Map of the Ganges River and Brahmaputra River basins.

iBase ID

381414

Creator

Caracappa-Qubeck, Amy

Title

Map of the Ganges River and Brahmaputra River basins.

Type

Illustration

Date

05/21/2012

File name

Ganges_Map.jpg

Notes

Caption from Oceanus magazine, vol. 49, no. 2, page 5:
With global temperatures continuing to rise, huge reservoirs of organic carbon stored in large river basins could be converted into heat-trapping carbon dioxide (CO2) gas and intensify climate change, according to new research by Woods Hole Oceanographic Institution scientists. Geochemists Valier Galy and Timothy Eglinton, with French colleagues, collected river sediments from the vast drainage basins of the Ganges River and the Brahmaputra River in Tibet, Nepal, northeastern India, and Bangladesh. They used radiocarbon dating to measure how long organic carbon remained in soils and river sediments before being flushed into the ocean. Although a fraction of organic carbon moved through the basins in a few hundred years, on average it remained in the river system for 3,000 years and in some cases more than 17,000 years. That means heavy loads of organic carbon were not flushed quickly out of the upper reaches of the rivers. Nor was the carbon rapidly decomposed by microbes, a process that converts organic carbon into CO2. The scientists hypothesize that warmer temperatures will stimulate more microbial decomposition of the stored organic matter and accelerate the release of more CO2 into the atmosphere. Similar stocks of ancient carbon may exist elsewhere in low-latitude river catchments, the scientists said. Global warming would likely destabilize this ancient carbon, generating an extra flux of CO2 to the atmosphere, which in turn would further warming. Galy and Eglinton compared the potential situation to a similar one in the Arctic, where microbes in thawing permafrost could convert large amounts of stored organic carbon into CO2. The study was part of a multiyear project funded by the National Science Foundation on the flow of terrestrial organic carbon from world rivers into the ocean. It was published in November 2011 in the journal Nature Geoscience.
Image Of the Day caption:
During monsoons, the Ganges and Brahmaputra Rivers export 50 metric tons of carbon-containing sediments per day into the Bay of Bengal. WHOI scientists study rivers around the world to analyze how much carbon comes from plants versus rocks and how that has changed over time. The studies can unravel interrelationships among geologic, climate, and anthropogenic changesfrom the emergence of the Himalayas and monsoons to the rise in greenhouse gases and dams. In one study, they found that global warming could destabilize a large pool of carbon stored in Ganges-Brahmaputra sediments and similar places on Earth, potentially releasing more carbon dioxide into the atmosphere.

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Illustration by Amy Caracappa-Qubeck

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