The average global cloudheight is linked to the average global temperature generally, the higher the average cloudheight, the higher the average surface temperature, and vice versa.
Davies and Molloy are therefore properly cautious with their conclusions, but nonetheless note that a comparison of the beginning and endpoints for their study, which minimizes the La Nina contribution, still showed a decline in cloudheight.
Based upon data from the paper, the cooling climate impact from the decrease in the average global cloudheight more than offset the positive forcing from an increase in greenhouse gases from human activities in the last decade.