Breakthrough study will help identify which planets can support life

A recent study led by the University of Bristol has uncovered new insights into the evolution of oxygen, carbon, and other essential elements on Earth, which could potentially help in identifying other planets capable of supporting life, from vegetation to complex organisms similar to humans.

Acceleration of oxygen production 

This is the first time the role of carbon-rich rock accumulation in the acceleration of oxygen production and release into the atmosphere has been identified. 

The discovery addresses a longstanding mystery in science, offering a resolution to the diverse and conflicting theories about how Earth’s atmosphere became rich in oxygen.

Earth’s oxygenation history 

“Oxygenation of Earth’s atmosphere and oceans played a pivotal role in the evolution of the surface environment and life,” wrote the study authors. 

“It is thought that the rise in oxygen over Earth’s history was driven by an increasing availability of the photosynthetic limiting nutrient phosphate combined with declining oxygen-consuming inputs from the mantle and crust. However, it has been difficult to assess whether these processes alone can explain Earth’s oxygenation history.”

Dynamics of the carbon cycle

The experts examined how carbon dioxide, released by volcanic activity, dissolves into oceans and contributes to the formation of carbonaceous rocks such as limestone. These rocks, over time, can release carbon through tectonic activities like mountain formation and metamorphism, enriching the atmosphere with oxygen.

Utilizing sophisticated computer modeling, the researchers were able to simulate the intricate dynamics of carbon, nutrient, and oxygen cycles across more than four billion years of Earth’s history, achieving an unprecedented level of accuracy.

Potential for oxygen-breathing life on other planets

“This breakthrough is important and exciting because it may help us understand how planets, other than Earth, have the potential to support intelligent, oxygen-breathing life,” explained lead author Lewis Alcott, an earth scientist at Bristol.

“Previously we didn’t have a clear idea of why oxygen rose from very low concentrations to present-day concentrations, as computer models haven’t previously been able to accurately simulate all the possible feedbacks together. This has puzzled scientists for decades and created different theories.”

Progressive increase in oxygen production over time

The study suggests that planets older than Earth, which have had ample time to accumulate carbon-rich deposits, might be more likely to undergo processes that facilitate the cycling of carbon and nutrients essential for life. 

The research shows that the gradual increase in crustal carbon leads to a corresponding rise in the recycling rates of carbon and minerals, including those vital for photosynthesis. This process, in turn, contributes to a progressive increase in oxygen production over Earth’s geological timeline.

Life may be restricted to older worlds

“This work has both positive and negative implications for the likelihood of aerobic, complex life existing on other worlds,” wrote the researchers.

“On one side, we can create an oxygenated world in our model without needing a succession of specific tectonic or biological events to do so, meaning that one might expect more photosynthetic Earth-like planets, with an atmosphere, ocean and active crustal recycling, to be oxygen-rich.” 

“However, the long timeframe of carbonate build-up on Earth implies that an oxygen-dependent biosphere could have been stymied on a similar sized rocky planet until billions of years after planetary formation, thus it may be more probable that intelligence is restricted to older worlds or those with styles of crustal recycling permissive to more rapid build-up of crustal carbon inventories.”

Predicting the potential chemistry of other planets

Initiated during Alcott’s tenure as a Hutchinson Postdoctoral Fellow at Yale University, this research lays the groundwork for future explorations into the complex interplay between planetary temperature, oxygen levels, and nutrient availability.

“We have lots of information about distant stars and the size of the planets that orbit them. Soon this could be used to make a prediction of the planet’s potential chemistry, and new advances in telescope technology should let us know if we are correct,” concluded co-author Benjamin Mills, a professor of earth system evolution at the University of Leeds.

The study is published in the journal Nature Geoscience.

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