Study says ozone depletion triggered mass extinction in ‘fish age’

359 million years ago, the Earth’s protective ozone layer was devastated by a catastrophic destruction that could have caused destructive ultraviolet radiation to affect the planet and trigger a global extinction, according to a new study. The sudden warming of the ozone layer may happen again in the future as climate change continues to warm our planet, the researchers behind the study warn.

Study says ozone depletion triggered mass extinction in 'fish age'

The Earth’s ozone layer has long been an effective shield against harmful ultraviolet radiation from stars. However, this does not mean that the evolution of life on Earth is not being challenged. Earth’s geological records show evidence that there have been periodic, planet-crossing extinctionevents on Earth, each time taking the lives of countless species and changing the course of evolution.

The most famous mass extinction event is undoubtedly the asteroid impact, which can be said to have been the extinction of dinosaurs 66 million years ago. Other events, however, are triggered by volcanic eruptions around the world, which degrade the Earth’s surface and alter the chemistry of the atmosphere. Now, a team of scientists has found evidence that life on Earth is not always protected by its parent star. More specifically, the evidence suggests that the destruction of the ancient Earth’s ozone layer may have allowed a burst of ultraviolet radiation to engulf the Earth, alter the environment and kill many marine species.

The mass extinction studied by scientists is thought to have occurred about 359 million years ago, when The Earth was emerging from the ice age near the end of the mud basin. This history is commonly known as the “Fish Age”. At that time, life was largely confined to the ocean, where impressive shark species such as Titanicthys dominated.

Study says ozone depletion triggered mass extinction in 'fish age'

The team collected samples from modern Greenland — the dry interior of the northernmost supercontinent(once an ancient lake bed) and the Andes in Bolivia, which should be on the edge of melting ice. This allows scientists to compare extinction data collected near the equator with extinction data from the Ancient Earth’s Antarctic region.

Once transported to the lab, the team began dissolving rock samples in hydrofluoric acid to obtain well-preserved microplant spores dating back to the Mass Extinction event.

It turned out that many spores were darker in color than expected, with unusual stings on the surface. According to the team, the color change is likely to be a protective response to excessive ultraviolet radiation. This wavelength of radiation may also destroy the DNA of the spores, triggering the growth of abnormal stings. But how did such destructive ultraviolet radiation reach the Earth’s surface? The team believes that ozone damage is a natural part of the Earth’s climate cycle, not an anomaly caused by intense volcanic eruptions.

After the melting of the continental ice sheet at the end of the Mud basin ice age, the climate suddenly became very warm. Excess heat over the continent can act with the fragile ozone layer above, destroying chemicals in the atmosphere and destroying their protection. This, in turn, causes dangerous ultraviolet radiation to reach the surface. Ozone may have existed in this weakening state for thousands of years, during which ultraviolet radiation caused severe damage to the Earth and the collapse of forest ecosystems, wiping out entire marine life and surface plant species.

In addition to marine life, tetrapods are likely to be affected. Habitat destruction and loss can lead to evolutionary bottlenecks in fish and tetrapods, changing our evolution.

According to the team behind the study, we should be alert to the dangers of future ozone depletion as our world continues to warm as a result of climate change. “Current estimates suggest that we will reach a global temperature similar to that of 360 million years ago, and that the ozone layer is likely to collapse again, exposing surface and shallow sea life to deadly radiation,” commented lead researcher Professor John Marshall, a principal researcher at the School of Marine and Earth Sciences at the University of Southampton. “This will shift us from the current state of climate change to a state of emergency. “