Google the Northwest passage. And how it will be ice-free in a few years.
It is a massive short cut for China to transport its shit to western markets. A short cut means lower fuel costs, and enhanced ability to undercut western manufacturers.
Greenland, Canada and Panama are all about this. The NWP goes up the west coast of Greenland and across the top of Canada. Both Greenland and Canada will soon become very rich due to fees for shipping passing through, and fees for rescues and ice-breaking.
I don't see how Greenland could charge fees as the ships wouldn't pass through Greenland. Sailing the ocean next to Greenland doesn't give them a right to fees. It's quite different with Canada of course.