As the Earth continues to heat up, the consequences of global warming are becoming increasingly evident worldwide. However, looking back in geological history, we find that episodes of global warming are not altogether uncommon. Researchers from Mainz University have recently published a research paper in Nature Geoscience, exploring the potential of blending crushed rocks with arable soil to mitigate rising temperatures. By analyzing global warming events that occurred 40 and 56 million years ago, the study offers insights into the relationship between climate change and weathering processes.
Approximately 56 million years ago, the Earth experienced a period known as the Paleocene-Eocene Thermal Maximum (PETM). During this time, average temperatures rose by 5 to 8 degrees Celsius. This increase in temperature was likely caused by heightened volcanic activity, leading to the release of large amounts of carbon dioxide into the atmosphere. These elevated temperatures persisted for approximately 200,000 years. Similarly, around 16 million years after the PETM, the Middle Eocene Climatic Optimum (MECO) saw another period of climate warming, lasting a staggering 400,000 years. Despite comparable levels of volcanic activity and carbon dioxide release to the PETM, the climate took significantly longer to stabilize during the MECO.
The Role of Weathering
Professor Philip Pogge von Strandmann of Johannes Gutenberg University Mainz and his team sought to understand the factors contributing to the prolonged stabilization period during the MECO. The researchers analyzed 40-million-year-old oceanic carbonates and clay minerals, comparing them with similar samples from the PETM. They found that, unlike during the PETM, the Earth’s surface 40 million years ago was predominantly covered by clay minerals rather than exposed rock. As clay does not weather like rock, this phenomenon known as “soil shielding” prevented effective weathering despite the high temperatures.
Building upon their findings, the researchers considered how this knowledge could be applied to address current climate challenges. They propose the concept of enhanced weathering to harness the positive impact of weathering on global temperatures. This could involve the addition of finely crushed rock to agricultural fields, stimulating rapid erosion and the binding of atmospheric carbon dioxide. The goal would be to enable the climate to recover through the removal of carbon dioxide from the atmosphere.
However, the efficiency of such a method hinges on the outcome of weathering. If rock particles fully dissolve during the process, the effectiveness of enhanced weathering would be 100%. Conversely, if all weathered materials turn into clay, the climate impact would be nullified. In reality, the result would likely fall somewhere between these two extremes. The extent of rock dissolution and clay formation depends on various local factors, including pre-existing levels of clay and rock.
Before implementing enhanced weathering on a large scale, several crucial factors need to be evaluated. One such factor is the determination of clay formation during the weathering process at potential locations. Additionally, negative emissions technologies (NETs), such as enhanced weathering, are currently under intense global research. It is important to understand the overall efficiency and long-term implications of these technologies.
The study conducted by researchers at Mainz University provides valuable insights into the potential of enhanced weathering as a means to mitigate global warming. By understanding the relationship between climate change and weathering processes, we can explore innovative strategies to address the challenges posed by rising temperatures. While enhanced weathering shows promise, further research is needed to fully determine its efficacy and ensure its application aligns with the long-term sustainability goals of combating climate change.