global warming and extinction, is there a model?

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Thu Sep 29 03:08:15 CDT 2005


> >... there's a lot more
> >going on in the oceans than warming. And I seem to remember that ocean
> >temperatures have changed in the past, at times not associated with mass
> >extinctions.
>
> What about models of geographical displacement of biotas, rather than (or
> combined with) possible extinctions ?
> Seems that when conditions get too warm here, they could become
> quite fine
> elsewhere... raising the problems of available routes for active
> or passive
> dispersal (water currents, landscape corridors...), timing of
> extinction /
> colonization, and local fate of invaders and invaded...

These are the same two points I raised with Charlie Veron when I discussed
the fate of coral reefs.  He was very persuasive in convincing me of two
things:

1) Modern climate models indicate a much faster temperature change over the
next half-century to century than indicated for past climate changes of
comparable magnitude; and

2) Most habitat at suitable depth at higher latitutdes, where one might hope
new reefs would form in a warmer climate, consist of predominantly basaltic
rock.

Charlie reckons there simply is not enough time for reefs to develop the
necessary limestone foundation for proper reef formation at these northern
and southern regions -- even if water temperatures there warm sufficiently
to sustain corals.  It's not, in Charlie's vision, so much the fact that
particular coral species will go extinct.  Rather, it is more the entire
reef ecosystem that will cease to exist (taking many reef-dependant species
with it).

I would like to be more optimistic than Charlie on this, but having
witnessed the devestating effects of large-scale bleaching events
first-hand, and understanding what temperatures caused these events in the
context of predicted sea-surface temperatures over the next several decades,
it's really hard to stay opitmistic.

I'm a fish guy -- not a coral guy -- so I can't defend these statements with
as much confidence as coral experts can.  Maybe Charlie is off his rocker,
but the more I read and learn about the growing body of science around
global warming, the more depressed I become.

Aloha,
Rich




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