Reducing carbon footprint of coastal engineering

A new white paper from Wetlands International, released on June 21, 2022, reveals the critical need to restore wetlands – with urgency and at scale. 

The report, developed in cooperation with Witteveen+Bos and Deltares, outlines a simplified methodology for quantifying the ecosystem-based carbon footprint of coastal engineering projects.

Greenhouse gas emissions from coastal engineering do not only involve emissions from dredging vessels, but also from impacting sediments and coastal ecosystems.

Also, the organizations presented potential options to reduce the carbon footprint – including the Nature-based Solutions.

Wetlands cover just 6% of the Earth’s surface but are home to a staggering 40% of the world’s plant and animal species.

In fact, every year 200 new species are discovered in freshwater wetlands and these precious habitats store almost a third of global soil carbon.

Nevertheless, wetlands are disappearing three times faster than forests, with 35% of wetland ecosystems lost since 1970. 

Coastal engineering projects like land reclamation, port development and coastal protection involve activities that interfere with the carbon cycle of sediments and coastal ecosystems, which can result in significant emissions, both on or off-site.

This includes dredging and displacement of sediment, or activities that change the hydrological or sedimentation dynamics.

Under some circumstances such disturbance causes previously sequestered carbon to be emitted as greenhouse gases.

The new methodology presented in the report simplifies the complexity of organic carbon cycling in coastal systems.

It distils the most relevant information that needs to be assessed in the form of a ‘sediment passport’, based on which one can zoom in on those engineering activities that influence key carbon stocks and processes.

This in turn helps to identify potential ways to reduce emissions or sequester carbon.

To succeed in staying below 1.5 degree temperature rise as set out in the Paris Agreement, drastic reduction of emissions as well as removals of emissions are needed in all sectors.

Ambitious targets have been adopted by governments and companies, including from the maritime and dredging sector, some of which have adopted voluntary net zero targets by 2030.

Current efforts to reduce the carbon footprint from coastal engineering focus mostly on the emissions related to the deployment of construction vessels and the use of materials such as concrete and steel.

However, the impact of these projects on the carbon balance of coastal wetlands may be far greater.

Although the emissions arising from the burning of fossil fuels can be very thoroughly quantified, emissions from ecosystem and sediment disturbance have not, until now, been sufficiently accounted for.

This study is a first step to address this discrepancy.