Country's native environment

[TheDarkMaster]

At the start of the game, assign natural environments to all nations in either the history files or based on their capital province. Nations who colonize in those natural environments get reduced penalties for doing so. This natural environment cannot be changed after the game starts or the nation is released.

 

[Chief of Staff]

This sounds like giving AI countries terrain affinity in colonization based on the terrain of their native lands. For example, Spanish and Portuguese are more likely to colonize the warmer, humid climate regions like Mexico and Brazil as they're closer to that of climate in Iberian Peninsula to some degree, whereas French and British are more likely to colonize terrains of cooler or colder climate like Canada and North America. Is this basically what you're proposing?

 

[TheDarkMaster]

This sounds like giving AI countries terrain affinity in colonization based on the terrain of their native lands. For example, Spanish and Portuguese are more likely to colonize the warmer, humid climate regions like Mexico and Brazil as they're closer to that of climate in Iberian Peninsula to some degree, whereas French and British are more likely to colonize terrains of cooler or colder climate like Canada and North America. Is this basically what you're proposing?

Something like that. Helping Norway colonize Greenland and Canada as well.

Also letting natives living in harsher climates actually be capable of colonizing at all, since their colonial growth from tech is so low that they can't overcome the growth penalties. You end up in a situation where a people who've been living in a jungle for centuries can't actually settle new land, unless they leave their jungles behind. While the newly arrived settlers who have no experience living in the jungle at all are capable of settling that land.