Sarpeidon's ice age.
An ice age is a period of long term reduction in the surface temperature on a planet, leading to the expansion of ice sheets, polar caps, and mountain glaciers. (TOS episode & Star Trek 4 novelization: All Our Yesterdays; TOS - The Yesterday Saga novels: Yesterday's Son, Time For Yesterday)
Thousands of years ago, an ice age was triggered by meteor impacts on Pollux V. To survive, the native Nauians put themselves in suspended animation, but the subsequent breakup of the planet's moon prevented their sonambutron from reviving them as scheduled. They remained in stasis until the 2260s, after the ice age ended and the planet had been colonized. (TOS video game: 25th Anniversary mission: "Demon World")
In the 23rd century, Artemys 314 was in the midst of a global ice age estimated to last two million years. (TOS comic: "All the Ages Frozen")
A powerful alien race——possibly the Borg—caused an ice age on the homeworld of the Cetacean Probe's creators by reducing the energy output of the local star when they were unable to conquer the planet. (TOS novel: Probe)