CO2-driven climate change causes Hurricane Milton to explode into a Category 5, heading for Florida

Author: Ali Sarhadi, Georgia Institute of Technology | –

(The Conversation) – Hurricane Milton went from minor hurricane strength to a dangerous Category 5 storm in less than 24 hours as it headed through the Gulf of Mexico toward Florida.

As wind speeds increased, Milton became one of the fastest-growing storms on record. Taking into account the sustained winds of 300 km/h and very low pressure on October 7, 2024, it also became one of the strongest storms of the year.

Less than two weeks after Hurricane Helene’s devastating impact, this type of storm was the last thing Florida wanted to see. Hurricane Milton was expected to make landfall as a major hurricane late October 9 or early October 10 and has already caused widespread evacuations.

What exactly is rapid intensification and what does global climate change have to do with it? We study the behavior of hurricanes and teach meteorology. Here’s what you need to know.

What is rapid intensification?

The National Weather Service defines rapid intensification as an increase in a tropical cyclone’s maximum sustained wind speed of at least 30 knots, or about 35 miles per hour, over a 24-hour period. This increase could be enough to escalate the storm from a Category 1 to a Category 3 on the Saffir-Simpson scale.

Wind speeds at Milton increased from 80 mph to 175 mph from 1 p.m. Sunday to 1 p.m. Monday, and pressure dropped from 988 millibars to 911.

The National Hurricane Center warned that Milton was likely to become a major hurricane, but this type of rapid intensification could catch people by surprise, especially when it occurs close to landfall.

Hurricane Michael caused billions of dollars in damage in 2018 when it quickly intensified into a Category 5 storm just before making landfall near Tyndall Air Force Base in the Florida Panhandle. In 2023, Hurricane Otis’s maximum wind speed increased by 100 mph in less than 24 hours before it hit Acapulco, Mexico. Hurricane Ian also rapidly intensified in 2022 before making landfall just south of where Milton is expected to cross Florida.

What causes hurricanes to rapidly intensify?

Rapid intensification is difficult to predict, but there are several factors driving this process.

• Ocean heat: Warm sea surface temperatures, especially as they reach deeper layers of warm water, provide the energy necessary for hurricanes to intensify. The deeper the warm water, the more energy the storm can draw on, which increases its strength.

• Low wind shear: Strong vertical wind shear – the rapid change in wind speed or direction with height – can disrupt storm organization, while low wind shear allows hurricanes to develop more quickly. In Milton’s case, weather conditions were particularly conducive to rapid intensification.

• Moisture: Higher sea surface temperatures and lower salinity increase the amount of moisture available to storms, fueling their rapid intensification. Warmer waters provide the heat needed to evaporate moisture, while lower salinities help retain this heat near the surface. This allows heat and moisture to transfer more sustainably into the storm, causing it to intensify faster and stronger.

• Storm activity: Internal dynamics, such as the outbreak of intense thunderstorms during a cyclone’s rotation, can reorganize the cyclone’s circulation and lead to a rapid increase in strength, even if other conditions are less than ideal.

Studies have shown that worldwide, most Category 3 and above hurricanes intensify rapidly over their lifetimes.

How does global warming affect the strength of hurricanes?

If it seems like you’re hearing about rapid intensification more and more in recent years, that’s partly because it’s happening more often.

A 2023 study examining the links between rapid intensification and climate change found an increase in the number of tropical cyclones experiencing rapid intensification over the past four decades. This includes a significant increase in the number of hurricanes, which intensify rapidly and repeatedly as they develop. Another analysis comparing trends from 1982 to 2017 with climate model simulations found that natural variability alone cannot explain the increase in the number of rapidly intensifying storms, pointing to the likely role of human-induced climate change.

An active area of ​​research is the impact of future climate change on hurricanes. However, as global temperatures and oceans continue to warm, the frequency of major hurricanes is expected to increase. Extreme hurricanes in recent years, including Beryl in June 2024 and Helene, are already raising alarms about the increasing impact of warming on the behavior of tropical cyclones.

Zachary Handlos, atmospheric science educator, Georgia Institute of Technology and Ali Sarhadi, assistant professor of atmospheric sciences, Georgia Institute of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.