We have known since the 1800s that carbon dioxide traps heat in the atmosphere. The right amount keeps the climate conducive to human life.

If humanity wishes to preserve a planet similar to that on which civilisation developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO₂ will need to be reduced from its current 385 ppm [parts per million] to at most 350 ppm... If the present overshoot of this target CO₂ is not brief, there is a possibility of seeding irreversible catastrophic effects.

I think we have a very brief window of opportunity to deal with climate change. No longer than a decade at most.

We have at most ten years - not ten years to decide upon action, but ten years to alter fundamentally the trajectory of global greenhouse emissions... We are near a tipping point, a point of no return, beyond which the built in momentum and feedbacks will carry us to levels of climate change with staggering consequences for humanity and all of the residents of this planet.

The trains carrying coal to power plants are death trains. Coal-fired power plants are factories of death.

Coal is the single greatest threat to civilization and all life on our planet.

What we are doing to the future of our children, and the other species on the planet, is a clear moral issue.