Atmospheric CO2 concentration
We used annual mean values of atmospheric CO2concentration (ppm) from the Mauna Loa record (NOAA, 2020;
www.esrl.noaa.gov/gmd/ccgg/trends/weekly.html accessed March 17, 2020).
We used in the models the CO2 value corresponding to the
mid-point of each census interval. Note that atmospheric
CO2 concentration (CO2) is strongly
correlated with year (r = 0.99) (Figure S1).