The world's nights are getting alarmingly brighter—bad news for all sorts of creatures, humans included. A German-led team of researchers says light pollution is threatening darkness almost everywhere, the AP reports. Satellite observations during five Octobers show Earth's artificially lit outdoor area grew by 2% a year from 2012 to 2016. So did nighttime brightness. Light pollution is actually worse than that, according to the researchers. Their measurements coincide with the outdoor switch to energy-efficient and cost-saving light-emitting diodes, or LEDs. Because the imaging sensor on the polar-orbiting weather satellite can't detect the LED-generated color blue, some light is missed.
The findings shatter the long-held notion that more energy-efficient lighting would decrease usage on the global—or at least a national—scale. "Honestly, I had thought and assumed and hoped that with LEDs we were turning the corner," says lead researcher Christopher Kyba of the GFZ German Research Center for Geosciences. "It is quite disappointing." The biological impact from surging artificial light is also significant, according to the researchers. People's sleep can be marred, which in turn can affect their health. The migration and reproduction of birds, fish, amphibians, insects, and bats can be disrupted. Plants can have abnormally extended growing periods. And forget about seeing stars or the Milky Way, if the trend continues. (NASA plans to start releasing stunning "night lights" images more often.)