There is, even today, a Flat Earth Society that meets every year to say the Earth is flat. The science about climate change is very clear. There really is no room for doubt at this point.

Please eat less meat - meat is a very carbon-intensive commodity.

An extremely effective instrument would be to put a price on carbon. It is only through the market that you can get a large enough and rapid enough response [to climate change]

We have embarked globally on a path of unsustainable development. Our lifestyles, the way we produce goods and services, are all part of a system that is completely unsustainable. I see solutions to climate change leading to a much larger philosophical shift in the way human society develops. We need a new matrix to define what human progress is.

Warming of the climate system is unequivocal...most of the global average warming over the past 50 years is very likely due to anthropogenic greenhouse gases increases.

Climate change is for real. We have just a small window of opportunity and it is closing rather rapidly. There is not a moment to lose.

Climate change: It's here. If we don't react, war, pestilence and famine will follow close behind