The Weakening of the Sea Goblin Oceanic Current

This event in my world is an allegory to what is currently happening with the currents that go through Europe's Eastern coast (especially England) due to climate change
During the last centuries of the 1st millennia BBE, the dwarves of the Kingdom of Hakyama boosted a lot their production of weapons and armor due to the Republic Federation of Rockvar, located to the south, requiring a good amount of these items (the human realm invested intensively in the dwarven's industry). 
Since the dwarves would build their hot forges inside the mountains near the icecaps, the sudden increase of heat inside these places caused the melt of the ice, which in turn lowered the salt concentration on the northern part of the ocean, weakening then the so-called Sea Goblin Oceanic Current. 
That current brought heat waters from the tropics and, due to its weakening, the temperature in the local terrestrial region known as Ögro Boros has dropped a lot. This was one of the reasons on why the eastern Snow Green Goblins decided to wage War against the dwarvish realm.

Manifestation

It manifests itself due to the warming of the northern part of the sea. With that

Localization

This event has occured in The Lost Sea. It is situated alongside all of North-Adwana, encompassing the western coast of the realms of Hakyama and Rockvar as well as the eastern coast of the Free Kingdom of Alistar.

Type

Natural