The solar power arriving to Earth from the Sun, the so called Total Solar Irradiance (TSI), has a significant impact on the terrestrial atmosphere on time scales ranging from days to millennia. While recent TSI variations have been monitored from space since the 1970s, TSI variations over several centuries or millennia can only be estimated using measurements of the cosmogenic isotope concentrations in tree rings and ice cores.
Using data from plage and sunspot areas starting from the late 19th century and the solar modulation potential derived from the analysis of 14C isotope over the last 500 years, our team has reconstructed the area coverage of faculae (plages) and sunspots from 1513 to 2001. These reconstructions made it possible to estimate the Total Solar Irradiance during the same period.
The result of this work plays a fundamental role in the study of the link between the Maunder minimum and a possible cold period, the so-called Little Ice Age, possibly forced by a variation of the TSI. We estimate that the change in TSI levels between the Maunder minimum and the present epoch is approximately 2.5 W m−2. This TSI variation would change the global temperatures by about 0.13oC, an extremely small variation. The present work supports the idea that the Little Ice Age was not a global cooling phenomenon, but rather a regional moderate average cooling (which included European region).
This study has been carried out by a team of researchers from the Department of Physics, University of Rome Tor Vergata (Italy) and from National Solar Observatory (Boulder, USA).
Référence: Penza, Berrilli, Bertello, Cantoresi, Criscuoli, Giobbi, Total Solar Irradiance during the Last Five Centuries, The Astrophysical Journal, 937:84, 2022