The Southern Hemisphere is stormier than the north. Now, scientists think they know why

A new study led by a University of Chicago climate scientist has revealed new theories about the relationship between storms and hemispheres.

For centuries, sailors have understood that the Southern hemisphere has threatened the most severe storms but with little to no scientific explanation behind it. Now, we have fresh confirmation that the Southern hemisphere is 24% stormier than the Northern.

Tiffany Shaw, climate scientist at the University of Chicago, has coined the world’s first tangible explanation. The study cites ocean circulation and the large mountain ranges in the Northern hemisphere as the dominant factors, further finding that this asymmetry has increased since the dawn of the satellite era in the 1980s.

The findings concluded that this increase was consistent with climate change forecasts developed by physics-based models.

“You can’t put the Earth in a jar”, Shaw told EurekaAlert.org. “So instead we use climate models built on the laws of physics and run experiments to test hypotheses.”

Testing topography – or the forms and features of land surfaces – the study found that large mountain ranges interrupt airflow, thereby reducing storms. The Northern hemisphere has a higher quantity of these mountain ranges, so when Shaw’s study flattened all the world’s mountains roughly half the difference in storminess between the two hemispheres disappeared.

Ocean circulation was also tested. Varying processes between the two hemispheres create an energy imbalance, so water sinks in the Arctic, moving along the bottom of the ocean and eventually rising – carrying energy with it – in Antarctica. The second part of the experiment removed this so-called conveyer belt system, eliminating the remaining half of the difference in storminess in the process.

Notably, the study concluded that the storminess asymmetry has increased since the 1980s, with the Southern hemisphere becoming increasingly stormier. By contrast, there’s been little to no change in the Northern hemisphere.

So, why did it take so long to answer this question? Weather and climate physics are relatively young fields of study, as scientists only began to investigate this question mark after World War II. With these concrete answers, climate scientists will now be empowered to make vital predictions as climate change accelerates.

“By laying this foundation of understanding, we increase confidence in climate change projections and thereby help society better prepare for the impacts of climate change”, Shaw explained to EurekaAlert.org. “The stakes are high and it’s important to get the right answer for the right reason.”