April 16, 2024
Is CO2 a Forcing or Feedback
Jim Church
H/T Joseph Fournier, LinkedIn
D.R. Feldman et al's 2015 publication served as one of the first long term measurements and confirmation of the spectroscopic changes occurring along the characteristic absorption / re-emission spectral lines of atmospheric CO2.
The authors refer to these changes as a "radiative forcing or RF", which in physics is different than "radiative feedbacks". For while a forcing can induce a change, a feedback can only alter the rate (+/-) of change.
These authors quantified the RF from the 22 ppm rise in CO2 over the measurement period to be a mere 0.2 Wm-2decade-1.
The white elephant in the room seen in this plot is the fact that the strong seasonal cycle influence on the intra-annual RF.
From the influence of the seasonal cycle we see the RF rapidly rise in the Spring and then decline in the Fall. Note the slopes (+/-) here are much greater than the longer term RF of 0.2 Wm-2decade-1.
Note that there is no allowance in mainstream climate debates for CO2 to be anything more than a RF, while skeptics such as myself continue to argue that CO2 like H2O may simply be a feedback.
Note that the rise in CO2 in the spring is the only empirical evidence of where it LEADS changes in temperature. In the seasonal cycle in the Northern Hemisphere, CO2 concentrations peak in April, while temperatures peak in July.
No one would say that in this scenario, CO2 is causing the surface to warm, as we all know that orbital dynamics and changes in sunshine are responsible.
Likewise, we all know that CO2 peaks in April given the rates of photosynthesis at this point in the seasonal cycle begin to outpace the rates of decay and that the true RF here is from visible light (aka sunshine).
In conclusion, while this pivotal paper definitely shows a small rise in long term RF from rising CO2 of only 0.2 Wm-2decade-1, more importantly it shows that CO2 is also a feedback in response to change sunshine intensity as modulated by orbital dynamics (aka seasonal cycle).
The phrase "orbital dynamics" is used purposefully, as there is ample evidence that longer term changes in CO2 are also induced by orbital dynamics. In my view, Milankovitch Cycles down to the ENSO cycle, can be collectively viewed as orbital dynamics.
http://asl.umbc.edu/pub/chepplew/journals/nature14240_v519_Feldman_CO2.pdf
H/T Joseph Fournier, LinkedIn
D.R. Feldman et al's 2015 publication served as one of the first long term measurements and confirmation of the spectroscopic changes occurring along the characteristic absorption / re-emission spectral lines of atmospheric CO2.
The authors refer to these changes as a "radiative forcing or RF", which in physics is different than "radiative feedbacks". For while a forcing can induce a change, a feedback can only alter the rate (+/-) of change.
These authors quantified the RF from the 22 ppm rise in CO2 over the measurement period to be a mere 0.2 Wm-2decade-1.
The white elephant in the room seen in this plot is the fact that the strong seasonal cycle influence on the intra-annual RF.
From the influence of the seasonal cycle we see the RF rapidly rise in the Spring and then decline in the Fall. Note the slopes (+/-) here are much greater than the longer term RF of 0.2 Wm-2decade-1.
Note that there is no allowance in mainstream climate debates for CO2 to be anything more than a RF, while skeptics such as myself continue to argue that CO2 like H2O may simply be a feedback.
Note that the rise in CO2 in the spring is the only empirical evidence of where it LEADS changes in temperature. In the seasonal cycle in the Northern Hemisphere, CO2 concentrations peak in April, while temperatures peak in July.
No one would say that in this scenario, CO2 is causing the surface to warm, as we all know that orbital dynamics and changes in sunshine are responsible.
Likewise, we all know that CO2 peaks in April given the rates of photosynthesis at this point in the seasonal cycle begin to outpace the rates of decay and that the true RF here is from visible light (aka sunshine).
In conclusion, while this pivotal paper definitely shows a small rise in long term RF from rising CO2 of only 0.2 Wm-2decade-1, more importantly it shows that CO2 is also a feedback in response to change sunshine intensity as modulated by orbital dynamics (aka seasonal cycle).
The phrase "orbital dynamics" is used purposefully, as there is ample evidence that longer term changes in CO2 are also induced by orbital dynamics. In my view, Milankovitch Cycles down to the ENSO cycle, can be collectively viewed as orbital dynamics.
http://asl.umbc.edu/pub/chepplew/journals/nature14240_v519_Feldman_CO2.pdf
Posted by: Timothy Birdnow at
11:34 AM
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