International shipping, which moves more than four-fifths of world trade, is under growing pressure to clean up its climate footprint. Studies estimate the sector produces around 3% of global greenhouse gas emissions, putting it on par with a mid-sized industrial economy.
In , the International Maritime Organization (IMO) has adopted a revised greenhouse gas strategy that calls for net-zero emissions from international shipping by or around 2050, with ambitious checkpoints in 2030 and 2040. For tanker fleets trading to and from ports in Pakistan and the wider region, these policies are no longer distant discussions in conference rooms – they are beginning to influence everyday engineering decisions on board.
Among the engineers dealing with these changes at sea is Marine Chief Engineer Zafar Ali, a Pakistani maritime specialist with more than 15 years’ experience on crude oil, product and chemical tankers, currently sailing with a major international ship management company. From drydock projects in Dubai, China and Bahrain to routine voyages, he has seen how environmental rules now sit alongside safety and cost in every major technical choice.
“A few years ago climate felt like a policy topic far away from the engine room,” Zafar says. “Now every big job on a ship comes with three questions: is it safe, is it economical and what does it do to our emissions?”
The regulatory push covers everything from fuel quality to how ships are maintained. The IMO’s
response 2023 strategy is being translated into detailed measures such as stricter carbon-intensity targets, mandatory energy-efficiency plans and the building blocks of a global carbon-pricing regime for shipping. Older tankers that burn more fuel per tonne-mile face increasing pressure to upgrade or risk higher compliance costs.
In Zafar’s experience, the most visible changes on tankers involve the systems that sit around the main engine. Ballast Water Management rules require ships to install and run approved ballast water treatment systems (BWTS) to stop harmful species moving between ports, while exhaust gas cleaning systems (EGCS) help ships meet sulphur limits and cut local air pollution. But he says the real impact comes from how reliably these systems operate.
On one tanker undergoing scheduled repairs in drydock, his team conducted a full overhaul of the existing ballast water system, replacing the original reagent-type TRO (Total Residual Oxidant) sensors with more reliable direct halogen TRO sensors. This upgrade, along with a simplified control layout, improved the system's integration with the ship's automation system, reducing alarms and downtime during port calls. The clearer procedures and better integration enabled the crew to operate the system more efficiently, achieving stable disinfection performance and predictable compliance. Another project focused on fine-tuning of electronic engine settings and tightening up fuel-performance monitoring, leading to noticeable fuel savings over the following trading year.
For Pakistan, these technical details link directly to national climate ambitions. Research suggests that ships serving Pakistani trade routes emit a substantial volume of greenhouse gases each year, contributing to the country’s broader transport-sector emissions. As Pakistan pursues cleaner transport and coastal environments, vessels calling at Karachi, Port Qasim and Gwadar are expected to demonstrate both environmental compliance and operational reliability.
Zafar’s day-to-day role reflects that mix of priorities. He plans drydock work so that conventional maintenance – hull cleaning, machinery overhaul, safety upgrades – is paired with targeted energy-efficiency measures, such as optimising propeller and hull condition, improving boiler settings or adjusting auxiliary power management. He also emphasises data: simple trend charts of fuel consumption and exhaust emissions, he says, often reveal issues before they become expensive problems.
“You can’t treat decarbonisation as a one-off retrofit and tick it off the list,” Zafar says. “The ships, the crew and the shore office all have to treat energy performance as something they manage every day, just like safety.”
Looking ahead, global shipyards are building more dual-fuel vessels capable of running on alternatives such as LNG and methanol, while proposals for a global carbon levy on shipping create additional incentives for low-emission operations. But Zafar believes that, for now, the biggest gains still lie in disciplined engineering and operations onboard today’s tankers.
“New fuels and new designs will arrive in time,” he says. “If we look after the basics – good maintenance, careful energy management and well-trained crews – then when the cleaner technology comes, our ships will be ready to use it responsibly.”