There has been no net warming in the Rocky Mountains in the last 500 years.
Image Source: Berkelhammer and Stott, 2012
Image Source: Heeter et al., 2020
The northern Rocky Mountains were also as-warm or warmer during the 1600s and 1700s with no unusual recent warming (Kipfmueller, 2008).
Image Source: Kipfmueller, 2008
The glaciers in Glacier National Park (northern Rockies) experienced substantially higher melt rates in the 1920s to 1940s, only to return to Little Ice Age melt rates in the following decades (Pederson et al., 2004).
Image Source: Pederson et al., 2004
The press release for a new study by the very same authors of last year’s reconstruction of southern Rocky temperatures screams that the northern Rockies are now “hotter than ever.” However, the temperature record from the study itself shows ~2°C cooling from 1940-1970 and a more sustained warm temperatures during Medieval times and especially the late 1500s to early 1600s.