A Fair Plan to Safeguard Earth’s Climate. 3: Outlook for Global Temperature Change throughout the 21st Century

We apply Singular Spectrum Analysis to four dataseis of observed global-mean near-surface temperature from start year t sub( o) through 2012: HadCRU (t sub( o) = 1850), NOAA (t sub( o) = 1880), NASA (t sub( o) = 1880), and JMA (t sub( o) = 1891). For each dataset, SSA reveals a trend of increasing temperature and several quasi-periodic oscillations (QPOs). QPOs 1, 2 and 3 are predictable on a year-by-year basis by sine waves with periods/amplitudes of: 1) 62.4 years/0.11 degree C; 2) 20.1 to 21.4 years/0.04 degree C to 0.05 degree C; and 3) 9.1 to 9.2 years/0.03 degree C to 0.04 degree C. The remainder of the natural variability is not predictable on a year-by-year basis. We represent this noise by its 90 percent confidence interval. We combine the predictable and unpredictable natural variability with the temperature changes caused by the 11-year solar cycle and humanity, the latter for both the Reference and Revised-Fair-Plan scenarios for future emissions of greenhouse gases. The resulting temperature departures show that we have moved from the first phase of learning-Ignorance-through the second phase-Uncertainty-and are now entering the third phase-Resolution-when the human-caused signal is much larger than the natural variability. Accordingly, it is now time to transition to the post-fossil-fuel age by phasing out fossil-fuel emissions from 2020 through 2100.