Bodies in a morgue in Karachi, June 2015, during a heatwave in which almost 700 people died. Photograph: Rizwan Tabassum/AFP/Getty Images
The last time it was 4C warmer there was no ice at either pole and sea level was 80 metres higher than it is today. …The problem is that humans can’t even handle a hot week today without the power grid failing on a regular basis. … Today, the most common maximums for wet-bulb temperatures around the world are 26C to 27C. Wet-bulb temperatures of 35C or higher are lethal to humanity. … In the near term – 2050 or 2070 – the US Midwest is going to be one of the hardest hit,….