Colder weather can be attributed to an increase of atmospheric humidity levels over the arctic region, due to heating and evaporation, which in turn has led to increased snowfall across Eurasia and northern America. And furthermore the de-glaciation makes the ocean, which is becoming more exposed to solar radiation, heat up and thus add more energy to the atmosphere than usual, which is having an effect on the jet streams in the stratosphere so that they push down the cold polar air over parts of the northern hemisphere and create "pockets" of extreme winter weather.