What do you mean by world crisis?
I mean if it is about a global nuclear war, I think we should not worry about bitcoin. I mean, it will clearly not be a priority!
If you mean dealing with current problems (poverty, hunger, access to clean water, etc), I guess bitcoin could help... The only (big) issue is that in the concerned countries, it can be difficult to have 2 hours of electricity per day. So a computer? No way...
Eventually, I think that crypto currencies can be used as alternative way of financing projects (whatever the projects, not necessarily for the greater good). Actually, this is also why most people are investing in bitcoin: in case it turns out to be very profitable in the future... Will it be? We can hope so!