However, what is really worrying about the report is how little it has to say about the future of the Himalayas-Hindu Kush, a region on which nearly 40% of the world’s population depends for water. There was a striking lack of useful data on the possible fate of the largest store of fresh water outside the poles – and no available fieldwork, it would appear, on glaciers that feed all the major river systems of Asia.
There is a further worrying unknown: what impact might the loss of the Himalayan glaciers have on the monsoon, on which food security in south Asia depends? When the report was under preparation, it seems that the science of this region – one of the world’s most sensitive and volatile – was a black hole.
There are reasons for this lack of data. There are tens of thousands of glaciers that are difficult and expensive to get to. They are scattered across three major weather systems and countless microclimates. The countries in which they lie are not good neighbours and have little history of scientific co-operation.
To be a glacier scientist in tropical and temperate zones requires both scientific training and mountaineering skills. In most of the Himalayas, those with mountaineering skills are tribal people, and those with scientific training middle-class and urban. Since the glaciers lie in some of the most sensitive security regions in the world, scientists from elsewhere can find their work frustrated by national security suspicions.
Studying the glaciers, until recently, was not a high priority. Unlike the Alps, the Himalayas has a patchy photographic record and the history of scientific glaciology is short. Climate modelling is unreliable across big variations in altitude, and in the Himalayas it needs to be tested against data collected on the ground. But the collection of even basic data is sparse: for instance, weather stations on the Qinghai–Tibet plateau were located in towns so as to be easy to read. The result was that nothing was known about precipitation at high altitude, where the glaciers are.
This is one of the most complex regions on earth, and there are confusing local variations, such as in the Karakoram, where glaciers are advancing. But this anomaly does not alter the overall picture of retreat that affects 80% of the region’s glaciers, a retreat recorded by the Chinese Academy of Science’s extensive inventory.
The people of the region know that climate change has long-term implications for their water and food security. In the short term, it threatens the energy supplies of all the nations that rely on hydropower to fuel their economies.
Farmers in Nepal are already reporting new pests and diseases. Kyrgyzstan, scientists predict, will lose 80% of its water supply. Pakistan and India’s great rivers may become seasonal, and their monsoons erratic. The Yangtze and Yellow rivers will lose volume. The pace and pattern of glacier retreat is urgent, and needs to be understood through science – not dismissed by ignorant sceptics.