The Conversation contributed the article to Space.com's expert voices.
Dietmar Müller (opens in new tab), Professor of Geophysics, University of SydneyAdriana Dutkiewicz (opens in new tab), ARC Future Fellow, University of SydneyAndrew Merdith (opens in new tab), Research fellow, University of LeedsBen Mather (opens in new tab), Research fellow, University of SydneyChristopher Gonzalez (opens in new tab), Research Fellow, The University of Western AustraliaSabin Zahirovic (opens in new tab), Postdoctoral Research Associate, University of SydneyTobias Keller (opens in new tab), Senior Scientist in Computational Geosciences, Swiss Federal Institute of Technology ZurichWeronika Gorczyk (opens in new tab), The University of Western Australia
Contributor:
The level of carbon dioxide in the atmosphere has fluctuated for hundreds of millions of years. Humans have pushed CO2 levels to their highest in 2 million years due to burning fossil fuels, causing global warming that may make parts of the globe uninhabitable.
What can be done to make things better? Earth scientists look at how natural processes have recycled carbon from atmosphere to Earth and back in the past to find answers to this question.
In our new research, we show how volcanic activity, earthquakes, and erosion have controlled Earth's climate in the past. The " Goldilocks (opens in new tab) " climate our planet has enjoyed may be maintained with the help of these processes.
In the geological past, there were hothouse and icehouse climates. The temperature in the hothouse was up to 10 degrees higher than today and atmospheric CO2 levels were over a thousand parts per million.
During the Cenozoic Era, Earth's climate began to cool around 50 million years ago, with temperatures dropping to 7 degrees C.
The change in global climate was sparked by something.
We suspected that Earth's tectonic plates were to blame. We built a computer model of the carbon conveyor belt to better understand how plates store, move and emit carbon.
When two plates move away from each other, carbon is released into the atmosphere and magma rises to the surface.
Plates are pulled down and recycled back into the deep Earth at the same time. They carry carbon back into the Earth's interior, but also release some CO2 through volcanic activity.
Our model shows that the hothouse climate was caused by fast- moving plates, which increased CO2 emissions from mid- ocean ridges.
Volcanic CO2 emissions began to fall during the transition to the Cenozoic icehouse. We found a more complex mechanism hidden in the conveyor belt system that involved mountain building, continental erosion and burial of the remains of organisms on the sea.
The Himalayas and the Alps formed over the last 50 million years as a result of the slow down of the twinning plates. The volcanic CO2 emissions should have been reduced by this.
They tracked their source to carbon-rich deep-sea sediments being pushed downwards to feed volcanoes, increasing CO2 emissions and canceling out the effect of slowing plates.
What was the cause of the drop in CO2?
The mountains were responsible for slowing down the plates and storing carbon in the deep sea.
The mountains begin to be eroded as soon as they are formed. The mountain rocks are broken down by the rainwater containing CO2. The minerals are carried into the sea by rivers. The dissolved products are used by marine organisms to build their shells.
The process of forming new mountain chains was accelerated by the erosion of rocks. The planet cooled even though massive amounts of CO2 were stored away.
If the world is to reach net-zero greenhouse gas emissions, large-scale deployment of carbon dioxide removal methods is unavoidably.
A mineral called olivine is found in basalt, a rock that is very efficient in reducing atmospheric CO2. According to some estimates, spreading olivine on the beach could absorb up to a trillion tons of CO2 from the atmosphere.
Reducing our carbon emissions very quickly is necessary to avoid catastrophic global warming. Some human help may help maintain Earth's "Goldilocks" climate.
The study was carried out by researchers from the University of Sydney's Earth Byte Group and the University of Western Australia. The Office of the Chief Scientist and Engineer of the Department of Industry in the state of New South Wales was able to enable this.
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