How can artificial nighttime lighting impact biological features on Earth?

According to some research, the emission spectrum of artificial light at night (ALAN) can affect biological phenomena, including physiology, behavior, community structure, and ecosystems. Some phenomena, such as melatonin suppression, can be sensitive to ALAN.

To understand how ALAC can affect the environment, researchers from the University of Exeter used images from the International Space Station to create the first composite nighttime color maps of Europe. They compared the periods of 2012-2013 and 2014-2020 to analyze changes in public lighting.

The results obtained by the researchers suggest that during 2012-2013, typical streetlights were predominantly a mixture of high-pressure sodium lamps and white lamps, while during 2014-2020, white LED lamps or other white technologies dominated the market. However, these changes are not consistent across countries, as some countries have experienced more changes than others.

Concerning intensity, researchers found that between 2012-2013 and 2014-2020, there was an increase in emissions from 11.11% to 24.4%, suggesting that while the LED revolution promoted energy consumption reduction in countries and regions, emissions and likely consumption increased. This can be explained by the “rebound effect” or “Jevon’s paradox,” where the increase in energy efficiency and the perceived decrease in cost have driven a higher demand for light, negating any efficiency gains.

Regarding the impact of ALAN on biodiversity, researchers found that increasing ALAN, particularly in the blue wavelengths, has a biological impact on organisms. This includes the suppression of melatonin production, changes in the phototactic response of moths and other insects, and worsening visibility of stars in Europe.

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