Article
BAMOS July 2021
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The Sudden Stratospheric Warming over the Southern Hemisphere in September 2019 . Red / blue shows geopotential height anomalies of 2019 compared to a “ standard ”
( climatological ) year : if everything was “ normal ”, nothing would be seen . Credit : Martin Jucker . and they have only been around since the end of the 1970s . Before that , balloon measurements give us some indication that nothing similar has happened since the 1950s . And before that , we have no idea .
Running climate models which include a good representation of the stratosphere is very expensive , but people didn ’ t think it was important to run these investigations — at least , compared to what the oceans and other things do to local climate and weather . As a result , those climate model simulations we did have of this part of the atmosphere were usually not reliable or simply too short .
This is why we spent a long time running a very good climate model for a very long time — 9,900 years to be precise ( the simulated time , not the time it took us to run it ). With this simulation we were able to determine how many times events like those in 2019 would have happened . We found they would have occurred about once every 22 years under conditions similar to the year 1990 . That aligns well with the 17 years between the sudden stratospheric events in 2002 and 2019 . However , we also found that in the future ( a world similar to 2080 ), due to greenhouse gas emissions , these events tend to decline rapidly , happening about once every 300 years .
We are already a third of the way to 2080 ( since 1990 ), so these stratospheric events already happen less frequently than once every 22 years . So , what will the world look like in 300 years if that is the next time a Sudden Stratospheric Warming event occurs ? Probably nothing like 2021 ( remember the year 1721 ?), but the chances are that until another such event happens in the southern hemisphere , we will have to deal with lots of other catastrophic events related to climate change . In the balance of things , perhaps having a few more Sudden Stratospheric Warming events and learning how to deal with them would be better than dealing with the consequences of climate change . But make no mistake , the stratosphere still influences our weather , whether there are Sudden Stratospheric Warmings or not .
This article is a '
Research Brief ' from the ARC Centre of Excellence for Climate Extremes , based on the paper :
Jucker , M ., Reichler , T ., & Waugh , D . W . ( 2021 ). How frequent are Antarctic sudden stratospheric warmings in present and future climate ?. Geophysical Research Letters , 48 , e2021GL093215 .
https :// doi . org / 10.1029 / 2021GL093215