I think you and I are seeing it right now. Our kids and grandkids will be living it.I'm guessing no one alive today though will witness consequences. True?
There's no 100% in life, but just this past week the North Shore of Alaska, currently in 24/7 winter darkness, saw 40 degree Fahrenheit temps. Highest temperature ever in the darkness period in 100+ year records, broke the record for high temperature in December by 6 degrees. That is freakishly high. The weather two summers ago in the Northwest was a freak thing too.
We are now hitting records yearly at a way higher than random pace. Uncorrelated to skyrocketing CO2? Possible, but smart money says they are related.
Kind of like how home run records started falling once PEDs hit the locker room. Something changed.
We are definitely see ocean acidification too. No confusion on that.