Winter 2021. Record snow in Greece and Spain, and now 20°C+ temperatures all around Europe? What is going on with the climate?
This winter every country in Europe has experienced a rollercoaster of weather patterns. From snow in the acropolis, to skiiers down Madrid’s streets, to a bizzare 20°C degrees even in Berlin—in February!
So what is happening?
In short this year there has been a weak jet stream that has destablized the polar vortex.
Jet streams are currents of fast-flowing cold air. The polar-front jet stream (northern hemisphere) tends to separate cold weather to warmer weather—above it is cold, below it is warm. This year the jet stream has displayed a meandering behaviour following stratospheric warming.
The wavy jet stream created a weak polar vortex (areas of low pressure and cold air surrounding Earth’s north and south poles) allowing extreme cold air to pour out of the Arctic into usually warmer climates.
This also explains the unsual weather in Texas.
So is climate change to blame for the stratospheric warming? An ongoing debate:
Scientists are torn about blaming climate change for these radical weather patterns. A sudden stratospheric warming could happen around six times in a decade. Thus an unstable jet stream and polar vortex could be quite common. However, one can argue that no, these very very radical weather patterns have not happened six times in the last ten years. In some regions, they have never occured before. So, other scientists are arguing that as temperatures rise the intensity and frequency of a stratospheric warming will also increase.
More research is needed to fully analyse how climate change could be affecting these weather phenomena.