Continental rifting can heat up the planet
When it comes to carbon emissions in our atmosphere, a major producer was at work long before humans began spewing greenhouse gases from factories and vehicles: Earth itself. Continental rifting – the process in which continents break apart from one another – releases massive amounts of carbon dioxide into the air.
A team of scientists from Potsdam’s GFZ German Research Centre for Geosciences recently turned their focus on rifting, to discover whether the shifting of the Earth’s tectonic plates has more or less of an effect on atmospheric carbon than underwater volcanic activity.
More than 99 percent of the carbon on Earth is captured deep underground. Volcanic activity can allow some of this carbon to escape in gas form and enter the atmosphere.
However, the team led by Dr. Sascha Brune found that continental rifting releases much more carbon dioxide from under the Earth’s surface.
“Rift systems develop by tectonic stretching of the continental crust, which may lead to break-up of entire plates,” Brune said. “The East African Rift with a total length of [more than 3,720 miles] is the largest in the world, but it appears small in comparison to the rift systems which were formed 130 million years ago when the supercontinent Pangea broke apart, comprising a network with a total length of more than [24,800 miles].”
Using scientific models, the team worked backwards to see where and how active rift systems may have been during the past 200 million years of Earth’s history. They found that 50 million and 130 million years ago, rift systems may have been much larger and more active than at other points in geological history.
When they compared their findings against models showing the makeup of the Earth’s atmosphere during those periods, they found spikes in atmospheric carbon.
Human activity releases more carbon dioxide than continental rifting does, Brune noted.
“The global [carbon dioxide] degassing rates at rift systems, however, are just a fraction of the anthropogenic carbon release today,” he said. “Yet, they represent a missing key component of the deep carbon cycle that controls long-term climate change over millions of years.”
The study has been published in the journal Nature Geoscience.
Image credit: Dr. Sascha Brune, NASA WorldWind