James Hansen

...99 percent confident that the world really was getting warmer and that there was a high degree of probability that it was due to human-made greenhouse gases.

We need to send a message to Congress and the president that we want them to take the actions that are needed to preserve climate for young people and future generations and all life on the planet.

Coral reefs, the rain forest of the ocean, are home for one-third of the species of the sea. Coral reefs are under stress for several reasons, including warming of the ocean, but especially because of ocean acidification, a direct effect of added carbon dioxide. Ocean life dependent on carbonate shells and skeletons is threatened by dissolution as the ocean becomes more acid.

Rising carbon price is essential to 'decarbonize' the economy - to remove the nation towards the era beyond fossil fuels.

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.

'Goals' and 'caps' on carbon emissions are practically worthless, if coal emissions continue, because of the exceedingly long lifetime of carbon dioxide in the air.

On a per capita basis, Britain is responsible for more of the carbon dioxide now in the atmosphere than any other nation on Earth because it has been burning it from the dawn of the Industrial Revolution.

The evidence for human-made climate change is overwhelming.

You can't tie a rope around the ice sheet. You can't build a wall around the ice sheets.

The danger is that the compromises and special interests inherent in Kyoto-style targets and cap-and-trade will be accepted because of bureaucratic momentum.

The climate is nearing tipping points. Changes are beginning to appear and there is a potential for explosive changes, effects that would be irreversible, if we do not rapidly slow fossil-fuel emissions over the next few decades.

How long have we got? We have to stabilize emissions of carbon dioxide within a decade, or temperatures will warm by more than one degree... We don't have much time left.

Coal is responsible for as much atmospheric carbon dioxide as other fossil fuels combined and it still has far greater reserves. We must stop using it.

You can't turn on your television without seeing these advertisements about clean coal, clean tar sands and the claim that there's more jobs associated with fossil fuels than other industries. That's of course not true. But they're hammering that into the voters' heads.

After spending three or four years interacting with the Bush administration, I realized they were not taking any actions to deal with climate change. So, I decided to give one talk, and then it snowballed into another talk and eventually to even protesting and getting arrested.

If your child gets asthma, the fossil fuel industry doesn't pay. Or if there's a natural disaster, the bill is paid by the taxpayer, not the fossil fuel company.

Adding CO2 to the air is like throwing another blanket on the bed.

As species are exterminated by shifting climate zones, ecosystems can collapse, destroying more species.

Climate change is analogous to Lincoln and slavery or Churchill and Nazism: it's not the kind of thing where you can compromise.

The carbon emissions from tar shale and tar sands would initiate a continual unfolding of climate disasters over the course of this century. We would be miserable stewards of creation. We would rob our own children and grandchildren.

Imagine a giant asteroid on a direct collision course with Earth. That is the equivalent of what we face now with climate change, yet we dither.