In addition to specific cycles, there are also occasional major impacts from huge volcanic eruptions. The recent major eruptions by the Hunga-Tonga volcano which threw huge volumes of water into our upper atmosphere may be one reason for the pattern of droughts and floods experienced throughout the world these past two years. In a few years we will have a better analysis of those effects as the water vapor comes out of the upper atmosphere.
https://www.nasa.gov/earth/tonga-eruption-blasted-unprecedented-amount-of-water-into-stratosphere/
If you look at the blue line in the graph at comment #2, you will see that at around 75,000 years ago there was a sharp drop in the blue line, indicating a severe fall in temperature. This was caused by the volcano Toba Indonesia which left a caldera around 18 miles by 65 miles in dimension. This sharp drop in temperature apparently caused a severe decline in the human populations. Scientists have calculated that possibly only 10,000 pairs of breeding homo sapients survived the Nuclear Wintor that occurred, which can be determined by our studies of DNA. Almost no human remains have been discovered for the period between 75k and 50k years ago.
https://www.thecollector.com/mount-toba-supervolcano-wipe-out-humans/
You will note that eventually the blue line rose to continue the downward slope that was occurring before the major Toba event.
Volcanism is analogous to acne. The Sun is overwhelmingly responsible for the climate of the Earth.
Non-cyclic occasional ‘black swan’ impact events have caused all the glaciation events of the past two million or so years, beginning with the Eltanin impact (perhaps impact cluster).