A new study has revealed that a cataclysmic disruption of Earth’s protective ozone layer may have allowed damaging levels of ultraviolet (UV) radiation to saturate the Earth 359 million years ago, triggering a global mass extinction. The researchers behind the study warn that the sudden warming process that caused the ozone layer to weaken could occur again in the future, as our planet continues to heat up as a result of climate change.
Now, a team of scientists has discovered evidence to suggest that life on Earth has not always been protected from the dangers posed by our parent star. More specifically, the evidence suggests that a collapse of ancient Earth’s ozone layer may have allowed a burst of UV radiation to engulf the planet, altering the environment and killing off many ocean species.
The mass extinction examined by the scientists is thought to have occurred roughly 359 million years ago as Earth was emerging from an ice age near the end of the Devonian period. This part of our Blue Marble’s history is colloquially referred to as the Age of Fishes.
how did such a damaging amount of UV radiation reach Earth’s surface? The team believe that the ozone disruption was a natural part of Earth’s climate cycle, rather than an aberration stemming from a bout of powerful volcanic eruptions.
Following the melting of continental ice caps at the close of the Devonian ice age, the climate would have suddenly grown very warm. This excess of heat above the continents could have interacted with the delicate ozone layer above, destroying chemicals in the atmosphere and disrupting its protective properties. This in turn could have allowed dangerous levels of UV radiation to reach the surface.
The ozone may have existed in this weakened state for a period of several thousand years, during which time the UV radiation wreaked havoc on our world, collapsing forest ecosystems, and wiping out entire species of marine life and surface plants.
The bone-armored giant sharks were killed off, along with countless other species, but other sharks and bony fish were able to survive along with some hardy plants that were able to cling to existence on the supercontinents above.
Our own ancestors – the tetrapods – were likely also affected. The disruption and loss of habitat would have led to evolutionary bottlenecks in fish and tetrapods that shifted the course of our evolution.
According to the team behind the study, we should be alert to the danger of ozone depletion in the future, as our world continues to warm as a result of climate change.
https://newatlas.com/science/ozone-depletion-mass-extinction-radiation/