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:

http://markbahner.typepad.com/random_thoughts/2005/06/proposed_bets_f...

My comments are interleaved:

There's your first mistake, because I have previously pointed directly
(at least twice) to the obviously relevant sentence in the TAR Summary:

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

"anthropogenic warming is likely to lie in the range of 0.1 to 0.2°C
per decade over the next few decades"

[Reference to this is on my blog at
http://julesandjames.blogspot.com/2005/06/reason-betting-on-climate-c...
and also mentioned at
http://julesandjames.blogspot.com/2005/06/predicting-climate-change-2...)

To put it bluntly, that is your problem, not mine, and this is your
second mistake.

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
keep going.

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.

http://en.wikipedia.org/wiki/Satellite_temperature_record

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).

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...

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.

However:

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,

James
--
James Annan
see web pages for email
http://www.ne.jp/asahi/julesandjames/home/
http://julesandjames.blogspot.com/