People came into North America more than 15,000 years ago and have experienced both massive and minor shifts in climate ever since. At the end of the last very cold phase of the most recent Ice Age, about 11,500 years ago, temperatures rose extremely rapidly-as much as 10℃  in a decade in some regions. This undoubtedly contributed to the extinction of large mammals like mammoths and mastodons that people hunted alongside many other resources . There were so few people on the land, though, and other resources were so abundant, that the long-standing human means of coping with climate variability- switching foods and moving on-were sufficient.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report