I ghiacciai dell’Himalaya forniscono acqua ed energia a quasi due miliardi di persone.

Vast mountain glaciers helping provide water, irrigation and power for up to two billion people are expected to shrink by at least a third as temperatures heat up this century, scientists have warned.

The ice caps of the Hindu Kush Himalaya region feed some of the world's mightiest rivers and have been likened to the “water tower of Asia” (the Hindu Kush Himalaya holds more ice than anywhere outside the two poles).

But global warming is on course to thaw swathes of their cover even if the world hits ambitious targets to limit temperature rises, according to a new report on their future.

Forecasts of the impact of climate change have focused on islands and coastal zones, overlooking the effect on an area known as a “third pole” because of the amount of ice it holds.

"This is the climate crisis you haven't heard of," said Philippus Wester, who led the report.

The glacier region straddling Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal and Pakistan will shrink by two-thirds if no progress is made reining in emissions, he predicted.

"Global warming is on track to transform the frigid, glacier-covered mountain peaks of the HKH cutting across eight countries to bare rocks in a little less than a century," said Mr Wester of the International Centre for Integrated Mountain Development (ICIMOD).

The report, by 210 authors, said 36 per cent of the ice in the region will melt by 2100 even if governments hit the most ambitious 2015 Paris climate agreement targets to limit temperature rises to one-and-a-half degrees.

If not action is taken to reduce emission of green house gases, two-thirds of the ice will go.

Glaciers have thinned and retreated across most parts of the region since the 1970s. Ice in the Hindu Kush Himalaya region would push up sea levels by 1.5 metres if it all melted, Eklabya Sharma, deputy director general of ICIMOD, told Reuters.

The thaw will disrupt rivers including the Yangtze, Mekong, Indus, Yellow, Ganges which directly or indirectly supply billions with food, energy and livelihoods.

The Himalayan glaciers, formed some 70 million years ago, are highly sensitive to changing temperatures. Since the 1970s, they have thinned and retreated, and areas covered by snow and snowfall have decreased.

Effects from their melting will range from worsened air pollution to more extreme weather. Changed river flows will throw urban water systems and food and energy production off-kilter, the study warned.

As glaciers have retreated they have also increased the number of dangerous glacial lakes that can burst unleashing catastrophic floods into valleys below.

Pakistan is thought to have some 3,000 glacial lakes alone and and a survey has found 33 considered at risk of bursting in Gilgit-Baltistan and Khyber Pakhtunkhwa, threatening seven million people.

The 2015 Paris Agreement seeks to keep a global temperature rises this century well below two degrees Celsius above pre-industrial levels, and aim to keep them to 1.5 degrees if possible.

  • World leaders in December agreed on a common rule book to implement the accord. But major polluters, including the United States and Saudi Arabia, disputed a landmark scientific report released in October that suggested nations must slash fossil fuel use by nearly half in a little over a decade. ( Ben Farmer - Telegraph)