Roy W. Spencer, Ph. D.
SUMMARY: A simple time-dependent CO2 budget model shows that yearly anthropogenic emissions compared to Mauna Loa CO2 measurements gives a declining CO2 sink rate, which if continued would increase atmospheric CO2 concentrations and presumably anthropogenic climate change. But accounting for ENSO (El Nino/La Nina) activity during 1959-2021 removes the decline. This is contrary to multiple previous studies that claimed to account for ENSO. A preprint of my paper (not yet peer reviewed) describing the details is at ENSO Impact on the Declining CO2 Sink Rate | Earth and Space Science Open Archive (essoar.org).
UPDATE: The CO2 model, with inputs and outputs, is in an Excel spreadsheet here: CO2-budget-model-with-EIA-growth-cases.
I decided that the CO2 model I developed a few years ago, and recently reported on here, was worthy of publication, so I started going through the published literature on the subject. This is a necessary first step if you want to publish a paper and not be embarrassed by reinventing the wheel or claiming something others have already “disproved”.
The first thing I found was that my idea that Nature each year removes a set fraction of the difference between the observed CO2 concentration and some baseline value is not new. That idea was first published in 2013 (see my preprint link above for details), and it’s called the “CO2 sink rate”.
The second thing I found was that the sink rate has (reportedly) been declining, by as much as 0.54% (relative) per year, even after accounting for ENSO activity. But I only get -0.33% per year (1959-2021) before accounting for ENSO activity, and — importantly — 0.0% per year after accounting for ENSO.
This last finding will surely be controversial, because it could mean CO2 in the atmosphere will not rise as much as global carbon cycle modelers say it will. So, I am posting the model and the datasets used along with the paper preprint at ENSO Impact on the Declining CO2 Sink Rate | Earth and Space Science Open Archive (essoar.org). The analysis is quite simple and I believe defensible. The 2019 paper that got -0.54% per year decline in the sink rate uses complex statistical gymnastics, with a professional statistician as a primary author. My analysis is much simpler, easier to understand, and (I believe) at least as defensible.
The paper will be submitted to Geophysical Research Letters for peer review in the next couple days. In the meantime, I will be inviting the researchers who live and breathe this stuff to poke holes in my analysis.