ARTICLES
Dinosaurs could have avoided mass extinction (continued)
occurred. Earthquakes and volcanic activity would have been
triggered worldwide, and pieces of burning debris may have
started extensive wildfires.
the material thrown into the upper atmosphere. In most other
locations, it wouldn’t have produced such devastating results.
It seems that the Earth could not have been hit anywhere much
worse.
But it’s unlikely this would have caused the global extinction of
huge numbers of species. Such immediate effects were relatively
short-lived, and the real damage, as the researchers show,
probably came from fine particulate matter ejected high into the
stratosphere. The worst culprit, they argue, would have been
fine hydrocarbon soots. This new research claims that those
catapulted into the upper atmosphere probably originated from
rocks at the impact site rather than from forest fires.
The next mass extinction
All species inevitably go extinct and the history of life on Earth is
one of constant turnover. Extinctions also occur at all scales, from
the demise of individual species to what we call “mass events”
that see 75% or more of species wiped out globally. There have
been five such mass events over the last half billion years, and
we appear to be sleepwalking into a sixth of our own making
thanks to pollution, habitat destruction and hunting.
Soot in the stratosphere could have simply blocked out the sun
over a period of years, creating the equivalent of a nuclear winter,
shutting down photosynthesis and decimating ecosystems
as a result. But the researchers argue that as well as general
darkening, the effects upon climate were more varied, resulting
in droughts towards the equator and more extreme cooling at
mid to high latitudes. Sulphate aerosols would also have caused
acid rain, altering ocean chemistry and stressing marine and
terrestrial ecosystems alike.
The possibility of a future asteroid impact is also very real. NASA’s
Near Earth Object Program seeks to map out the trajectories of
comets and asteroids that appear set to come close to the Earth.
Plans are afoot to develop technologies capable of deflecting
objects on a collision course.
But in the meantime, this new research suggests that we should
worry slightly less about the probable consequences of the next
extraterrestrial disaster, focus our attention closer to home, and
reflect on our outrageous good fortune for being here in the first
place.
The Tohoku scientists used global climate models to predict
the size of these effects depending upon the geology of where
the asteroid struck, as well as the volume and chemistry of
Global blackout
This article was first published in ‘The Conversation’ on 10th November, 2017. Once again SEN is grateful to ‘The Conversation’ for its
generous policy of encouraging republishing of articles, and also to Dr Matthew Wills, who contributed this fascinating article. Dr Wills is
the Professor of Evolutionary Palaeobiology at the Milner Centre for Evolution, University of Bath.
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SCIENCE EDUCATIONAL NEWS VOL 67 NO 1