5 Co-Benefits of Decarbonizing Maritime Shipping


In the wake of the recent IPCC report, climate change is at the center of many conversations on Earth Day this year. Currently emitting close to 1 billion tonnes of greenhouse gasses a year, the maritime shipping sector has historically been and continues to be a major contributor to climate change.

The climate impact of the maritime shipping sector is the primary focus of the Aspen Institute Shipping Decarbonization Initiative, which is why we’re working with cargo owner companies through our Cargo Owners for Zero Emission Vessels (coZEV) initiative to accelerate the pace of shipping decarbonization. While decarbonizing shipping has obvious climate benefits, there are several broader benefits to ocean and coastal ecosystems and economies. In honor of Earth Day, here are five co-benefits that should be considered and incorporated into plans to decarbonize the shipping sector.

1. Reducing air pollution in port communities

In addition to the climate pollutants that ships emit both during voyages and at port, another serious shipping “emission” concern has to do with the suite of air pollutants that results from burning fossil fuels. Harmful particulate pollutants like nitrous oxide and black carbon create smog and cause wide-spread health effects in port cities. While ships aren’t the only source of air pollutants at ports – fossil-powered trucks, trains, and cargo handling equipment are also to blame – there are significant localized air pollution and environmental justice benefits to decarbonizing shipping. Future zero emission fuels need to be winners from a climate perspective and an air pollution perspective.

While zero emission ships are being retrofitted and built, one of the most immediate ways to lower air pollution at ports is through shore power, where ships turn off their engines and plug into the grid while at berth. Partnerships between ports and the private sector – like the recent partnership agreement between Aspen Ideas: Climate host Miami Beach, Florida, Florida Water and Power, and six major cruise lines – are crucial to getting shore power funded and widely available at ports around the world.

2. Addressing increasing ocean noise

Large ocean-going ships are as loud as jets upon takeoff, emitting as much as 190 decibels of noise once underway. When you multiply this by the 100,000 vessels that comprise today’s global commercial fleet, it’s not hard to see how commercial shipping has become the predominant source of human noise pollution in the ocean. This cumulative noise has, in many areas, degraded the natural ocean habitats that whales and other long-lived marine mammals have evolved in beyond recognition.

The trends in vessel noise pollution are discouraging. Ocean noise has been doubling each decade since 1950, spurred by the continued expansion of the global shipping fleet. While it is not likely we will ever be able to zero out underwater noise from ships completely, it can be drastically reduced through innovative propeller designs and technologies – the predominant source of underwater noise. Designing and building ships that are both quiet and carbon-free will help in addressing the twin crises of climate change and biodiversity loss.

3. Increasing economic benefits and creating jobs

The decarbonization of the maritime shipping sector doesn’t only result in environmental benefits; there are significant economic benefits associated with reducing maritime emissions and decarbonizing major maritime port operations. A 2021 study by University of California Berkeley’s Center for Environmental Public Policy, commissioned by coZEV partner Ocean Conservancy, found that in the U.S. alone, investing in maritime decarbonization could result in almost 100,000 jobs created over the next 10 years in construction, solar power generation, ship building/repair, industrial truck manufacturing, and maintenance and repairs. Globally we would expect similar levels of job growth as supply chains decarbonize and a new market for scalable zero emission fuels is built, including in less developed countries with abundant renewable energy resources (see the next section). As humans are essential players in the Earth’s ecosystems, it’s essential to consider direct and indirect economic benefits and the impact on jobs and quality of life as shipping transitions to zero emissions.

4. Facilitating renewable energy growth

In order for shipping to decarbonize, the future fuels under consideration must be zero emissions on a lifecycle basis, meaning there must be no emissions resulting from the energy produced to make the fuel, through the supply chain, to when the fuel is used to power the ship. Achieving zero emissions from a “well to wake” perspective relies on the use of renewable energy to produce these fuels, transforming the “well” to a “turbine” or “solar panel”. As the shipping sector works to green its fuels, renewable energy will naturally play an increasingly important role. Ocean carriers are already signing green fuel agreements with major renewable energy companies like the recent offtake agreement between Maersk and Ørsted. In the drive to decarbonize shipping and create these green fuel supply chains, these agreements are likely to become more common, and demonstrate that shipping decarbonization can be a major driver for increased renewable energy development and investment around the globe.

5. Ensuring a “just” transition to zero emissions

In their September 2021 brief “Charting a 1.5°C Trajectory for Maritime Transport”, the UN Global Compact – a corporate sustainability and social responsibility-focused United Nations initiative – championed the concept of a “just” transition toward zero emission shipping, meaning that as shipping moves to zero emissions, sustainability goals must go hand-in-hand with equitable socio-economic development and growth goals. One of the primary equity concerns crucial to shipping decarbonization is seafarer safety related to future zero emission fuels.

To decarbonize deep sea shipping, e-ammonia, a hydrogen-derived fuel resulting from water electrolysis powered by renewable energy, has been identified by many experts as a prime candidate. Although one of the most widely traded commodities globally, ammonia’s toxicity and corrosiveness require stringent guidelines to protect port worker and seafarer health and well being before it can be approved for use as a maritime fuel. Classification society DNV and partners in Singapore – the world’s largest ship refueling hub – are currently developing a robust set of safety guidelines related to ammonia bunkering with safety of seafarers at the forefront.

Now more than ever, society’s solutions to the climate crisis must be multifaceted; we don’t have time to first fix the climate and then consider issues of human health or socio-economic issues. These five co-benefits of decarbonizing the shipping sector demonstrate the intrinsic interconnections present in any work on climate change, and underline the fact that we are all on this journey to create a liveable Earth together.

Contributors: Regan Nelson – NRDC, Greg Gershuny, Maria Ortiz Perez, Ingrid Irigoyen

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