There'll come a time when airplanes are much more efficient when it comes to producing lower levels of greenhouse gas emissions, there'll come a time when we'll be able to offset those emissions much more effectively than we do now. But alas at the moment, flying airplanes is really one of the least defensible things that we do and it's one of the things that I indulge in quite frequently, alas.

Aristotle thought that humans are rational animals and Hobbes thought that we act on the basis of rational self-interest. If only! It's not that we never do these things, it's that they are hardly constituative of who and what we are.

One of the real dangers of our time is people's indifference to history.

When it comes to climate change it's all the usual barriers: greed, mendacity, ignorance, short-sightedness and so on, manifest in the extreme power of corporations, the weakness of government, and the indifference of citizens.

We live on a restless planet in a violent universe.

We're not good at noticing slow, steady changes in our environments, our senses are not very acute compared to those of many animals, and we're pretty awful at abstract thought, much less acting on it.

Increasingly both environmentalists and animal ethicists recognize the enormous destruction caused by animal agriculture.