[Vision2020] NASA GISS Climate Scientist Gavin Schmidt 9-19-21: The definitive CO2/CH4 comparison post

[Ted Moffett]

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Note in the comments section that someone suggests Schmidt made an error,
which he readily admitted!  If a scientist of Schmidt's undeniable
competence and voluminous peer reviewed publishing is so open to humility
facing mistakes, I am more inclined to trust his scientific integrity.

Anyway, the excerpted paragraph below on the time scales of CO2 versus CH4
impacts on climate relating to the often stated goal of
temperature stabilization
requiring zero anthropogenic CO2 emissions, is an amazingly clear and
simple statement of what could be a dauntingly complex discussion.
Sometimes the most brilliant minds have skill at expressing the essence of
critical scientific etc. subjects/issues in language most everyone can
grasp.  Bertrand Russell?
Bertrand Russell - Wikipedia
<https://en.wikipedia.org/wiki/Bertrand_Russell>
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NASA GISS: Dr. Gavin A. Schmidt <https://www.giss.nasa.gov/staff/gschmidt/>

RealClimate: The definitive CO2/CH4 comparison post
<https://www.realclimate.org/index.php/archives/2021/09/the-definitive-co2-ch4-comparison-post/>

Stocks and flows

Before we go any further though, we need to understand that the effective
perturbation time for CO2 and CH4 in the atmosphere are very
different. CO2 emissions
embed themselves in the atmosphere/biosphere/upper-ocean carbon cycle and
have very long-term impacts (under natural conditions, some 15% of the
CO2 perturbation
will still be in the atmosphere thousands of years from now). In contrast,
methane has a perturbation time-scale of about 12 years. This implies that
the impact of CO2 on temperature is cumulative (a function of the total
emitted CO2 or *stock*), while the impact of CH4 is a function of current
(~decadal) emissions (the *flows*). Stabilizing temperature effects
from CO2 means
getting down to *net-zero* anthropogenic emissions, while stabilizing
temperature effects from CH4 means simply stabilizing emissions.
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