India's sunlight hours continue to decline due to rising pollution
What's the story
India has witnessed a significant decline in sunlight since 1988, primarily due to rising air pollution levels. A recent study by scientists from Banaras Hindu University (BHU), Pune's Indian Institute of Tropical Meteorology (IITM), and the India Meteorological Department (IMD) found that the country's annual sunshine hours have been steadily decreasing. The research was published in the journal Nature.
Research findings
Study analyzed data from 1988 to 2018
The study analyzed data from 1988 to 2018, covering 20 meteorological stations across nine regions. It found a "persistent decline of SSH (sunshine hours) in the Indian subcontinent on all temporal scales," except for the northeastern region, where mild seasonal leveling off was observed. The researchers also noted a "significant increment from October to May followed by significant drops from June to July in six regions."
Urban impact
Urbanization and industrialization are major reasons
The study attributes the decline in sunshine hours to rising aerosol levels, which have increased due to urbanization since the early 1990s. During this period, India's economic growth led to urbanization, land-use changes, and industrialization. These developments resulted in higher fossil fuel consumption, vehicular emissions, and biomass burning. Consequently, aerosol concentrations in the atmosphere increased, and solar radiation decreased.
Environmental factors
Clouds are also blocking sunlight
The study also highlights that weather conditions have contributed to the reduction in sunlight. Clouds have been blocking sunlight, which further reduces solar radiation and sunshine hours. Aerosols are blamed for the increasing cloud cover. The researchers explain that when aerosol levels rise in a constant humidity environment, smaller-sized cloud droplets are created and their lifespan is extended. This ultimately affects the duration of solar radiation reaching Earth's surface.