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New Orleans is sinking

August 14, 2025 By EarthWise Leave a Comment

As climate change accelerates, rising sea levels are putting coastal communities at greater risk of flooding and storm surge. Driven by melting glaciers and warming oceans, global sea levels are rising at an increasing rate. For low-lying cities like New Orleans, even small increases can have serious consequences. And that risk is compounded by another factor: the land itself is sinking.

Much of New Orleans already sits at or below sea level, and parts of the city and its surrounding wetlands are gradually sinking. While most of the city remains stable, a new study by researchers from Tulane University suggests that sections of the region’s $15 billion post-Katrina flood protection system may require ongoing upgrades to keep pace with long-term subsidence.

The study, recently published in the journal Science Advances, used satellite data to track changes in ground elevation across Greater New Orleans between 2002-2020. The researchers found that some areas – including neighborhoods, wetlands, and even concrete floodwalls – are sinking by more than an inch each year. In some spots, the land is dropping by nearly two inches annually.

Alarmingly, some of the concrete floodwalls and levees built to protect the city after Hurricane Katrina are themselves sinking. In a few cases, they are losing elevation faster than sea levels are rising, reducing their capacity to block storm surges.

The study highlights how satellite monitoring can play a critical role in guiding infrastructure maintenance and urban planning – not just in New Orleans – but in vulnerable coastal cities around the world.

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Vertical land motion in Greater New Orleans: Insights into underlying drivers and impact to flood protection infrastructure

Photo, posted September 22, 2010, courtesy of U.S. Army Corps of Engineers via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Natural solutions for coastal defense

May 30, 2024 By EarthWise Leave a Comment

Protecting coastal cities and towns from the dangers of tsunamis, storm surges, and sea-level rise has become an ever-increasing challenge. There are so-called hard coastal defenses as well as nature-based solutions. A new study by the University of Tokyo has found that combining the two types of defenses may be the most effective way to protect, support, and enrich coastal communities.

Sea walls, dikes, dams, and breakwaters are the traditional hard measures. They are popular and have proven track records but are facing challenges to keep pace with increasing climate risks. They are expensive to build and require continuous upgrades and repairs. While they do provide protection from many disaster risks, they also can cause significant disruption to coastal ecosystems as well as to coastal communities.

Nature-based coastal defenses include such things as mangroves and coral reefs. So-called soft measures involve restoring, rehabilitating, reforesting, and nourishing natural ecosystems that protect coastal areas.

The Tokyo researchers analyzed the defense strategies in terms of risk reduction, climate change mitigation, and cost-effectiveness over a 20-year period. The results of the study were that among all coastal defense options in lower-risk areas, hybrid measures provide the highest risk reduction and can harness the advantages of both hard and soft measures.

The findings provide strong evidence for integrating nature-based components into coastal defenses, but these approaches have not yet been adequately tested in circumstances of extreme events and high-risk urgency. Research in this area has important implications for policy makers, coastal planners, and communities looking to make evidence-based decisions.

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A natural touch for coastal defense

Photo, posted October 22, 2021, courtesy of Kevin Dooley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Electric Cars And Apartments | Earth Wise

July 10, 2023 By EarthWise Leave a Comment

The transition to electric cars is underway. People are increasingly buying them, carmakers are switching over to making them, and governments are providing incentives as well as legislating the changeover. More and more consumers want to lower their carbon footprints and stop burning fossil fuels. But one very large group of consumers faces an uphill battle in switching to electric cars: people who rent their dwellings.

About one third of our country lives in rented apartments or houses. These nearly 110 million Americans are more likely to be in the bottom half of income and net worth and are more likely to be people of color. These people are less likely to have the spare cash to make upgrades to their property such as car chargers and may not be able to get permission from their landlords to do it anyway.

Renters face what is known as the “split-incentive problem” or the “landlord-tenant problem.” Three-quarters of tenants in the US pay their own utility bills, so they have a strong incentive to conserve electricity, water, and gas. Their landlords, on the other hand, have little incentive to upgrade appliances and systems to be more environmentally responsible. Studies have shown that on average renters use 3% more energy than homeowners for this reason.

There are some landlords who are being proactive and installing facilities for charging cars on their properties. This will undoubtedly become an increasingly sought-after feature for renters. But in the meantime, millions of them have a more difficult time driving electric cars. They can charge at public chargers or perhaps at work. But at the moment, homeowners are three times more likely than renters to own an electric car.

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The coming battle between Americans who want to go electric and their landlords

Photo, posted July 22, 2022, courtesy of Chris Yarzab via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

California Offshore Wind | Earth Wise

November 16, 2022 By EarthWise Leave a Comment

California has tremendous potential offshore wind resources. The state set a preliminary target of 15 GW of offshore wind by 2045 earlier this year and may increase that number to 25 GW. But installing offshore wind on the West Coast is much more challenging than it is on the East Coast. The reason is that the ocean floor drops off rapidly on the Pacific Coast and it is simply not practical to attach wind turbines to the sea bottom. Instead, floating turbine technology will be required. That is more complicated and more expensive.

Despite the challenges, offshore wind in California is moving forward. The federal Bureau of Ocean Energy Management announced that the auction for rights to develop waters off central and northern California will be held on December 6. This will be the first wind auction ever along the U.S. Pacific Coast.

The auction will include three lease areas in the Morro Bay Wind Energy Area and two proposed areas in the Humboldt Wind Energy Area. Combined, the two areas cover over 370,000 acres and could potentially host over 4.5 GW of wind generating capacity. The projects developed in these areas are likely to become the first floating offshore wind projects in operation in the U.S.

Apart from the challenges of building floating wind installations, there will be the issue of the electric grid in the proposed regions being able to support the added generation from the wind farms. Substantial grid upgrades will be needed to accommodate all the power coming from the offshore facilities. In addition, California offshore wind projects will need to jump-start new supply chains in the U.S.

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Date is set for California offshore wind lease auction

Photo, posted March 24, 2016, courtesy of Andy Dingley / TEIA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

More Dam Failures Likely | Earth Wise

June 24, 2020 By EarthWise Leave a Comment

Two dams in Central Michigan were breached by rain-swollen floodwaters in May and forced the evacuation of tens of thousands of residents and prompted officials to warn of life-threatening danger from a flooded chemical complex and a toxic waste cleanup site. Engineers say that most dams in the U.S. were designed many decades ago – in some cases, a century ago – and are not suited to a warming world with ever stronger storms.

The dams in Michigan gave way for the same reason behind most dam failures: they were overwhelmed by water, in this case by five inches of rain falling over two days after earlier storms had saturated the ground and swollen rivers.

It can’t be proven whether this specific set of events was triggered by climate change, but global warming is definitely causing some regions to become wetter and is increasing the frequency of extreme storms. And these trends are expected to continue as the world continues to warm.

All of this puts more of the 91,500 dams in the U.S. at greater risk of failing. The American Society of Civil Engineers, in its latest report card on infrastructure issued in 2017, gave the nation’s dams a “D” grade.

Historically, dams have been designed based on past weather history to predict the magnitude of the maximum potential flood that a dam would have to withstand. There was no expectation that future weather patterns might be very different. Infrastructure designers will clearly need to change their practices.

For existing dams, operational changes might be called for, such as reducing water levels in anticipation of more extreme storms. Upgrades might include changing spillway designs to accommodate larger water volumes over a longer time period.

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‘Expect More’: Climate Change Raises Risk of Dam Failures

Photo courtesy of Eye in the Sky/Youtube.

Earth Wise is a production of WAMC Northeast Public Radio.