Poverty must be eradicated, the resources of our planet used sustainably, human rights respected, equality between men and women strengthened, HIV/AIDS and other diseases prevented, terrorism stopped, and disarmament and non-proliferation secured.

I think the Greens are posing some of the most important questions of our time, for example how we live sustainably on a planet of finite resources and a rising population, and how do we do that in a way that doesn't exceed environmental limits and which is fair.

Determining the value of individual texts has been an ideological scuffle in literary criticism for centuries: but the environmental cost of printing them hauls this dispute from the ivory tower into day-to-day decision-making. Is it right to write? The publishing industry is slowly beginning to commit to using sustainably harvested trees.

Everything depends on our ability to sustainably inhabit this earth, and true sustainability will require us all to change our way of thinking on how we take from the earth and how we give back.