3 ms·
I'm having a hard time nailing down the math. I know that the estimate is that we were at 280ppm pre-industrial, and that one recent reading was 412ppm. I think
by tunesmith 6y ago
I'm having a hard time nailing down the math. I know that the estimate is that we were at 280ppm pre-industrial, and that one recent reading was 412ppm. I think that corresponds to 2187 GTCO2 and 3217 GTCO2 respectively. But the IPCC - a while ago - said we had to stay below 2900 to have a 2/3 chance of remaining below 2 degrees. Another source says we're at 2300 anthropogenic GTCO2 now. How do I square that math? I know that there's a difference between "total" GTCO2 and anthropogenic GTCO2, and I also know that the planet absorbs about 55% of anthropogenic.
- saalweachter 6y agoDoes it work out if you account for the increased CO2 dissolved in the ocean?
- tunesmith 6y agoOh... I think I got it. 3217-2187 = 1030 anthropogenic in the atmosphere, and 55% will get reabsorbed, so that put us at the 2289 total that won't get reabsorbed. And since we emit 37.1 per year (figure probably out of date), and 45% of that sticks around, we have about 36 years before we go past 2900 (at this rate). Although I'm not sure if that reabsorption is already figured in to the 37.1 figure.
- tunesmith 6y agoTo clarify... 2289 is the amount anthropogenically emitted, before reabsorption (whatever the correct term is). 1030 is the amount left behind after reabsorption. The (probably out of date) IPCC guideline is to stay under 2900 emitted, and the 37.1 is how much is emitted per year, so those numbers don't have to take absorption into account. Therefore, the difference is 611, or about 16.5 years from whenever that measurement was taken. So, roughly - 2036. The world needs to be carbon neutral by 2036, according to that math. (And those numbers are behind the science in more recent articles, which are implying overshoot and that 2 degrees is inevitable.)