[Vision2020] NASA GISS Director Gavin Schmidt: The Silurian Hypothesis

[Ted Moffett]

Almost as burning and vital an issue as the Herman's Hermits!

The Silurian Hypothesis!

But seriously, this is straight-faced scientific analysis, named from a Dr.
Who episode, and published in a peer-reviewed science journal, *International
Journal of Astrobiology*:
https://www.cambridge.org/core/journals/international-journal-of-astrobiology/article/silurian-hypothesis-would-it-be-possible-to-detect-an-industrial-civilization-in-the-geological-record/77818514AA6907750B8F4339F7C70EC6

However, Schmidt also wrote a short story on this subject, *Under the Sun:*
https://motherboard.vice.com/en_us/article/3kj4y8/gavin-
schmidt-fiction-under-the-sun

Much discussion in the comments section lower down at this website:

http://www.realclimate.org/index.php/archives/2018/04/
the-silurian-hypothesis/#more-21256

The Silurian Hypothesis
— gavin @ 17 April 2018

One of the benefits of working for NASA is that the enormous range of
science the agency covers – from satellite records for the present day, to
exoplanet climates, from early Mars and deep time on Earth to the far
future – and the opportunity to think ‘big’. This week sees the publication
of a paper I wrote with Adam Frank that we hope might provoke some ‘big’
thinking.

The Silurian Hypothesis
<http://www.realclimate.org/index.php/archives/2018/04/the-silurian-hypothesis/#ITEM-21256-0>
(preprint <http://arxiv.org/abs/1804.03748>) is the idea if industrial
civilization had arisen on Earth prior to the existence of hominids, what
traces would be left that could be detectable now? As a starting point, we
explore what the traces of the Anthropocene will be in millions of years –
carbon isotope changes, global warming, increased sedimentation, spikes in
heavy metal concentrations, plastics and more – and then look at previous
examples of similar events in the geological record. What is unique about
our presence on Earth and what might be common to any industrial
civilization? Can we rule out similar causes?


(Dino Street (University of Rochester illustration/Michael Osadciw)
<http://www.rochester.edu/newscenter/astrobiology-we-think-were-the-first-advanced-earthlings-but-how-do-we-really-know-311002>

Adam had a nice piece in the Atlantic
<https://www.theatlantic.com/science/archive/2018/04/are-we-earths-only-civilization/557180/>
and there is also a good write up on Motherboard
<https://motherboard.vice.com/en_us/article/mbxk4y/a-new-study-suggests-there-could-have-been-intelligent-life-on-earth-before-humans>.


The naming of this idea comes from a 1970 Dr. Who episode where an ancient
race of reptilians (“Silurians”) who had put themselves in hibernation to
avoid a global catastrophe were awakened by experimental nuclear physics
experiments. (I tried to find ‘prior art’ on pre-human terrestrial
civilization that wasn’t based on notions of panspermia or ancient
astronauts, but I haven’t yet been successful – anyone?). Needless(?) to
say, we aren’t proposing any such occurrence (not least because the
Silurian period is too early for the development of complex life on land).

The ideas in the paper lead naturally to many lines of speculation, some of
which are relevant to us today, and some of which are just interesting (to
us at least). For instance, given that the more sustainable a civilization
is, the smaller its geophysical footprint might be, what does that imply
for the detectability of long-term civilizations? Does the onset of ocean
anoxia at the end of many of these events suggest a possibility of cycle
where the collapse of one civilization provides the seeds (fossil fuels)
for the next?

The whole idea is so intriguing that I wanted to do more with it than is
possible in a journal article. Other scientists have occasionally dabbled
in science-fiction (notably Carl Sagan and Fred Hoyle) and so, following
their lead, I wrote a short story “Under the Sun”
<https://motherboard.vice.com/en_us/article/3kj4y8/gavin-schmidt-fiction-under-the-sun>
about the consequences for finding such a signal.

Literary as well as scientific criticism welcomed!
References

   1. G.A. Schmidt, and A. Frank, "The Silurian hypothesis: would it be
   possible to detect an industrial civilization in the geological
record?", *International
   Journal of Astrobiology*, pp. 1-9, 2018. http://dx.doi.org/10.1017/
   S1473550418000095

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Vision2020 Post: Ted Moffett
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