Tropical Ice Core Reveals Pre-Industrial Methane Source Patterns

Discovery in the Peruvian Andes

Researchers have established a 2,000-year record of atmospheric methane by analyzing an ice core from the summit of Nevado Huascarán, the highest tropical mountain in the world located in the Peruvian Andes,. By examining small air bubbles trapped within the ancient ice, the team studied how methane concentrations evolved over two millennia.

The study found that methane concentrations recorded in the tropical ice core broadly align with global fluctuations previously documented in polar ice cores. However, the concentrations found at Nevado Huascarán were slightly higher than those recorded in polar regions.

Tropical Methane Contributions

To determine the origin of the gas, Kara Lamantia and her colleagues applied the measured data to a model simulating how gases move between different latitudes. The resulting estimates indicate that tropical sources supplied approximately 24% more methane than data from polar cores alone had previously implied.

Lamantia clarified that these findings do not alter the total amount of methane estimated to have existed in the pre-industrial atmosphere, but rather clarify the geographic origin of the emissions. "This doesn’t necessarily change how much methane was in a pre-industrial atmosphere but rather where it was produced," Lamantia told Earth.com.

Pre-Industrial vs. Industrial Drivers

The results provide empirical support for a long-standing scientific hypothesis regarding the shift in methane drivers over time. The data suggests that methane emissions from tropical sources, such as the Amazon rainforest, likely dominated global emissions during the pre-industrial period.

This tropical dominance contrasts with the modern era, where there has been a rise in methane emissions driven by human activities, specifically industrial processes and agricultural practices.

Future Applications

Researchers intend for these findings to be incorporated into future climate models to improve the accuracy of Earth's atmospheric history. According to the research, understanding the past behavior of methane sources is essential for better understanding current climate conditions and planning for future environmental changes.