I agree with your first sentence, but an inflection point is where the second derivative changes sign: in other words, you switch from deceleration to acceleration, or vice versa.

But the climate catastrophe has been accelerating my whole life and continues to accelerate.

I doubt future historians, assuming there are any, will remember 2023 particularly.

I think they'll remember 9/11, remember COVID, they'll remember the first year that some developed country goes into civil disorder (perhaps as soon as 2025 if Trump wins, perish the thought), but 2023 will be just another rung on the ladder down to Hell.