Investigations into the impact of astronomical phenomena on the terrestrial biosphere and climate
Since Nobel laureate Alvarez and his colleagues' revolutionary
research on associating the K/T extinction event with an asteroid
impact (Alvarez et al. 1980), numerous astronomical hypotheses of mass
extinction events have been proposed. These studies of mass extinction
on the Earth have not reached a consensus on a common causes of these
extinction events. One of the problems is the use of overly simple and
even inappropriate model inference methods (e.g. Bailer-Jones
2009). Fabo Feng's PhD project addressed this issue by building
astronomical models to predict geological time series (e.g. impact
cratering, species extinction rates) and applying Bayesian methods to
compare these astronomically motivated models with other models. This
work has led to a number of interesting and exciting conclusions:
- astronomical phenomena purely dependent on the local stellar density
cannot explain the variation of extinction rate in the past 550 Myr
(Feng & Bailer-Jones 2013 and Bailer-Jones & Feng 2014)
- cometary impacts (as opposed to just
asteroids) contribute to a small fraction of terrestrial craters over
the past 250 Myr (Feng & Bailer-Jones 2014)
- spiral arms and the
Galactic bar do not significantly influence the flux of long period
comets (Feng & Bailer-Jones 2014)
- the anisotropic perihelia of long period comets are caused by
the combined perturbation from the Galactic tide and the anisotropic
stellar encounters arising from the solar apex motion
(Feng & Bailer-Jones 2014)
- the variation of the Earth's obliquity played a main role in triggering the ice sheet deglaciations over the past 2Myr while precession became important in determining the deglaciations
after 1Myr ago (Feng & Bailer-Jones 2015)
The PhD thesis is available
from arXiv.
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