The warming ocean is putting coastal economies in hot water

Ocean-related tourism and recreation supports more than 320,000 jobs and $13.5 billion in goods and services in Florida. But a dip in the ocean became much less attractive in the summer of 2023, when water temperatures off the coast of Miami reached as high as 37.8 degrees Celsius.

The future of some jobs and businesses in the ocean economy has also become less certain as the ocean warms and damage from storms, sea level rise and marine heat waves increases.

Ocean temperatures have been rising over the past century, reaching record highs for much of last year, mainly due to increases in greenhouse gas emissions from the burning of fossil fuels. Scientists estimate that more than 90% of the excess heat produced by human activities has been absorbed by the ocean.

That warming, hidden for years in data only of interest to oceanographers, is now having profound consequences for coastal economies around the world.

Understanding the role of the ocean in the economy is something I have been working on for more than forty years, currently at the Center for the Blue Economy at the Middlebury Institute of International Studies. I usually study the ocean’s positive contributions, but this is starting to change, sometimes dramatically. Climate change has made the ocean a threat to the economy in several ways.

The dangers of sea level rise

One of the biggest threats to the economy from ocean warming is sea level rise. As water warms, it expands. Together with the meltwater from glaciers and ice caps, the thermal expansion of water has increased flooding in low-lying coastal areas and endangered the future of island states.

In the US, rising sea levels will soon overwhelm Isle de Jean Charles in Louisiana and Tangier Island in the Chesapeake Bay.

Flooding at high tide, even on sunny days, is becoming increasingly common in places like Miami Beach; Annapolis, Maryland; Norfolk, VA; and San Francisco. High tide flooding has more than doubled since 2000 and will triple along the country’s coasts by 2050.

Satelliet- en getijdenmetergegevens tonen de verandering van het zeeniveau tussen 1993 en 2020. <a href=National Climate Assessment 2023” data-src=”–/YXBwaWQ9aGlnaGxhbmRlcjt3PTk2MDtoPTcyNw–/ 2bc7dabc3d594304f611c5″/>

Rising sea levels also push saltwater into freshwater aquifers, from which water is drawn to support agriculture. The strawberry crop in California’s coastal areas is already being affected.

These effects are still small and very local. Much larger impacts come with storms that are amplified by sea level.

Higher sea levels can worsen storm damage

Warmer ocean water fuels tropical storms. It’s one reason why forecasters warn of a busy hurricane season in 2024.

Tropical storms pick up moisture above warm water and transfer it to cooler areas. The warmer the water, the faster the storm can form, the faster it can intensify and the longer it can last, resulting in devastating storms and heavy rains that can flood cities even far from the coast.

Now when these storms come on top of already higher sea levels, the waves and storm surge can dramatically increase coastal flooding.

Tropical cyclones caused more than $1.3 trillion in damage in the US between 1980 and 2023, with an average cost of $22.8 billion per storm. Much of those costs have been absorbed by federal taxpayers.

It’s not just tropical storms. Maine saw what could happen when a winter storm in January 2024 produced tides five feet above normal and filled coastal streets with seawater.

Een winterstorm die bij vloed toesloeg, zorgde ervoor dat het water in januari 2024 de straten van Portland, Maine in stroomde. <a href=AP Photo/Robert F. Bukaty” data-src=”–/YXBwaWQ9aGlnaGxhbmRlcjt3PTk2MDtoPTYwMw–/ 31c7355c59c08a7a3a030bd” />

What does that mean for the economy?

The possible future economic damage resulting from sea level rise is not known because the rate and extent of sea level rise are unknown.

One estimate puts the cost of sea level rise and storm surge alone at more than $990 billion this century, while adaptation measures can reduce it by only $100 billion. These estimates include direct material damage and damage to infrastructure such as transportation, water systems and ports. Not included are agricultural impacts due to saltwater intrusion into aquifers that support agriculture.

Heat waves at sea cause fishing problems

Rising ocean temperatures are also impacting marine life through extreme events known as marine heat waves and more gradual long-term temperature shifts.

In the spring of 2024, a third of the world’s oceans experienced heat waves. Corals are struggling through their fourth-ever global bleaching event as warm ocean temperatures cause them to push out the algae that live in their shells and give the corals color and provide food. Although corals sometimes recover from bleaching, about half the world’s coral reefs have died since 1950, and their future after mid-century looks bleak.

Gezonde koraalriffen dienen als viskwekerijen en leefgebied.  Deze schoolmeestersnappers werden gespot op Davey Crocker Reef nabij Islamorada in de Florida Keys.  <a href=Jstuby/wikimedia, CC BY” data-src=”–/YXBwaWQ9aGlnaGxhbmRlcjt3PTk2MDtoPTcyMA–/ ca04e83f271395077b3f”/>

The loss of coral reefs is about more than just their beauty. Coral reefs serve as nurseries and breeding grounds for thousands of fish species. By NOAA’s estimate, about half of all federally managed fisheries, including snapper and grouper, rely on reefs at some point in their life cycle.

Warmer waters cause fish to migrate to cooler areas. This is especially notable in cold-water-loving species such as lobsters, which are steadily moving north to escape warming seas. Southern New England’s once robust lobster fishery has declined significantly.

Hoe drie vis- en schaaldiersoorten tussen 1974 en 2019 voor de Amerikaanse Atlantische kust migreerden.  Stippen tonen de jaargemiddelde locatie.  <a href=NOAA” data-src=”–/YXBwaWQ9aGlnaGxhbmRlcjt3PTk2MDtoPTgyNQ–/ 2f613ae300855e87a5a9fbf5″/>

In the Gulf of Alaska, rising temperatures nearly wiped out snow crabs, forcing a $270 million fishery to close completely for two years. A major heat wave off the Pacific coast stretched over several years in the 2010s and disrupted fisheries from Alaska to Oregon.

This won’t change anytime soon

Accumulated ocean heat and greenhouse gases in the atmosphere will continue to affect ocean temperatures for centuries to come, even if countries reduce their greenhouse gas emissions to net zero by 2050 as hoped. So while ocean temperatures fluctuate from year to year, the overall trend is likely to rise for at least another century.

There is no cold water tap that we can simply turn on to quickly return ocean temperatures to “normal,” so communities will have to adapt as the entire planet works to slow greenhouse gas emissions to protect ocean economies for the future.

This article is republished from The Conversation, an independent nonprofit organization providing facts and analysis to help you understand our complex world.

It was written by: Charles Colgan, Middlebury Institute for International Studies.

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Charles Colgan receives funding from several sources, including NOAA and Lloyds of London. He authored the 5th Chapter of the National Climate Assessment on Oceans and the 4th Chapter of the California Climate Assessment on Coasts and Oceans.

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