I am maths dyslexic and need #help

The update to the 2019 IPCC Special Report on Ocean and Cryosphere https://iccinet.org/statecryo2022/ chapter 4 states that CO2e from permafrost at current policy scenario requires removal per century of 400Gt CO2.
(Yes, permafrost is officially thawing and it is officially now requiring CO2 removal.)

The report doesn't say but I assume they use the official GWP by UNEP, 25 over 100 years.

How do I back-calculate those 400Gt CO2e to see how much methane it is that's going to be released per decade?

My calculation ends in a crazy warming of 1.6ºC per decade from permafrost thaw. Can you point me to where my mistake is?

It goes like this:
400Gt CO2e / 25 = 16Gt? If true, then CH4 from permafrost per decade is 1.6Gt. If true, and if the OH-sink stays the same, it'd mean 1.6ºC warming each decade.

Why 1.6ºC/decade:
*because #AR6-WG1 states that 2010-2019, methane caused 0.51ºC warming.
*from the Global Methane Project's top down view, we know that ~600Mt were released/yr
* and from NOAA, we know that the concentration was Ø 1830ppb in that decade.

It follows that in the decade 2010-2019, with the particular capacity of the OH-sink in that decade, 1Mt CH4 emissions resulted in 3.111 ppb and 0.001 ºC.

If these conditions stay the same, and if my back-calculation is correct for CO2e==>CH4, then the scientists are saying we're going to make permafrost thaw release 1.6Gt CH4 per decade which results in an immediate warming of 1.6ºC / decade, and to the weather and social chaos from this warming.

But I reckon, I must have omitted a zero somewhere. 0.16ºC feels more logical to me. I just don't know where I went wrong.

#Help #MathsDyslexia
#CO2e #GWP #CH4 #Permafrost #SROC #OHSink