Pune: Solar radiation in the city has been declining at a rate of 0.21% per year since 1993, a new study has found. What's worse, between 2018 and 2022, a steeper decline of 1.
21% per year was found, raising several concerns. Decreased sunlight exposure can impact Vitamin D levels in people. Earlier studies over Australia, Brazil and USA have shown that reduced sunlight can also affect crop yield and quality, besides impacting food security.
Clouds and aerosols (dust and pollutants) linked to air pollution are emerging contributors to this "solar dimming" effect. The study was conducted over three decades by researchers from Savitribai Phule Pune University (SPPU), Indian Institute of Tropical Meteorology (IITM) and Aryabhatta Research Institute of Observational Sciences (ARIES). The study revealed that clouds reduced solar radiation by about 30%, while aerosols caused a reduction of nearly 18% compared to clear-sky conditions.
While this study focussed on Pune, another study by the India Meteorological Department (IMD) in 33 cities, including New Delhi, Mumbai and Ahmedabad, earlier this year found a similar reduction in global radiation between 1985 and 2019. Global radiation refers to the total amount of solar energy received on the Earth's surface. IMD scientist Dr Sudeep Kumar told TOI, "Our study found a significant decrease in global radiation in New Delhi, Shillong, Ahmedabad, Kolkata, Nagpur, Mumbai, Pune, Visakhapatnam, Goa, Chennai and Thiruvananthapuram.
Among the.