The latest science suggests that it is too late to prevent human-induced climate change. Technological optimists are now turning their minds to mitigation through techniques of geo-engineering, like giant space mirrors or seeding the oceans with iron to prompt carbon-absorbing algal blooms. But projects to alter the entire planet will expose all life to massive risk.

So, why not address the source of the problem and engineer humans to reduce our environmental impact and adapt? Genetic engineering could make us smaller or reduce our appetite for meat. Doses of Oxytocin could make us more sympathetic and cooperative. Such possibilities are criticised as extreme, but are they any more so than re-engineering the planet? S. Matthew Liao is a professor of philosophy at New York University.