Not exact matches
Until I can find a source that covers 1950 to the 1970s we have to assume that the increase
which began around 1948 continued until another decrease began around 1980 as per this from the
Earthshine project:
This was prior to the recent data from CERN,
which might provide a mechanism for the observations of Spencer and the independent
Earthshine results on clouds.
This is based primarily on the huge
earthshine - derived albedo increase in 2003,
which the authors now admit may be caused by undersampling of the data but was the the highlight of the authors» recent Science paper (Palle et al, 2004).