[EMAIL PROTECTED] wrote:
> How do we know that "noise" is unlikely to have a time scale also of
> decades, centuries or millennia with a significant amplitude?
As with so much in science, this is not amenable to direct proof, but
more a matter of finding that all the evidence - theoretical and
practical - points in much the same direction.
First, there are energy balance considerations. If the planet (or
anything else) warms up, it radiates away more energy. Things don't just
heat up and warm down (much) by themselves. Variability is the flip-side
of sensitivity here, since a planet that varies by 0.3C in the absence
of any external forcing is likely to vary by rather a lot when it
actually *is* forced!
There is also the point that no-one has managed to create a credible
climate model with such large natural variability. Our models simulate a
whole lot of processes and variability on a range of time scales
reasonably well, so it is hard to justify the belief that they are
completely useless just for a particular phenomenon where we have little
direct evidence. The onus is very much on those who suggest that climate
change is just natural variability, to demonstrate how this can be
simulated by models that are compatible with our understanding of the
climate system. Don't forget, science isn't really about "proof" so much
as building up a consistent picture of how the world works, modifying
our hypotheses as new evidence arises.
James
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
Global Change ("globalchange") newsgroup. Global Change is a public, moderated
venue for discussion of science, technology, economics and policy dimensions of
global environmental change.
Posts will be admitted to the list if and only if any moderator finds the
submission to be constructive and/or interesting, on topic, and not
gratuitously rude.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/globalchange
-~----------~----~----~----~------~----~------~--~---
