Many amateur astronomers are also interested in wildlife, plants and biosciences. Threats to biodiversity are perhaps the most worrisome aspect of light encroachment.
This item about moths from New Scientist shows how artificial light is forcing rapid evolution in short timeframes. https://www.newscientist.com/article/2421950-city-moths-may-have-evolved-smaller-wings-due-to-light-pollution/
British Astronomical Association
Supporting amateur astronomers since 1890