"Century warmth" refers to the level of warmth experienced in a particular century. It suggests how warm the temperatures are compared to those in previous centuries, indicating a change in climate over the course of 100 years. Full definition
So stats won't help us solve this problem of 20th century warmth in the context of the last few centuries. (realclimate.org)
Most of the reconstructions indicate late 20th century warmth that is unprecedented over the past 1000 years, without any consideration of the instrumental record. (realclimate.org)
The report states: «The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1000 years. (newscientist.com)