The researchers grouped up all measurements of methanethiol in seawater and added them to measurements made in the Southern Ocean and the Mediterranean coast. Using seawater temperature collected from satellite data, they then used statistics to calculate their results. Yearly, methanethiol increases marine sulfur emissions by 25%.
“It may not seem like much, but methanethiol is more efficient at oxidizing and forming aerosols than dimethyl sulfide and, therefore, its climate impact is magnified,” says Dr. Julián Villamayor, a researcher at the Blas Cabrera Institute of Physical Chemistry in Spain.
The team also added marine methanethiol emissions to a climate model to measure their effects on the planet’s radiation. The impact is more visible in the Southern Hemisphere, where there are more oceans and fewer humans burning fossil fuels. While sulfur aerosols are important in cooling the planet, the authors note that human behavior will determine whether the planet continues to warm.
Paper Summary
Methodology
The research team embarked on a comprehensive study of methanethiol (MeSH), a little-known sulfur compound in the ocean. They collected seawater samples from diverse marine regions, including the Atlantic Ocean, Nordic Seas, Northeast Pacific, Southern Ocean, and Mediterranean Sea. By carefully measuring the concentrations of MeSH and dimethyl sulfide (DMS) in these samples, the researchers developed a sophisticated statistical model to predict MeSH concentrations.
This model took into account various environmental factors such as sea surface temperature, water depth, and chlorophyll concentration. After creating global maps of MeSH emissions, they used an advanced climate model called CAM-Chem to simulate how this compound interacts with the atmosphere.
Key Results
The study uncovered fascinating insights into ocean chemistry and climate regulation. Researchers discovered that MeSH, previously overlooked, is a significant player in the Earth’s climate system. This compound represents approximately 19% of ocean-emitted sulfur compounds, and when incorporated into climate models, it increases atmospheric sulfur by 34%.
The Southern Ocean emerged as a particularly important region for MeSH emissions, especially during summer months. The most groundbreaking finding was MeSH’s role in creating more reflective aerosols, which can help cool the planet by reflecting sunlight back into space.
Study Limitations
The team acknowledged the scarcity of historical data on MeSH concentrations, with most measurements taken during the summer months. Their global emissions estimates relied on statistical models, which inherently carry some uncertainty. The researchers also recognized potential variations in the chemical reaction rates and MeSH production by marine microorganisms. These limitations don’t invalidate the research but provide important context for understanding the study’s scope and potential areas for future investigation.
Discussion & Takeaways
The study challenges previous understanding of how oceans regulate climate. It reveals that MeSH is more than just a simple byproduct – it’s an important climate agent. The research suggests that ocean microorganisms produce a more complex array of sulfur compounds than scientists previously believed. By including MeSH in climate models, researchers might better explain existing discrepancies in Southern Ocean climate simulations.
The findings lend additional support to the long-standing CLAW hypothesis, which proposes that marine life plays a crucial role in climate regulation through the emission and transformation of volatile sulfur compounds.
Funding & Disclosures
This international research effort was supported by a diverse array of funding sources, including the European Research Council, Spanish Ministry of Science and Innovation, Argentine research institutions, the US National Science Foundation, Alfred Wegener Institute, French research programs, and the Indian Ministry of Earth Sciences. Despite the multiple funding sources, the researchers emphasized their commitment to scientific integrity by declaring no competing interests.
The study was a collaborative effort involving researchers from multiple international institutions, with a special acknowledgment to Ron Kiene, a pioneering researcher in marine sulfur compounds.