What would a fair UN climate change deal look like?

Great piece — here – on the Responding to Climate Change site, on our Climate Equity Reference Calculator.

Great but not perfect, alas.  For example, the opening tag says “New equity calculator says UK needs to cut emissions 94% by 2020, US by 73% and China just 9.4%.”  And of course this will be read as implying that the is the one sole result of the calculator.  When in fact is it one among many.

Here’s comment that I made soon after the piece was posted:

“Not that I’m complaining about the publicity, but one clarification.   Where the RTCC author says . . .

China’s emission trajectory for 2020 is a whopping 16,688 MtCO2e, just under the target total for the whole world. But the ERF calculator says it just needs to shave off 1,575 MtCO2e, or 9.4%.

What he should have said is something like . . .

China’s emission trajectory for 2020 is a whopping 16,688 MtCO2e, not much less than the mitigation target for the whole world. Of this, according to the ERF calculator, it needs to itself finance mitigation of 1,575 MtCO2e, or 9.4%.  (It’s “fair share”).  The total mitigation that needs to take place within its borders is, of course, much greater, and amounts to about 4,673 MtCO2e, or 28% of China’s projected 2020 baseline emissions.

The problem is that this last number is hard to read out from the Calculator UI as it currently stands.   We will fix this.

Also, the case RTCC used is (Include land use emissions, 1950 responsibility start date, weak 2C pathway, Capacity/Responsibility = 50/50, development threshold = $7,500) is not the one I would have chosen.  If you exclude land-use emission from the calculation and use 1990 as the responsibility start year (this reduces the global mitigation requirement) the readout on China would be:

China’s emission trajectory for 2020 is a whopping 16,750 MtCO2e, more than the mitigation target for the whole world. Of this, according to the ERF calculator, it needs to itself finance mitigation of 1,845 MtCO2e, or 11%.  (It’s “fair share”).  The total mitigation that needs to take place within its borders is, of course, much greater, and amounts to about 4,690 MtCO2e, or 28% of China’s projected 2020 baseline emissions.”