New Orleans could effectively be surrounded by the sea and submerged within this century as global warming accelerates sea level rise, according to a new outlook. Experts warned that long-term plans, including potential relocation of the city, must be drawn up now rather than after the damage materializes.
CNN reported on Wednesday, citing a recent analysis published in the international journal Nature Sustainability, that sea levels along the Louisiana coast could rise by 3 to 7 meters in the coming decades. In that scenario, about 75% of the remaining wetlands would disappear, and the coastline could retreat inland by up to 100 kilometers, the analysis showed.
New Orleans is home to about 360,000 residents. The city sits in a basin below sea level and lies at the center of the rapidly shrinking Mississippi River Delta, making it long recognized as vulnerable to sea level rise and storm surges.
The wetlands surrounding New Orleans have served as a natural barrier against hurricanes and storm surges. But expanded development, canal construction for the oil and gas industry, and river levee installations have sharply reduced the sediment supply that sustains the wetlands. Since the 1930s, an estimated 2,000 square miles, or about 5,180 square kilometers, of wetlands have disappeared in Louisiana.
The authors of the paper concluded that "the region has already passed the point of no return." They said New Orleans is highly likely to be surrounded by the Gulf of Mexico before the end of the century.
An ancient coastline formed about 125,000 years ago has been identified north of New Orleans. Sea levels at that time are estimated to have been at least 3 meters higher than today. Torbjörn Törnqvist, a geology professor at Tulane University who led the study, said, "Sea levels are very likely to rise to that height in the future."
Population decline is already underway. New Orleans lost about 25% of its population after Hurricane Katrina struck in 2005. Experts said a so-called "staircase migration," in which residents leave en masse each time a major storm or flood hits, has been repeating itself.
The biggest problem is the population without the means to relocate. Financially comfortable residents can leave high-risk areas first, but low-income groups are likely to be left behind in the city amid falling home prices, rising insurance premiums, and deteriorating public services. Experts warned that "without a systematic 'managed retreat' plan at the government level, this could lead to a 'catastrophic every-man-for-himself' situation in which the wealthy leave first and only the poor remain."
The Swedish northern city of Kiruna was cited as a reference case for urban relocation. After mining operations raised the risk of ground subsidence, Kiruna passed a residents' vote in 2004 and is pursuing a plan to move its urban functions to a safer area by 2035. The plan includes relocating major cultural heritage sites in their entirety, such as a more-than-100-year-old church.
Professor Törnqvist noted that "as the population declines, tax revenues will fall, public services will deteriorate, home values will collapse, and insurance premiums will surge, further deepening existing social inequalities."
He stressed, "The crisis facing New Orleans is a mirror of the future that all coastal cities around the world will face within this century," adding, "We must now build a proactive relocation model that combines sustainable development with coastal restoration."
