As it turns out, the tipping action may have been a direct result of global warming.
When you think of global warming, you think hot temperatures. It refers to the rise in average temperature across the world, causing record highs and the polar caps to melt.
Around there is usually where our mental picture of global warming ends. What we fail to think about is the enormous effects of all those high temperatures and melted ice.
The warming of the arctic may have actually caused a change in the jet stream, which led to the tipping of the polar vortex. Between the North Pole and the equator, there is a balance of heat, which directly affects the upper level winds of the jet stream. Manmade climate change may have upset the balance, causing a shift of the wind flow.