I would highly encourage you to read [1] to get a better sense of the potential available in the North. The arctic is estimated to have over 22% of the world's oil and gas reserve [2]. Around 10-12% of the world's population is dependent on fisheries and aquacultures for their livelihood [3], so naturally, as fisheries become depleted in other parts of the world [4], the value of Northern fish stock (especially wild caught) is likely to rise. Minerals are already extracted all around the northern territories, an increase in temperature is likely to make some regions/zones economically viable, just take a look at Europe and China's race towards Greenland's potential rare-metal stock [5]. As a trade route, it can be considered one of the safest and fastest route to connect the East of North America and Europe to Asian markets. Just to give you a sense of how much money circulates in Trade Routes, the Suez Canal in Egypt hit a record revenue of $5.5billion in 17-18 [6]. Even if the northern region only becomes viable for half of the year, it may still be worthwhile, just look at other industries (think Tourism) that are on the same boat.
Countries have gone to war for territory and resources for millennia, if Canada doesn't position itself well to protect it, someone else may come and try to take it away from you. This can happen via fisherman/oilers invading your territory, among many other ways. Always remember, if you are not willing to take the risks and investment is potentials, someone else is and when they strike gold, you may only be able to watch it.
There's no infrastructure in the Arctic North, which means anyone seeking to exploit mineral bounties has to be willing to pay exorbitant amounts of money to build the infrastructure to export it.
The Yukon and Northwest Territories, with relatively easy access to the passable infrastructure of the Alaska Highway. Yet the cost of mining operations in these areas has caused most of the operations to close down. Similarly, a lot of the Siberian mining operations shut down when the Soviet Union's collapse meant that it could no longer afford the subsidies needed to keep the remote outposts running.
I don't expect the mineral wealth to be economically exploitable anytime soon (this century), and the sovereignty of Canada over its Arctic archipelago and Denmark over Greenland are quite secure, unlike the potential for bounties in marine domains, where the international boundaries and rights are far less clear.
As a counterpoint, we can agree that the sea has lots of resources as well and that does not mean that we are all going to live in an oil platform because that is simply not ideal. There are well paying jobs to be had in those regions, but I do believe the parent post has a point on limiting stuff. Is it economically viable to build a underwater community? towns in the middle of the mosquito infested Amazon? etc etc
Countries have gone to war for territory and resources for millennia, if Canada doesn't position itself well to protect it, someone else may come and try to take it away from you. This can happen via fisherman/oilers invading your territory, among many other ways. Always remember, if you are not willing to take the risks and investment is potentials, someone else is and when they strike gold, you may only be able to watch it.
[1] https://en.wikipedia.org/wiki/Arctic_resources_race [2] https://www.reuters.com/article/us-russia-arctic-insight-idU... [3] Food and Agriculture Organization of the United Nations [4] https://www.weforum.org/agenda/2018/07/fish-stocks-are-used-... [5] https://www.nytimes.com/2012/09/19/science/earth/arctic-reso... [6] https://uk.reuters.com/article/uk-egypt-economy-suezcanal/eg...