The PCCN cites 2050 as the target year for net zero emissions worldwide for heating to stay below 1.5 degrees C, and congratulates itself for setting a 2040 target for the U-M. But this misreads the IPCC SR18 report, which never states we can wait that long. First, the IPCC estimates that 2050 gives only a 50% chance of staying at 1.5 degrees; second, its models assume widespread deployment of negative emissions technologies, which is unlikely; third, it explicitly excludes feedbacks like methane emissions from melting arctic permafrost; and finally the 2050 target omits the principle of global equity and justice, which holds that rich countries, which have benefited far longer from an advanced carbon economy and have emitted vastly more per capita than poor countries, must decarbonize first in order to give poor countries more time to catch up in development. All told, a 2035 target date for net zero--at the very latest--is now the consensus norm for rich countries. Not 2050 or 2040.
The PCCN cites 2050 as the target year for net zero emissions worldwide for heating to stay below 1.5 degrees C, and congratulates itself for setting a 2040 target for the U-M. But this misreads the IPCC SR18 report, which never states we can wait that long. First, the IPCC estimates that 2050 gives only a 50% chance of staying at 1.5 degrees; second, its models assume widespread deployment of negative emissions technologies, which is unlikely; third, it explicitly excludes feedbacks like methane emissions from melting arctic permafrost; and finally the 2050 target omits the principle of global equity and justice, which holds that rich countries, which have benefited far longer from an advanced carbon economy and have emitted vastly more per capita than poor countries, must decarbonize first in order to give poor countries more time to catch up in development. All told, a 2035 target date for net zero--at the very latest--is now the consensus norm for rich countries. Not 2050 or 2040.