It's still widely open to misinterpretation. Does it refer to the carbon emissions while they pass through the canal, or is it the total carbon emissions of all ships that have passed through the canal? Is the statistic just showing that lots of ships go through the canal in a year?
Specifically, the unqualified judgement you made was "nasty" in reference to "bunker fuel".
Well to be fair, regardless of its suitability as a long term viable fuel source, it is nasty stuff. It's basically tar. It has to be kept heated to about 70c less it become to viscous and can't be pumped anymore and heated even more before being used in the engine.