It is perhaps trite in this day and age to observe that human numbers and technological capacity have become significant factors in the functioning of Earth systems. In particular Herbert Simon's artificial now rivals the natural in determining the evolution of our planet's future.

I saw a book today by the founder of Greenpeace. The book is called Thermageddon and, based on the jacket blurbs it argues that Earth is on the verge of an irreversible transition due to the ongoing increase in CO2 concentration in our atmosphere. The possiblility of such transition is real and we should do everything we can to avoid them, but in recognizing their possibliltity, we should also consider how we might manage the risk. Planetary Management is the effort to develop and implement managment structures that recognize the spatial and temporatl scales of human activities in relation to the functioningn of our planet.