Indicator landscape

Light emissions

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.

Assessment of the state
poor poor
Assessment of the trend
negative negative
Switzerland's average light emissions 2012*: 77 Switzerland's average light emissions 2011*: 70 Switzerland's average light emissions 2010*: 69 Switzerland's average light emissions 2009: 56 Switzerland's average light emissions 2008: 52 Switzerland's average light emissions 2007: 50 Switzerland's average light emissions 2006: 46 Switzerland's average light emissions 2005: 44 Switzerland's average light emissions 2004: 44 Switzerland's average light emissions 2003: 44 Switzerland's average light emissions 2002: 44 Switzerland's average light emissions 2001: 42 Switzerland's average light emissions 2000: 40 Switzerland's average light emissions 1999: 42 Switzerland's average light emissions 1998: 42 Switzerland's average light emissions 1997: 45 Switzerland's average light emissions 1996: 40 Switzerland's average light emissions 1995: 35 Switzerland's average light emissions 1994: 32
* The data come from different satellite platforms and are therefore not entirely comparable with previous years (1994-2009).

Data for the graph: Excel
Source: FOEN: Landscape Monitoring Switzerland (LABES)
Switzerland's average light emissions 2020: 1.31722 Switzerland's average light emissions 2019: 1.326499 Switzerland's average light emissions 2018: 1.308052 Switzerland's average light emissions 2017: 1.399263 Switzerland's average light emissions 2016: 1.193556 Switzerland's average light emissions 2015: 1.240524 Switzerland's average light emissions 2014: 1.227989
The data come from VIIRS VCMSL Day/Night Band (DNB) satellite platforms. They are not comparable with previous data from other satellite platforms.

Data for the graph: Excel
Source: FOEN: Landscape Monitoring Switzerland (LABES)
Average light emissions 2020 Southern Alps: 1.190252 Average light emissions 2020 Western Central Alps: 0.541065 Average light emissions 2020 Eastern Central Alps: 0.889628 Average light emissions 2020 Northern Alps: 0.746806 Average light emissions 2020 Central Plateau: 2.514801 Average light emissions 2020 Jura: 1.375678 Average light emissions 2020 Switzerland: 1.31722
The data come from VIIRS VCMSL Day/Night Band (DNB) satellite platforms. They are not comparable with previous data from other satellite platforms.

Data for the graph: Excel
Source: FOEN: Landscape Monitoring Switzerland (LABES)
Comment

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.

International comparison

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.

Method

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.

Basis for assessment of the trend
Targeted trend Initial value Final value Variation in % Observed trend Assessment
Decrease Average 2014-2016 Average 2018-2020 7.91% Growth negative
 
Last updated on: 14.03.2023

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