The picture we often associate volcanoes with is red-hot lava and smoke from the eruption. However, a new study says that volcanoes may have been responsible for not only adding carbon dioxide to the surface atmosphere of the earth, but also removing it. In this way, volcanoes may have helped in stabilising the temperatures of the Earth’s surface.
Rocks on the surface of the Earth undergo chemical weathering. This is the process of disintegration and dissolution of rocks through various chemical reactions. When rocks undergo chemical weathering on the surface, some components are washed away into the water bodies such as rivers and oceans. When elements such as calcium and magnesium end up at the beds of water bodies, they interact with the carbon dioxide and lock it there.
This process, over time, helps with the regulation of the earth’s climate, through the regulation of CO2. “Many Earth processes are interlinked, and there are some major time lags between processes and their effects”, said Eelco Rohling, Professor in Ocean and Climate Change at ANU and co-author of the study. “Understanding the relative influence of specific processes within the Earth system response has therefore been an intractable problem.”
To study interaction in the Earth system, the researchers created an ‘Earth network’. It used a machine-learning algorithm and plate tectonic reconstructions. They found that for over 400 million years, continental volcanic arcs played an important role in weathering intensity. The arc refers to a chain of volcanoes, usually formed over a subducting plate. Several such arcs are present all across the world today, including the Andes, Philippines, and the Andaman & Nicobar Islands.
Volcanic rocks are one of the most chemically reactive and fragmented rocks. They erode rapidly and are weathered and flushed into the oceans. Thus, over geological history, volcanoes have been playing an important role in balancing the CO2 in the atmosphere. While they release carbon dioxide, they also play a part in trapping it back over time. The balance is reached over long periods of time.
Previous ideas suggested that ‘a balance between weathering of the seafloor and continental interiors’ was associated with the climate stability on the planet. “The idea of such a geological tug of war between the landmasses and the seafloor as a dominant driver of Earth surface weathering is not supported by the data,” noted lead author Dr. Tom Gernon, Associate Professor in Earth Science at the University of Southampton, and a Fellow of the Turing Institute.
Does that mean that active volcanoes can save us from the threat of the climate change we face today? “Unfortunately, the results do not mean that nature will save us from climate change”, stresses Dr. Gernon. “Today, atmospheric CO2 levels are higher than at any time in the past 3 million years, and human-driven emissions are about 150 times larger than volcanic CO2 emissions. The continental arcs that appear to have saved the planet in the deep past are simply not present at the scale needed to help counteract present-day CO2 emissions.”
Nonetheless, the authors suggest that the findings of the study may offer some hope. They suggest artificial weathering as a possible aid to push us closer to resolving the bigger problem. Using volcanic rock in the atmosphere and spreading it across wider land areas for faster chemical reactions, could help with CO2 removal.
The authors acknowledge that this may not be a complete solution to the climate crisis and that reducing carbon dioxide emissions is an urgent need. The results of this study have been published in the Nature Geoscience journal.
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