Although it is located on the far western side of the Hindukush-Karakoram-Himalaya (HKH) massif, Pakistan lies still at its center. It’s the only country with a share in all three mountain ranges and it lies at the bank of the Indus, a river especially sensitive to any change further upstream.
The three mountain ranges that span from Kabul in the west all the way to the easternmost parts of India are dominated by surprisingly different climates. Westerlies bring a lot of winter precipitation to the Hindukush and the Karakoram, while most of the water that reaches the Himalaya from above comes through the summer monsoon, with otherwise relatively dry periods. As simple as this differentiation sounds, it is important to understand the current state and future challenges of the region.
Glaciers have always captivated the human mind for their vastness, them being a source of life and risk at the same time and because through them we can see our climate changing in an especially striking manner. Significantly, they are not the only direct source of water to the big waterways running down from the Asian Water Towers – a term made popular by a widely cited publication that highlights the crucial role of mountains in Asia’s water supply. A large part of runoff is generated directly from rain and melting snow, and what we know least about yet is the part that first reaches the groundwater before it wells up again as springs. When talking about water sources all these parts of the equation need to be kept in mind – none of these alone can sufficiently tell us about volume, time, and location of surpluses or shortages in future.
However, looking at scientific work in the area, most of the focus still lies on glaciers. We can observe them from space more easily than changing fields of snow and the highly variable precipitation patterns. One major challenge for all studies is still a lack of weather stations in the region. While we can get all climatic variables from satellites, we are doing a horrible job in representing the local patterns in mountains accurately from space. Field data is necessary to validate these products and to calibrate larger scale models. However, such field work takes time and resources – and a passion for working outside. Our work tries to balance this – bringing insight from the field into models and datasets that will eventually tell us something about changes on a larger scale.
Glaciers – recent changes and current challenges
Like everywhere else on the planet, glaciers in High-Mountain Asia are overall in constant retreat. But recent studies emphasize that, firstly, changes in runoff are likely not going to be rapid anywhere soon, the seasonal availability may shift which is a crucial aspect when looking at hydropower and irrigation, and natural hazards associated to glacier retreat may become more frequent. Secondly, changes in the region are highly heterogeneous, ranging from rapid mass loss in the East to even mass gains on glaciers in Northern Pakistan and on the Chinese side in the Kunlun Shan range. Pakistan lies at the focus of all of these and at the same time our understanding of processes and available data here is still very poor.
Relevant for irrigation and hydropower use in the Indus basin is that summer discharge peaks are expected to decrease towards other seasons and extreme events are going to become more frequent. On the local scale, increasing lakes with retreating tongues hold a potential for more violent floods that can be threatening towards infrastructure and agriculture. In the Karakoram specifically, a very peculiar form of glaciers pose an additional risk. Glacier tongues that repeatedly extend in length – but while doing so, keep a stable mass or even lose mass – are especially common in the region. These surging glaciers make up nearly 50 percent of all the glaciers found here. A very well studied surging glacier in the Shimshal valley is currently being monitored as it has created a lake further downstream, which could eventually break. It’s important to note that this is a process that is likely not related to a changing climate, but concerns a type of glacier that is still poorly understood but common in the area.
What makes these surging tongues even more confusing is the fact that at the same time the Karakoram-Kunlun Shan region seems to have very stable ice masses or even some increases over multiple years, contrary to everywhere else in High-Mountain Asia. We refer to this as the Karakoram anomaly, and possible reasons are larger climatic variability or increased snowfall stemming from more irrigation in the Western Chinese Oasis, as was recently shown in new scientific research.
Finally, contrasting patterns in mass change were also brought in relation to the fact that glaciers in the region actually look quite different in the areas where they melt, the so called ablation zone. While glaciers are mostly imagined to be white masses of ice as far as the eye can see, many glaciers – the Baltoro flowing from the foot of the K2, one of the most famous examples – are covered in thick layers of rocks. This layer inhibits melt but at the same time features like ice cliffs and ponds appear on its surface that show high melt rates, making this a very challenging problem. However, the most curious feature of these features are probably the so called ice-sails.
Most of our research is currently still focused on trying to understand what happened in the past and what processes we can observe and explain today. But with the help of climate change projections, we can also take first peeks into the future. A recent study showed that under climate change scenarios that are currently being considered as possible in the international community, between 50 and 65 percent of all the glacier ice in High-Mountain Asia could disappear by the end of the century.
All these studies look at the sources of water, how these sources may change over time, and what possible consequence that will have for supply. An important part of the equation, however, is still not explored at all – how does the demand of the population downstream change? Populations grow rapidly, so does prosperity. As a consequence, the way people use water changes not just in volume, but also in the sector of industry. Any projections of change of the source should always be questioned regarding possible outcomes on the demand side. The politics and societal changes associated to that may be a multitude more complicated than the purely natural scientific challenges we face in the cryosphere.
Jakob Steiner is based at the University of Utrecht in the Netherlands and researches glaciers and hydrology in High-Mountain Asia, with a focus on catchments in Nepal and Pakistan. He has previously lived and worked in Pakistan.