We have used the majority of our carbon budget and we are already at dangerous levels of CO2 concentrations, about 400 parts per million. The levels were 250 before industrialization. So the problem is what we have done already and, therefore, what must be undone.

Changing the world's oceans to increase their uptake of CO2, as other geoengineering solutions propose, is equally dangerous, as the increased resulting acidity of the oceans kills tiny crustaceans, such as krill, that are the basis of the pyramid of life on the planet as we know it.

Signs of a poorly understood but treatable house fire requires action, not inaction.

Climate change is due to the use of energy for industrial growth, which has been and is overwhelmingly based on fossil fuels.

The first reaction to trauma is denial, then comes anger and finally, acceptance. I think the US is still between denial and anger, and I hope we will reach acceptance because almost perversely, right now, only the US has the technology that is needed for global economic change.

The sun is the source of all energy on planet Earth and we cannot experiment with our only energy source.

The transformation of capitalism is unstoppable because we need limits on resources for humans to survive.