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A new internal report from the International Maritime Organization has cast further doubt over the environmental safety of using exhaust gas cleaning systems — more commonly referred to as “scrubbers” — to reduce air pollution on cruise ships.

The International Maritime Organization, a United Nations body that regulates the cruise and shipping industries, convenes its pollution subcommittee in London this week to, among other items, discuss the further implementation of global anti-pollution regulation known as IMO 2020. As first covered by the UK’s Guardian on Monday, the report suggests that the agency itself — which already green-lit scrubbers as a legitimate form of compliance for the rule — might have reason to doubt the environmental safety of the technology.

As Skift reported in October, much of the cruise industry opted to meet this year’s new lower pollution standard with the use of scrubbers instead of switching to cleaner-burning, more expensive fuel. These systems “scrub” the smokestack with sea or fresh water to remove sulfur, but in the process create a discharge — some of which is deposited into the sea. Critics have pointed out that scrubbers merely swap air pollution for water pollution, a charge which the industry has denied.

The aforementioned report was completed at the request of the IMO by the UN’s Group of Experts on the Scientific Aspects of Marine Environmental Protection, an independent advisory body. In examining the potential environmental and public health effects of scrubber systems — specifically their waste products, known as effluent — it cites several places where data in the existing literature was missing or inadequate, thereby making it impossible to formulate a reliable risk assessment in key areas. It called for “an increased and broad focus on this topic from both the science community and from policymakers,” to provide a framework “allowing a more accurate estimation and prediction of current and future” effects of the chemicals contained in scrubber effluent.

Skift was able to obtain a copy of the report before publication of this story. The IMO told Skift the report was part of an ongoing attempt to review scrubber guidelines “in the light of experience gained with their application.” It did not directly answer a question about why it has already approved the use of scrubbers if the science around their environmental effects is still clearly ongoing.

Critics say this discrepancy is grounds to stop using them. “A key shortcoming of nearly all scrubber wash-water analyses/reports is that they focus only on concentrations of various pollutants in the water, instead of investigating possible actual negative impacts on marine life,” said Lucy Gilliam, senior shipping and aviation campaigner at Brussels-based NGO Transportation and Environment. She is calling for moratorium on the use of open-loop scrubbers — which emit the most wastewater into the ocean — on precautionary grounds.

A separate paper submitted to this week’s proceedings by a consortium of environmental non-profits similarly pointed out that the discharge from these systems “pose[s] an immediate, ongoing, and growing threat to aquatic ecosystems, wildlife, and humans.”

“This week’s negotiations on the use of scrubbers is timely and urgent, as increasing numbers of ships are installing these systems so they can circumvent the IMO’s 2020 fuel sulfur standards while continuing to burn heavy fuel oil,” Kendra Ulrich, senior shipping campaigner at non-profit Stand.earth, said in a statement. “The cumulative impacts on the marine environment of increasing volumes of scrubber waste being discharged into our seas was not adequately considered prior to allowing their use.”

The cruise industry has conducted its own research on the matter, too. A study sponsored by CLIA and completed last year found that the systems have a limited impact on water quality. A CLIA spokesperson told Skift that this study and two others released in 2019 serve as “important validators that these systems, whether operated in open or closed-loop modes, are safe for the environment, in compliance with the new restrictions set forth in IMO 2020 and in keeping with the industry’s commitment to responsible tourism practices.”

Due to a lack of consensus over their safety, several ports including those in California and Singapore have banned the most common variant, open loop scrubbers, from being used in their waters.

The IMO’s meeting this week will also discuss several matters related to the Arctic, which is becoming an ever-more popular destination for luxury cruises. Among other things, environmental advocates are calling for a complete ban on the carriage of heavy fuel oil in the Arctic — meaning scrubbers would be rendered useless, as vessels would no choice but to burn cleaner fuel in the region — to mitigate the risk of oil spills in the sensitive region.

On Monday, environmental protestors from groups including Extinction Rebellion staged a mock Arctic crime scene to bring attention to the issues at hand.

Photo Credit: The IMO headquarters in London. IMO / Flickr