Nick Beckstead just published a post on disaster shelters over at the Effective Altruism Blog. Summary:

What is the problem? Civilization might not recover from some possible global catastrophes. Conceivably, people with access to disaster shelters or other refuges may be more likely to survive and help civilization recover. However, existing disaster shelters (sometimes built to ensure continuity of government operations and sometimes built to protect individuals), people working on submarines, largely uncontacted peoples, and people living in very remote locations may serve this function to some extent.

What are the possible interventions? Other interventions may also increase the chances that humanity would recover from a global catastrophe, but this review focuses on disaster shelters. Proposed methods of improving disaster shelter networks include stocking shelters with appropriately trained people and resources that would enable them to rebuild civilization in case of a near-extinction event, keeping some shelters constantly full of people, increasing food reserves, and building more shelters. A philanthropist could pay to improve existing shelter networks in the above ways, or they could advocate for private shelter builders or governments to make some of the improvements listed above.

Who else is working on it? Some governments maintain bunkers in order to maintain continuity of government and/or to protect their citizens. Some individuals purchase and maintain private disaster shelters.

Questions for further investigation: With the possible exception of pandemic specifically engineered to kill all humans, I am aware of no scenario in which improved disaster shelters would plausibly enable a small group of people to survive a sudden near-extinction event. In the case of other catastrophes where a much larger number of people would survive, I would guess that improved refuges would play a relatively small role in helping humanity to recover because they would represent a small share of relevant people and resources. Many challenging questions about improving refuges remain, but I would prioritize investigating other issues at this point because refuges seem likely to be of limited value and alternative strategies (such as improving biosecurity and increasing the resilience of industrial and agricultural systems) seem more likely to effectively reduce the global catastrophic risks that improving refuges might plausibly address.