Based on the environmental issues that are taking place in real life, there is a strong chance our planet will die and we would have nowhere else to turn to. However, I have always found colonizing other worlds an intriguing idea. However, there are two main variants of this project. One involves colonizing a parallel universe while the other involves colonizing other planets. Both ideas are promising with their own unique benefits and difficulties.
When it comes to colonizing other planets, there could be other Earth-like worlds out in the universe, but they are often too far away and we won’t know what their conditions are like until we actually reach the planet. Also, the planet in question may not have an atmosphere or environment that would sustain human life, which would make colonizing the planet even more difficult without the use of terraforming technology.
As for parallel dimensions, each variant of our world would be similar to ours with only small differences that would be manageable to overcome. The only problem is developing the right technology to cross over into that dimension and if the dimension already has a civilization, colonizing there would be nearly impossible. So you would have to pick a dimension that has a very simple environment that would be easy to adapt to.
I plan to experiment with this concept in my future works.