1. Equivalent carbon dioxide (eCO2) – a combined measure of all major GHGs controlled under the Kyoto protocol calculated
using carbon dioxide radiative forcing relationships integrated with the effects of aerosols and particulates (Gohar and
Shine, 2007).
2. The Southern Oscillation Index (SOI) – a measure of ENSO variability measured by the pressure differences between Tahiti
and Darwin (Allan, 2000).
3. Total solar irradiance – a measure of the incident sunlight received by the Earth’s atmosphere (Benestadt and Schmidt,
2009); and
4. Volcanic stratospheric aerosol radiative forcing – a measure of the impact of volcanic activity (Meinshausen et al., 2011).
These covariate data (Fig. 2) were obtained from a variety of sources as presented in Table 1. Some of these data required
post-processing to ensure consistency of record length and data frequency: