▁of ▁some ▁change ▁in ▁a ▁polar ▁temperature ▁to ▁a ▁corresponding ▁change ▁in ▁a ▁bro ader ▁average ▁temperature : ▁ ▁, ▁ ▁where ▁ ▁is ▁a ▁change ▁in ▁polar ▁temperature ▁and ▁ ▁is , ▁for ▁example , ▁a ▁corresponding ▁change ▁in ▁a ▁global ▁mean ▁temperature . ▁ ▁Common ▁implementations ▁define ▁the ▁temperature ▁changes ▁directly ▁as ▁the ▁anom al ies ▁in ▁surface ▁air ▁temperature ▁relative ▁to ▁a ▁recent ▁reference ▁interval ▁( typ ically ▁ 3 0 ▁years ). ▁ ▁O thers ▁have ▁used ▁the ▁ratio ▁of ▁the ▁var ian ces ▁of ▁surface ▁air ▁temperature ▁over ▁an ▁extended ▁interval . ▁ ▁Am pl ification ▁phase ▁ ▁It ▁is ▁observed ▁that ▁Ar ctic ▁and ▁Ant ar ctic ▁war ming ▁commonly ▁proceed ▁out ▁of ▁phase ▁because ▁of ▁orb ital ▁forcing , ▁resulting ▁in ▁the ▁so - called ▁polar ▁see - s aw ▁effect . ▁ ▁Pale oc lim ate ▁polar ▁ampl ification ▁The ▁gla cial ▁/ ▁inter g la cial ▁cycles ▁of ▁the ▁Ple ist oc ene ▁provide ▁extensive ▁p ala e oc lim ate ▁evidence ▁of ▁polar ▁ampl ification , ▁both ▁from ▁the ▁Ar ctic ▁and ▁the ▁Ant ar ctic . ▁In ▁particular , ▁the ▁temperature ▁rise ▁since ▁the ▁last ▁gla cial ▁maximum ▁ ▁years ▁ago ▁provides ▁a ▁clear ▁picture . ▁ ▁Pro xy ▁temperature ▁records ▁from ▁the ▁Ar ctic ▁( Green land ) ▁and ▁from ▁the ▁Ant ar ctic ▁indicate ▁polar ▁ampl ification ▁factors ▁on ▁the ▁order ▁of ▁ 2 . 0 . ▁ ▁Rec ent ▁Ar ctic ▁ampl ification ▁ ▁S ugg ested ▁mechan isms