We have wide belts of forests in the north that are warming and are potentially at risk for massive fires, which would make the problem significantly worse. So, before the taiga burns.
Or, before species reduction causes ecosystems to collapse, reducing biodiversity and ability to support humans.
Or before temperatures rise high enough that wet bulb temperatures in the summer are fatal to humans, causing parts of the globe to become inhabitable, creating refugee crises and conflict (and presumably mass starvation and death.)
Or before permafrost gets warm enough to start emitting methane, pushing our atmosphere past the point of it's ability to maintain homeostasis, putting us on a path to a Venusian atmosphere.
Or before we lose the beautiful parts of the world to decay due to increased pest pressure, decreased ability for plants and animals to survive, and general reduction in system health.
Or before we lose our ability to have wonderful winter sports in the parts of the world where skiing and snowboarding are popular.
Or before we damage the oceanic currents enough to fundamentally destroy the climate in regions like Europe and England.
Or before raising temperatures cause seafood stocks to plummet, reducing the amount of food we can harvest from the oceans (or leading us to depleting critical stocks entirely), reducing our capacity to feed ourselves as a species.
Or before fresh water becomes scarce enough that wars are fought over it, and people die unnecessarily.
I dunno. Before one of those. Or any of the other easily predictable, innumerable steps along the way to those.
Too late for what, exactly?