In the third season finale, Clarke manages to destroy A.L.I.E. and it is revealed the world faces another nuclear disaster because of nuclear reactors around the world that have fallen into disrepair and are irradiating Earth, once again threatening to make it uninhabitable.
Clarke manages to destroy A.L.I.E.. This is in the third season finale. The world faces another nuclear disaster because of nuclear reactors around the world. This was what it is revealed in the third season finale. This world have fallen into disrepair. It are irradiating Earth, once again threatening to make it uninhabitable. This is in the third season finale.