The scientific evidence is now overwhelming: climate change presents very serious global risks, and it demands an urgent global response.

Climate change represents the greatest and widest-ranging market failure ever seen

A diet that relies heavily on meat production results in higher emissions than a typical vegetarian diet. Different individuals will make different choices. However, the debate about climate change should not be dumbed down to a single slogan, such as 'give up meat to save the planet.

We run enormous risks and we know what kind of reductions of greenhouse gases are necessary to drastically reduce risks. Reducing emissions by half by 2050 is roughly in the right ballpark. It would bring us below 550 ppm.

Those who say that climate change doesn't exist are being understood as the flat-earthers that they are, as the people who deny the link between smoking and cancer, as the people who denied the link between HIV and AIDS.

This [climate change] is potentially so dangerous that we have to act strongly. Do we want to play Russian roulette with two bullets or one?

The record rainfall and storm surges that have brought flooding across the UK are a clear sign that we are already experiencing the impacts of climate change.