The eighth federal government High Tide Flood Status Report is his starkest assessment, detailing the rising trends of rising seas pouring into coastal cities.
Earlier this month, scientists at NOAA’s National Ocean Service – the agency’s water counterpart to the National Weather Service – reported three- and five-fold increases since 2000 in high-tide flooding on sunny days. for the southeastern United States and the western Gulf Coast, respectively. Despite an ongoing La Niña in the eastern Pacific, which may temporarily dampen sea levels along the U.S. coast, the frequency of relentless saltwater flooding – unrelated to extreme weather – has continued to accelerate in the United States in 2022.
Report highlights alarming growth in chronic flooding in sunny weather at nearly 100 NOAA-monitored tidal locations along the U.S. coast, testing the ability of modern infrastructure to gradually adapt to contain high tides increasingly disruptive and destructive. The latest outlook predicts flooding on sunny days – now occurring around once every two months in any given location, on average nationwide – will become as common as every other day by the end of traditional mortgages. 30 years from today.
Sea level rise driven by global warming
Several factors affect local sea level elevation differences, including land subsidence and a slowing of the current of the Gulf Stream along the east coast, particularly along the southern extension of the Gulf Stream known as the Florida Current.
But even in places like South Florida, prone to both subsidence and fluctuations in the nearby Florida Current, government scientists estimate the vast majority – about 8cm of the 11cm increase over the past 20 years – is due to warming oceans and melting land ice due to global climate change. The octopus in the parking garage may be the modern canary in the coal mine for rising seas, with sea life swept up by the rising tides and bubbling through the porous bedrock below.
The latest report completes an extensive NOAA Task Force Report released last February updating sea level projections for the U.S. coastline based on climate change scenarios outlined in the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report released last summer. These new updates, the first since 2017, build scientific confidence in the next century of deleterious consequences for U.S. coastal communities and ecosystems unless comprehensive mitigation measures are taken.
Rising seas and coastal populations…and future storm surges
The US population looking for permanent housing along the coasts is booming. Nearly 40% of the nation’s 330+ million live in a coastal county on land comprising less than 10% of the total land area of the United States, excluding Alaska. In many hurricane and storm-surge prone areas along the gently sloping Gulf Coast, population and attendant wealth have soared. In Collier County on Florida’s southwest coast, home to Naples and one of the most prosperous communities in the countrythe population has climbed almost 1000% over the past 50 years. About 40% of the population of Florida is at risk of being inundated by storm surges, highest concentration of storm surge losses per capita along the southwest coast of Florida.
Similar to lowering the ledge of a basketball goal (or raising the ground below the basket), rising seas will lower the bar for future storm “dunks”, making extreme flooding even worse. if the characteristics of the storms do not change. Recent studies conclude damage from storm surges and sea level rise under a moderate global warming scenario could exceed $1 trillion by the end of the century in the United States – most blatant on the Atlantic and Gulf coasts. In a scenario of extreme global warming, this damage could exceed $14 trillion worldwide without appropriate adaptation measures to reduce risks.
Added to the tidal wave of coastal concerns are the problems of climate change, which can accelerate the destructive feedback loop.
As government scientists noted in their annual high tide flood report, colder than average waters around the equator in the eastern Pacific – a phenomenon called La Niña – have reduced otherwise higher seas , especially on the west coast of the United States. This very persistent La Niña, in its third consecutive year and only the third triple dip in the 73-year record, has been a deceptive boon to chronic coastal flooding in recent years. Due to global warming, however, El Niño events—the warming of the eastern Pacific that can exacerbate sea levels along the east and west coasts—not La Niña events should eventually become more common later this century, although this question remains an active area of research.
Meanwhile, scientists are seeing higher precipitation rates in tropical cyclones, especially near their centers where the winds are strongest. In a document published earlier this year in the journal Nature, scientists from Princeton University and MIT examined the combined impacts of worsening storm surges from rising seas and increased rainfall in tropical cyclones. The authors found an increase in the incidence of extreme flooding caused by tropical cyclones – up to 36 times in the southern United States and 195 times in the northeastern United States by the end of the century .
Disadvantaged populations – as so often – the hardest hit
Economically disadvantaged populations and communities of color are projected to be disproportionately exposed to coastal flooding from sea level rise in years to come. A study 2021 in the Journal of Climate Change and Health found that over the next three decades in North and South Carolina, rising sea levels could increase low-level flooding by up to 700% in black communities low-income compared to higher-income white communities. These findings are consistent with extensive peer-reviewed research showing a higher risk of natural disasters for low-income households, under-resourced communities, and communities of color.
In recent years, the Federal Emergency Management Agency, FEMA, explicitly prioritized to the needs of historically underserved communities. The agency at the beginning of August announced an injection of 3 billion dollars in federal flood mitigation and resilient infrastructure programs targeting communities most at risk.
Sea level rise remains one of the most visible and important spots of global warming. Its effects are vast and pervasive, and to ignore the rising tide is to dismiss the business card of climate change. Some changes are less noticeable, but in cities from Galveston to New Orleans, Miami to Charleston, Norfolk to Boston and the hamlets in between, the fingerprints of the speeding seas are unmistakable. And the costs – both ecological and economic – have never been higher… and are only expected to increase.
Michael Lowry is a hurricane specialist and storm surge expert with WPLG, the ABC affiliate in Miami, Florida. He is a former FEMA emergency management officer and senior scientist at the National Hurricane Center.