With technology constantly improving, we are giving ourselves more and more tools to study our planet. Part of the mission these scientists are undertaking is the story of the past, and how our planet came to be what it is now.
We’ve had studies tackling topics ranging from where some of the water on Earth came from to why all the oxygen then may have taken some time to settle in. Now, recent studies into our planet’s tumultuous past reveal that, in a conclusion that sounds perhaps unsurprising to some of you, may actually be worse than it sounded. The novel research was published in the journal Royal Society Open Science.
To be precise, a team of scientists led by University of Leeds astrophysicist Gregory Cooke now believes that previously predicted ultraviolet (UV) radiation levels showered upon the early Earth may be severely underreported, and are actually almost ten (10) times more intense than previously thought.
“We know that UV radiation can have disastrous effects if life is exposed to too much,” said Cooke. “For example, it can cause skin cancer in humans. Some organisms have effective defense mechanisms, and many can repair some of the damage UV radiation causes.”
“Whilst elevated amounts of UV radiation would not prevent life’s emergence or evolution, it could have acted as a selection pressure, with organisms better able to cope with greater amounts of UV radiation receiving an advantage.”
To Cooke and team, the early Earth needed a 5-10% oxygen level before enough of the ozone layer could have formed to keep most of the harmful UV radiation away from Earth’s surface—an almost 10 times increase to the 1% oxygen level that was previously thought to be necessary.
This meant that, during the early Earth, the thin ozone layer was insufficient to block out most of the damaging UV rays, thus bathing the surface with harmful radiation that would have throttled most of life’s attempts to evolve. (Similarly, scientists also recently found that iron may have played a major role in the rapid evolution of organisms on Earth.)
Cooke continued: “If our modeling is indicative of atmospheric scenarios during Earth’s oxygenated history, then for over a billion years the Earth could have been bathed in UV radiation that was much more intense than previously believed. This may have had fascinating consequences for life’s evolution.”
Oxygen levels on our planet’s surface wouldn’t reach modern-day levels until about 400 million years ago, according to ScienceAlert. However, Cooke and the team remain positive that there’s still much to learn about our planet’s past aside from what they had found.
“It is not precisely known when animals emerged, or what conditions they encountered in the oceans or on land,” Cooke noted. “However, depending on oxygen concentrations, animals and plants could have faced much harsher conditions than today’s world. We hope that the full evolutionary impact of our results can be explored in the future.”
References
- Cooke, G. J., Marsh, D. R., Walsh, C., Black, B., & Lamarque, J.-F. (n.d.). A revised lower estimate of ozone columns during Earth’s oxygenated history. Royal Society Open Science, 9(1), 211165. https://doi.org/10.1098/rsos.211165
- Nield, D. (2022, January 8). We may have seriously underestimated how hostile conditions on early earth were. ScienceAlert. https://www.sciencealert.com/conditions-on-ancient-earth-were-probably-more-hostile-than-previously-thought
- University of Leeds. (2022, January 5). Study reveals hostile conditions on Earth as life evolved. https://www.leeds.ac.uk/news-science/news/article/4994/study-reveals-hostile-conditions-on-earth-as-life-evolved
