Ahmedabad: The city’s artificial light at night has more than doubled in the last eight years between 2014 and 2022. . Researchers say that if nothing is done, night-time brightness could rise by an alarming 46.2 percent more by 2027.Satellite data shows Ahmedabad’s night-time radiance rose from 29.7 to 63.3 nanowatts per square centimetre per steradian (nW/cm2/sr) between 2014 and 2022. This unit measures how much light goes from the Earth’s surface up to a satellite. The growth rate was almost 9% per year. Researchers predict the number could reach 93.39 by December 2027 if the trend continues. The city began 2023 at 63.88.Researchers link the rise mainly to fast city expansion, inefficient streetlights, and mushrooming advertising billboards. On satellite maps, areas that earlier looked light blue, showing lower brightness, are turning red, showing stronger light.The study titled ‘An Alarming Threat of Light Pollution in Ahmedabad City: Efficient Time-Series Forecasting Framework’ was authored by Saikat Mondal and Parag Kumar Guha Thakurta from the Department of Computer Science and Engineering, NIT Durgapur, and PL Sikdar from the Department of CSE (IoT), Techno Main Salt Lake, Kolkata. The study has been published by Springer Nature Switzerland AG in a special journal.The researchers said street lighting and outdoor advertising need urgent control. They also said the increase is not the same everywhere in the city. They studied night-time radiance around Bhadra and Lal Darwaza within 500 metres. “At this single location, radiance grew from 38.473 nW/cm2/sr in 2014 to 53.888 in 2022 — and is projected to reach 62.86 by December 2027. “The city is not brightening uniformly. It is intensifying most aggressively at its centre.,” stated the study.The study also warns that too much light at night can harm health by disturbing the body’s sleep-wake cycle. “The long-term artificial light exposure at night can alter circadian rhythms, which may result in sleep issues and mental health issues, behavioral changes and metabolism “ It adds that without action there will be “worsening the negative impacts on human health”.The study says the growing glow also affects the view of the night sky. It notes that “the city at night may now witness fewer celestial objects with astronomy instruments due to night sky brightness that impairs human vision and observation of the universe”.It adds that wildlife may also suffer. It lists birds, amphibians, reptiles, and coral reefs as being harmed by the “excessive grouping of bright, confusing, or uncoordinated light sources”.The researchers used satellite data from the National Oceanic and Atmospheric Administration’s (NOAA, US) Visible Infrared Imaging Radiometer Suite (VIIRS) to study and predict changes in Ahmedabad’s light pollution from 2014 to 2022.
