An example of why the Global Warming Potential (GWP) is not the best emission metric...
The GWP relates to the total energy added to the system, most of which is lost to space (grey) or in the deep ocean (dark blue). Little remains on the surface.
iopscience.iop.org/article/10.108
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Conversation
The amount of energy lost to space relates to the integrated Global Temperature Potential (iGTP), while the energy at the surface is proportional to the surface temperature.
More info here.
iopscience.iop.org/article/10.108
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The temperature at the surface, the AGTP, is shown here in blue. There is much more energy in the deep ocean, despite the lower temperature, because of the high specific heat capacity in the deep ocean.
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The first tweet was for CH₄, but it is similar for CO₂, except that CO₂ does not decay to zero, so the energy added keep rising over time (there is permanently additional CO₂ in the atmosphere).
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The CO₂ figures (previous tweet) looks very similar profile to a sustained forcing of 1W/m² (not different scale). Basically, emitting a cumulative pollutant like CO₂ is very similar to a step change in forcing.
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A step change in forcing is one way to estimate the climate sensitivity, which the surface temperature converges to, which in the model here is 1.06°C/(W/m²), & will be reached in some thousands of years.
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A single instantaneous pulse of radiative forcing of 1W/m² eventually decays out of the system. The light blue, surface ocean, is proportional to the Impulse Response Function for temperature used in the analysis.
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All these figures are constructed with impulse response functions, which are equivalent to a layered model of the energy balance (& similar for emissions to concentration). All following the methods here iopscience.iop.org/article/10.108
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Replying to
The plan is to play with this types of figures, to help explain the temperature response to different emissions, emission pathways, etc. When I get time...
Here is a small thread yesterday, just on the pulse figures.
twitter.com/Peters_Glen/st
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Quote Tweet
How does the climate system response to a single pulse of 1W/m²?
Initially, most energy is in the surface ocean (atmosphere), but this is either radiated back to space (grey) or transported to the deep ocean (dark blue).
Most is radiated back to space!
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