Wednesday, March 3, 2010

Long Range Forecasting

Keep in mind, the people who forecast a warm winter in Great Britain when the actual winter was the coldest in more than 30 years are the same people who say the "science is settled" 50 and 100 years into the future.

Question:  If you can't make an accurate forecast at 100 days, why do you think you can make an accurate forecast at 100 years?


  1. Hi Mike,
    The answer to your question lies in the fact that climate scientists aren't predicting what the actual high temperature will be on July 4th, 2099.

    If you were to pick 10 random Julys and 10 random Januarys, I predict that the mean July temperature will be warmer than the mean January temperature.

    Sure, it is possible that the maximum mean January temperature will be warmer than the lowest mean July temperature, but, when averaging over a lot of January and July months, the Julys will be warmer. That's essentially what a climate prediction is...the mean temperatures for a lot of months are warmer (cooler, or neutral) than they used to be. No one is trying to predict an actual year or an actual event. They are simply looking at the statistics.

  2. Climate scientists are making weather forecasts decades into the future. Here is one example,

    “By the period 2080-2099, devastating heat waves of the kind that killed more than 700 people in Chicago in 1995 will occur three times per year.” (latest USCCP, p. 119)

    That is a forecast of specific weather conditions at a specific place at a specific time -- a weather forecast.

    You can read more of my thoughts on that topic at: My essay begins under the cartoon.

  3. When climate scientists make statements with that much specificity, feel free to bash away - I agree it is ludicrous, and have consistently stated that. However, a wrong *specific* forecast might still have valuable information with respect to longer-term signal. An incorrect conclusion doesn't necessarily mean everything else was wrong. It just means an incorrect conclusion was drawn.

    Don't throw the baby out with the bathwater.

  4. Patrick,

    Unfortunately the USCCP document is riddled with those types of forecasts. And, because it is a U.S. government document it conveys a sense of "authority" and these forecasts have been quoted in my local newspaper.

    I doubt that over a cup of coffee we would be that far apart in our beliefs. I am a "lukewarmer" per Judith Curry's definitions (i.e., dump enough greenhouse gas into the atmosphere for enough decades and eventually a problem develops, other factors equal).

    That said, I am completely against the anti-science behavior of a number of leading climate 'scientists,' the hyping of our ability to forecast the climate (even Trenberth agrees with me on this point) and hysteria surrounding the subject.

    So, I feel obliged to add what I see as some balance.


  5. I guess from my perspective I don't see it as balance. I see it as very one sided. Most, not all, of your posts deal with discrediting potential impacts - and, believe it or not, I'm okay with that. I think there is no way we can prove what might happen 100 years from now in a warmer earth...just like we couldn't do it for a cooler earth. Too many outside factors could happen ranging from volcanic activity to solar activity. I've published climate change impact papers (relating to severe convection), and in every one of them I stress that these results are based on our best *current* understanding and aren't a concrete prediction of what *will* happen. I think it is naive of scientists to claim we know how the earth will respond to what climate scientists argue is an "unnatural warming".

    But when the very best models we have continue to indicate a warming on the average of 3C over the next 100 years, when you can mathematically prove that, all things equal, more C02 in the atmosphere results in a greenhouse effect, I have to take notice and I have to say something when I feel distortion is occurring.

    For example, in this post you could have blasted the prediction you quoted in your comment above or you could have blasted the fact that scientists missed this year's winter forecast in Europe and I wouldn't have said anything unless I was agreeing with you. But why don't you give credit to NCEP's CPC for correctly predicting a cooler and wetter winter across the south? In all your posts about how cold and snowy it has been in the US, why don't you talk about the above normal temperatures in Canada or Greenland?

    If you stick to discrediting specific forecasts (such as 3 heat waves a year, disappearing glaciers in 25 years, etc), I won't disagree one bit. But when you attempt to discredit everything on the basis of specific forecasts, I'll speak up.

    And since you've stated what you believe, I'll state that I believe humans are likely to have contributed to an unnatural warming of the earths climate (although there is a chance we haven't). However, I also believe we do not know what the final magnitude of the warming will be, nor what the specific impacts of this warming will be.

    Finally, I know that online it is easy to read more into what someone says than was actually intended. I thank you for taking my comments seriously and not taking them personal. I believe continuing to have discussions that are open and civil are a benefit to all.


  6. Patrick,

    Your comments (and those from others who wish to comment) are always welcome because you are both respectful and constructive.

    Whenever I give my 'global warming' talk, I state there is a chance I am wrong. I also say that GW may be a serious threat ( I think it is a threat, but would characterize it as small) but that the IPCC has failed to make the case. I can't explain all of my reasons in a comment. That said, I'd like to point you to: if you are interested in learning more about my position on GW.


  7. Hi Mike,

    I thought you might be interested in the following article in The Washington Times:

    While the title might not sound appealing to you, the following from/about Dr. Judith Curry is spot on.

    "Not all climate scientists agree with forcing a political fight.

    "Sounds like this group wants to step up the warfare, continue to circle the wagons, continue to appeal to their own authority, etc.," said Judith A. Curry, a climate scientist at the Georgia Institute of Technology. "Surprising, since these strategies haven't worked well for them at all so far."

    She said scientists should downplay their catastrophic predictions, which she said are premature, and instead shore up and defend their research. She said scientists and institutions that have been pushing for policy changes "need to push the disconnect button for now," because it will be difficult to take action until public confidence in the science is restored.

    "Hinging all of these policies on global climate change with its substantial element of uncertainty is unnecessary and is bad politics, not to mention having created a toxic environment for climate research," she said.

    Ms. Curry also said that more engagement between scientists and the public would help - something that the NAS researchers also proposed."

  8. Patrick,

    Amen! I agree especially with the "toxic environment for climate research" comment. We NEED quality research into climate. We don't need "scientist-politicians."

    Thanks for posting.



Note: Only a member of this blog may post a comment.