Sudden Stratospheric Warmings (SSWs) are events in the upper atmosphere where the usually strong eastward winds over the winter pole suddenly slow down and even reverse direction. These events have been linked to extreme weather events such as cold spells and heatwaves.

It is not clear what initiates these events and whether it matters for their surface impact. This study investigates the question of whether the way in which they are initiated matters.

Using a simplified climate model, the researchers forced the polar winds to reverse arbitrarily and found that the final impact at the surface is indistinguishable from events where the winds reverse in response to natural phenomena.