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

Abstract

We apply Singular Spectrum Analysis to four datasets of observed global-mean near-surface temperature from start year t o through 2012: HadCRU (t o = 1850), NOAA (t o = 1880), NASA (t o = 1880), and JMA (t o = 1891). For each data set, 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°C ; 2) 20.1 to 21.4 years/0.04°C to 0.05°C ; and 3) 9.1 to 9.2 years/0.03°C to 0.04°C. The remainder of the natur°l variability is not predict able 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.