'Night-shining' clouds normally found above the poles have now been seen as far south as Los Angeles.
The US government is set to make it easier for oil and gas firms to leak methane into the atmosphere.
The treaty to limit the destruction of the ozone layer is hailed as the most successful environmental agreement of all time. Three decades on, the ozone layer is slowly but surely returning to health.
Australia needs stronger policy aimed at curbing air pollution, but the options currently on the table fall short. For now, we could all aim to drive less and turn off the engine when the car is idle.
Labor's shadow environment minister, Mark Butler, said Australia is now "pretty much the only major advanced economy where pollution levels are going up, not coming down." Is that right?