Today, when our weather forecasters tell us a heatwave is coming, we can be quietly confident of the time it will arrive and the temperatures that will be reached. When western Sydney broke records on January 7, hitting 47 degrees, the Bureau of Meteorology had warned us, enabling individuals and organisations to prepare. While analysis of this event is ongoing, researchers at the Australian Research Council’s Centre of Excellence on Climate Extremes found a similar Sydney heatwave last year was twice as likely due to the climatic impacts of humans.