The final paragraph of the cited paper:
It seems to me that the portion of the conclusion I have emboldened suggests that it isn't the Sun.
Changes in extraterrestrial irradiance over the solar cycle surely contribute a portion of the variability deduced at the polar surface for the 320–400 nm region, although the magnitude of this contribution is uncertain. However, the inferred solar cycle dependence in the 400–600 nm visible band is too large to be of extraterrestrial origin unless one adopts values at the lowest end of the error range. Uncorrected instrument drifts and discontinuities can always introduce artifacts into a dataset. However, for this to explain the observed behavior, any such unknown problems must have a spurious correlation with the solar cycle. Given the small magnitude of the inferred changes, the uncertainties in the measurements and the limited duration of the dataset, a confirmation of the solar cycle effect based on independent data would be of value.
(My emphasis.)
(My emphasis.)
It seems to me that the portion of the conclusion I have emboldened suggests that it isn't the Sun.
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