In 1998, the wrath of Hurricane Mitch claimed between 11,000 and 18,000 lives in Latin America and Florida. Hurricane Wilma, the most intense Atlantic hurricane in history, inflicted $21 billion worth of damage in Florida, Mexico, and Cuba in 2005.
James Kossin and his team have determined that global warming is linked to stronger storms in the Atlantic Ocean.
Photo Credit: Ross KaplanJust a few months before Wilma, Hurricane Katrina—one of the deadliest hurricanes in the history of the United States—left at least 1,800 victims and $81.2 billion of damage in its wake. The carnage and devastation left by recent high-intensity storms has sparked a new level of concern in how these natural disasters develop, as a better understanding of the contributing factors might help prevent Katrina-scale tragedies in the future.
This concern, coupled with the increasing intensity and frequency with which storms occur, has led to further research on their causes. Based on a theory of correlation initially proposed by Kerry Emanuel, atmospheric scientist at the Massachusetts Institute of Technology, in 2005, a group of scientists at UW-Madison and the National Climatic Data Center have found evidence that one of the causes of intensifying storms might be the climate changes caused by global warming. The research has determined that global warming, by way of increasing sea-surface temperatures, contributes to stronger storms in the Atlantic Ocean.
James Kossin, an atmospheric research scientist in the Cooperative Institute for Meteorological Satellite Studies at UW-Madison, has helped lead the research group’s quest to confirm this correlation between temperature and storm occurrence. According to Kossin, hurricanes need temperatures of approximately 26.5 degrees Celsius (81 degrees Fahrenheit) at the water’s surface in order to form. His group’s findings indicate that the Atlantic Ocean’s surface temperature near the Caribbean Sea is about equal to this threshold temperature. The effect of global warming pushes it just over the temperature and into the type of conditions that could produce the massive storms that the area has experienced.
Kossin’s research focuses on the Atlantic Ocean due to restrictions in data. Equipment used to identify and track hurricanes has changed drastically in the last 50 years and being able to translate this data has been a difficult task.
“The science behind the data is clear. But the data collecting, in itself, has not been,” Kossin says. The team has worked on smoothing out the data collected from the Atlantic Ocean basin since 1983 when equipment became advanced enough to provide reasonable data they can utilize today. The fact that the focus is on one particular area is significant, since it means that none of the effects of sea-surface temperature that the team has found apply to the rest of the world—not for now, at least.
Another important factor to consider is that increases in sea-surface temperature are not the sole determinants in creating the hurricanes that have ravaged the United States and Latin America. Often, hurricanes are “basin-dependent,” meaning they occur because of patterns in the Earth’s composition. Also, vertical wind sheer, caused by the east-west trade winds, is critical to these storms since the pressure created by their interaction with sea-surface temperatures begins the process of creating a hurricane.
Overall, as Kossin says, the effects of these storms “have a lot of variability—interannual variability, and very, very long cycles—and there are those who certainly believe such a cycle is taking place” in the Atlantic Ocean, as well as across the rest of the world. The issue of whether or not hurricanes can be traced back to global warming is hotly debated and many argue that they are mostly caused by natural weather-cycle patterns. However, in the end, Kossin believes that the cause of the increasingly intense hurricanes in the Atlantic Ocean can be traced back to humanrelated causes; the same ones that have made global warming such a pressing issue in recent years.