Climate change is making ocean waves more powerful, threatening to erode many coastlines


by Thomas Mortlock (Macquarie University), Itxaso Odériz (Universidad Nacional Autónoma de México (UNAM)), Nobuhito Mori (Kyoto University), and Rodolfo Silva (Universidad Nacional Autónoma de México (UNAM))

Sea level rise isn’t the only way climate change will devastate the coast. Our research, published today, found it is also making waves more powerful, particularly in the Southern Hemisphere.

We plotted the trajectory of these stronger waves and found the coasts of South Australia and Western Australia, Pacific and Caribbean Islands, East Indonesia and Japan, and South Africa are already experiencing more powerful waves because of global warming.

This will compound the effects of sea level rise, putting low-lying island nations in the Pacific — such as Tuvalu, Kiribati and the Marshall Islands — in further danger, and changing how we manage coasts worldwide.

But it’s not too late to stop the worst effects — that is, if we drastically and urgently cut greenhouse gas emissions.

An energetic ocean

Since the 1970s, the ocean has absorbed more than 90% of the heat gained by the planet. This has a range of impacts, including longer and more frequent marine heatwaves, coral bleaching, and providing an energy source for more powerful storms.

Since at least the 1980s, wave power has increased worldwide as more heat is pumped into the ocean. Shutterstock

But our focus was on how warming oceans boost wave power. We looked at wave conditions over the past 35 years, and found global wave power has increased since at least the 1980s, mostly concentrated in the Southern Hemisphere, as more energy is being pumped into the oceans in the form of heat.

And a more energetic ocean means larger wave heights and more erosive energy potential for coastlines in some parts of the world than before.

Ocean waves have shaped Earth’s coastlines for millions of years. So any small, sustained changes in waves can have long-term consequences for coastal ecosystems and the people who rely on them.

Mangroves and salt marshes, for example, are particularly vulnerable to increases in wave energy when combined with sea level rise.

To escape, mangroves and marshes naturally migrate to higher ground. But when these ecosystems back onto urban areas, they have nowhere to go and die out. This process is known as “coastal squeeze”.

These ecosystems often provide a natural buffer to wave attack for low-lying coastal areas. So without these fringing ecosystems, the coastal communities behind them will be exposed to more wave energy and, potentially, higher erosion.

Mangrove forests are among the most imperilled ecosystems as sea levels rise and ocean waves crash harder against the coast. Shutterstock

So why is this happening?

Ocean waves are generated by winds blowing along the ocean surface. And when the ocean absorbs heat, the sea surface warms, encouraging the warm air over the top of it to rise (this is called convection). This helps spin up atmospheric circulation and winds.

In other words, we come to a cascade of impacts: warmer sea surface temperatures bring about stronger winds, which alter global ocean wave conditions.

Our research shows, in some parts of the world’s oceans, wave power is increasing because of stronger wind energy and the shift of westerly winds towards the poles. This is most noticeable in the tropical regions of the Atlantic and Pacific Oceans, and the subtropical regions of the Indian Ocean.

But not all changes in wave conditions are driven by ocean warming from human-caused climate change. Some areas of the world’s oceans are still more influenced by natural climate variability — such as El Niño and La Niña — than long-term ocean warming.

In general, it appears changes to wave conditions towards the equator are more driven by ocean warming from human-caused climate change, whereas changes to waves towards the poles remain more impacted by natural climate variability.

Ocean waves are generated by winds blowing across the ocean surface. Shutterstock

How this could erode the coasts

While the response of coastlines to climate change is a complex interplay of many processes, waves remain the principal driver of change along many of the world’s open, sandy coastlines.

So how might coastlines respond to getting hit by more powerful waves? It generally depends on how much sand there is, and how, exactly, wave power increases.

For example, if there’s an increase in wave height, this may cause increased erosion. But if the waves become longer (a lengthening of the wave period), then this may have the opposite effect, by transporting sand from deeper water to help the coast keep pace with sea level rise.

Sandy beaches, including those around South Australia and Western Australia, may see greater risk of erosion in coming decades as wave power increases. Shutterstock

For low-lying nations in areas of warming sea surface temperatures around the equator, higher waves – combined with sea level rise – poses an existential problem.

People in these nations may experience both sea level rise and increasing wave power on their coastlines, eroding land further up the beach and damaging property. These areas should be regarded as coastal climate hotspots, where continued adaption or mitigation funding is needed.

It’s not too late

It’s not surprising for us to find the fingerprints of greenhouse warming in ocean waves and, consequentially, along our coastlines. Our study looked only at historical wave conditions and how these are already being impacted by climate change.

But if warming continues in line with current trends over the coming century, we can expect to see more significant changes in wave conditions along the world’s coasts than uncovered in our backward-looking research.

However, if we can mitigate greenhouse warming in line with the 2℃ Paris agreement, studies indicate we could still keep changes in wave patterns within the bounds of natural climate variability.

Still, one thing is abundantly clear: the impacts of climate change on waves is not a thing of the future, and is already occurring in large parts of the world’s oceans.

The extent to which these changes continue and the risk this poses to global coastlines will be closely linked to decarbonisation efforts over the coming decades.

Thomas Mortlock, Senior Risk Scientist, Risk Frontiers, Adjunct Fellow, Macquarie University; Itxaso Odériz, Research assistant, Universidad Nacional Autónoma de México (UNAM); Nobuhito Mori, Professor, Kyoto University, and Rodolfo Silva, Professor, Universidad Nacional Autónoma de México (UNAM)

This story is part of Oceans 21
The Conversation’s series on the global ocean opened with five in depth profiles. Look out for new articles on the state of oceans in the lead up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The drought in the western U.S. is getting bad. Climate change is making it worse

Read the full story from NPR.

By almost every measure, the drought in the Western U.S. is already one for the record books…That’s creating a fundamental threat to the way Western water systems operate, because they were built around the idea that the climate would remain constant. Historical climate data such as river flows and rainfall totals told engineers how big to build reservoirs and canals. The data also told them how much water was available to divide up among cities and farms.

Earth & Wheat ‘rescues’ 30 tonnes of surplus bread

Read the full story at Food Manufacture.

Baked goods redistribution company Earth & Wheat has ‘rescued’ 30 tonnes of surplus bread since it launched 12 weeks ago through its online delivery platform.

Shipping is tough on the climate and hard to clean up – these innovations can help cut emissions

Shipping is responsible for a large portion of global emissions. William William/Unsplash, CC BY

by Jing Sun (University of Michigan)

Ships carry more than 80% of world trade, and they rely heavily on some of the least environmentally friendly transportation fuels available.

There are no cheap, widely available solutions that can lower the shipping industry’s planet-warming carbon emissions – in fact, shipping is considered one of the hardest industries on the planet to decarbonize – but some exciting innovations are being tested right now.

As a professor of naval architecture and marine engineering, I work on ship propulsion and control systems, including electrification, batteries and fuel cells. Let’s take a look at what’s possible and some of the fuels and technologies that are likely to define the industry’s future.

Shipping’s climate problem

Shipping is the cheapest way to move raw materials and bulk goods. That has given it both an enormous economic impact and a large carbon footprint.

The industry emits roughly 1 billion metric tons of carbon dioxide per year – nearly 3% of global emissions, according to the International Maritime Organization, a specialized U.N. agency made up of 174 member nations that sets standards for the industry. If shipping were a country, it would rank between Japan and Germany as the sixth-largest contributor to global carbon dioxide emissions. Moreover, nearly 70% of ships’ emissions occur within 250 miles (400 kilometers) of land, meaning it also has an impact on air quality, especially for port cities (view the chart).

Technological innovation, in addition to policies, will be crucial for achieving low-carbon or zero-emission shipping. Academic research institutes, government labs and companies are now experimenting with electrification; zero- or low-carbon fuels such as hydrogen, natural gas, ammonia and biofuels; and alternative power sources such as fuel cells and solar, wind and wave power. Each has its pros and cons.

Why electrifying ships matters

Just as on land, electrification is one key to cleaning up the industry’s emissions. It allows engines operating on fossil fuels to be either replaced by alternative power generation technologies, or downsized and modified for low-emissions operation. It also allows ships to connect to electric power while in port, reducing their emissions from idling.

Ship electrification and hybridization are significant trends for both commercial and military vessels. Electrifying a ship means replacing its traditional mechanical systems with electrical ones. Some fleets have already electrified propulsion and cargo handling. Hybrid power systems, on the other hand, integrate different power-generation mechanisms, such as engines and batteries, to leverage their complementary characteristics.

I see deeper electrification and broader hybridization as a core strategy for achieving green shipping.

Cranes load shipping containers onto a ship docked in port.
Ships that can connect to electric power in port can cavoid burning fuel that produces greenhouse gases and pollution. Ernesto Velázquez/Unsplash, CC BY

Tremendous opportunities also exist for improving the operation of the existing fleet – and reducing fuel use – through automation and real-time control. Advanced sensors, artificial intelligence and machine learning can help ships to “see,” “think,” and “act” better to improve efficiency and reduce emissions.

Greener fuels for ocean voyages

Shifting to cleaner and greener fuel sources will be essential for decarbonizing the shipping industry.

Most of the power plants on today’s ships are based on internal combustion engines that use cheap heavy fuel oil. Innovations in marine diesel and gas turbine engine design and treatment of exhaust gas have lowered harmful emissions. However, most of the “low-hanging fruit” has been harvested, with little room left for dramatic improvement in traditional power sources.

The focus now is on developing cleaner fuel sources and more efficient alternative power generation technologies.

2021 U.S. EPA data in kilograms of carbon dioxide per gallon of fuel
Chart: The Conversation/CC-BY-ND Source: EPA Get the data

Low or zero-carbon fuels, such as natural gas, ammonia and hydrogen, are predicted to be the dominant energy sources for shipping in the future. Ammonia is easy to transport and store, and it can be used in internal combustion engines and high-temperature fuel cells. But like hydrogen, it is largely still made with fossil fuels. It’s also toxic. Both have the potential to be made with water and renewable energy using electrolysis, but that zero-carbon technology is still in the early stages and costly.

These fuels have started replacing heavy diesel fuels in some marine segments, primarily as demonstration projects and at a slower rate than needed. Cost and infrastructure remain major barriers.

Renewable energy sources, such as wind, solar and wave energy, are also promising. Integrating renewable sources as cost-effective and reliable energy solutions for oceangoing vessels is another challenge developers are working on.

Powering ships using fuel cells and batteries

Fuel cells and batteries also hold promise as alternative power generation technologies.

Through electrochemical reactions, fuel cells generate electric power in a highly efficient and clean manner, making them very attractive for transportation. Fuel cells are operated with pure hydrogen or reformed gases, except for high-temperature fuel cells that can use natural gas or ammonia as fuel.

Given the existing fuel infrastructure, most maritime fuel cell demonstration projects today have to store liquid hydrogen or use onboard systems that convert natural gas or other fuel to hydrogen-rich syngas. Infrastructure for hydrogen storage has to be developed for widespread adoption of fuel cell technology.

Battery technology is essential for electrification, even for ships with an internal combustion engine as their prime mover. It also has its own unique challenges. In addition to ensuring the batteries are safe and reliable – you don’t want a fire or power outage in the middle of the ocean – ruggedness and flexibility are necessary for powering operations such as cargo handling and tugboat operations.

Investing in the future

In 2018, the International Maritime Organization’s Marine Environment Protection Committee set targets to reduce the carbon intensity of the global fleet by at least 40% by 2030 and to cut its greenhouse gas emissions in half by 2050 from the 2008 levels.

Those targets are important, but they leave the deadlines for action well into the future. At its June 2021 meeting, the IMO agreed to some small short-term targets, including lowering ships’ carbon-intensity by 2% a year from 2023 to 2026. It also agreed to ban the use of heavy fuel oil in the Arctic starting in 2024, but with waivers allowing some ships to continue using it there until 2029.

Countries and some shipping companies are recommending a faster transition. In early June, the governments of Denmark, Norway and the United States, along with the Global Maritime Forum and the Mærsk Mc-Kinney Møller Center for Zero Carbon Shipping, announced a new Zero-Emission Shipping Mission to try to scale up and deploy new green maritime solutions faster.

The shipping giant AP Møller-Maersk has said it could support a carbon tax of $150 per ton of carbon dioxide to encourage more innovation and a faster transition, though others in the industry argue that a tax like that would nearly double the cost of bunker fuel and make freight far more expensive, with repercussions throughout the global economy.

I believe the grand vision of zero-emission shipping can be realized if the ship design and fleet operation communities work together with policymakers, the logistics industry and the broad academic and industry technical communities to find solutions.

This is an exciting time to work in the area of energy and power solutions for shipping. The technology developed today will have a transformative impact, not only on the marine industry but also on society.

This story was updated June 17, 2021, with the IMO meeting results

Jing Sun, Professor and Department Chair, Naval Architecture and Marine Engineering, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.

At these low-income apartment buildings, solar power helps pay for free Wi-Fi

Read the full story at Fast Company.

After installing panels on the roof, the electricity savings from common areas in the buildings will be passed on to residents in the form of free internet access.

Robeco publishes framework guiding investor sustainability engagements with governments

Read the full story in ESG Today.

International asset manager Robeco announced today the release of a new Sovereign SDG Engagement Framework for investors, aiming to guide them in engagements with governments on tackling sustainability challenges.

According to Robeco, the framework was developed in order to address a lack of clear, methods to navigate the complex, emerging area of sovereign engagement, and the impact that sustainability issues can have an impact on the value of sovereign bonds.

The framework, originally published earlier this month in the Journal of Sustainable Finance and Investment, addresses three key considerations for investors to engage with governments. The main steps include prioritizing countries based on their relevance in the investment universe and portfolios and the country’s progress on the SDGs, and determining where investors can make a difference, selecting SDGs facing slow progress in the individual countries, and setting a detailed roadmap for conducting the engagement, encompassing goal setting, finding partnerships in the process, reporting and monitoring progress.

Dallas adopts its first urban forest master plan

Read the full story at Smart Cities Dive.

The Dallas City Council this week unanimously adopted the city’s first urban forest master plan, with 14 recommendations for a unified approach to build a resilient and equitable urban forest. They include ensuring city regulations support tree canopy preservation and growth, maximizing investment in urban forest programs and management, and creating a city storm response and recovery plan. Improved air quality and reduced temperatures are among the most sought-after benefits.

The plan, which the nonprofit Texas Trees Foundation created, notes that Dallas is already the nation’s ninth-most-populous city and is poised for further development. That development threatens to remove tree cover from Dallas’ southern neighborhoods, which could create new heat island effects that affect a significant number of economically and medically vulnerable residents, the authors wrote.

A key impetus for this plan was an earlier heat island management study by the foundation that found Dallas is heating up faster than every other U.S. city except for Phoenix, said Rachel McGregor, urban forestry manager at Texas Trees Foundation. The report cites data indicating that by 2050, Dallas could have 30 to 60 additional days over 100 degrees F per year.

The green energy revolution is coming — with or without help from Washington

Read the full story at CNN.

The American clean energy industry is primed for a boom. The only question is whether Washington can help juice the transition.

In both red and blue states, the revolution has already begun. But even as private industry invests in the future, the speed and scale of its efforts is in the hands of Congress, where Republicans and centrist Democrats are locked in negotiations with the Biden administration over President Joe Biden’s ambitious infrastructure plan.

Michigan’s climate-ready future: wetland parks, less cement, roomy shores

Read the full story at Bridge Michigan.

As climate change alters our world, Michigan’s bounty of fresh water — if managed smartly — could be the foundation of a thriving state economy and superior quality of life. This could be the Detroit of our future, part of a state that’s prepared for inevitable change.

Ancient gardens persist in British Columbia’s forests

Read the full story at Hakai Magazine.

Indigenous-managed landscapes retain higher biodiversity than surrounding areas a century after the people who kept them were displaced.