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By Sourasis Bose

(Reuters) - The shipping industry's pledge to limit its carbon footprint may suffer a setback as the current Red Sea crisis prompts it to use more vessels and take longer routes to ensure the smooth sailing of global maritime trade.

Iranian-backed Houthi militants' attacks on vessels passing through the southern Red Sea have choked trade through the Suez Canal, driving many container shipping companies to add 10-14 days to the voyages between Asia and Europe and add more vessels.

The disruption has raised doubts about the sector's ability to stay on track to meet the International Maritime Organization's mandate for a 20% reduction by 2030. The shipping industry accounts for nearly 3% of global carbon dioxide emissions.

"The extended travel times necessitate adding at least two more ships to maintain weekly Asia-Europe services per operator, further increasing the total emissions from the fleet for the same amount of cargo," said Yiannis Parganas, head of shipbroker Intermodal's research department.

The re-routing, which is leading to higher fuel consumption, is projected to result in a 42% rise in emissions per ship for a standard Asia-North Europe weekly liner service, Parganas said.

Emissions from container ships hit 231 million tons in 2023, touching pre-pandemic levels.

Niels Rasmussen, chief shipping analyst at ship-owner association BIMCO, said the longer route has necessitated an 8-10% increase in container ship usage, compared with a year earlier, leading to an equivalent rise in emissions.

Container ship emissions could rise by as much as 11% to 257 million tons in 2024 if disruptions including in the Red Sea and Panama Canal continue, according to consultancy firm AlixPartners.

The Red Sea crisis has also put plans of some operators to replace aging fleets with newer more fuel-efficient ships on the backburner.

"The numbers (freight rates) are very healthy and those who intend to scrap their ship have deferred their decision," said Symeon Pariaros, chief administrative officer of ship-owner Euroseas.

(Reporting by Sourasis Bose in Bengaluru; editing by Arpan Varghese and Anil D'Silva)