Here are some of my thoughts on Frozen 2. I feel Frozen 2 is an allegory about aboriginal land right disputes, environmentalism and democracy. The story feels fairy tale for the children who do not understand science and politics.

The dam which King Runeard built is said to have anger the four spirits dam. I believe the four elemental spirits are a metaphor of the nature.

The building of the dam caused changes to the local microclimate. It is likely that the Enchanted Forest is quite up north, so it is quite cold. There is a lot of geothermal activities in the region. The geothermal activities heat up the lake and cause evaporation. The cold air cause the water vapour to condense, resulting a thick fog. Before the dam was built and the lake was formed, the lack of a large body of water probably meant that there was not much fog.

The fog prevented people from entering or leaving the Enchanted Forest. I believe it is a metaphor for the importance of having good outdoor navigation skills. It has been shown that people walk around in a circle when they cannot see the Sun¹⁾. Queen Elsa probably has superior navigational skills, that's probably why she managed to penetrate the fog. She was probably trained in navigation, as being the leader of a country probably require good geography skills, and she probably has to lead her army.

The rock giants are probably a metaphor of the dam-induced seismicities ²⁾.