Some ancient air bubbles that were discovered to be trapped in 2.7 billion year old lava flows in Western Australia's Pilbara, now provide possible evidence about how Earth's atmosphere would have weighed less than half of its volume today, suggesting it was thinner and more tenuous than first thought.

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This also means that Earth could have stayed almost free from any ice during that time even if the sun was much cooler before as opposed to today.

Researchers from the University of Western Australia examined and analyzed air bubbles found inside lava flows located in the Beasley River, in the aboriginal Pilbara region of Western Australia. These lava flows possess distinct features such as "toes", with cracked, glassy surfaces, suggesting that massive ribbons of this molten hot rock have crawled and dived into a beach.

According to author of the study, astrobiologist David Catling from the University of Washington, the sun was apparently about less than 20 percent luminous some 2.7 billion years ago, which means that Earth's atmosphere would have been covered in ice crystals today if the sun still shined the way it did billions of years ago. However, there are still similar conditions on Earth that still remain.

Catling says that the climate system back then also had rainfall and rivers and it is also possible that polar ice caps existed, however it is still warm enough for the planet to be not covered entirely in ice.

Today, theories about warmer than usual climate conditions involve our atmosphere becoming thicker and more dense through time, insulating the planet.

However, this new evidence of air bubbles preserved in rock that would have originally been under sea level reveals a totally different idea about the planet's atmospheric pressure especially during the Archean period, spanning from the formation of the crust 4 billion years ago to 2.5 billion years back.

In this new study, researchers compared the sizes of the air bubbles trapped on the surface of the lava flows which have been only affected by air pressure, and air bubbles trapped at the base of the molten rock, that have been affected by both air pressure and the lava itself, to determine the precise air pressure of the planet when this lava flow occurred.

Catling says that the results revealed that the atmosphere is basically a lot thinner during that time, weighing less than half of how it is today.

This would also mean that Earth some 2.7 billion years ago was home to only single celled organisms, as sunlight was one fifth weaker, and most importantly, the planet's atmosphere has no oxygen yet. A lighter atmosphere means weaker winds, different climate patterns including boiling point of liquids.

This new study is published in the journal, Nature Geoscience.

Tagsair pressure, early earth atmosphere, ancient lava bubbles, Western Australia, earth ancient atmosphere thin