What is the northernmost point on land in the world?

The answer is probably Kaffeklubben Island. It is to the north of Greenland.

In 1969 a Canadian team calculated that its northernmost tip lies 750 metres (2,460 ft) farther north than Cape Morris Jesup, thus claiming its record as the most northerly point on land.

Since then, several gravel banks have been found to the north, most notably Oodaaq and 83-42, although there is debate as to whether such gravel banks should be considered for the record since they are rarely permanent, being regularly swallowed by the moving ice sheets, shifting, or becoming submerged in the ocean.

https://en.wikipedia.org/wiki/Kaffeklubben_Island

This is further north, so it counts if you acknowledge "shifting, semi-permanent archipelago land" as being eligible.

Dennis Schmitt is credited with the July 2007 discovery of the northernmost island on Earth, named Stray Dog West by Holly Wenger. Stray Dog West belongs to a shifting, semi-permanent archipelago locked in the sea ice north of Peary Land in northeast Greenland, named the Stray Dog Islands. "Stray Dog West" is at 83º40'30"N

link https://en.wikipedia.org/wiki/Dennis_Schmitt
link http://jeffshea.org/greenland-stray-dog-west-expedition/

The northernmost point of the world is the geographic North Pole, in the Arctic Ocean.

The northernmost point on land is Kaffeklubben Island, east of Greenland, which lies slightly north of Cape Morris Jesup, Greenland Various shifting gravel bars lie further north, the most famous being Oodaaq. The term Ultima Thule was given by medieval cartographers for the northernmost point of land.

http://www.sheppardsoftware.com/worldgeographymainpage/worldstatistics2.htm