The normalized impulse response of Carbon Dioxide concentration due to an impulse in CO2 emissions derived from observed time series using the ARX method (solid line). Also shown are the model-derived, normalized impulse response functions of Maier-Reimer and HasselmannĀ  (dotteded lines).

Plain Language Summary

When using climate models to make projections of future climate it is important to know how the atmospheric concentration of CO2 will change in response to changes in carbon emissions. The “impulse response” of concentration due to emissions summarises the required information in a single curve from which the response to any arbitrary emissions scenario can be easily determined. It is a curve showing how the concentration will change following a single short impulse in emissions. The impulse responses widely accepted by the modelling community all have a “remnant fraction” of between 10 and 20 percent implying that this fraction of emitted CO2 remains in the atmosphere forever. These curves are, themselves, based on circulation models similar to climate models. This paper develops a statistical technique for estimating the impulse response directly from the data while making no assumptions about the underlying physics. The impulse response estimated in this way shows that CO2 remains in the atmosphere for a shorter time than hitherto supposed and has no remnant fraction. All the CO2 presently generated by fossil fuel will ultimately leave the atmosphere; half will be gone in the next half century.

See the original paper – here: MS

Journal Correspondence

Dear Dr. Reid:

Thank you for submitting “The regression of atmospheric concentration on carbon dioxide emissions” (2022GL098531) to Geophysical Research Letters. I am rejecting your paper because it does not connect with the vast literature on this topic. As made popular by Carl Sagan, “Extraordinary claims require extraordinary evidence.”

I suggest that you expand your manuscript and submit it to a more specialized, full-format journal. GRL’s mandate to publish important new science at the forefront of AGU disciplines (see Eos, Vol. 97, doi:10.1029/2016EO056437 at https://eos.org/agu-news/new-geophysical-research-letters-editorial-revisions-policies) means that we must decline many good manuscripts.

My decision does not reflect a judgment on the quality of your work, but that I consider the focus of the material better suited for another journal.

Thank you again for your interest in GRL. I am sorry I am unable to give you a more positive response. Please consider GRL in the future to publish your best work.


Christopher Cappa
Geophysical Research Letters


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