Correct. We are somewhere between 250 megayears and 2 gigayears away from the Earth becoming another Venus depending on whose models you look at (the runaway greenhouse being one of 2 or 3 endpoint outcomes for a terrestrial planet given enough time).
This being said, the whole of earth’s history might not be relevant to look at for complex life. Eukaryotes are OLD, gigayears old, but there’s a set of paleontologists who think that the Cambrian diversification of macroscopic animals 550+ megayears ago might have been CAUSED by increasing oxygen concentrations which might have something to do with the running down of Earth’s geology. More on this in another post; for now I recommend the book “Oxygen: A 4 Billion Year History.” If one uses this notion of a windowed subset of time when complex life is possible we could be roughly in the middle of THAT.
I think that intelligent life tends to find itself not in the middle but near the end of any “a windowed subset of time when complex life is possible”. One reason for it is observation selection and some considration about distribution of peroids of stability. The longer periods of stability should be more rare. The large catastrophe may be overdue and could be easily triggered by our actions.
Another reason is more speculative (if anything could be more speculative here). It suggest that large changes in climate helps human evolution as they favour more universal ways of fitness, that is human intelligence. But such unstable environment may be near the end of stability period needed for evolution of complex life. (Think about recent Ice ages in last several millions years that coincide with development of Homo.)
Correct. We are somewhere between 250 megayears and 2 gigayears away from the Earth becoming another Venus depending on whose models you look at (the runaway greenhouse being one of 2 or 3 endpoint outcomes for a terrestrial planet given enough time).
This being said, the whole of earth’s history might not be relevant to look at for complex life. Eukaryotes are OLD, gigayears old, but there’s a set of paleontologists who think that the Cambrian diversification of macroscopic animals 550+ megayears ago might have been CAUSED by increasing oxygen concentrations which might have something to do with the running down of Earth’s geology. More on this in another post; for now I recommend the book “Oxygen: A 4 Billion Year History.” If one uses this notion of a windowed subset of time when complex life is possible we could be roughly in the middle of THAT.
Thanks for the link on the book.
I think that intelligent life tends to find itself not in the middle but near the end of any “a windowed subset of time when complex life is possible”. One reason for it is observation selection and some considration about distribution of peroids of stability. The longer periods of stability should be more rare. The large catastrophe may be overdue and could be easily triggered by our actions.
Another reason is more speculative (if anything could be more speculative here). It suggest that large changes in climate helps human evolution as they favour more universal ways of fitness, that is human intelligence. But such unstable environment may be near the end of stability period needed for evolution of complex life. (Think about recent Ice ages in last several millions years that coincide with development of Homo.)
My earlier article on the topic is here (need to be retranslated and rewriten):https://www.scribd.com/doc/8729933/Why-anthropic-principle-stopped-to-defend-us-Observation-selection-and-fragility-of-our-environment