The increasingly intensive use of space by humans can clearly be seen from light emissions at night. As settlements and infrastructures expand, the areas in which darkness can be experienced are becoming fewer. Many people are therefore unable to observe the Milky Way or the starry sky in its full glory. Excessive light emissions can also affect the habitat quality of nocturnal animals, disturb their orientation or shorten their activity time. And finally, light can destabilise the human sleep cycle, which has a negative impact on our health.
A comparison of satellite data shows that areas in Switzerland with low night-time light emissions have decreased drastically over the last 30 years. The rate of decrease slowed between 2014 and 2020. On the Swiss Plateau, light emissions are significantly higher than in other regions of Switzerland.
Ein Bericht im Auftrag der Europäischen Umweltagentur (EEA) von Ende 2022 hat basierend auf Satellitenbildern historische Trends in Europa modelliert und die nächtlichen Lichtemissionen in den einzelnen Ländern verglichen. Die Lichtemissionen in der Schweiz entsprechen von 2014 bis 2021 ziemlich genau dem Durchschnitt der 38 Mitgliedsstaaten der EEA.
Since 2014, the parameter has been based on evaluations of satellite images from the Visible Infrared Imaging Radiometer Suite (VIIRS) (Day/Night Band (DNB), taken with the Suomi National Polar Partnership (SNPP) and flown jointly by NASA and NOAA. From 1994 to 2012, there was a consistently processed annual time series of night lights created from low-light image data from the US Air Force Defense Meteorological Satellite Program (DMSP)'s operational linescan system (OLS). The two time series 1994–2012 and 2014–20 are difficult to compare because resolution issues and technical parameters.
For the indicator, sunlight data, glare effects, moonlight data, cloud observations and illumination by auroras are adjusted to create a world map with quantitative brightness values between 0 and 63 and a cell size of 15x15 arcseconds. The map is then reprojected onto the Swiss coordinate system and converted into grid cells of 1km2.
|Targeted trend||Initial value||Final value||Variation in %||Observed trend||Assessment|
|Decrease||Average 2014-2016||Average 2018-2020||7.91%||Growth||negative|