You are using chance variations to come up with increased prior warming and decreased modern warming. (realclimate.org)
(There's also the possibility of a warming trend caused by some other factor, such as cosmic rays — as with chance variation, unlikely but not impossible). (johnquiggin.com)
Darwin's theory of the natural selection of chance variations put an emphasis on the role of chance in determining the order of nature in the living world. (religion-online.org)