A couple of problems: 1. We no longer have access to easy to mine resources, which is also how we know that there weren't any really advanced civilizations pri

A couple of problems: 1. We no longer have access to easy to mine resources, which is also how we know that there weren't any really advanced civilizations prior us. 2. A lot of knowledge has been lost on how to do the incremental steps between ice age to here. 3. Lots of people will die. 4. We have very little genetic diversity as a consequence of the previous ice-ages, and we haven't actually recovered.