----- Original Message -----
From: "James Annan" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, November 28, 2006 2:02 AM
Subject: [Global Change: 1024] Re: Is (climate) change bad?
>
> Alastair McDonald wrote:
>>> That hardly has any relevance for practical decision making, though. I
>>> see no plausible mechanism whereby anything we do over the next 100
>>> years (let alone the next decade or two) could result in a 20C
>>> temperature rise, even as a future commitment let alone 2100 climate.
>>
>> But have you looked for a plausible mechanism? If not, then it is not
>> surprising that you have not found one.
>
> OK, more pedantically, "No-one has presented any plausible mechanism..."
There is a plausible mechanism, and that is the warming we produce triggers
a catastrphic release of methane from clathrates. This is one of the ideas
behind the cause of the P-T mass extinction, and also the Paleocene-
Eocene Thermal Maximum.
The ClimatePrediction models were coming up with a 10K rise, but we
know the models cannot replicate abrupt warming, so that could easily
translate into 20K by an abrupt warming unpredicted by the model.
For a 20K rise it would need to be abrupt, becasue otherwise we would
take action to prevent it when temperatures had risen above 5K say.
But there is another problem. As it stands the 20K will only be felt in
the Arctic. In the tropics the clouds will prevent temperatures rising
by much. Hoever, the jungle is being cleared and that is the main
source of the water in the tropical clouds over land. It is quite
plausible that we will end up with dustbowls where the tropical
rain forests used to be. Then tropical temperature will soar too.
>> But worse, you seem to equate beliefs with scientific judgments.
>
> No, I was actually objecting to Coby's statement of belief *in advance
> of any scientific judgement*. In a strict sense, the existence of a
> prior belief is necessary given a basically Bayesian approach, but in
> that case it had better be pretty vague. If your belief is not amenable
> to being influenced by scientific evidence, then you aren't being
> scientific.
But Coby's beliefs do not require scientific judgement. Beliefs do
not equate to scientific judgements. They are the ideas one holds
where science does not have an answer. Where science does
have an answer, then a sensisible man would believe that to be true,
but the scientific establishment has been proved wrong time and
time again. The point to realise is that the mistakes are forgotten,
and it is only the correct answers that enter the textbooks.
I agree with Coby's idea of protecting the diversity of species. For
me this is mainly an aesthetic judgement. I prefer a landscape filled
with a myriad of detail, rather than monocultural fields. However,
there is another argument, and that is we do not know the consequences
of outr actions. I have already given two instances of that, with the
plowing up of the dust bowl, and the felling of the tropical forests.
Change can be both good and bad. If we make many changes, such
as eradicating every species we don't find useful, then we are bound
to make a mistake (Sod's Law - a corrolalry of the Second Law of
Thermodynamics.) And here again we will not know that a species
is a vital component of the food web until it is removed - which
will be too late!
It is all very well quoting Popper and playing around with Bayseian
statistics, but when it comes to the real world, we are just educated
apes wrecking up a world we don't understand.
Cheers, Alastair.
>
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