Message from discussion Mark Bahner's climate bet offer
From: "James Annan" <still_the_same...@hotmail.com>
Subject: Mark Bahner's climate bet offer
Date: 12 Jun 2005 23:52:00 -0700
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Mark Bahner recently wrote an article on his blog challenging me to a
series of bets relating to GHG emissions and climate change. Rather
than blogging back-and-forth, I think it is more sensible to discuss
the offers on an open forum. So here is my reply. His full original can
be seen at:
My comments are interleaved:
> Proposed bets for James Annan, regarding IPCC TAR
> I have been having a discussion with James Annan about betting on
> climate change. James Annan asked, "So, Mark, will you step in where all
> these sceptics fear to tread and bet against the consensus on 20-30 year
> temperature changes?"
> Here are my responses:
> a) Don't you mean, "septics?" (See your comment on William Connolley's
> blog, "...I have tried to contac(sic) Mark Bahner about his bet, but have
> not received a reply and he seems to be doing the same wriggle and
> squirm that all the septics do when asked to put their money where
> there(sic) mouths are.")
> b) You seem to know-or think you know-what the IPCC "consensus" is. (As
> if "consensus" even had any scientific value!) But you have not
> identified what you think the IPCC "consensus" is.
There's your first mistake, because I have previously pointed directly
(at least twice) to the obviously relevant sentence in the TAR Summary:
"anthropogenic warming is likely to lie in the range of 0.1 to 0.2=B0C
per decade over the next few decades"
[Reference to this is on my blog at
and also mentioned at
> c) If I was personally trying to figure out what the "consensus" was in
> the farce known as the IPCC TAR, I'd go to Wigley and Raper's 2001
> article in Science
To put it bluntly, that is your problem, not mine, and this is your
> I'm willing to bet against that "consensus," based on satellite
> measurements of the temperature in the lower troposphere in 1990 versus
> in 2030.
Lower troposphere? Surely you cannot be unaware of the fact that all of
the projections, model results and predictions are provided in terms of
_surface_ air temperature, (conventionally 2m). Strike three...but I'll
>The measurements should be based on a three-year average
> centered around those years (i.e., satellite measurements for 1989,
> 1990, 1991 versus satellite measurements for 2029, 2030, and 2031).
Which satellite measuremments? There are at least 4 interpretations,
which give historic trends ranging from 0.09 to 0.24/decade. That is,
Spencer and Christy, Mears et al, Vinnikov and Grady, Fu et al.
No doubt you will demand to use whichever analysis gives the coldest
result...or perhaps argue that it is all too uncertain. Sounds like you
are trying to build in an escape route. Strike 4?
I've already suggested using the _surface_ air temperature analysis
(um...to judge the _surface_ air temperature forecast which you
dispute) of NASA GISS. If you think this analysis is seriously
disputed, then some citations of alternatives would be appreciated. If
you are going to wibble about urban heat islands, we could use only the
ocean surface data, but that would require some revision of the
temperatures in the bet (since the ocean warming will obviously be
lower than the land).
> the temperature increase in the lower troposphere is more than 0.75
> degrees Celsius, I will pay you $100. If the temperature increase is
> between 0.62 and 0.75 degrees Celsius, I will pay you $50. If the
> temperature increase is between 0.48 and 0.62 degrees Celsius, you will
> pay me $50. If the temperature increase is less than 0.48 degrees
> Celsius, you will pay me $100.
Huh? That bet is centred on 0.62C warming in 4 decades. That's more
(just) than the IPCC forecast! How is this contradicting the consensus?
Why would I want to bet on that? The bet has negative value to anyone
who takes the IPCC summmary at face value.
So I reckon that makes 5 mistakes. I'm afraid that is only worth a
"could do better", but I sincerely hope you do try, annd I look forward
to your revised offer.
If you could predict what _you_ think the temperature change will be by
2030, as measured by surface air measurements, then I could also try to
form a mutually acceptable bet rather than simply shooting holes in
your rather ill-considered offer.
I do, however, wonder if many of the critics of the IPCC report have
actually read it...
> However, I also challenge you to bet on methane atmospheric
> concentrations, and CO2 emissions and atmospheric concentrations.
Well, these are primarily issues of politics, population growth,
economics and technology, none of which is my field, and the IPCC makes
no forecasts on these matters. In fact it quite explicitly states that
the scenarios do not form any sort of probabilistic prediction. So
basically, I have little interest in your challenges here.
> CO2 concentrations: The CO2 atmospheric concentration in 1990 was
> approximately 354 ppm. The IPCC TAR projects a 50 percent chance that
> the CO2 atmospheric concentration will be more than 438 ppm in 2030. If
> the CO2 atmospheric concentration is more than 438 ppm in 2030, I will
> give you $25. If the CO2 atmospheric concentration is less than 438 ppm
> in 2030, you give me $1. Again, I'm offering you 25-to-1 odds on
> something that, if the IPCC TAR was correct, should be even money.
This sounds sufficiently attractive that I will take you up on it, even
though I am not primarily interested in predicting CO2 emissions and
the IPCC explicitly avoids making such a forecast.
To make it worthwhile, I suggest upping the stakes a bit - how about my
$100 v $2500 from you (I'll go substantially higher if you are prepared
to), and also I'd like to inflation-proof it by tying the value to the
retail price index (I'd suggest the UK RPI, but probably there is a USA
equivalent, and I'm not really too fussy about which one we use)?
Although gambling debts may be hard to enforce, we should try arranging
this in the form of a contract that is binding on our estates.
Better confirm that you will aceept Mauna Loa measurements, and won't
pull some random Russian's back-garden observations out of a hat...
Look forward to hearing your further commments,
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