We analyse annual mean and annual growth rate measurements of the global CO 2 abundances taken from the NOAA General Monitoring Laboratory (GML). The annual CO 2 variations are shown to be best described by a parabolic fit with concavity up, in contrast to a linear trend often attributed to fossil-fuel emissions. Global CO 2 abundance variations were shown to correlate (r = 0.60) with variations of the Global Mean Sea Level (GMSL), Oceanic Nina Index/El Nino Southern Oscillations (ONI/ENSO) (r = 0.24) and global terrestrial temperature (r = 0.82). De-trended CO 2 variations show much stronger correlation with ONI/ENSO (r = 0.79). Morlet wavelet spectral analysis of CO 2 abundances reveals significant periods of 21.4, 9, and 3.7 years. Similar periods appear in GMSL (21.4 and 8.5 years), ONI/ENSO (21.4, shared 21.4-year period indicates influence from cyclic variations in solar magnetic activity (double solar cycle). The 9-year CO 2 oscillation, together with the strong correlation of detrended CO 2 with ONI/ENSO, links to ENSO variations spanning 4.5 - 12 years. The spectral analysis with Morlet’s wavelet of the variations of CO 2 abundances reveals the natural periods of 21.4, 9 and 3.7 years. The similar periods are derived for the variations of GMSL (21.4, and 8.5 years), ONI/ENSO index (21.4, 12 and 4.5 years) and the GLB terrestrial temperature (21.4, 8.36 and 3.75 years). The presence of a common period of 21.4 years indicates that all the datasets are affected by cyclic variations of the solar magnetic activity in a double solar cycle. The measured CO 2 oscillations with a period of 9 years combined with the correlation of the de-trended CO 2 abundances can be linked to the ONI/ENSO variations ranging within the periods of 4.5 and 12 years. Cross-correlation analysis shows a time lag of approximately one year in variations of the global CO 2 abundance relative to the global terrestrial temperature. Wavelet coherence analysis confirms a time lag of 1.2 - 1.8 years for the global CO 2 abundance to fall behind the temperature during most temporal intervals. These results indicate that global CO 2 variations follow temperature variations rather than driving them.
KeywordsSun: Magnetic FieldEarth: TemperatureEarth: Sea LevelEarth: Carbon DioxideWavelet Analysis
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