I have an earth-like planet with a roughly earth-like orbital period, that is in a stable co-orbital scenario with another largish body. Similar to Janus and Epimetheus but planets rather than moons.
At every approach/exchange the planet experiences geologic upheaval and climatic shift. Geologic due to tidal forces from the close approach, causing severe earthquakes. Climatic because of the exchange of orbital position.
This is for a young adult scifi. The scenario will only be described indirectly and will not have to stand up to hard scifi level scrutiny, but I would like to keep it realistic and plausible.
How much climate shift would be possible?