The UV radiation on Earth has changed over the last 2 billion years. The Royal Society Open Science has a credit.
According to new computer simulations, the Earth may have been more inhospitable to life than previously thought.
Researchers believe that the UV radiation reaching the Earth's surface could have been underestimated, with UV levels being up to ten times higher.
UV radiation can damage and destroy biologically important Molecules such as proteins.
Oxygen levels in the atmosphere rose from zero to 400 million years ago.
More complex multicellular organisms and animals began to colonize land during this time.
The findings raise new questions about the evolutionary impact of UV radiation as many forms of life are known to be negatively affected by intense doses of UV radiation.
He said that UV radiation can have disastrous effects if it's too much. It can cause skin cancer in humans. Some organisms can repair damage caused by UV radiation.
It could have acted as a selection pressure, with organisms better able to cope with greater amounts of UV radiation receiving an advantage, if elevated amounts of UV radiation had not prevented life's emergence or evolution.
The research "A revised lower estimate of ozone columns during Earth's oxygenated history" is published today in the scientific journal Royal Society Open Science.
The figure shows a rough outline of oxygen concentrations in the atmosphere. The estimated range for O2 is shown in the brown blocks. The emergence of animals and the emergence of Eukaryotes were some of the important events for the evolution of life. There are black arrows that refer to events where atmospheric oxygen concentration changed. The Archean, Proterozoic, and Phanerozoic are geological periods. GOE, NOE, CE, and LE are the terms used for the Great Oxidation event, the Neoproterozoic Oxidation event, and the Cambrian explosion. The Royal Society Open Science has a credit.
The researchers said that the ozone in the atmosphere limits the amount of UV radiation reaching the Earth because it is one of the most important molecules for life.
Ozone forms as a result of sunlight and chemical reactions, and its concentration is dependent on the level of oxygen in the atmosphere.
Scientists have believed for the last 40 years that the ozone layer protects life from harmful UV radiation when the level of oxygen in the atmosphere is less than one percent.
That assumption is challenged by the new modeling. It suggests that the level of oxygen needed may have been higher.
UV radiation levels at the Earth's surface could have been much higher, and this could have been the case for most of the Earth's history.
If our modeling is indicative of atmospheric scenarios during Earth's oxygenated history, then the Earth could have been bathed in UV radiation that was much more intense than previously believed.
This may have had interesting consequences for life's evolution. It's not known when animals emerged or what conditions they encountered in the ocean. Animals and plants could have faced harsher conditions if oxygen concentrations were higher. We hope that the full evolutionary impact of our results can be explored in the future.
The results will lead to new predictions for exoplanet atmospheres. There are planets that are in the same space as other stars. The results of this study will aid in the scientific understanding of surface conditions on other worlds, as oxygen and ozone may indicate the possibility of extra-terrestrial life.
A revised lower estimate of ozone columns during Earth's oxygenated history was published in the Royal Society Open Science. Royalsocietypublishing.org has a DOI of 10.1098/rsos.211165.
The Royal Society Open Science has a journal.
The study reveals hostile conditions on Earth as life evolved.
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