Polar vortex -is it due to global warming

USA is in the grip of severe cold wind . Temperature range isof -23c . Meaning a cup of boiling water on exposure to air will turn into ice .. why is it ? Rail , air and land transport is affected . Everything turned into a frozrn ice .Is it due to global warming . While one part of the world have extreme climate of one type while other part is engaged another type of issues while is contradictory to the first type .
School book definition of global warming says that  the amount of ice in the pole are reducing due to rise in global temperature . But what is happening now is temperature is dropping well below mark . An exposure of skin to such conditions will result in instinct freeze and skin will start to tear apart .
There is drastic drift in the weather pattern . Is the school book definition of global warming right or shall we change our school of thinking from global warming to global climate shift and  explore to find the reasons .  Last year we had drought , typhoons, cyclone,  floods and npw polar vortex all in extreme conditions. 
It is awesome to find liquidus, solidus , gaseous point is clearly visible due to the polar vortex. 
Hope scientists will come with a reason .