Thread by @tjayaraman

Misrepresenting science in the GLOBAL METHANE PLEDGE? This EU-US initiatative, begins with a flaky inference from a key IPCC result. Follow this thread to find out. The Pledge can be read at whitehouse.gov/briefing-room/… @JMauskar @KanitkarT @n_thanki @3rdworldnetwork @bforboseman

From the Pledge: "Methane ... according to the latest report of the Intergovernmental Panel on Climate Change, *accounts for about half of the 1.0 degree Celsius net rise in global average temperature* since the pre-industrial era."

Here is a graphic from the IPCC AR6 Working Group I Summary for Policymakers (SPM). This is Fig. SPM.2 (c). You can see here that methane contributed 0.5 deg C warming. True. But can you say that methane accounts for half of the 1 deg C net rise?

NO. YOU CANNOT. The graph does not imply that the -ve contributions from the aerosols lowered the gross increase to a net 1 deg rise only with reference to all the non-methane contributions, leaving methane untouched.

Correct statement is that the net rise of 1 deg C came from balancing out all +ve contributions, which comes to a little over 1.5 deg C, which is then balanced out by the -ve aerosol and such contributions. So saying methane contributes half the net observed warming is fake!!

If we are looking at net contributions, i.e. +ve warming from which GHG is lowered by -ve warming (cooling) from which GHG, then really it is CO2 that must be set apart -- while the others balance each other out. Why? They are all short-lived climate forcers compared to CO2.

In fact in the discussion on air pollution and climate change in Section D of the SPM, it is methane whose effect is traded off against the aerosols contributing to particulate pollution.

We will come back to this Global Methane Pledge again. There are other interesting things to say as well. 😃

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