Ocean-related tourism and recreation supports more than 320,000 jobs and $13.5 billion in goods and services in Florida. But in the summer of 2023, swimming in the ocean became much less appealing as water temperatures rose to 101 degrees Fahrenheit (37.8 Celsius) off the coast of Miami.
The future of some jobs and businesses in the ocean economy has also become less secure as oceans warm and damage from storms, sea level rise and marine heatwaves increases.
Ocean temperatures have been rising over the past century, reaching record levels for much of the past year; This is mainly due to the increase in greenhouse gas emissions resulting from the burning of fossil fuels. Scientists estimate that more than 90% of the excess heat produced by human activities is absorbed by the oceans.
This warming, hidden for years in data that was of interest only to oceanographers, now has profound consequences for coastal economies around the world.
Understanding the ocean’s role in the economy is something I’ve been working on for more than 40 years, now at the Blue Economy Center at the Middlebury Institute of International Studies. I mostly study the positive contributions of the ocean, but this has begun to change, sometimes dramatically. Climate change has made the oceans a threat to the economy in many ways.
Dangers of sea level rise
One of the biggest threats to economies from ocean warming is sea level rise. As water heats up, it expands. Meltwater from glaciers and ice sheets, as well as thermal expansion of water, has increased flooding in low-lying coastal areas and put the future of island nations at risk.
Rising sea levels in the U.S. will soon exceed Isle de Jean Charles in Louisiana and Tangier Island in the Chesapeake Bay.
Flooding is increasingly common in places like Miami Beach when the water rises, even on sunny days; Annapolis, Maryland; Norfolk, Virginia; and San Francisco. High tide flooding has more than doubled since 2000 and is on track to triple along the nation’s coasts by 2050.
Rising sea levels also push saltwater into freshwater aquifers, where water is withdrawn to support agriculture. The strawberry crop along the California coast is already being affected.
These effects are still small and fairly localized. Much larger impacts come with storms as sea level rises.
High sea levels could worsen storm damage
Warmer ocean water fuels tropical storms. That’s one reason why forecasters are warning of a busy hurricane season in 2024.
Tropical storms remove moisture from warm water and transfer it to colder areas. The warmer the water, the faster the storm can form, the faster it can intensify, and the longer it can last, causing devastating storms and torrential downpours that can flood even cities far from the coasts.
When these storms rise above already high sea levels, waves and storm surges can significantly increase coastal flooding.
Tropical cyclones caused more than $1.3 trillion in damage in the United States from 1980 to 2023, with an average cost of $22.8 billion per storm. Most of this cost was covered by federal taxpayers.
It’s not just tropical storms that are the problem. Maine saw what could happen if a winter storm in January 2024 created tides 5 feet above normal and flooded coastal streets with seawater.
What does this mean for the economy?
Because the rate and extent of rising sea levels are unknown, the potential future economic harms of sea level rise are unknown.
One estimate suggests that costs from sea level rise and storm surge alone are over $990 billion this century, and adaptation measures could reduce that by just $100 billion. These estimates include direct property damage and damage to infrastructure such as transportation, water systems and ports. The effects on agriculture of saltwater intrusion into groundwater that supports agriculture are not included.
Marine heat waves put fisheries in trouble
Rising ocean temperatures also affect marine life through extreme events known as marine heat waves and more gradual long-term changes in temperature.
In the spring of 2024, one-third of the global ocean experienced heat waves. Corals are struggling with the fourth global bleaching event on record as warm ocean temperatures cause them to expel the algae that live in their shells, which give corals color and provide food. Although corals sometimes recover from bleaching, nearly half of the world’s coral reefs have died since 1950, and their future after the middle of this century is bleak.
Losing coral reefs is about more than their beauty. Coral reefs serve as breeding and feeding grounds for thousands of fish species. Nearly half of federally managed fisheries, including snapper and grouper, rely on reefs at some point in their life cycles, NOAA estimates.
Warm waters cause fish to migrate to cooler areas. This is especially notable for cold-water-loving species such as lobsters, which continually migrate north to escape warming seas. The once-strong lobstering business in southern New England has declined significantly.
Rising temperatures in the Gulf of Alaska nearly wiped out snow crabs, forcing a $270 million fishery to be completely shut down for two years. A major heat wave along the Pacific coast spanned several years in the 2010s and disrupted fishing from Alaska to Oregon.
This won’t get better soon
Even if countries reduce greenhouse gas emissions to net zero by 2050, as hoped, ocean heat and greenhouse gases accumulating in the atmosphere will continue to affect ocean temperatures for centuries. So, while ocean temperatures fluctuate from year to year, the overall trend is likely to continue upward for at least a century.
There is no cold water tap we can simply turn on to quickly return ocean temperatures to “normal,” so communities will need to adapt as the entire planet tries to slow greenhouse gas emissions to protect ocean economies in the future.
This article is republished from The Conversation, an independent, nonprofit news organization providing facts and analysis to help you understand our complex world.
Written by: Charles Colgan, Middlebury Institute of International Studies.
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Charles Colgan receives funding from various sources, including NOAA and Lloyds of London. He was the author of the 5th National Climate Assessment chapter on oceans and the 4th California Climate Assessment chapter on coasts and oceans.