Climate change is irreversible and we need to move beyond zero emissions. Zero emissions are not enough. According to IPCC, we need to start by using zero carbon, then we need to start putting carbon back in the ground. And we need to do it now.
“A large fraction of climate change is largely irreversible on human time scales,” the IPCC tells us, “unless net anthropogenic carbon dioxide emissions were strongly negative over a sustained period.” This quote comes from the Summary for Policy Makers from the first report in the 2013 IPCC series released October 2013 (Physical Science Basis). (1) It means that somehow, today’s 400 parts per million (ppm) concentration of carbon dioxide in our atmosphere must begin to lower, not continue to rise.