October 04, 2006

SciAm: October's read of the month

I always like picking up Scientific American when I can. Frequently it will flag emergent research-based issues several years ahead of popular awareness or consensus. The most obvious example is the link between circumcision and AIDS prevention in Africa, which SciAm wrote about over a decade ago but is just now becoming widely known.

This month, there is a remarkable piece by Peter Ward which provides a plausible mechanism connecting those previous mass extinctions that had contemporaneous global temperature warming events: basically that extremes in the warming cycle can lead to the oceans releasing large amounts of toxic gas as the chemocline rises to the surface.

While the K-T extinction we're all familiar with is still pretty strongly linked with an asteroid impact, evidence for asteroid impact during all the other mass extinctions in earth's history remains rare. The other big problem that vexed theorists in this area until now is that mass extinctions seemed to be a land-and-sea phenomenon, which seemed to rule out a lot of possible explanations that couldn't affect both realms simultaneously.

If Ward is right, the greatest threat from global warming may not be the onset of a new ice age, but instead a devastating poisoning of the atmosphere itself.

If the theory were to bear out (and I'm obviously hoping it doesn't) then at current rates of temperature increase we're about two centuries years away from the threshold that would trigger a mass extinction event. Obviously worth more study, and worth a read.

Posted by BruceR at 10:04 AM