The world’s leading climate scientists have now revised the highest safe level of CO2 to 350 parts per million. As James Hansen of America’s National Aeronautics and Space Administration, the first scientist to warn about global warming more than two decades ago, wrote recently,
“If humanity wishes to preserve a planet similar to that on which civilization 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 to at most, 350 ppm.
This will be a hard task, but will not be impossible. We need to stop taking carbon out of the ground and putting it into the air. Above all, that means we need to stop burning so much coal – and start using solar, wind and tidal energy and other such sources of renewable energy. By decreasing use of other fossil fuels, and improving agricultural and forestry practices around the world, scientists believe we could get back to 350 by mid-century. But the longer we remain in the danger zone – above 350 – the more likely that we will see disastrous and irreversible climate impacts.