From extreme flooding to droughts, find out more about the impacts that climate change is wreaking upon the Ganges
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Stretching from the Himalayas to the Bay of Bengal, the Ganges is a vital lifeline to many. In its entirety, the river basin supports 650 million people and flows through some of Asia’s most densely-populated regions. It also holds a quarter of India’s freshwater.
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However, the Ganges is transforming rapidly thanks to the ill-effects of a warming planet. From the melting of vast glaciers that exist near the river’s origin to droughts impacting its flow, the impacts of climate change on the river basin are severe and multifaceted.
Read on to find out more about some of these effects…
Glacial melting
The Ganges begins in the Himalayas, primarily from the Gangotri Glacier in the Indian state of Uttarakhand.
In the Himalayas, the largest body of ice on the planet outside of polar regions can be found – but climate change is accelerating the melt of the glaciers there with far-reaching impacts to the Ganges. In the last 70 years, the Gangotri Glacier has reportedly retreated more than 1,500 metres. And a 2019 report from the International Centre for Integrated Mountain Development found that the region could lose up to two-thirds of its glaciers by 2100 under high emissions scenarios.
Such melting is significant for the Ganges. In the short term, it may cause river flows and flooding to increase. But in the long term, reduced ice reserves threaten water supplies for millions of people. As such, a paradox is created: more floods in the short term, but more water scarcity in the future.
More intense droughts
In just the last few decades, the Ganges river basin has faced some of its worst droughts in its history, leaving stretches of river entirely unnavigable in summer. Canals that used to irrigate fields dry up early; wells that protected families for decades now produce little more than a trickle. In fact, scientists have said that the recent droughts that the Ganges has faced fall well outside the range of natural climate variability and can be attributed to climate change.
Drivers for this change include weaker monsoons driven by Indian Ocean warming, aerosol pollution and prolonged groundwater pumping.
Using paleoclimate reconstructions and hydrological modelling, scientists at the Indian Institute of Technology Gandhinagar and the University of Arizona have shown that the decline in streamflow since the 1990s has surpassed even the devastating 16th-century drought that led to widespread and severe famine across northern India.
Droughts impact the Ganges’ flow, which also has a cascading impact on its ability to dilute pollution. This has reinforced it as one of the most contaminated rivers in the world, since lower discharge means pollutants become more concentrated.
Dwindling biodiversity
Climate change is also posing a real threat to the biodiversity of the Ganges.
One study found that the river basin is losing oxygen 20 times faster than the global average, a phenomenon that scientists attribute largely to a warming planet. Since the waters of the Ganges were already warm, they already had lower levels of dissolved oxygen. This means it was already closer to reaching a state of hypoxia – a state whereby water has insufficient oxygen to sustain most life.
With rising temperatures only adding to this warmth, it’s clear to see how the river loses a large majority of its oxygen. Even a small drop in levels can quickly lead to mass die-off events for a variety of marine species.
Warmer waters are also alluring to non-native species in the Ganges, like the common carp or Eurasian carp (Cyprinus carpio), Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus). The introduction of these fish has critically depleted many native species – especially Indian carps – in the Ganges.
As climate change continues, non-native species will only continue to thrive in the river basin. In contrast, native species face greater stress due to changes in rainfall and temperature.
What can be done to help?
Researchers stress the need for urgent, coordinated action to help protect the Ganges for generations to come.
Firstly, this will involve reducing unsustainable extraction of groundwater, so supplies can replenish. As well as this, improved climate models, which are able to include human pressures – such as irrigation and damming – will help to guide accurate and effective water policy.
Cooperation between countries is also vital, with scientists advocating that Nepal, Bangladesh and India should manage dams, share data and plan for climate change collectively.
In addition, governance should be inclusive, incorporating local voices to shape river restoration efforts alongside scientists and policymakers.
Ultimately, a lot of hard work and perseverance are needed to protect the Ganges – but without such efforts, it is almost certainly going to be altered by the impacts of a warming planet.
