There is not only climate change but also variability from year to year in seasonality. That influences where people go to harvest, what time of year they go fishing or hunting for caribou in different places, and their understanding of the different landscapes or migratory pathways of species affected by the seasons or the conditions of sea ice.
People adapt to the local conditions. It's just that the reference point for what the future is going to look like looks very different from the past, and it's changing very quickly.