Why Beyond 1.5ºC?

I wanted to see exactly how much carbon we've put into the atmosphere since the industrial revolution. I graphed cumulative emissions from fossil fuels and human land-use change since 1751 to the present, along with how much science has figured where this carbon has accumulated. I also wanted to see what it was like in the atmosphere before humans were changing the atmosphere. The result is the graph below:

From my paper to be published, and presented in the poster session at the International Conference on Negative CO₂ Emissions at Chalmers University of Technology, Götenborg Sweden. Note: the start of the left hand axis equals 113.18 ppm which equates to 0 GtC of anthropogenic emissions increases.

I've stacked the data from the land and ocean sinks below the atmosphere which make up the green, dark blue and light blue curves, respectively. As one moves along the red curve, the other three curves grow correspondingly. In a relatively short time, we've made radical exponential forcing to the natural sinks such that we have global climate warming.

Targeting below 1.5ºC or RCP 1.9 which is radiative forcing of 1.9 would bring back warming to what it was around the time of 1984.

https://www.esrl.noaa.gov/gmd/aggi/aggi.html

Looking at the exponential forcing in the diagram above, and remembering the extreme El Niño of '82-83, we have quite a bit of warming we induced from our emissions.

As much of the current policy is around getting below 2ºC and 1.5ºC, we should have more studies on what is the optimum carbon concentration that should remain in the oceans an atmosphere to return climate back to pre-anthropogenic change. We should also study what's the fastest, and safest way to get to that optimum.