...That is not conclusive just because you can't stand 60 degrees of heat, the climates range from negatives to the mid thirties usually, so humans have gotten used and formulated methods to respond to that range of living.
...In general a global rise of 4 degrees would be useful for the temperate countries, and not affect the tropics by all that much.
If we put one of our feet on ice and the other in fire, the average feeling is not equal to good. We can't add 4 or minus 4 and average them like what we do in statistical studies.
The snowcaps help keep the earth cool by reflecting away heat from the sun. When global temp rises, we will loss these snowcaps and also a big portion of the icebergs. Major rivers will burst its banks and a lot of farm lands will be lost due to rising sea level. Land salination is irreversible. No more coral reefs and fish stocks.
In temperate countries, warmer summer also equal harsher winter... Plus snow stroms, torrential rains ect due to climate changes.
It is not +4 in summer = +4 in winter.