Biodiversity and the fossil record

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>So here is the question for you to kick around:  Based on our knowledge
>of mass extinctions and recoveries -life has always managed to recover,
>including the big one (Permian/Triassic)- how concerned is the
>paleontological community regarding the current 'mass extinction'?

As a paleontologist I think this current perturbation will have been
repaired by evolution in a few million years. As a living creature on this
planet, I don't like the idea of mass extinctions. It causes a lot of
trouble for us, right?

In an analysis of migration histories of planktic (!) foraminifera in the
Atlantic I learned that biogeographic radiation of species takes between
100 Ka to millions of years. These time scales are valid even when only
existing species shall replace the extinct ones. The time scales may be
different for terrestrial organisms, but 10 Ka are still long enough for
the human species. Considering the decay time of plutonium (about 50 Ka),
the human impact on biodiversity may have time-scales similar to
radioactive waste. As a geologist I would say the same amount of thinking,
planning, and money (as for radioactive waste disposal sites) should be
invested before human activity  leads to extinction of species. Maybe even
more. We know, radioactivity is unhealthy. The role of most species on
Earth, however, is basically unknown.

Norm wrote:
>The thing that strikes me about the current "Are we in a mass extinction?"
>debate is that no one seems to be paying much attention to the types of
>organisms that are going extinct in the last few decades. The ones I keep
>hearing about would have very little chance of being preserved in the
>fossil record.

That's the point. I hear about changes in the circum-Antanrctic plankton
(including diatoms) through increases in UV radiation in response to the
ozone hole. The acid rain over the South Atlantic through biomass burning
in the Amazon Basin is dramatic and affects the marine plankton ecosystem.
Things are getting to a point where future paleontologists may really see
something.

Paleontologists should tell the public about the time scales of extinction.
What, if stone-age people would have spread their toxic waste over the
planet and we would still be killed when we find a disposal site? How will
later generations think about disturbed water cycles, extreme variability
in non-equilibrium ecosystems, acceleation of climate change, or reduced
natural resources (genetics, food)? They may not be happy with us.

Heinz Hilbrecht




Address:

Heinz Hilbrecht
Geological Institute
ETH Zentrum
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