Where solar energy is concerned - and wind energy and battery storage and electric vehicles and efficiency technologies - that is what we are now seeing. So, yes, I'm very optimistic, but anyone who works on the climate crisis has an internal struggle between hope and despair. I won't deny that, but hope has always prevailed in my outlook.

If you want your energy bills to go up, you should support an ever greater dependence on foreign oil, because the rate of new discoveries is declining as demand in China and India is growing, and the price of oil and thus the price of coal will go sky high.

Winston Churchill aroused this nation in heroic fashion to save civilisation in World War Two. We have everything we need except political will, but political will is a renewable resource.

Take it from me, every vote counts.

We have to abandon the conceit that isolated personal actions are going to solve this crisis. Our policies have to shift.

During my service in the United States Congress, I took the initiative in creating the Internet. I took the initiative in moving forward a whole range of initiatives that have proven to be important to our country's economic growth and environmental protection, improvements in our educational system.

Although I have a variety of obligations, the climate crisis is my central concern.