policy i.e. if we rely on coal-fired energy production the global temp is going to be toward 5.8°C.

    Projections therefore indicate choices

    Where am I going wrong????

  44. 23
  45. Mark Shapiro Says:

    All – thanks for keeping the prediction/projection discussion so lively. The distinction is fine, and easy to blur. And it is important.

    One way to look at it is to say that a prediction is unconditional, such as “x will happen”, whereas a projection is 2 or more conditional predictions: “if a, then x will happen; if b, then y will happen”.

    The value lies in isolating and defining at least one element of uncertainty. That allows policymakers a view into potential effects of their actions.

    Roger – thanks for posting the direct link to the McCracken paper. I think it is useful. I also saw the link to your projection book, and the chapter headings that are available online make it look quite pertinent. But I’m not sure why you say that the prediction/projection distinction is meaningless in the case of climate science. If you mean that the distinction is lost on people, then we must educate.

    Certainly the names of the government agencies don’t help. At DOE “Climate Change Prediction Program” is unfortunately presumptuous and misleading at best. Then the “Accelerated Climate Prediction Initiative” within that group again says “Prediction”. Unfortunate.

    Steve H – if your parameters of albedo, transpiration, and solar forcing turn out to be controlling, time will tell. But it’s worth a look at IPCC TAR and following research to see why that’s not looking likely.

  46. 24
  47. Mark Bahner Says:

    Hi Hugh,

    You write, “Okay, I’m biting my lip here a bit because I seem to be walking headlong into one of your booby traps…”

    One of my “booby traps?”

    ???

    “Any device or material which is designed, constructed or adapted to kill or injure and which functions unexpectedly when a person or object (vehicle) disturbs or approaches an apparently harmless object or performs an apparently safe act.”

    Geez! I think I have a bit more sense of perspective than to use those! ;-)

    Anyway, your opinion is that the statement, “The globally averaged surface temperature is projected to increase by 1.4 to 5.8°C (Figure 5d) over the period 1990 to 2100″…is a “projection” rather than a “prediction.”

    I guess I shouldn’t even have asked, because I’m still confused. I apologize, I have more questions:

    1) Since that statement is a “projection” rather than a “prediction,” is it falsifiable? That is, is there any future that renders the “projection” false?

    2) The temperature “projection” of 1.4 to 5.8 degrees Celsius is presumably based on supporting “projections,” e.g., methane atmospheric concentrations and CO2 emissions and atmospheric concentrations. For example, if I go to Figure 5 of the IPCC TAR, I see these “projections” for CO2 emissions and atmospheric concentrations:

    http://www.grida.no/climate/ipcc_tar/wg1/figspm-5.htm

    Are there any future events which can falsify those “projections” (i.e., show them to be wrong)?

    3) Of what possible use for policy making is a “projection” of 1.4 to 5.8 degrees Celsius temperature rise? Don’t you think it makes a big difference, from a policy standpoint, if the warming is 1.4 degrees Celsius vs 5.8 degrees Celsius?

    4) Suppose I told you (and I do! :-) ) that I predict there is approximately 50% probability that warming in the lower troposphere from 1990 to 2100 will be less than 1.4 degrees Celsius. In your opinion, is my “prediction” compatible or incompatible with the IPCC TAR “projection?”

    Best wishes,
    Mark

  48. 25
  49. Mark Bahner Says:

    Oh, nooooooooo!

    I had comments to Hugh that I just sent. It’s taken me a while to finish them. I swear I was signed in when I started them. But now I’m not. Again, I forgot to cut/paste them to my email. (I probably should just do everything by my email.)

    Could someone retrieve them? Sorry!

    Thanks,
    Mark

  50. 26
  51. Mark Bahner Says:

    What a disaster. :-(

    Could someone recover my comments/questions to Hugh? No need to recover my request for recovery…when I also forgot to sign in. :-(

    Thanks!

  52. 27
  53. Mark Bahner Says:

    Mark Shapiro writes, “One way to look at it is to say that a prediction is unconditional, such as ‘x will happen’, whereas a projection is 2 or more conditional predictions: ‘if a, then x will happen; if b, then y will happen’.”

    “The value lies in isolating and defining at least one element of uncertainty. That allows policymakers a view into potential effects of their actions.”

    That’s a nice theory, but the fact of the matter is that ALL the scenarios in the IPCC Third Assessment Report are based on no government intervention (at least specifically for climate change).

    So policymakers are told that, without government intervention:

    “The globally averaged surface temperature is projected to increase by 1.4 to 5.8°C (Figure 5d) over the period 1990 to 2100″…

    …but the IPCC Third Assessment Report doesn’t say whether the warming is likely to be in the lower part of that range (or even BELOW that range) or in the upper part of that range.

  54. 28
  55. Steve Hemphill Says:

    Mark – you forgot one consideration in the “other than CO2 forcings” list – that would be other GHG’s.

    Although there are cherry-picked anecdotal studies in either vibrant and robust, or on the other end nutrient poor conditions, competent studies indicate that there will be some increase in arable land with an increase in CO2. Balance that against the the fact the magnitude of the CO2 component to increased warming is highly uncertain. The question is: should we be looking to limit CO2 emissions at all?

    We just don’t know, and the risk that just eliminating that food enhancement could be devastating to a large part of the world’s population means the Precautionary Principle really says don’t waste money throttling back productivity, instead spend money realistically researching climate components and fine tuning models.

    The key word here, of course, is “realistically.”

  56. 29
  57. Steve Hemphill Says:

    P.S. in trying to find information on the Hadley Centre concerning uncertainties, I came across this about prediction vs. projection:

    http://tinyurl.com/gubph

    You will also notice at the bottom of this they refer to their model outputs as “data.”

    http://tinyurl.com/hj7uq

    Freudian slips? Clearly they think they have eliminated all potential uncertainty. It would be nice to have that crystal ball…