> One of the stock objection of greenhouse skeptics (like Herb
> Schmertz or his epigone that's still writing advertorials for Exxon
> now that they've become ExxonMobil) is that there have been large
> variations in global temperature over the last 3 millennia, and that
> variation during the "medieval warm period" (circa 1000 years ago)
> and the "little ice age" (circa 400 years ago) were both more
> extreme and happened more quickly than the variation we've
> experienced over the last century.
yes, climate has changed in history (for carrol: climate is its history).
there are a number of changes which can be correlated with natural causes, like enhanced volcanism, wandering of the earth's spin axis, etc. when those causes disappear, climate will change again, perhaps even back to its orginal state prior to the event.
There is quite a lot of work being done now to look at these known climate shifts in prehistory and see if one can match causes. This project will take some good time.
We face here a different situation, where its pretty clear human energy use has created climate change as well. and we assume our interest lies in a continuation of the species, having lights at night, running some machinery, etc...
so we don't have a situation where the cause can be expected to fade out like many of the historical causes, unless something drastic changes in the way we live energetically.
i've heard all kinds of things: the earth has been wrmer (colder) in the past and yet here we are. but again, these don't address the current situation, whcih is energetics of life by billions of people for whom, in a warm fuzzy world, it'd be nice to have us all stick around.
[one can envision nightmare scenarios where instead of an Earth First! organiation 100 years from now, we have a USEarthFirst!, where presidential candidates promise swift destruction of lesser-developed nations that can't curb their CO2 production.].
but there is a lot more literature on this subject. i havent looked at in in a year or so. it will be good to go back and try to find some responses to these Exxon political hacks. i had a conversation with a climatologis at UMass last year, i'll see if i can dig it up asi think we went over some of this stuff.
to sum up this section: climate change happens, yes. the question is, are we putting the change on a permanent trend basis, and in a direction bad for sustaining life [broadly defined].
> The implication is that there are chaos-like structures leading to
> global temperature variation that are as yet unaccounted for in our
> theories, and that might well swamp the effects of human industry --
> in which case, if we have to spend billions of dollars either way,
> we are better off spending them adapting to climate chage than
> trying to prevent it. Is there any truth to this position? Does it
> have an obvious flaw?
is this business about chaos your take or was it explicated by the Exxon goons? if the latter, i gotta something to say about bringing chaos into this conversation, but i will hold my toungue till i hear its source.
les schaffer