Around the world, global heating is already causing more frequent heatwaves that last longer and bring more heat. Guardian Australia's Graham Readfearn has put his body to the test in an experiment see what effects the heatwaves of the future will have on humans. At the University of Sydney, he steps into a climate chamber that simulates the increased temperatures and humidity predicted in a rapidly warming climate. 'The sweat is stinging my eyes,' he says. 'It's 43C and the air is sticky and humid. It's getting hard to breath.'