10-Year Anniversary of Hurricane Katrina

Ten years ago this week, Hurricane Katrina became one of the worst natural disasters in U.S. history. It caused the deaths of an estimated 1,200 people and more than $100 billion in damage as it barreled across Florida and then slammed into the Gulf Coast as a Category 3 hurricane (after peaking at Category 5 strength).

Katrina’s highest storm surge, some 27.8 feet, was recorded at Pass Christian, Miss. While in New Orleans, a surge from 5-10 feet piled up along the western shores of Lake Pontchartrain, straining the levee system until parts of it gave way, eventually inundating about 80% of the city in waters that reached up to 20 feet.

The storm was bookended by two major studies into the question of how climate change might impact hurricanes and helped to spur intensive study into that very question in subsequent years. Over the past decade, scientists have come to a general consensus that while globally there will be about as many — or perhaps even fewer — tropical cyclones as there are now, they will become more intense.

A 2013 study did find that surge and flooding from Katrina was anywhere from 15-60% higher than it would have been under the climate and sea level conditions around 1900. This was primarily from local land subsidence, which accounted for about 1.8 feet of an estimated 2.4 feet of local sea level rise.

• Here's a link to that report: Simulations of Hurricane Katrina (2005)

The researchers explain how the loss of protective wetlands and barrier islands contributed to the increased surge and flooding. Part of the reason these features are being lost is the lack of replenishing silt in the Mississippi Delta because of dams and other constructed features farther upriver.