ISLAMABAD, March 11: The Planning Commission expects glacial reservoirs feeding Pakistan’s irrigation system will be empty after about 50 years, resulting in up to 40 per cent permanent reduction in river flows owing to fast depletion of Himalayan glaciers.

Estimates show that an increase in global warming will be fast melting glaciers in the next 50 years. River flows would increase in these years. But after 50 years, "there is likely to be a dramatic permanent decrease in river flows by 30-40 per cent in the Indus Basin," reads a working draft of Vision 2030.

It also says that nine out of 10 general circulation models used by the Intergovernmental Panel on Climate Change (IPCC) project during summer monsoon will increase substantially. This increase in the overall monsoonal rainfall in Pakistan is "likely to be poorly distributed" in the sense that much of the additional rainfall is likely to be in "high-intensity storm events".

Based on this premise, the Planning Commission pleads that building of major new water storages and raising of many of the existing ones will allow exploiting one positive aspect of global warming. These plans (also including already announced five mega dams) should also dovetail some major run-of-the-river hydropower projects because these are cheap and eco-friendly, providing more energy and also regulating flow of water into the sea.

The Planning Commission also envisages "extensive use" of coal-fired plants based on indigenous and imported coal over the next two decades, domestic exploration of oil and gas and promotion of efficiency, conservation and demand management. It also plans to facilitate Pakistani companies like OGDCL and other oil and gas exploration entities to enter into joint ventures for overseas projects for securing oil and gas reserves.

Senior officials told Dawn that the Planning Commission in reaching these conclusion had relied on recent reports of the Pakistan Meteorological Department, IPCC and Earth Policy Institute, suggesting that Pakistan was likely to face major water crisis -- flood and drought -- in the next 20-50 years owing to unusually fast depletion of the Himalayan glaciers and other related uncertainties.

Sources cited some reports that indicated that the Himalayan glaciers, contributing over 80 per cent water to river Indus that fed more than 65 per cent of the country's agriculture, were receding at a rate of 30 metres to 50 metres annually. The Himalayas contain world's third largest ice mass after Antarctica and Greenland.

One of these reports, according to the sources, said that most Himalayan glaciers had been thinning and receding over the past 30 years, with losses accelerating to alarming levels in the past decade. “This means which should have the capacity to save today’s water for tomorrow and live for 100 years or so without any major crisis,” they said.

Another report suggested that some of the scientists, who had noticed the retreating trend of glaciers, indicated that the depletion was occurring faster on the Eastern side than the Western side of Himalayas which fed Pakistan's rivers. The higher pace of glacier melting could trigger huge water flows 20 years from now but it could cause severe drought in the next 20 to 25 years.

The Met office has recently provided a detailed report on the impact of climate change on Indus river flow and on glacier's eco-hydrology. The report had categorised the Himalayan mountain system as one of the youngest, most sensitive and interactive atmosphere-snow-land-ocean mountain systems on the planet. The Himalayan snow-glacier system formed the tallest water tower.

The report said that the average annual water flow in the river Indus had been about 34 million acre-foot (MAF) for the period 1975-90 despite a wet-spell that increased the discharge by more than 40 per cent to an annual average of 51.16 MAF.

The report said that Himalayan snow and ice region covered an area of about 4.6 million square kilometres above 1,500 metres, 3.2 square kilometres above 3,000 metres and 0.56 square km above 5,400 meters. Talking about the distribution of permanent snow and ice in the Himalayan region, the report said that glaciers covered between 10 and 20 per cent of the total surface area, seasonal snow cover was 30 to 40 per cent of the surface area and melt-water contribution diminishes from west to east, being the greatest in the Indus basin.

An official, quoting one of these reports, said that as glaciers melted, they were rapidly filling glacial lakes, creating a flood risk.

An international team of scientists warned that if the current melt rates persisted, it was possible that at least 44 glacial lakes in the Himalayas could burst their banks within the next five years.