I have the pleasure of teaching the science of weather and climate to non-scientists again this Fall/Winter session at Toronto’s York University. In the Fall 2011 Term, time was spent discussing the origin and evolution of Earth’s atmosphere. What follows is a post I just shared with the class via Moodle (our LMS):
Photosynthesizing anaerobic lifeforms in Earth’s oceans were likely responsible for systematically enriching Earth’s atmosphere with respect to O2. Through chemical reactions in Earth’s atmosphere, O3 and the O3 layer were systematically derived from this same source of O2. The O3 layer’s ability to minimize the impact of harmful UV radiation, in tandem with the ascent of [O2] to current values of about 21% by volume, were and remain crucial to life as we experience it today.In tracing the evolution of Earth’s second atmosphere from a composition based on volcanic outgassing to its present state, the role of life was absolutely critical.On my drive home tonight after today’s lecture, I happened upon a broadcast regarding synthetic life on CBC Radio‘s Ideas. Based upon annotated excerpts from a Craig Venter lecture, this broadcast is well worth the listen in and of itself. And although I’m no life scientist, I can’t help but predict that Venter’s work will ultimately lead to refinements, if not a complete rewrite, of life’s role in the evolution of Earth’s second atmosphere.
If you have any thoughts on this prediction, please feel free to share them here via a comment.