Climate change and the rise of atmospheric oxygen

March 23, 2006

Today's climate change pales in comparison with what happened as Earth gave birth to its oxygen-containing atmosphere billions of years ago. By analyzing clues contained in rocks, scientists at the Carnegie Institution's Geophysical Laboratory have found that the initial rise of oxygen (O2) was transitory and that its final emergence may have been linked to volcanoes and catastrophic glaciations.

"Rocks contain fingerprint-like clues to the past environment through specific variations in elements such as sulfur," explained Carnegie researcher Shuhei Ono. "Our Earth didn't start out with oxygen in the atmosphere. It probably contained methane and hydrogen, but no oxygen. We think that there were microbes in the oceans, before the oxygenated atmosphere, which would have used methane for energy. Measuring sulfur isotopes--different versions of the atom with the same number of protons, but a different number of neutrons--in rock samples provides a sensitive way to monitor ancient oxygen levels. Oxygen first appeared on the surface of the Earth when microbes developed the capacity to split water molecules to produce O2 using the Sun's energy. This is a bit advanced biochemistry, but we think this biological revolution emerged sometime before 2.7 billion years ago," he continued.

Ono looked at sulfur isotopes from South African drill-core samples covering the time interval from 3.2 to 2.4 billion years ago. Around 2.9 billion years ago, the methane-dominated atmosphere provided a greenhouse effect and kept the planet warm. His analysis suggests that when oxygen first appeared in the atmosphere, around that time, it would have reacted with the methane, destabilizing the atmosphere and triggering the Mozaan-Witwatersrand glaciation.

The oxygen atmosphere wasn't here to stay, however. "It was a raucous time," stated Carnegie's Andrey Bekker. "Volcanoes peppered the Earth's surface, belching gases and particulates into the atmosphere. That material rained back to the surface and oceans, affecting ocean chemistry and the ocean and atmospheric cycles. We looked at sulfur isotopes in shale and pyrite from Western Australia and found that between 2.47 and 2.463 billion years ago oxygen levels started to rise. But the intense volcanic activity made it almost disappear again. Despite these fits and starts, our oxygen atmosphere prevailed in the end."

The work is presented in several talks at NASA's Astrobiology Science Conference (AbSciCon) 2006 in Washington, D.C., March 26-30. See for details.

Source: Carnegie Institution

Explore further: The moon

Related Stories

The moon

September 21, 2015

Look up in the night sky. On a clear night, if you're lucky, you'll catch a glimpse of the moon shining in all it's glory. As Earth's only satellite, the moon has orbited our planet for over three and a half billion years. ...

Researcher discusses where to land Mars 2020

September 8, 2015

In August 2015, more than 150 scientists interested in the exploration of Mars attended a conference at a hotel in Arcadia, California, to evaluate 21 potential landing sites for NASA's next Mars rover, a mission called Mars ...

Ice sheets may be more resilient than thought

September 3, 2015

Sea level rise poses one of the biggest threats to human systems in a globally warming world, potentially causing trillions of dollars' worth of damages to flooded cities around the world. As surface temperatures rise, ice ...

The gas giant Jupiter

August 26, 2015

Ever since the invention of the telescope four hundred years ago, astronomers have been fascinated by the gas giant known as Jupiter. Between it's constant, swirling clouds, its many, many moons, and its red spot, there are ...

Recommended for you

Perfectly accurate clocks turn out to be impossible

October 7, 2015

Can the passage of time be measured precisely, always and everywhere? The answer will upset many watchmakers. A team of physicists from the universities of Warsaw and Nottingham have just shown that when we are dealing with ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

3 / 5 (2) Apr 08, 2009
How DARE the earth change the climate without first consulting with the dominant species on the planet, the UN IPCC! I doubt the UN IPCC would have approved of the outrageous pumping of deadly gases like pure oxygen into the pristine and fragile atmosphere of the early earth.

I suggest an additional 25% across the board income, energy, and consumption tax on all U.S. citizens AND their pets and livestock who breathe oxygen as a retroactive penalty for benefiting from this horrible climate crime perpatrated only a scant few billion years ago.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.