2016

While trying to work out how a forest had grown on Earth overnight, the Twelfth Doctor compared a tree to a time machine, and determined that this had to have happened due to messing with the fabric of time, as "you [couldn't] create a whole overnight forest with extra special fertiliser". He referred to a hypothetical scenario, where "[y]ou plant[ed] a little acorn in 1795, and in the year 2016, there [was] an oak tree, there in the same spot, with a tiny, little bit of 1795 still alive inside of it." (TV: In the Forest of the Night)

Behind the Scenes
According to DWA15 12 the Mire planned on launching a surprise invasion of Earth in 2016. UNIT cracked the code of their invasion plans and deciphered it, with the help of the reader. The Mire's secret message was, "Let us feast on their warriors".