[gmuslera]

Civilization existed for around 10-15k years, around the time climate got stable enough to get agriculture in a scale to support big cities. The changes that had been since then in global climate weren't sudden enough to put that in danger. Eventually plants and animals adapt to hotter climate if given time and don't surpass some critical thresholds.

But we are changing climate at a speed which precedents were around mass extinctions. Adaptation will be hard, adaptation of what we need at the scale we need to support a civilization will be harder, and we don't know yet if we will cross some threshold that may be lethal for us, at least at the time scale we live.

And that is just about averages. In recent years we had big heatwaves covering most of US and Europe, reaching near 50ºC even at high latitudes. You may be able to survive averages, but what about peaks for 55ºC or more? Check your cooling devices and electrical grids safe margins if you think AC will save from that.