From the paper:
"the longest continuous run of seasonal drought during the modern period was 5 years, whereas the pre-modern period contained episodes of six, seven and eight consecutive-year droughts. Similarly, the 20th century, with only 9 winter and 12 summer droughts, contained fewer multiyear events than any other century. The uniqueness of the 20th century is further highlighted by the marked occurrence of protracted dual-season pluvials, rather than drought, over this period. Perhaps of greatest relevance, this study suggests that severe and sustained episodes of dual-season drought, which are largely missing from the instrumental period, have occurred multiple times in the past (e.g., 1660s, 1740s, 1890s)."