Update written two years later, on noticing that this post is currently the highest ranking Google search result for "Eating the Sun" that I have any contol over.
I just sent off the manuscript for the new book. Here's what I think is going to be said about it in the Fourth Estate (UK) catalogue
Photosynthesis is the most mundane of miracles. Every day it lets the world's plants turn a nuclear war's worth of solar power into new leaves and stems and branches; if it stopped, there would be no food to eat or air to breathe. Eating the Sun tells the remarkable story of the scientists who discovered the workings of this miracle, and reveals the epic scale of its power to shape the environment. Showing everything from the evolution of life to the current climate crisis in a new green light, Eating the Sun will change the way the reader sees the world.
It is, in short, about the attribute of the earth which is least Mars-like...
And now off to Glasgow, where it appears I may also be appearing on this.