Long-term trends of light pollution

I am happy to announce that our paper on long-term trends in light pollution has been recently published in Monthly Notices of the Royal Astronomical Society.

In the paper we present long-term (4–10 yr) trends of light pollution observed at 26 locations, covering rural, intermediate, and urban sites, including the three major European metropolitan areas of Stockholm, Berlin, and Vienna.

The average increase in light pollution at our 11 rural sites is 1.7 per cent per year. At our nine urban sites, we measure an increase of 1.8 per cent per year and for the remaining six intermediate sites, we find an average increase of 3.7 per cent per year. These numbers correspond to doubling times of 41, 39, and 19 yr.

The development at intermediate sites is particular worrisome, reflecting the fact that at locations with yet only low-to-moderate light pollution levels the night sky brightness will dramatically increase in the near future (being twice as bright as today in less than 20 years). The number and size of areas with naturally dark skies is thus constantly decreasing, showing that it is important to raise awareness of the current development and establish Dark Sky Parks wherever possible in order to preserve the natural heritage of dark skies for future generations to come.