(1) They really didn’t see many spots during the Maunder Minimum, so that is not in doubt (2) When Eddy looked at this it was thought [based on Abbot’s measurements that a 1-2% change in solar constant depending on solar activity was possible. That translates into a ~1 degree K change in temperature, so a Maunder Minimum was a plausible cause of the LIA. (3) Measurements during the space age showed a variation 10-20 times smaller, leading to a correspondingly smaller temperature change (4) Jack Eddy gave the After-Dinner talk at the SORCE 2003 meeting lasp.colorado.edu/sorce/news/2003ScienceMeeting/dec03_meeting_final_science_program.html Nice photo of Jack here: lasp.colorado.edu/sorce/news/sns/2003/sns_dec_2003.pdf
He told us that when the spacecraft data became available, it was clear to him that the association between MM and LIA would have to be abandoned on grounds of energy: there is simple not enough variation in the sun’s output to have much of an effect. And I happen to agree with him.