Sinking feeling: cruise ships chart return to Australia amid emissions concerns

It would be a significant engineering milestone for an industry that contributes an unknown but not trivial amount to the 940m tonnes of CO2 generated by marine transport each year, or roughly 2.5% of global emissions.

The chief executive of Northern Xplorer, Rolf Sandvik, says the vessel will be entirely sustainable and emissions-free on the day it leaves the dock.

The Norwegian government has limited the number of calls that can be made to world heritage-protected fjords and imposed zero-emissions requirements on vessels that do so from 2026.

The scale of this return has raised questions about sustainability and whether an opportunity has been missed to transition to a zero-carbon industry.

During the downtime, authorities in some places have worked to resolve pressing environmental problems.

In March, the Port Authority of NSW announced it would install a $60m ship-to-shore power system at the White Bay terminal in Sydney Harbour, after a 10-year campaign by residents against the fumes created by idling ships.

Hooking cruise ships up to a power source on land while they are docked means they do not have to run auxiliary engines to keep their electrical systems running.