paleoclimatology (n.)

before vowels pale- word-forming element used in scientific combinations (mostly since c. 1870) meaning "ancient, early, prehistoric, primitive, fossil," from Latinized form of Greek palaios "old, ancient," from palai "long ago, far back" (from PIE root *kwel- (2) "far" in space or time).

"scientific study of climates," 1803, from climate + -ology.  In 19c., more or less equivalent to meteorology.