Study by Oxford University Reveals Surprising Source of Carbon Emission

A new study finds that rocks release as much CO2, as volcanoes. This discovery reshapes climate science, raising questions about its impact on climate models.

Rock formations
Once believed to be great carbon absorbers, rocks have recently been discovered to release carbon into the atmosphere in quantities similar to that of volcanoes.

When it comes to carbon dioxide (CO2) sources, our focus often centers on fossil fuels and industrial emissions. However, recent research led by the University of Oxford has shed new light on a lesser-known player in the Earth's carbon cycle: rocks. This new discovery could have far-reaching implications for our climate.

The Earth's Carbon Balance

Scientists have long known that rocks hold a vast reservoir of carbon, stemming from the ancient remains of plants and animals that lived millions of years ago. This discovery unveils the profound role of the "geological carbon cycle," acting as a thermostat that helps regulate Earth's temperature.

For instance, during a process called chemical weathering, certain minerals in rocks can absorb CO2 when exposed to the mild acid found in rainwater.

This natural process counters the continuous CO2 emissions from volcanoes globally, contributing to Earth's natural carbon cycle, which has sustained habitable conditions for life for eons.

Unveiling the Startling Discoveries

However, for the first time, this study quantified an additional, previously overlooked natural process of CO2 release from rocks to the atmosphere.

Astonishingly, it is on par with the CO2 emissions from volcanoes worldwide. This process remains absent from most models of the natural carbon cycle.

The Mechanism Behind CO2 Release

This phenomenon occurs when rocks that formed on ancient seafloors, where the remains of plants and animals were buried in sediments, resurface.

As these rocks ascend to the Earth's surface, they expose the organic carbon trapped inside to oxygen in the air and water. This interaction triggers a chemical reaction that releases the trapped CO2.

In essence, instead of being a carbon sink (a source of carbon absorption), weathering rocks become a significant source of CO2 emissions.

This happens during tectonic activities that lead to the formation of mountains like the Himalayas or Andes.

Challenges in Measuring CO2 Release

Until now, measuring the release of CO2 from weathering organic carbon in rocks has proven to be a challenging task. In this study, researchers employed a unique approach using a tracer element, rhenium. When rock organic carbon reacts with oxygen, it releases rhenium into water.

By sampling river water to measure rhenium levels, the researchers were able to quantify CO2 release. However, the complexity arises when trying to scale this process up to a global level, as sampling all river water worldwide presents a daunting challenge.

Understanding the Global Impact

To estimate CO2 release on a global scale, the researchers took two crucial steps. First, they determined the quantity of organic carbon present in rocks near the Earth's surface. Second, they identified areas where these rocks were being exposed rapidly, primarily through erosion in steep, mountainous regions.

Work continues to be done to determine how human activity and climate change could exacerbate the natural release of carbon from rocks into the atmosphere.