Thread by @GHGGuru

THREAD. I am growingly allergic to articles that compare various sources of GHG emissions such as cows, planes, cars, babies, clothes etc.
These activities and sectors should not be compared by their warming effects described by CO2 equivalent (CO2e) units and here is why. /1

Back in the 1990s, Global Warming Potentials and a pseudo-normalizing CO2e (CO2 equivalence factor) were developed “... to boil all climate forcings down to a single handy-dandy number that can be used in climate treaties and national legislation.” /2

Aerosols, short-lived GHG [e.g. methane], and CO2 emissions are separate dials, controlling very different aspects of the Earth’s climate future. /3

“CO2 emissions play a distinguished role, because they ratchet up the Earth’s thermostat. It’s a dial you can turn up, but you can’t turn it back down. CO2 is a genie you can’t put back in the bottle.” /4

“Climate forcings should not be aggregated. Each category [e.g. CO2 vs CH4] should be treated in its own right. Otherwise, there are perverse incentives to do too much too soon on short-lived forcings and too little too late on CO2.”

realclimate.org/index.php/arch…
/5

One such way to treat short-lived climate pollutants according to their real climate forcing is the use of GWP*.
I am hopeful that GWP20 & GWP100 and the use of CO2e will cease for methane in the near future to allow us to arrive at science based public policies. /6

carbonbrief.org/guest-post-a-n… /7