Finally, we understand why there are more storms in the southern hemisphere.

 January 3, 2023

By David Nield

In 2012, an extratropical cyclone formed off the coast of Australia.

The two sides of our planet do not experience an equal distribution of storms and other severe weather occurrences. In fact, for reasons that haven't been entirely understood up until now, the Southern Hemisphere experiences storminess that is around 24 percent greater than the Northern.

The heights of mountain ranges and the movement of energy across the seas are two key elements in determining how storms develop above and below the equator, according to a new research that examines global storm patterns in depth.

A group of scientists from the Universities of Chicago and Washington used a variety of modified climate models to come to their results, examining the effects of altering factors like topography and ocean currents on the frequency of storms.

According to Tiffany Shaw, a climate scientist at the University of Chicago, "you can't put the Earth in a jar, so instead, we utilise climate models established on the rules of physics and perform experiments to evaluate our assumptions."

One component of the researchers' climate models was altered at a time. Half the difference in storminess vanished when they levelled the continents in the Northern and Southern Hemispheres.

When warm water cools and dips in the Arctic, travels south, then rises with wind-driven upwellings in the Antarctic, they stop a large worldwide ocean circulation known as a "conveyor belt." This decrease in energy transmission caused the mountains throughout the planet to flatten, and it also aligned the storm levels in the two hemispheres.

The frequency of storms has also been growing in the Southern Hemisphere during the 1980s, whereas it has stayed fairly stable in the Northern Hemisphere, according to satellite studies.

That's probably due to current fluctuations brought on by variations in the temperature of the atmosphere and ocean. While these changes are occurring all around the planet, they are somewhat offset in the north by the melting of snow and sea ice as well as higher levels of solar absorption.

According to the researchers' published work, "the Southern Hemisphere is anticipated to grow stormier, but Northern Hemisphere storminess changes are muted due to a tug of war between tropical and polar climatic changes."

Scientists began studying the weather and temperature throughout the world only after World War II, despite the fact that sailors had long been aware of the various circumstances in each hemisphere.

Researchers were able to gather a plethora of fresh information on meteorological conditions with the advent of large-scale, real-time satellite imaging at the beginning of the 1980s, enabling them to map out and monitor how they were changing over time.

In order to better understand how the warming globe can effect storms and weather patterns differently in the two hemispheres—and which factors will be most important—these new discoveries will be incorporated back into climate change models.

Shaw claims that by establishing this foundation of knowledge, we boost confidence in climate change forecasts and so aid society in better preparing for its effects.

"Understanding if models are providing us with accurate information today will help us believe what they predict about the future, which is one of the main themes of my research. Because the stakes are so high, it's critical to choose the best course of action."