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Abstract

Recently, many sports stadiums have begun using high power lighting systems to help the grass grow on the playing surfaces. These lights supplement winter sunlight, which is sometimes insufficient due to the low elevation of the sun and shading from the surrounding walls. In many stadiums, grow lights are operated at night, and the waste light emissions from these stadiums are extraordinary in comparison to most other areas in the cities in which they are located. Here we present space-based observations of the radiance of fourteen stadiums located in towns and cities of varying sizes and in varying geographical locations across England which each have a Premier League football stadium. We show that stadiums have dramatically brightened (typically by factors of 2-5) in recent years compared to the situation in 2012. We also show that stadiums are often responsible for an important fraction of the total light emission of the cities they are in (often 10% or more, and in one case up to 30%). Because the light emissions from many English towns have been reducing in recent years, the overall fraction of light due to the stadiums is increasing. In some cases, total city emissions have actually increased due to the stadiums, undermining the environmental impact of reductions in radiance in the rest of the community. We believe that stadium grow lights are an excellent target for sustainable lighting initiatives, both because of their considerable environmental impact (especially when located near sensitive areas) and the possibility of high profile and successful waste light mitigation projects.