The Intrinsic Valuation of Biodiversity Loss

We explore the costs of the loss of animal life in a consequentialist total utilitarian framework that incorporates the intrinsic value of living beings through their sentience. Moral philosophy and neuroscience define sentience as the capacity for valenced experience. Observable performance on cognitive tests represents a conservative lower bound on sentience under plausible neuroscientific assumptions. We estimate the relationship between cognition and neuron counts to cardinalize sentience. We collect population and neuron data for a wide range of animal species, and aggregate them into a single measure. Across a wide range of parameters, the aggregate sentience losses of animals in the past half century outstrip the sentience gains to humans from population growth 100-fold. Breaking even in welfare terms requires assigning a correspondingly small welfare weight to animals, at which each square kilometer of the Amazon still holds more than a million dollars’ worth of biodiversity. Including the benefits of economic growth to humans does not alter these conclusions.