Explainer: How a total solar eclipse impacts the ecosystem and human health

In regions within the path of totality, where the sun’s rays are completely obscured, the environment undergoes dramatic changes reminiscent of twilight. (Photo: Justin Dickey via Unsplash)

When a total solar eclipse casts its shadow, nature responds in mysterious ways. Birds cease their songs, crickets begin to chirp, and bees retreat to their hives, fooled by the false dusk that descends upon the land. The peculiar behaviours exhibited by animals during eclipses have intrigued scientists for centuries.

To shed light on this phenomenon, a NASA-funded Eclipse Soundscapes Project will harness the power of citizen science during the forthcoming total solar eclipse on April 8. By enlisting the help of interested individuals, the project aims to explore how eclipses impact various ecosystems through sight, sound, and sensation.

During a total solar eclipse, the moon positions itself directly in front of the sun, momentarily blocking its light. In regions within the path of totality, where the sun’s rays are completely obscured, the environment undergoes dramatic changes reminiscent of twilight. Temperatures drop, stars appear, and diurnal animals may alter their behaviour in response to the sudden darkness.

With over 30 million people in North America poised to witness the 2024 eclipse, the event presents a unique opportunity for large-scale scientific inquiry. By collecting multisensory observations, including audio recordings and written accounts, the project seeks to unravel the mysteries of animal behaviour during eclipses. Particularly intriguing is the question of how nocturnal and diurnal creatures respond to the temporary disruption of their natural rhythms.

This, however, isn’t the first to study the notable influence on the environment. A 2023 study found that while the effects of solar eclipses, such as changes in temperature, wind patterns, and impacts on plant and animal behaviour, are relatively short-lived, they can have a significant impact on ecosystems and food production.

The sudden temperature drop, especially pronounced during total solar eclipses, can hinder plant growth, impacting regions where the phenomenon lingers. Moreover, the diminished sunlight disrupts the earth’s surface heating and cooling, leading to atmospheric pressure changes and consequent alterations in wind circulation. These atmospheric shifts can manifest as changes in local weather patterns, further influencing ecosystems.

Animals, particularly those reliant on sunlight for navigation like birds and insects, may experience disorientation, altering their typical behaviour such as feeding or migration. Additionally, the reduced sunlight hampers plant photosynthesis, impeding their growth. Thus, the study concluded that despite their brief duration, solar eclipses can instigate a ripple effect across ecosystems, influencing various facets of plant and animal life, weather dynamics, and agricultural productivity.

While solar eclipses pose little to no direct threat to human health, precautions must be taken. Dr Manoj Kamath, a general practitioner based in Mumbai, says, “Looking at the sun during an eclipse can hurt your eyes badly or even make you blind. The sun's UV rays can hurt the part of your eye that takes in light, called the retina. This can happen even if the sun is only partly covered by the moon.”

He suggests using special filters made for looking at the sun or trying indirect ways to see the eclipse, like using a pinhole camera. Regular sunglasses or homemade filters might not keep your eyes safe enough, so it's best to avoid using them.