Ganga drying at an unprecedented rate; water, food security of 600 million threatened

The Ganga River basin is experiencing a severe and unprecedented drying trend, threatening water and food security of around 600 million people in India and neighboring countries, a new research study has warned.

In fact, the crisis is quite severe and the river is experiencing its worst drying period in 1300 years, the study underlined. As the Ganga is a vital source of water for drinking, agricultural production, industrial use and wildlife, the study has recommended implementing new adaptive water management strategies to mitigate potential water scarcity.

Using a combination of historical data, paleoclimate records and hydrological models, the study by researchers from IIT Gandhinagar and the University of Arizona in the US discovered that human activity is the main cause. The current drying is more severe than any recorded drought in the river’s history, the researcher noted.

The Ganga River has profound religious, cultural, and economic significance for millions living in India, Nepal, and Bangladesh. The river has been facing drying trends, but it had largely remained unclear so far whether the recent drying was unprecedented.

In their study, published in the Proceedings of the National Academy of Sciences, researchers first reconstructed the river’s flow for the last 1300 years by analyzing tree rings from the Monsoon Asia Drought Atlas (MADA) dataset. Then, they used powerful computer programmes to combine this tree-ring data with modern records to create a timeline of the river’s flow. To ensure its accuracy, they double-checked it against documented historical droughts and famines.

The scientists found that the recent drying of the Ganges River from 1991 to 2020 is 76 per cent worse than the previous worst recorded drought, which occurred during the 16th century. Not only is the river drier overall, but droughts are now more frequent and last longer. The main reason, according to the researchers, is human activity. While some natural climate patterns are at play, the primary driver is the weakening of the summer monsoon.

This weakening is linked to human-driven factors such as the warming of the Indian Ocean and air pollution from anthropogenic aerosols. These are liquid droplets and fine solid particles that come from factories, vehicles and power plants, among other sources and can suppress rainfall. The scientists also found that most climate models failed to spot the severe drying trend.

“The recent drying is well beyond the realm of last millennium climate variability, and most global climate models fail to capture it. Our findings underscore the urgent need to examine the interactions among the factors that control summer monsoon precipitation, including large-scale climate variability and anthropogenic forcings”, the authors noted.

Given the mismatch between climate models and what they actually found, the researchers are calling for better modeling to account for the regional impacts of human activity.