  Solar surface magnetic field seems to be able to explain variations in Total
Solar Irradiance on timescales from hours to decades. Using magnetograms from
spacecraft (MDI and HMI) and ground-based observatories (MWO and WSO) I build a
composite dataset of the Total Line-of-Sight Unsigned Magnetic Flux over the
solar disk stretching back to 1976, validated by excellent correlations with
the solar microwave flux (F10.7) and the Sunspot Group Number. Direct
measurements of TSI by space borne sensors have been carried out since late
1978. The early instruments were plagued by scattered light entering the
aperture, but this construction flaw can be corrected for. At the AGU 2018
meeting, a new TSI composite has been proposed based on a novel mathematical
method vetted by representatives from all current and most past TSI
instruments. Although an 'official' release of the dataset has not been offered
yet, a preliminary version is available. Anticipating that any last-minute
changes might be minor, I compare this new version with the magnetic flux
composite. It is clear that we have two TSI populations: values before 1993
that are seriously too low and values from 1993 onwards. I elect to normalize
the magnetic flux (the driver of variations of TSI) to a New TSI using the
regression equation for the recent population with the smallest uncertainty.
With this normalization, there is now total agreement between the variation of
the magnetic flux and of the New TSI as well as with the F10.7 and Group Number
proxies. We now have two choices: (1) the Sun underwent a dramatic change in
how its magnetic field drives variation of TSI or (2) the New Consensus TSI
reconstruction does not work and the new dataset is premature and not useful
neither for solar nor for climate research. Following David Hume, we should
always believe whatever would be the lesser miracle, which in our case would be
choice (2).
