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A recent statement caught my attention from a CleanTechnica reader mentioning the uniformity of sea level rise worldwide. This notion seems quite logical. Imagine having a bathtub filled with water where the surface level remains the same at both ends. Add more water, and the surface quickly adjusts to the increased volume. Nevertheless, when we talk about the vast oceans, we are dealing with distances spanning tens of thousands of miles and countless cubic feet of water. According to data from NOAA, there are more than 321 million cubic miles of water in all the world’s oceans. This immense volume of water does not slosh back and forth simultaneously across the Earth daily as tides ebb and flow. Consequently, there are noticeable disparities in ocean levels depending on the location where measurements are taken.
An article by the Washington Post sheds light on an alarming development. Sea levels in the Gulf of Mexico have surged by six inches or more over the last decade — a significantly faster rise than what the scientific community was anticipating. Most oceanographers had projected that such a rate of change would not occur until the end of this century and would only be likely if the Earth was heading towards surpassing a temperature increase of 2º C above pre-industrial levels. The sudden increase in sea level in the Gulf has caught scientists off guard, prompting urgent investigations to determine the underlying cause. The prevailing question is whether these observed changes are temporary or a precursor to a more rapid escalation in ocean levels in the Gulf of Mexico.
Surge in Sea Level Rise Exceeding Expectations
The heightened sea levels are already causing detrimental effects on coastal areas bordering the Gulf of Mexico. A study suggests that recent catastrophic hurricanes like Michael in 2018 and Ian last year were significantly exacerbated by the accelerated rise in the ocean level. Data from federal tide gauges at Lake Pontchartrain in New Orleans indicate that the sea level has risen by eight inches from its level in 2006, shortly after Hurricane Katrina. Consider for a moment the implications of an additional 8 inches of water if a similar storm were to strike New Orleans today.
“The entire Southeast coast and Gulf Coast are experiencing the repercussions of the accelerated sea level rise,” remarked Jianjun Yin, a climate scientist at the University of Arizona and the author of a recent research article in the Journal of Climate. His study indicates that the rate of sea level rise in the Gulf of Mexico since 2010 has exceeded one centimeter per year, amounting to nearly 5 inches in total by 2022. This rate surpasses the global average increase of approximately 4.5 millimeters per year since 2010 based on satellite observations of sea levels by researchers at the University of Colorado at Boulder.
Although the yearly increments may appear minor, even minor shifts in sea levels over time can lead to catastrophic outcomes. Yin’s study suggests that Hurricanes Michael and Ian, among the most intense stormsever to hit the United States, were significantly exacerbated by the rise in sea levels. “The water levels linked to Hurricane Ianreached a historic high due to the combined impact of sea level rise and storm surge,” Yin explained.
Unprecedented Growth in Sea Levels
A second analysis from a team of sea level experts, spearheaded by Sönke Dangendorf from Tulane University and published in Nature Communications, confirms the same trend observed since 2010 along the U.S. Gulf Coast and southeastern shorelines, branding the surge as “unprecedented in at least 120 years.” Dangendorf conveyed to the Washington Post, “It’s a glimpse into the future.” The pace at which sea levels are ascending along the Gulf of Mexico in recent years is so rapid that it mirrors projections for the end of the century in a worst-case greenhouse gas emissions scenario.
Two other studies on the rapid rise in sea levels and its impact on the Gulf Coast have been released by researchers in preprint form pending peer review. Collectively, these studies are remarkable as they link the swift sea level surge to profound transformations in the ocean. In certain regions of Texas and Louisiana, subsiding land has been a long-term contributor to the relatively rapid sea level rise. Nonetheless, the latest research reveals a marked elevation in sea levels in areas like Pensacola and Cedar Key, Florida, where the land issinking at a slower ratecompared to locations such as Grand Isle, Louisiana, or Galveston, Texas.
Broadly speaking, increased sea levels in the Gulf of Mexico and around Florida heighten the hurricane risks in some of the most vulnerable and storm-prone regions of the United States. Furthermore, individuals continueto relocateto high-risk coastal areas. Scientists warn that millions of acres of land and hundreds of thousands of homes and businessesmight fall belowhigh tide levels. Experts from the nonprofitFirst Street Foundation recently forecasted that properties in numerous coastal areas might experience a decline in value as flooding becomes more severe, a change that could negatively impact homeowners and diminish local tax revenues.
There is a lack of consensus among scientists regarding the factors fueling this phenomenon, or whether the recent surge in rising sea levels will persist at such a rapid rate. Scientists typically prefer to rely on long-term data to gain more confidence in climate system trends and their underlying causes. Given the recent spike in sea levels over a relatively short period, this trend is as puzzling as it is concerning
Warmer Water Expands
The swift increase in sea levels observed by researchers seems to originate in the Gulf of Mexico, which has been heating up considerably faster than the global ocean. Warm water expands, contributing to the rise in sea levels. This warm water is also carried by currents away from the Gulf towards the East Coast, impacting regions such as Georgia and the Carolinas.
The warm waters that have been driving the increase in sea levels in the Gulf of Mexico are remarkably warm even at significant depths, as indicated by a preprint study conducted by Jacob Steinberg and collaborators from the Woods Hole Oceanographic Institution, NASA’s Jet Propulsion Laboratory, the University of Hawaii at Manoa, and the National Center for Atmospheric Research. Steinberg and his team propose that a warm current known as the Loop Current, which enters the Gulf from the Caribbean Sea, is part of a larger circulation pattern in the Atlantic Ocean.
Dangendorf holds a differing view. His research indicates that the rise in water levels in the Gulf is influenced by a combination of factors, including some natural ones. By examining sea level data from Pensacola and Galveston dating back a century or more, the Gulf Coast experienced a rapid surge in sea level during the 1940s, a trend that abated by the 1950s. It remains unclear whether the current upsurge in sea levels might also be a temporary deviation.
“We are witnessing this forced acceleration, compounded by natural variability, and unfortunately, in recent years, we have been facing the double impact of this acceleration along with natural variability,” he remarked. Nevertheless, he deemed the rapid changes in sea levels worrying, reminiscent of what scientists might have predicted only if there had been sustained extensive emissions of planet-warming gases into the atmosphere.
This explains why nations worldwide have persisted in their emissions despite the scientific evidence linking elevated carbon dioxide levels to higher global temperatures. Their pretext often cites the lack of consensus among scientists, which they use as justification to maintain the status quo in the economic system. This rationale resonates with many individuals.
Magnified Impacts of Sea Level Rise
The repercussions of rising sea levels are amplified in low-lying regions with minimal elevation changes — a common feature along the Gulf Coast. In such communities, even slight increments in sea levels can significantly heighten the risks posed by storms. Waves encroach nearer to the shore, exacerbating erosion, while surges penetrate further inland and rapidly degrade coastal wetlands.
In a forthcoming study by researchers affiliated with the University of Miami, NOAA, NASA, and various institutions in the United States and Australia, it was highlighted that the substantial surge in sea levels in the Southeast since 2010 accounts for “30-50% of flood days in 2015-2020.” The study underscores that even a slight elevation in background sea levels in low-lying coastal regions can breach regional flooding thresholds and trigger coastal inundation.
An Anomaly or a Pattern?
The key query pertains to whether the current rate of changes as evidenced by researchers will persist, resulting in an excess of a foot of additional sea level rise in the next few decades, or if levels will revert to a more global average. Examining historical sea level records from Pensacola and Galveston dating back a century or more, the Gulf Coast previously experienced a swift rise in sea level in the 1940s, a trend that had subsided by the 1950s. However, the similarity of this event to the prevailing situation remains uncertain. Globally, the pace of sea-level rise is escalating, and scientists have unanimously asserted that sea levels will continue to rise significantly into the future, even if substantial reductions in greenhouse gas emissions are achieved.
In a report released last year, NOAA and other federal agencies projected that US coastlines, on average would experience an additional foot of sea level rise in the next three decades. The report issued notably high forecasts for the Gulf Coast, largely due to recent trends. “Predicting the short-term outlook is highly challenging,” remarked Ben Hamlington, a NASA expert on sea levels and a collaborator on Steinberg’s study. “These rates are not expected to turnaround immediately.”