Abstract

Humanity may underestimate the rate of natural global catastrophes because of the survival bias (“anthropic shadow”). But the resulting reduction of the Earth’s future habitability duration is not very large in most plausible cases (1-2 orders of magnitude) and thus it looks like we still have at least millions of years. However, anthropic shadow implies anthropic fragility: we are more likely to live in a world where a sterilizing catastrophe is long overdue and could be triggered by unexpectedly small human actions. In the same way, an over-inflated toy balloon, which will soon burst, is very fragile. Anthropic fragility can manifest itself in the higher chances of runaway global warming. It has often been suggested that the Earth's atmosphere remained life-supporting for billions of years by sheer chance. Therefore, the survival bias can be strong. It is also known that Earth-like water worlds could experience transitions into deadly moisture greenhouse (mean T = 65C). This means that relatively small anthropogenic actions could put the climate above an unpredictable tipping point, which could lead to the moisture greenhouse. Thus, it is necessary to carry out urgent geoengineering studies and prepare to prevent an unexpected climate catastrophe. There are three main counterarguments against the existence of the anthropic shadow: self-indication assumption (SIA), past observers and the Gaia hypothesis; we show that they fail. It was proposed that SIA exactly compensates the anthropic shadow as an observer unlikely to find herself in a world with a strong anthropic shadow; however, there is a baseline level of the anthropic shadow for all habitable planets, similar to the rate of evolutionary transitions like abiogenesis. There are no “past observers” as qualified observers appeared only 50 years ago. Gaia hypothesis assumes existence of self-stabilizing feedback in climate, but new types of events like quick CO2 growth could override its coping ability. We present a list of other catastrophes that may have been underestimated because of the anthropic shadow, including collider catastrophes, nuclear war and even an alien invasion. We also hypothesized that human intelligence is more likely to emerge in an unstable world that is nearing its end and thus we get a new form of Doomsday argument.