Please start with at least one thousand years survival metric. I personally think that modeling about the end of water and oxygen supplies in earth is too far out for beginning 'baby steps' (because there are too many factors being glossed over for media sensationalism). Just track the thing most likely to get me human life as a species, please.
Because, like, the atmosphere being oxygen toxic to kill all plant life in a billion years does not seem like a reasonable excuse to release as much carbon dioxide as possible right now (aren't humans, like only a few thousand years old?).