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WATER POLITICS

Courtesy of Circle of Blue, a report on how the melting of the Hindu Kush Himalaya region will alter water supplies for a quarter of the planet’s people:

• New analysis shows that the eight-country region will warm faster than the rest of the world in the coming decades

• At least one-third of the glacial ice will melt by 2100 even if the global temperature increase is held to 1.5 degrees Celsius

• At stake are the livelihoods of a quarter of the planet’s people, which are tied to the fate of 10 major rivers

The roof of the world is leaking and thawing, a heat-driven shift in ice and rain that will change the timing and availability of water for nearly two billion people from Afghanistan to China.

The Hindu Kush Himalaya region, a high-altitude tabletop from which nearly all of Asia’s great rivers spring, is at the front lines of climate change.

New analysis by an international consortium of some 350 scientists shows that the eight-country region, known as the Third Pole because of its massive ice fields, will warm faster than the rest of the world in the coming decades, especially at higher elevations.

If the global average temperature increase is held to 1.5 degrees Celsius (2.7 degrees Fahrenheit), an ambitious and increasingly unlikely target that requires net-zero greenhouse gas emissions by 2050, the Hindu Kush and Himalayas will see an additional 0.3 degrees Celsius of warming, according to the assessment.

The added heat is a death sentence for many of the region’s glaciers. At least one-third of the glacial ice will melt by 2100 even if the global temperature increase is held to 1.5 degrees Celsius. If the world continues on its current emissions and economic trajectory, half of ice could be lost, the report found.

“The massive size and global significance of the Hindu Kush Himalaya region is indisputable, yet this is the first report to lay down in definitive detail the region’s critical importance to the well-being of billions and its alarming vulnerability, especially in the face of climate change,” said David Molden, director general of the International Centre for Integrated Mountain Development, one of the organizations that guided the report.

At stake are the livelihoods of a quarter of the planet’s people, which are tied to the fate of 10 major rivers, including the Brahmaputra, Ganges, Indus, Mekong, and Yangtze, that are vital sources of water, food, and energy. Control of those rivers and access to their water are also delicate geopolitical concerns — such as between India and Pakistan over the Indus, and China and downstream countries over the Mekong — that could be upset by changes in river flow.

Each basin will feel the rise in temperature differently. In a few mountain basins, notably the Karakoram, glacier mass is expected to increase slightly because increased snowfall will offset melting.

Of the rivers, the Indus will be most affected by climate change, said Aditi Mukherji, a report co-author. That is because its flow depends more on glaciers and snow melt than rivers in the eastern half of the region, where the annual monsoon provides the bulk of the flow. A significant gap in understanding is the contribution of groundwater springs to rivers.

Rivers and mountains will be transformed in stages. In the short-term, flows will increase as glacial melt accelerates. But it is a one-time bonus, gone after the ice disappears.

The region is geologically young, the report notes, and like a teenager, is unruly and unsettled. Warmer temperatures aggravate this temperament by introducing more extremely hot days and more violent rainfall. In turn, there is a greater risk of deadly and destructive landslides, like the one in Nepal in August 2014 that killed hundreds of people, buried the main highway to China, and severed 10 percent of the country’s hydropower capacity. A year earlier, more than 6,000 people died in Uttarakhand in the worst flooding in the Indian state’s history.

Shrinking glaciers, though they provide additional water, also bring the risk of floods. Meltwater lakes that form at the toe of retreating glaciers can unleash powerful floods if natural rock dams give way or are overtopped. The International Centre for Integrated Mountain Development identified some 200 potentially dangerous glacial lakes. A ruptured glacial lake contributed to the Uttarakhand disaster.

Governments have options for adapting to changes in water availability, Mukherji told Circle of Blue. Most important will be managing stress within the agricultural sector. Two-thirds of water withdrawals in China and roughly 90 percent in the region’s other countries is used for irrigation.

“Agrarian transitions — moving people to non-farm sectors — is the most important thing we can do now to reduce pressure on land, and more importantly, reduce poverty, which in turn will open up other solutions,” Mukherji wrote in an email. “If governments do not manage these well, and chances are they won’t, we are looking at deepening farm distress.”

Even today, drought conditions and chronic water scarcity are forcing farmers in India, Pakistan, and elsewhere to abandon their orchards and fields and move to already-crowded cities to look for work.

There is much still to be learned about how rising temperatures will affect the region’s water, ice, and land, according to the report. Because of daunting terrain, on-the-ground measurements of snow and rain are scarce. At the same time, computer models struggle to account for local changes within the mountainous nooks and crannies.