An anthropogenic existential risk is an existential risk arising from intentional or accidental human activity rather than underlying natural processes.

New technologies have played a huge part in the massive growth in human flourishing over the past centuries. However, they also pose some serious risks. Nuclear weapons, for example, may have created the potential for wars that result in human extinction. Other technologies may pose similar risks in the future, such as synthetic biology (see global catastrophic biological risk) and artificial intelligence, as well as risks from fundamental physics research and unknown risks.

That our species has so far survived both natural and anthropogenic risks puts an upper bound on how high these risks can be. But humanity has been exposed to natural risks throughout the entirety of its history, whereas anthropogenic risks have emerged only in the last century. This difference between these two types of risks implies that their respective upper bounds are also very different. Specifically, this consideration is generally believed to warrant the conclusion that anthropogenic risks are significantly higher than natural risks.^[1][2][3] According to Toby Ord, "we face about a thousand times more anthropogenic risk over the next century than natural risk."^[4]