Terrestrial Palaeoecology and Global Change

Introduction
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indeed find such strict regionalism depressing. Anyway, the brave new tectonics managed
to rapidly overcome the initial scepticism that was soon replaced by a boundless
enthusiastic support. The believers hastened to proclaim it the only scientific global model
that explains everything worth explaining.
Actually the model only ventured to explain what happened, with no reference to
how and why. It therefore soon degraded to a body of ad hoc explanations linked by
special terminology alone. In any regional reconstruction there are plates to be rifted,
rafted, collided, subducted and obducted, with a ridge/trench system assumed for each
particular episode. A global perspective has been lost once again in the multitude of case
studies. As it is, plate tectonics is not a predictive theory.
The Popperian principle of testing theories by attempts at refutation rather than confirmation
(Popper, 1972) has been rarely if at all applied to the plate tectonics. Yet, as the
recent experience has repeatedly asserted, even the thoroughly refuted theories can be
kept afloat by a series of first-aid modifications, in which the original idea is either lost or
made totally meaningless.
As noted in (I.1), the original idea of global change has been prompted by the finds of
marine fossils on land and even now the geological record is most convincing in the case
of sea-level changes. Their plate tectonic explanation as the effect of an accelerated
sea-floor spreading (elevated spreading axes) is only half-heartedly accepted even by
the proponents for want of anything better. The consequences of sea-level changes for
the climate and biota are commonly believed to be significant, yet the specific mechanisms
of interaction are but dimly outlined.
There is little doubt that climate affects both geological and biological processes and
is in turn affected by them. Climatic events may then correlate with biotic turnovers,
evolutionary innovations, growths and declines of civilizations, a possibility tackled by
generations of palaeontologists, archaeologists, ethnologists, etc. However, a comprehensive
theory of climate change is wanting. There are several theories, the orbital,
geographical, CO 2
, etc., illuminating a few features rather than the whole picture. The
choice of a leading force (CO 2
at the moment) is arbitrary, mostly dictated by nonscientific
considerations.
Of all geological evidence, the records of climate change are the least direct. The
alleged proxies are ambiguous: different combinations of climatic variables may leave
similar isotopic, chemical or biotic signatures. A palaeoclimatic inference thus amounts
to disambiguating the proxies for which no methodology exists so far. No wonder then
that what we seem to firmly know about global climate change is not much.
As for the biological aspects, it should be reminded that current evolutionary theory
appeared as an organismic paradigm (Lamarck). It was then reformulated as a populational
paradigm (Darwin and population genetics). Recent contributions came from molecular
biology. The ecosystem level, though of primary importantce for the purposes of
deciphering and predicting global change, yet remains the least explored.