Smoke from Australia's megafires has already traveled tens of thousands of miles around Earth. "It circles the globe in roughly a week," said Manvendra Dubey, who researches air pollution and wildfire smoke at Los Alamos National Laboratory. 

Hundreds of blazes in Alaska, the Amazon, and the Arctic circle have also huffed thick plumes of smoke into the atmosphere over the past six months. These fumes — a mix of burnt particles and invisible gases — do gradually dissipate and eventually appear to vanish, of course. After all, after eons of wildfires and volcanic eruptions, the atmosphere isn't anything like the hazy air that amasses in a smoky bar.  Read more...