Is it 10 years, 20, 50 before we reach that tipping point where climate change becomes irreversible? Nobody can know. There's clearly a probability distribution. We need to ensure this planet, and we need to do it quickly.

I don't believe - till something radical changes that we are not on track to do - that hybrids are material to climate change. They're fashionable, everybody loves them, the Prius is selling well, but so are Gucci bags. But they don't impact the way the world carries stuff. You know it's a fashion statement.

Climate change is a complex problem with no central lever, and with unequal distribution of resources.

The measurements show long-term trends. Glaciers react to climate change, and warmer temperatures in the Alps are reflected in the results.

If we let climate change run its course, this could be a fairly typical winter 30 or 40 years from now.

We're vulnerable to begin with, and climate change exacerbates the vulnerability.