▁to ▁one ▁t enth ▁that ▁of ▁normally ▁clear ▁sky . ▁At ▁this ▁time ▁it ▁was ▁unknown ▁whether ▁the ▁ha ze ▁was ▁natural ▁or ▁was ▁formed ▁by ▁poll ut ants . ▁ ▁In ▁ 1 9 7 2 , ▁Gl enn ▁Shaw ▁of ▁the ▁Ge oph ys ical ▁Institute ▁at ▁the ▁University ▁of ▁Al aska ▁attributed ▁this ▁sm og ▁to ▁trans bound ary ▁anth rop ogen ic ▁poll ution , ▁where by ▁the ▁Ar ctic ▁is ▁the ▁recip ient ▁of ▁cont amin ants ▁whose ▁sources ▁are ▁thousands ▁of ▁miles ▁away . ▁Further ▁research ▁continues ▁with ▁the ▁aim ▁of ▁understanding ▁the ▁impact ▁of ▁this ▁poll ution ▁on ▁global ▁war ming . ▁ ▁Origin ▁of ▁poll ut ants ▁Co al - burn ing ▁in ▁northern ▁mid - lat itudes ▁contribute ▁a eros ols ▁containing ▁about ▁ 9 0 % ▁sul fur ▁and ▁the ▁remainder ▁carbon , ▁that ▁makes ▁the ▁ha ze ▁re dd ish ▁in ▁color . ▁This ▁poll ution ▁is ▁helping ▁the ▁Ar ctic ▁warm ▁up ▁faster ▁than ▁any ▁other ▁region , ▁although ▁increases ▁in ▁green house ▁g ases ▁are ▁the ▁main ▁driver ▁of ▁this ▁clim atic ▁change . ▁ ▁Sul fur ▁a eros ols ▁in ▁the ▁atmosphere ▁affect ▁cloud ▁formation , ▁leading ▁to ▁local ized ▁cool ing ▁effects ▁over ▁industrial ized ▁regions ▁due ▁to ▁increased ▁reflection ▁of ▁sun light , ▁which ▁mask s ▁the ▁opposite ▁effect ▁of ▁tra pped ▁warm th ▁beneath ▁the ▁cloud ▁cover . ▁ ▁During ▁the ▁Ar ctic ▁winter , ▁however , ▁there ▁is ▁no ▁sun light ▁to ▁reflect . ▁