Mohtalim

http://newsinfo.iu.edu/news/page/normal/4229.html

When Earth is nuked back to the PreCambrian, at least life will be able to carry on. Fun question: is the half-life of the radioactive byproducts of hydrogen bombs long enough for intelligent life to develop supported by radiosynthetic primary production?

I don't think humans could take out all vertebrates (to say nothing of all macroscopic life), even if we tried. Theoretically, the meteor that kill the dinosaurs blocked most sunlight for years, but rat-like mammals and other higher life forms survived. Given the number of backwater human communities scattered in various hellholes, I doubt we could even successfully wipe out humankind.