The Biomass Reallocation Program

Underlying human-caused extinctions, past and present, is a vast biomass reallocation program. Before our Neolithic forebears began changing the world, biomass was distributed quite evenly among species of animals and plants. The tenure of humans has seen a marked change in this, as biomass became progressively concentrated into a small number of species—us and animals we eat. Today, 96% of all mammalian biomass consists in humans and the mammals that humans farm. An additional 70% of all avian biomass consists in domestic fowl. This biomass reallocation is the most significant driver of species extinction. The number-one driver of species extinction today is change in land use. The most significant driver of change in land use is agricultural expansion. By far the most prominent form of agricultural expansion is pastoral farming and the growing of animal feed crops. Eating animals is, therefore, the most important driver of species extinction.

The Fire

Societies need energy in order to sustain themselves and their members. This energy comes in two forms: fuel and food. These are continuous: they are both means of energy acquisition consumed for the same purpose, the maintenance of a complex society. The energy sources that sustain a society—whether fuel or food—must have a sufficiently high aggregate energy returned on energy invested (EROI). The EROI of a source is the energy acquired from a source divided by the energy that the society had to invest in acquiring it. Once the EROI of a society’s energy sources drops below a certain threshold, societal collapse often results: the breakup of that society and the emergence of new, simpler societies. Calculations suggest that maintenance of a society recognizably similar to our own vis-à-vis socioeconomic parameters requires energy sources with EROIs in the 11–14 range. Maintenance of certain markers of liberal democracies may require higher EROIs, in the 20–30 range.

The End of Meat

The edge required by renewable technologies is provided by a simplification of the energy supply train. This simplification consists in no longer eating animals. Animals have upside-down energy returned on energy invested values (EROIs), with up to 30 times as much energy having to be put into raising them as we get out of them through eating them or their products. At one time, when our fossil fuels sported extraordinarily high EROIs—100:1 in some cases—we could afford to take this sort of hit on our food-based energy supply. Now, however, we can no longer afford to do so. Moreover, the results of this grossly inefficient energy exchange are rising greenhouse gas emissions. By no longer eating meat, we can reduce greenhouse gas emissions by roughly 14%. Importantly, much of this reduction will be in methane and nitrous dioxide, which have very high global warming potential relative to carbon dioxide.

One Hundred Years of Ineptitude

Most animal pathogens that infect humans employ an intermediate host. The original hosts of most coronaviruses are various species of bat. The original host of all flu viruses is the duck. But we tend to catch coronaviruses from animals that have been infected by bats. Influenza is more likely to be passed on by chickens or pigs. By eating animals, we engineer many opportunities for species, and their pathogens, to mix and mingle. We turn animals into intermediate hosts of harmful pathogens by inserting them into a particular point on a food chain that leads, ultimately, to us. These ideas are explained via SARS-CoV-1&2, the Spanish flu, the H5N1 influenza virus, and Nipah virus, among others. The role played by animal agriculture in virus mutation and reassortment is explained. By no longer eating animals, we would largely eliminate the threat of zoonotic diseases.

Pale Horse

The third benefit of no longer eating animals is a reduction in the prevalence of zoonotic diseases: diseases acquired from a nonhuman, vertebrate host. The majority of temperate diseases, almost all tropical diseases, and probably all newly emerging infectious diseases are zoonoses or they have zoonotic origins. A zoonotic pathogen can go through five stages, in which it transforms from one that afflicts only nonhuman species to one that is exclusively human. There are several factors that determine the likelihood of such a transformation. The most important of these, since it is most under our control, is the frequency of encounters between us and the animal reservoir. Eating animals and disturbing their environment are the two forms of human behavior most likely to increase frequency of encounters. Moreover, most disturbance of the environment is caused by expansion in animal agriculture. Eating animals, therefore, is the most important cause of zoonotic diseases.

The Wildwood

The three grave environmental threats that we face today are those of climate change, mass extinction, and pestilence. To mitigate these threats, the most important things we can do are (1) stop eating animals and their products and (2) afforest wherever and whenever we can. The first course of action makes possible the second. By no longer eating animals, we make available large areas of land suitable for afforestation. These twin policies will go a long way toward solving our three environmental threats. Afforested land will sequester significant amounts of carbon dioxide, arrest the changes in land use that are the most important cause of extinction, and provide a suitably undisturbed home for animal reservoirs of disease. In afforesting the land, we must let the past be our guide: restore the land to what it was before humans arrived and ruined the neighborhood.

The Great Dying

The benefits of no longer eating animals extend beyond climate mitigation. It will also mitigate current species extinction trajectories. This chapter looks at the history of human-caused extinctions. A great extinction occurs when a percentage of a species dies out (e.g., 75%). A mass extinction occurs when the actual rate of extinction exceeds the normal background rate by a certain margin (e.g., 1000×). There are good reasons for thinking that a mass extinction of species is currently occurring. Humans are the cause of this, as they have been the cause of all major extinction pulses since the Quaternary period. This chapter examines one of the Quaternary extinction pulses of 8000–11,500 years ago and defends the hominin paleobiogeography hypothesis, that is, that humans were substantially responsible for this pulse of extinctions. An undue focus on extinction, however, can mask the harm we are currently doing to species.

A Forest Future?

The other climate benefit of no longer eating meat is that it will make available huge swathes of new land for afforestation—the return of forests to land that has not recently been forested. One consequence of the inverted energy returned on energy invested (EROI) of meat is that we use far more land for farming than we would need if our diet were to be exclusively plant based. In the United States alone, somewhere in the region of 834 million acres could be made available through this strategy, much of it suitable for afforestation. Even the afforestation of land not currently used for farming has the potential to reduce global carbon dioxide emissions by nearly one-third. Adding in land currently dedicated to animal grazing and feed crops is a potentially game-changing development in the fight against climate change.

Salvation Technologies?

Available fossil energy sources are dubiously compatible with the goal of arresting climate change. Carbon capture and sequestration technologies currently do not work on an industrial scale, and even if they could be made to work, they will reduce the energy returned on energy invested (EROI) of fossil fuels to below acceptable levels. The EROI of nuclear fission is disputed, but most peer-reviewed work places it in the 5–14 range, making it of questionable utility. Nuclear fusion, if it works, will not be available in time. Some renewable sources—notably, various biofuels—have unacceptably low EROIs. The remaining forms of renewable energy—solar, wind, hydropower, and wave power—sport EROIs that are, at best, on the cusp of viability. There is reasonable hope for improvement in these technologies because they are, at present, immature. In the meantime, it would be ideal if we could find a way to give them an edge.

Welcome to Venus?

This chapter examines the reasons for thinking that anthropogenic climate change—planetary-level warming caused by human activity—is real. The science underlying the idea of anthropogenic global warming is explained. Several different forms of skepticism about climate change are explained and ultimately found to be lacking. The idea of a tipping cascade, and the consequent possibility of runaway warming, is explained. The ability to predict the ultimate severity of global warming relies on knowledge that we do not yet possess. Nevertheless, it is argued that, even if we adopt relatively conservative assumptions, it is very likely that global warming is going to have grave consequences, both for humans and for the rest of the natural world.