There is no disagreement on this.

If the greenhouse effect is real, and probably the majority of scientists believe that it is, then its damaging effects will likely get worse with time. So, it will never be to late to start efforts to avoid the damage. If the opportunity to avoid some damage is missed there will still be many more opportunities to avoid other types of damage.

Numerous systems can be affected. There are ocean water level changes and coastline damage, ocean acidity changes, forest stability changes and the consequences for wildlife in those area, food growing area changes, rainfall area shifts, and increased (or possibly decreased) hurricane and tornado activity to name just a few of the changes.

As I said, I feel that many and even most scientists around the world probably believe that it is better to act sooner rather than later. It is taking too much of a chance to wait for the data to confirm with 99.999 % certainty that these effects are real.