re: #82 Love-Child of Cassandra and Sisyphus

Emissions are plateauing.

Back during the Peak-Oil fad days the wiser among them conclude that liquids would plateau for awhile and then slowly decline, instead of drop off immediately and precipitously.

The plateau-folk were correct.

I expect that to happen to total global emissions.

We are already some years into a plateau, and I can see that going on for another 20 years or so before a noticeable decline.

So assuming the right half of the curve looks like the left, we’ll end up with a CO2 concentration of around 560ppm at the end of the century.

This is a doubling of pre-industrial levels.

The deep problem is that even if Hansen is not quite correct with an ECS of 4.8C, one thing for certain is that the long term warming (ESS) is much more than the ECS.

Even the IPCC accepts that if the world holds the immediate temp rise to 2C, there will be much more to come with the ESS over the next millennia or so, due to long-term feedbacks (such as the loss of ice sheets.)

And if Hansen is correct, the long term warming will take the surface temps back to the Eocene levels.

That kind of world will be very foreign to many of the living things we know, including us.

It is way past time for us to be able to return to normal. As I showed, CO2 ppm will increase 50% by 2100 even under the scenario I think we will hit. That is one reason why carbon sensitivity is such an important thing to know that we really do not as well as we need to.

Your last sentence is most likely correct. The only path I see away from that is having a huge effort to actively remove CO2, bringing it down faster than normal processes. I’ve seen some models that suggest we could get back to pre-industrial levels but they require a big effort. Not a big path but it the only one that holds out much hope for me.