Earth’s early atmosphere was hazy like Saturn’s moon Titan, a new study published Monday in the journal Nature Geoscience reveals. Scientists argue that Earth’s early atmosphere flip flopped between a hydrocarbon-free state and a hydrocarbon-rich sate, which is akin to Titan’s atmosphere. The research was spearheaded by scientists at Newcastle University.
“We find evidence for oxygen production in microbial mats and localized oxygenation of surface waters. Carbon and sulphur isotopes indicate that this oxygen production occurred under a reduced atmosphere that was periodically rich in methane, consistent with the prediction of a hydrocarbon haze,” the authors wrote in the study’s abstract.
The organic haze prefaced the formation of multiform life on Earth. In fact, the periodic flip flopping between organic haze and a haze-free atmosphere took place more than 2.5 billion years before the oxygenation of Earth.
The scientists believe that the flip flopping between two atmospheric states was a result of “intense microbial activity.” In fact, the acute nature of the microbial activity had a dramatic impact on Earth’s climate.
“Our simulations predict transitions between two stable atmospheric states, one with organic haze and the other haze-free. The transitions are presumably governed by variations in the amount of biological methane production during the Archaean eon,” the authors added.
The researchers believe that their discovery will help scientists understand more about Earth’s surface environment prior to oxygenation and the subsequent development of multiform life.
“We find that the isotopic signatures we observe are evident in other data sets from this period and conclude that methane was an important component of the atmosphere throughout the Archaean,” the authors posited.
“Models have previously suggested that the Earth’s early atmosphere could have been warmed by a layer of organic haze,” said the study’s lead scientist Aubrey Zerkle, a professor at the School of Civil Engineering and Geosciences at Newcastle University, in a press release. “Our geochemical analyses of marine sediments from this time period provide the first evidence for such an atmosphere,” Ms. Zerkle posited.
“However, instead of evidence for a continuously ‘hazy’ period we found the signal flipped on and off, in response to microbial activity. This provides us with insight into Earth’s surface environment prior to oxygenation of the planet and confirms the importance of methane gas in regulating the early atmosphere,” she added.
According to U.S. Environmental Protection Agency, methane is a greenhouse gas that endures in the atmosphere for 9-15 years. Methane is also very effective when it comes to keeping heat in the atmosphere (the EPA says it is 20 times more effective than carbon dioxide over a 100-year period). Methane is vented by a number of natural and human-influenced. Human-influenced sources include landfills, natural gas and petroleum systems.
Ms. Zerkle as well as James Farquhar, a professor at the University of Maryland and Simon Poulton, a professor at Newcastle University, examined the geochemistry of marine sediments scattered approximately 2.5 billion years ago in South Africa. The scientists located evidence of oxygen production by microbes in the oceans, but they contend that most of the oxygen did not enter the Earth’s atmosphere.
The scientists posit that Earth’s atmosphere continued to flip flop between organic haze and a haze-free atmosphere for approximately 100 million years after the marine sediments were scattered.
“What is most surprising about this study is that our data seems to indicate the atmospheric events were discrete in nature, flip-flopping between one stable state into another,” remarked Mr. Farquhar, one of the study’s co-authors, in a press release. “This type of response is not all that different from the way scientists think climate operates today, and reminds us how delicate the balance between states can be,” Mr. Farquhar added.
“Another important facet of the work is that it provides insight into the formation of atmospheric aerosols, particularly organic ones,” professed Mark Thiemens, Dean of Physical Sciences at the University of California San Diego, in a press release.
“Besides the obvious importance for the evolution of the atmosphere, the role of aerosol formation is one of the most poorly understood components in the present day climate models. This provides a new look into this process that is quite new and valuable,” Mr. Thiemens added.