This data was collected in order to investigate the level of evidence for: A) a relationship between the strength of the geodynamo and Earth surface UV-B irradiance; B) increased surface UV-B irradiance during the Laschamps Event (the last major geomagnetic excursion, ca. 41ka BP). The study considered subfossil Pinus Diploxylon (Pinus D.) pollen grains obtained from the annually laminated Japanese Lake Suigetsu sediment record (Bronk Ramsey et al., 2020; Nakagawa et al., 2003). The primary response variable is the abundance of para-coumaric acid (a UV-B absorbing compound) in the sporopollenin of the subfossil pollen grains. The secondary response variable is the probability of grain malformation. There are three key spreadsheets: 1) GCMS_pCA_day_dependent_calbration_simple.csv - estimated abundances of para-coumaric acid in the subfossil Pinus Diploxylon pollen at different depths/times of the Lake Suigetsu sediment core. 2) Suigetsu_malformations_simple.csv - malformations counts in the Lake Suigetsu subfossil Pinus Dipoxylon pollen 3) gc_cultivar_data_simple.csv - estimated abundance of para-coumaric acid in Pinus pollen in a controlled cultivar experiment (considering response to UV-B flux) Descriptor files (with corresponding names) are also provided. This dataset contains data generated by NERC Grant NE/Y002652/1:Reconstructing UV radiation over the Laschamps Geomagnetic Excursion.