Most of entries on the list are either not quantifiable even approximately to within order of magnitude. Of those that are (which is pretty much only "risks from nature" in Bostrom's system) many are still bad candidates for putting significant effort into, because:

• we either have little ways to deal with them (like nearby supernova explosions)
• we have a lot of time and future will be better equipped to deal with them (like eventual demise of Sun)
• they don't actually seem to get anywhere near civilization-threatening levels (like volcanoes)

About the only new risk I see on the list which can and should be dealt with is having some backup plans for massive solar flares, but I'm not sure what we can do about it other than putting some extra money into astrophysics departments so they can figure things out better and give us better estimates.