With certainty?
1. Temperatures will get warmer
2. Temperatures will get cooler
3. The weather changes.
4. In the past the earth has had periods of greater warmth where human society flourished and biodiversity exploded.
5. In the past the earth has had periods of much cooler and colder weather where mass extinctions occurred.
Other than 1-5 above we know very little. Science and mankind in general is still learning, and developing theories are quite interesting.
