What We Lose When a Species Disappears

Michael A. Livermore joined the University of Virginia's School of Law faculty in 2013 and teaches courses on environmental law, regulation and legal technology. His research focuses on environmental law, cost-benefit analysis and the application of data science techniques to legal texts. He is the co-author of Reviving Rationality: Saving Cost-Benefit Analysis for the Sake of the Environment and Our Health (Oxford University Press, 2020) and Retaking Rationality: How Cost-Benefit Analysis Can Better Protect the Environment and Our Health (Oxford University Press, 2008). Livermore earned his J.D. magna cum laude from NYU Law.

National Wildlife Day arrives this year against a sobering backdrop. According to the most recent Living Planet Report from the World Wildlife Fund, the populations of more than 5,000 vertebrate species have shrunk by an average of 73 percent since 1970. The figure is an average across populations rather than a count of animals, and some populations have grown while others have collapsed, but the direction of the trend is not in doubt. In the span of a single human lifetime, the abundance of wild animals on Earth has fallen by something close to three quarters. Losses in Latin America and the Caribbean have been steeper still, with populations down by roughly 95 percent.

A day set aside for appreciating wildlife is a good occasion to ask how that appreciation shows up in the decisions governments make. When an agency considers whether to protect a wetland, restrict a pesticide, or require pollution control, it usually has to say something about what the protection is worth. In the United States, that question is often answered through cost-benefit analysis, a tool I have spent two decades studying and defending. Cost-benefit analysis has a mixed reputation among people who care about nature, and part of the reason is that it can seem to leave out exactly the things that make wildlife worth protecting.

Some environmental benefits fit the framework comfortably. Wetlands filter water and buffer floods, pollinators support crops, and forests store carbon, so economists can estimate what those services would cost to replace. Other benefits are harder to pin down. Economists have developed survey methods to estimate how much people would pay to know that a species continues to exist, and those estimates do capture something real. Still, many people sense that the harm of extinction runs deeper than a drop in human satisfaction, and a framework that can only register the loss through its effect on human preferences will always seem to be measuring the wrong thing.

In a recent article, Valuing Diversity, I argue that the welfare framework underlying cost-benefit analysis can accommodate that intuition once we take seriously the fact that animals have experiences of their own. Welfare economics is built on the idea that subjective experience is what ultimately matters, and many now accept that the experiences of nonhuman animals count. My proposal adds one further step: the diversity of experience in the world has value in addition to the total quantity of well-being. This means that a world with many different ways of experiencing life is better than a world with the same amount of well-being but less diversity.

This idea explains a judgment that most people share and that standard approaches struggle to justify. Saving the last thousand members of a rare bird species matters more than saving a thousand common pigeons, even if the total well-being at stake is similar. Each species embodies a unique way of perceiving and inhabiting the world, one shaped by millions of years of evolution and manifested in distinctive body plans, sensory organs, and behaviors. When a species goes extinct, that way of being is gone for good.

The 73 percent figure from the Living Planet Report describes a world becoming poorer in exactly this sense. Most obviously, declining populations put species on the road to extinction. But even if we succeed in preserving every threatened species within protected areas, those remnant populations will hold only a sliver of the wild experience that existed fifty years ago. During the same decades when wildlife has been dying off, the number of domesticated animals (particularly farmed animals) has increased dramatically. By biomass, livestock outweigh wild mammals by roughly fourteen to one, while domesticated poultry outweigh wild birds by roughly three to one. The unhappy experience of a chicken in a cage or a pig in a confinement pen is reproduced billions of times. The diverse, self‐directed lives of wild animals are quickly being supplanted by the monotony and misery of industrial meat production.

Framing the harm this way allows cost-benefit analysis to treat diversity of experience as another benefit delivered by protective policies, alongside ecosystem services, health benefits, and existence value. That does not mean there are no hard technical questions about how to measure and weigh diversity of experience. Analysts would need to quantify how one organism’s experiences differ from another’s, and they would even need to determine which organisms have experiences at all—a difficult and contested question in its own right. The value of preserving the diversity of experience must also be weighed against other important considerations, including development, consumer prices, and individual autonomy. None of these questions has an obvious answer, but that has not stopped us from incorporating other hard-to-value effects, such as mortality risk reduction or the harms of climate change, into cost-benefit analysis.

The advantage of doing this work is that it gives environmental values a voice in the rooms where policy is actually made. Regulatory decisions are frequently framed in the language of welfare economics, and values that cannot be expressed in that language tend to lose. Wildlife is worth celebrating on September 4, and it is worth counting properly the other 364 days of the year as well.