Professor Tom Wagner of Newcastle University,
England, led a team which analysed a core of
sediment containing bands of black shale, formed
by dead organic matter, indicating massive
destruction of marine life as the oceans warmed
up and became depleted of oxygen. This process
occurred rapidly and repeatedly over a three
million year period.
Adding the results of a climate model, the
researchers found that the relative positions of
the Earth and the sun were highly significant.
Changes in the atmosphere were driven by the
large amount of solar energy hitting the upper
atmosphere when the Earth’s elliptical orbit took
it closest to the sun at the time of equinox.
These atmospheric changes triggered periods of
high river run-off into the oceans. This influx
of fresh water caused dramatic changes in ocean
chemistry which ultimately led to deep water
losing oxygen and becoming uninhabitable by most
life.
While modern climate change may be man-made in
part, Professor Wagner points out that we should
not lose sight of the fact that climate change
also occurs naturally and it is crucial that we
understand the mechanisms and warning signs by
studying past events.
Commenting on the Nature paper, Professor Wagner, of the University’s Institute for Research on Environment and Sustainability, said that today, the majority of the world’s population live in coastal areas, which were the most vulnerable to natural catastrophes as recorded in the
geological record.
‘Understanding the processes and feedbacks
controlling carbon and nutrient cycling in the
modern world and during past periods of extreme
warmth is therefore critical to separate human
impact on climate from natural variability and
underpins the ability to adapt to future
conditions,’ he said.
SOURCE: Newcastle University Press Office