Can the variability of the total solar irradiance be reconstructed from solar magnetic activity proxies?

Understanding how the Total Solar Irradiance (TSI) is related to solar activity is not only important for predicting its value in the past, but also for understanding what causes its variability. Many authors have attempted reconstructions of the TSI from various proxies for solar activity. Here, instead of seeking the best combinations of proxies, we determine: 1) if the TSI can be reconstructed at all from them and 2) what this tells us about the origin of the variability of the TSI. Our study is based on 29 years of daily measurements of 15 proxies, and we use information theoretic criteria to determine the causal connection between the TSI and the different proxies. The results show why the TSI cannot be reconstructed from combinations of existing proxies (which invalidates attempts to use the sunspot number to estimate past values of the TSI), and how regions with different magnetic fields contribute to the variability