We are on the precipice of climate system tipping points beyond which there is no redemption.
James HansenIf 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 COโ 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 COโ is not brief, there is a possibility of seeding irreversible catastrophic effects.
James HansenGlobal warming has already triggered a sea level rise that could reach from 6 metres (19.69 ft) to 25 metres (27.34 yards).
James HansenThe climate dice are now loaded. Some seasons still will be cooler than the long-term average, but the perceptive person should notice that the frequency of unusually warm extremes is increasing. It is the extremes that have the most impact on people and other life on the planet.
James HansenWe have to, in the next ten years, begin to decrease the rate of carbon dioxide emissions and then flatten it out. If that doesn't happen in ten years, we're going to be passing certain tipping points. If the ice sheets begin to disintegrate, what can you do about it? You can't tie a rope around an ice sheet.
James Hansen