I was doing some tests in Universe Sandbox a while ago and I noticed a strange behavior shown by giant planets on highly inclined orbits. In the simulation I placed an Earth at 1 AU around the Sun, and with an inclination of 0 degrees, and a Jupiter in a 2:1 resonance with Earth. The Jupiter was also at an orbital inclination of 20 degrees. When I ran the simulation, things seemed normal at first. However, I soon noticed a pattern with the Earth's movement.
In a period of around 100 years, the Earth's orbital inclination increased to around 40 degrees, then decreased again. It then continued until its orbital inclination was around -40 degrees and then increased, spanning a time of 2 centuries per cycle, which i dubbed "Inclinatory Cycles". I tested other things too. With further tests I concluded that the Earth will always deviate from its base inclination by twice the giant's inclination on each cycle, and that the higher the mass and the closer the giant, the faster the cycle.
So, I was wondering if these "Inclinatory cycles" could be used in seasonbuilding. After all, more extreme inclinations lead to more extreme seasons. I can imagine an intelligent species realizing that for half a century, the seasons get more extreme, with hotter summers and colder winters. and for the other half, they get less extreme. Seasonal floods in rivers from the melting poles during an extreme summer could be the telltale marking, and this could be used for agricultural purposes. Now, my question is: Is this setup with a highly inclined gas giant even possible, and what would be the ramifications it would have on agriculture?