How Hot Is Too Hot For Humans?

Us humans are warm blooded creatures and Climate Change is bringing extreme heat to us so how hot does it have to be before we all start dying from the heat?
Google states that the maximum temperature at which humans can survive is 108.14°F or 42.3°C and any higher leads to denature proteins and cause irreparable damage to brain but that temperature is generally hit in the hottest parts of the World, at the moment parts of Texas are suffering 46.1°C (115°F) and with Global Temperatures increasing by 0.18°C or 0.32°F per decade, then we will arrive at a point when it is just too hot for humans to exist.
Some climate models predict that large swaths of the globe will become too inhospitable for humans in the next century but it isn't as simple as saying you can kiss your sweaty backside goodbye if the thermometer hits 42.3°C, there are other factors which need to be taken into consideration.
The problems start when our bodies can’t lose heat fast enough and your core temperature gets too hot as our sweat can't evaporate to cool us down quick enough and then our organs such as kidney, brain and heart start to shut down and that starts at around 35°C or 95 °F and if you are unable to lose heat efficiently enough to maintain it's core temperature, something children and elderly people find difficult to regulate, brain and organ damage will start.
The Indiana University found that exposure to the 35°C for longer than 6 weeks can be deadly and although the human body can adapt to short bursts of extreme heat, evolution has not adapted us to survive much above 35°C for any length of time so either evolution gets a shift on or we are going to have to find
new ways to keep cool in the new, hotter age.