Geologists study the rock record to understand how our world came to be and to try to determine what geologic events might occur in the future. The field of geochronology provides the means for geologists to know when these past events took place.
The landscape of the greater Yellowstone region has evolved gradually over millennia, punctuated by rare cataclysmic events such as volcanic eruptions, major earthquakes, and glacial outburst floods.
Sediment from the bottoms of lakes in Yellowstone contain records of past changes to the landscape including how hydrothermal activity, vegetation, and climate in Lower Geyser Basin have evolved over time. The place used to look much different than it does today…
If you want to measure a climate trend, one thing you certainly have to account for is the seasons. It would be unwise to take one measurement in July, a second measurement in December, and declare that we are descending into an ice age. The same is true for measuring ground deformation. There is seasonal movement you have to consider, including in Yellowstone National Park.