We spoke to @BillGates about his new book, “How to Avoid a Climate Disaster,” the limits of his optimism, and how his thinking on climate change has evolved. This is a thread about that conversation.

Question: In the past, it seemed you would distance yourself from the policy side of climate change. Was there a shift in your thinking, or was it a deliberate choice to lay out the policy side in your book?

Q: How do you feel about our chances of making real political progress, particularly in the US, in the moment we find ourselves in?

Q: You’ve said a couple of times you’re optimistic, and that’s sort of famously your position on these things. But of course, optimism is a relative term. Do you think we can realistically hold warming to or below a 2 °C increase at this point?

Q: In the book you cover a broad array of hard-to-solve sectors. The one I still have the hardest time with, in terms of fully addressing it, is food. How hopeful are you about agriculture and climate emissions?