The Life and Death of Planet Earth
Peter D. Ward and Donald Brownlee 2002 0805067817
booknotes
I learned a lot from Ward&Brownlee's Rare Earth (2000), and Ward's Under a Green Sky (2007)
- I didn't see "Life and Death" until 10 years after publication, hence much of the contents are old news
- Subject: Long term climate change in a world without geoengineering
- Reiterates that we live at a time suited for intelligence, rare in Earth's very long history
- More glaciations due
Root cause, weathering of Himalayas and abnormally low CO2
- Previously warmer, wetter
- Future heating due to sun heating
- Solar heating because helium hotter at same pressure and density
- Denser hotter core means faster fusion
- Sun expansion at 7GY from now (not 10 as I remembered) oopsie
- Earth in old age - mostly because sun heating limits life span
Claims animal life possible only ± 500MY from now
- Dismisses space technology
- yes, rockets are expensive, book assumes forever
- Moving to Mars
- Who needs another (too small) planet?
- Moving earth with repeated cometary encounters
- 100 km diameter comet, go to mars orbit, would lose moon
- 2001 Don Korycanscky, Gregory Laughlin, Fred Adams
- 300 AU semimajor axis, 1e18 kg every 6000 years, 1 million times
- my note: how about ten 500 tonne objects a second? Or 1 million 5 kg objects a second?
- My heating recovery calculations:
Solar Shielding/reflector at 0.95 A.U., 10 grams per meter squared, 3e16 m2, 3e14kg
12 km/s delta V, 20% efficiency, 100 year mass replacement rate, --> 36 Terawatts
- 1e-13 of solar output