Time Lag and Amplitude Differences between Correlated Variables in Global Temperature Changes

Temperature changes were investigated via Fourier analysis for the entire globe, the 48 states, and the Japanese archipelago. A comparison of power spectra revealed that the amplitude of temperature changes in the Japanese archipelago was greater than that for the entire globe or the 48 states. The amplitude was particularly amplified during El Ni？o events. Temperature changes were observed with regular phase cycles. A similar Fourier analysis was performed on the correlation between the global temperature and the rate of increase in the CO₂ concentration reported in previous studies. The rate of increase in the CO₂ concentration was also confirmed to change with a regular phase cycle. Furthermore, a phase shift was confirmed between the two. Previous studies have shown that there is a time lag between the two, with temperature changes preceding the rate of increase in the CO₂ concentration. This result contradicts the IPCC’s theory that global warming is due to increased anthropogenic CO₂ concentrations. Temperature changes in specific regions can deviate significantly from global temperature changes. This deviation is even greater during El Ni？o events. Therefore, when considering global warming based on temperature changes in specific regions, care must be taken not to make excessive inferences.