The largest recorded ozone layer hole, 1 million square kilometers in size, has been repaired ... by Earth herself. The ozone layer hole over the Arctic was caused by the strong and consistent polar vortex and the resulting concentration of more ozone-depleting chemicals than usual. Scientists say it's still too early to know if this development is climate change-related, and it has nothing to do with the ongoing reduction in pollution due to Covid-19. Instead, they say, it is because of the polar vortex -- high-altitude currents bringing cold air to the polar regions. It has split in two, giving the Arctic region a relative heatwave, with temperatures up to 20C higher than normal for this time of year.