Lead designer Lee Hammock and game designer Stephen Cheney address the topic of Escalations in this latest video, explaining that each area of the map will have creatures that need to be dealt with or their power will escalate over time. These unchecked monsters will eventually burden the zone's resources and make it more difficult for a settlement to thrive in that area. But if the threat is dealt with completely, you will earn bonuses for your settlement.
Be sure to watch the entire video after the cut for more on Escalation cycles and how they work.
[Source: Pathfinder Online Kickstarter update email]