We already blew the deadline to avoid dangerous climate change

It’s too late to limit the world to 2°C of global warming, the level identified by climate negotiators as the threshold beyond which the world faces “dangerous” levels of climate change, said former NASA scientist and UK Environment advisor Sir Bob Watson today in a lecture at the American Geophysical Union. That’s because, by his interpretation of the best estimates of current climate models, rich countries would have had to halt the growth in their greenhouse gas emissions back in 2010.

Of course, the 2°C threshold was always somewhat arbitrary, the product of a consensus that was as much political as scientific. (Unfortunately, some assessments of its validity as a policy tool suggested that it was in fact too generous a limit.)

Despite our tardiness, Watson said that little has changed about what we must do to avert even worse climate change, reported Mark Fischetti of Scientific American. We’ll need plenty of carbon-free electricity, including nuclear power and fossil-fueled plants paired with carbon capture and storage systems, not to mention a high price on carbon in order to curb its use in all sectors and industries.

Scientists have also proposed “geoengineering,” or the process of deliberately manipulating Earth’s climate by affecting how much sunlight our atmosphere reflects back into space. One proposed method would essentially create an artificial volcano to cool the earth. Watson argued that such schemes will mostly be a distraction from the reductions in carbon emissions that we have to accomplish one way or another.

“And to be honest, we screwed up the earth by not understanding it, so I’m not sure trying to engineer it is a good idea,” said Watson.