Hurricane Helene left its mark on the ocean

Today’s Image of the Day from NASA Earth Observatory features brightly colored sediment that was stirred up in the Gulf of Mexico by Hurricane Helene. 

The category 4 storm made landfall on September 26, 2024 in Florida’s Big Bend area with peak wind speeds of 140 miles per hour.

“The heavy rains, high winds, and storm surge that affected land areas also left a mark on the ocean,” said NASA.

“Helene’s winds and waves churned up sediment from the seafloor along shallow coastal areas. Light reflects from these fine particles and makes the water appear bright blue.” 

Helene’s widespread devastation 

Hurricane Helene caused widespread destruction across the Southeastern U.S., including severe storm surges and catastrophic inland flooding.

Western North Carolina was hit particularly hard by the storm, with rivers like the French Broad River cresting at historic levels. 

Asheville and surrounding towns suffered extensive damage due to rising waters, landslides, and infrastructure collapses. Roads were blocked by mudslides – including parts of Interstate 40 – and bridges were washed away.

Entire communities, such as Chimney Rock Village and parts of Swannanoa, were virtually wiped out by several feet of fast-moving water and landslides.

Aging infrastructure in high-risk areas

In a recent report from Virginia Tech, experts describe Helene as a prime example of how a combination of natural forces, aging infrastructure, and human decisions can magnify the impact of disasters.

Professor Manoochehr Shirzaei warned that legacy systems – including levees, dams, bridges, roads, and electrical grids – were not originally designed to endure the growing severity of hurricanes exacerbated by climate change.

“As these structures deteriorate with time, their vulnerability to failure during extreme weather events increases,” said Professor Shirzaei.

As extreme weather events become more frequent in a warming climate, addressing the condition of aging infrastructure becomes critical to reducing future disaster risks. In addition, the number of people living in flood-prone areas has dramatically increased. 

Many communities are located in river valleys or downstream of dams. These areas are particularly vulnerable to sudden water discharges. 

“Over the past few decades, the expansion of human populations into flood-prone areas has accelerated worldwide,” said Professor Shirzaei.

Hurricane Helene and climate change

A recent report from ClimaMeter revealed that Helene’s rainfall totals and winds were strengthened by human-driven climate change, with up to 20 percent more rainfall and winds up to seven percent stronger.

Scientific consensus suggests that tropical storms will become increasingly more powerful in a warmer climate.

Increased hurricane intensity

Warmer ocean temperatures fuel hurricanes, giving them more energy and leading to more intense storms. Studies show that there has been an increase in the frequency of Category 4 and 5 hurricanes, the most powerful types of storms.

Heavier rainfall

Warmer air holds more moisture, meaning hurricanes are producing more intense rainfall. This can lead to greater flooding, which has become a more prominent feature of recent hurricanes.

Slower-moving storms

Some research suggests that climate change may be slowing down the forward motion of hurricanes, meaning they linger longer over affected areas. This results in prolonged rainfall and more damage to regions impacted by storm surges and wind.

Higher storm surges 

Rising sea levels due to climate change increase the height of storm surges, which are often the most dangerous and deadly part of a hurricane. Higher surges cause more flooding in coastal areas, even when the storm itself isn’t at peak intensity.

Broader geographic impact 

Climate change is pushing hurricanes into new areas that historically haven’t experienced as many storms, such as parts of the U.S. Northeast and Europe.

While climate change doesn’t necessarily increase the number of hurricanes overall, it tends to make them more intense, causing greater damage and increasing risks to life and property.

The image was captured on September 28, 2024 by the OCI (Ocean Color Instrument) on NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) satellite.

In the wake of Helene’s destruction, at least 223 people have been confirmed dead and hundreds are still missing.

Image Credit: NASA Earth Observatory 

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