▁change . ▁ ▁Studies ▁published ▁in ▁ 2 0 1 7 ▁and ▁ 2 0 1 8 ▁identified ▁st alling ▁patterns ▁of ▁ro ss by ▁waves , ▁in ▁the ▁northern ▁hem is phere ▁jet ▁stream , ▁to ▁have ▁caused ▁almost ▁station ary ▁extreme ▁weather ▁events , ▁such ▁as ▁the ▁ 2 0 1 8 ▁European ▁heat wave , ▁the ▁ 2 0 0 3 ▁European ▁heat ▁wave , ▁ 2 0 1 0 ▁Russian ▁heat ▁wave , ▁ 2 0 1 0 ▁Pakistan ▁flo ods ▁- ▁these ▁events ▁have ▁been ▁linked ▁to ▁global ▁war ming , ▁the ▁rapid ▁he ating ▁of ▁the ▁Ar ctic . ▁ ▁According ▁to ▁a ▁ 2 0 0 9 ▁study ▁the ▁Atlantic ▁Multi - dec adal ▁O sc ill ation ▁( AM O ) ▁is ▁highly ▁correl ated ▁with ▁changes ▁in ▁Ar ctic ▁temperature , ▁suggesting ▁that ▁the ▁Atlantic ▁Ocean ▁therm oh al ine ▁circul ation ▁is ▁linked ▁to ▁temperature ▁vari ability ▁in ▁the ▁Ar ctic ▁on ▁a ▁multi - dec adal ▁time ▁scale . ▁A ▁study ▁in ▁ 2 0 1 4 ▁concluded ▁that ▁Ar ctic ▁ampl ification ▁significantly ▁decre ased ▁cold - season ▁temperature ▁vari ability ▁over ▁the ▁Northern ▁Hem is phere ▁in ▁recent ▁dec ades . ▁Cold ▁Ar ctic ▁air ▁intr udes ▁into ▁the ▁war mer ▁lower ▁lat itudes ▁more ▁rapidly ▁today ▁during ▁aut umn ▁and ▁winter , ▁a ▁tr end ▁project ed ▁to ▁continue ▁in ▁the ▁future ▁except ▁during ▁summer , ▁thus ▁calling ▁into ▁question ▁whether ▁winter s ▁will ▁bring ▁more ▁cold ▁extrem es