The sheer scale of the bushfires sweeping through south-east Australia, turning the sky first black, then a terrifying apocalyptic red, defies the imagination. About 5.5m hectares of land has been burned; an area larger than Denmark and the Netherlands put together. This bushfire season began in the Australian spring and the blazes spread far and wide. The vast volume of dust and ash generated has turned the glaciers and snow-capped mountains of New Zealand’s South Island brown.