From “Human Engineering and Climate Change,” by S. Matthew Liao, Anders Sandberg, Rebecca Roache, published last year in Ethics, Policy & Environment.
A widely cited report by the United Nations Food and Agriculture Organization estimates that 18 percent of the world’s greenhouse emissions come from livestock farming, a higher share than from transport. More recently, it has been suggested livestock farming in fact accounts for at least 51 percent of greenhouse emissions. Even a minor (21 to 24 percent) reduction in red-meat consumption would achieve the same reduction in emissions as the total localization of food production — that is, having zero “food miles.” Human engineering could help here.
Eating something that makes us feel nauseated can trigger long-lasting food aversion. While eating red meat with an added emetic (a substance that induces vomiting) could be used as aversion conditioning, anyone not strongly committed to giving up red meat is unlikely to be attracted to this option. A more realistic option might be to induce mild intolerance — akin, for example, to milk intolerance — by stimulating the immune system against common bovine proteins. A potentially safe and practical way of delivering such intolerance might be to produce “meat patches” — similar to nicotine patches. We can produce patches for those animals that contribute the most to greenhouse-gas emissions and encourage people to use such patches.
Human ecological footprints are partly correlated with body size. As well as needing to eat more, larger people consume more energy in less obvious ways. For example, a car uses more fuel per mile to carry a heavier person than a lighter person; more fabric is needed to clothe larger people; heavier people wear out shoes, carpets, and furniture more quickly than lighter people; and so on. A way to reduce ecological footprints, then, would be to reduce size. There are several ways by which we could reduce adult height in humans. While genetic modifications to control height are likely to be quite complex and beyond our current capacities, it nevertheless seems possible now to use pre-implantation genetic diagnosis to select for shorter children. Another method of influencing height is to use hormone treatment either to affect somatotropin levels or to trigger the closing of the epiphyseal plate earlier than normal (this sometimes occurs accidentally through vitamin A overdoses). A more speculative and controversial way of reducing adult height is to reduce birth weight. Drugs or nutrients that either reduce the expression of paternally imprinted genes or increase the expression of maternally imprinted genes could potentially regulate birth size.
Another indirect means of mitigating climate change is to enhance and improve our moral decisions by making us more altruistic and empathetic. Many environmental problems are the result of collective-action problems. If people were generally more willing to act as a group and could be confident that others would do the same, we might be able to enjoy the sorts of benefits that arise only when large numbers of people act together. Whereas altruism and empathy have large cultural components, there is evidence that they also have biological underpinnings. Test subjects given the prosocial hormone oxytocin were more willing to share money with strangers and behaved in a more trustworthy way. Furthermore, oxytocin appears to improve the capacity to read other people’s emotional states. Conversely, testosterone appears to decrease aspects of empathy. These examples are intended to illustrate some possible human engineering solutions. Others like them might include increasing our resistance to heat and tropical diseases and reducing our need for food and water.