Pune: A new study of the upper Indus basin in the northwestern Himalayas has identified an unexpected geological source of atmospheric carbon dioxide (CO2): the oxidation of pyrite, commonly known as “fool’s gold”.
The study found that in the glaciated parts of the upper Indus basin, CO2 released through pyrite oxidation exceeds the CO2 consumed through silicate weathering. To quantify this process, the study analysed water chemistry along with sulfur and oxygen isotopes from the upper Indus catchment. The analysis allowed the researchers to distinguish the contribution of pyrite oxidation and assess its effect on the regional carbon balance. The result is a net geological release of CO2 from these landscapes. Glaciers, rivers and associated erosion continually expose fresh rock surfaces to chemical reactions, potentially accelerating processes such as pyrite oxidation. The researchers stressed that this is a long-term geological process, operating over timescales of millions of years, rather than evidence that Himalayan glaciers are suddenly becoming a major modern-day source of atmospheric CO2 comparable to human emissions. The study nevertheless highlights the complexity of the relationship between rock weathering and climate. the presence and oxidation of minerals such as pyrite can alter the overall carbon balance of a river catchment While silicate weathering is generally considered an important natural mechanism for removing atmospheric CO2.
The study was conducted by researchers from the Department of Earth and Climate Science, Indian Institute of Science Education and Research (IISER) Pune The study, published in the journal Chemical Geology on July 17, 2026, examines the role of pyrite oxidation in the carbon cycle of the upper Indus basin. Because the Himalayas are among the most rapidly eroding mountain systems on Earth, the finding is particularly significant.
