Our Final Hour is a 2003 book by the British Astronomer Royal Sir Martin Rees.

The full title of the book is Our Final Hour: A Scientist's Warning: How Terror, Error, and Environmental Disaster Threaten Humankind's Future In This Century—On Earth and Beyond.

Rees discusses a range of existential risks confronting humanity, and estimates that the probability of extinction before 2100 CE is around 50 percent, based on the possibility of malign or accidental release of destructive technology.

[1][2][3] In Our Final Hour, Rees explores various risks of human extinction and their likelihood, notably those caused by the unchecked consequences of new technologies (such as nanotechnology or machine superintelligence), uncontrolled scientific experimentation, terrorist or fundamentalist violence, or destruction of the biosphere.

He states that, in the 1990s, Aum Shinrikyo tried unsuccessfully to obtain an Ebola virus sample, which they could now create in their Mount Fuji lab, using ingredients and instructions from the Internet.