A new study from the non-profit research organization International Council on Clean Transportation (ICCT) has found that the Cayman Islands experienced the most scrubber discharges in port waters globally- 41.8 Metric tonnes- all of it by cruise ships, accounting for 14.1 per cent of the total amount discharged across all cruise ports pre-COVID-19.Scrubbers are exhaust gas cleaning systems used on ships. They are a sulfur cleaning technology intended to reduce air pollution from ships but, have been found to transfer pollution from the air to the sea. Scrubber washwater is hot and acidic and is discharged in areas with coral reef systems that are already impacted by ocean warming and ocean acidification.
The dangers of discharging scrubber wash water into the sea include the poisoning of marine life. It can also lead to increased toxic levels, decreased pH levels, and acid rain.
The ICCT study attempted to quantify for the first time just how much scrubber wash water was being dumped into the ocean, and found that cruise ships were the main culprits (96 per cent) for discharges in port waters.
ICCT estimated the mass and location of scrubber washwater discharges based on pre-pandemic traffic patterns for ships that had scrubbers installed by the end of 2020.
Ports in the Caribbean occupied 4 of the top 10 spots for cruise ship-related pollution.
Freeport (5.5 Mt, 74% from cruise ships) and Nassau in The Bahamas (4.8 Mt, 99% from cruise ships) ranked third and fifth for most scrubber wash water discharges, followed by St. George’s, Grenada (4.5 Mt, 100% from cruise ships), in sixth place.
“Our research shows that ships are dumping large amounts of contaminated, acidic scrubber washwater close to human settlements, near shore, and in ports. Moreover, 665 million tonnes of washwater will be released in Particularly Sensitive Sea Areas that are home to endangered marine species and fragile coral reefs. Governments should consider banning scrubber discharges in their waters and require ships to use cleaner fuels instead,” SAID Liudmila Osipova, PhD, Marine Researcher at ICCT.
In response to the International Maritime Organization’s 2020 0.50 per cent fuel sulfur rule, requiring ships to burn more expensive, lower sulfur fuels or to use cheaper high sulfur fuels and a scrubber, the number of ships using scrubbers has surged.
Scrubber washwater is more acidic than sea water and contains polycyclic aromatic hydrocarbons (PAHs), nitrates, sulfates, and heavy metals, all of which can harm wildlife and worsen water quality.
ICCT concluded that without additional regulations, approximately 3,600 ships with scrubbers will emit at least 10 billion tonnes of washwater each year for the next several years.
“This study gives much needed insight into where and how much ships are dumping polluted scrubber washwater. It is imperative for governments to know how much of this pollution is entering their waters so they can take actions to protect marine life and water quality, which could include banning scrubbers in their ports and in their national waters,” said Elise Georgeff, Associate Marine Researcher, ICCT.