Assessment of the amplitude of variations in total solar irradiance in the past

An assessment was made of how reliably various modern reconstructions of total solar irradiance reconstruct long-term changes in this value in the past. To solve this problem, a forecast of long-term changes in total solar radiation in 1978−2017 was made using seven reconstructions covering the last 12−13 centuries. The paleoreconstructions used describe long-term variations with average amplitudes from 0.22 W m–2 (series with low amplitude) to 2.36 W m–2 (series with high amplitude). A nonlinear analog prediction method was applied, and the prediction results were compared with the actually measured values. It turned out that the experimentally measured variations in total solar radiation are better predicted by the low-amplitude reconstructions. However, the possibility that solar radiation in the past experienced more significant variations and the increase in total solar radiation after the Maunder Minimum reached 2.5 W m–2 cannot be completely excluded yet. Possible climatic consequences of such solar radiation variations are discussed.