In most cases, we don't know what will happen. As a wise man (Yogi Berra!) once said: "Prediction is very difficult. Especially about the future."
That said, climate scientists are pretty knowledgeable about physics, and chemistry, and biology. We ARE seeing increasingly frequent and deadly superstorms, wildfires, flooding, droughts and more.
Yes, we dodged a bullet (so far) by avoiding nuclear war—but it was and still is a genuine danger. And climate collapse is not only a danger, but a danger we are doing nothing to prevent.
Let's do something!