The melting of the Himalayas and Karakoram ranges affects one billion Asians
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Nearly a billion people depend on the Indus, Ganges and Brahmaputra river basins for their lives and livelihoods, but they are threatened by the impact of global warming on the Himalayan and Karakoram ranges. According to a recent international study by researchers from India, Pakistan and Nepal, the melting of snow and glaciers will increase the flow of rivers. In addition, seasonal changes will affect agriculture, the hydroelectric sector and other livelihoods in the region, and will cause flooding.
In India, in the Indus River Basin, are the Union Territories of Jammu, Kashmir, and Ladakh, the states of Himachal Pradesh and Punjab, and northern parts of Haryana and Rajasthan. In the Ganges basin are Uttarakhand, Delhi, the rest of Haryana, Uttar Pradesh, Bihar, Jharkhand, West Bengal, and much of Rajasthan and Madhya Pradesh. Sikkim and Arunachal Pradesh, and most of Assam, Megalaya and Nagaland are located in the Brahmaputra river basin. The inhabitants of all these cities and regions represent almost 13% of the world's population, that is, one in eight people on the planet. These include citizens of the megacities of New Delhi, Lahore, Karachi, Calcutta and Dhaka.
According to the study, the usual runoff from rivers - the water that flows into them - in the Karakórum region, in the Himalayas (Himalaya-Karakoram, HK, in its acronym in English), is formed from the melting of glaciers and snow, from rainfall and groundwater flows, which are those that are stored in the subsoil with the rains that infiltrate.
Half of the ice in the HK region is held in glaciers. The rate and timing of these melts affects the flow of the river in different seasons. Normally, the rivers carry melted snow from the mountains of HK in summer, from April to June; in October, winter hardens it again.
Global warming, which is affecting glacier, snow and rainfall patterns in the HK region, will have consequences for river basins. The study predicts that by 2050 there will be an increase in the melting of glaciers, in the total flow of rivers and in flows.
HK's river basins cover an area of 577,000 square kilometers and have a hydroelectric power generation capacity of 26,432 megawatts. The possible changes in the current of the rivers will affect the time of melting and the volume of water, which is the same as that used for irrigation. This supply is critical during the spring planting season as well as for stable hydropower generation in the pre-monsoon season.
“In the future we will have higher flows due to the intense melting [of the glaciers] and the increase in monsoon rains. Also, the glaciers are melting before summer; instead of in June, they are doing it in April. This means that the change in the seasonality of meltwater will affect livelihoods and the economy,” says Mohd. Farooq Azam, lead author of the research and adjunct professor at the Indian Institute of Technology in Indore.
The Karakoram Anomaly
As the paper discusses, changes in local, regional and global weather patterns resulting from global warming will have different impacts on glaciers in the HK region. While the flow in the Indus basin depends mostly on meltwater from glaciers and snow, the Ganges and Brahmaputra basins depend more on monsoon rains, Azam explains. Therefore, earlier melting means a more adverse impact for the inhabitants of the Indus Basin.
The estimated contribution of melting ice and snow to the total flow of the Indus River ranges between 21-40% and 22-49%, with estimates varying due to different methodologies, models and the latest period considered in each study. , as previous reports have shown. On the other hand, in the upper Ganges basin, melting ice and snow accounts for 20% of the total flow, while rainfall and groundwater contribute 66% and 14%, respectively, according to this investigation.
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Glacial melting is already changing the water regimes of Himalayan rivers and some of the immediate effects are seen in the drying up of springs, which are the main source of drinking water for those who live in the mountains, according to scientist Anjal Prakash. Increased flows would contribute to flooding downstream and affect the lives and livelihoods of the inhabitants. Prakash is Research Director and Professor at the Bharti Institute of Public Policy, Indian School of Business, Hyderabad, and lead author of the so-called Special Report on the Ocean and Cryosphere in a Changing Climate, published in 2018 and produced by the Intergovernmental Group of Experts on Climate Change.
“Mountain and downstream communities are more prone to climate risks, and the incidence of these climate-related disasters has increased in the region over the past two decades. This would greatly affect its inhabitants, since the Hindu Kush in the Himalayas is one of the most densely populated mountainous regions, and one of the most poverty-stricken in the world. Any small climate change will affect a large proportion of people,” explains Prakash.
The various impacts of glacial warming are well illustrated by the so-called Karakoram Anomaly, a term used by the scientific community to refer to the trend of stability or growth of glaciers in the Karakoram Range. This is opposed to that of the Himalayas, whose glaciers are retreating due to climate change.
Glacial shrinkage or growth is called glacier mass balance, and indicates the sum of snow accumulation and loss of snow and ice during the summer. When accumulation exceeds loss, we speak of positive mass balance.
“Compared to other parts of the Himalayas, the Karakoram has a positive mass balance and is therefore an anomaly. Some say that it is due to the peculiar atmospheric conditions, the increase in snowfall or temperatures. Also, its glacial terrain is higher up,” says Anil Kulkarni, co-author and Distinguished Visiting Scientist at the Divecha Climate Change Center in Bangalore.
Study co-author Jeffrey Kargel, a senior scientist at the Planetary Science Institute in Tucson, Arizona, explains that the impact of climate change on glaciers in the HK region is very complex. Kargel argues that the climate is warming at different rates in different parts of the Himalayas, and that summer temperatures in the Karakoram, for example, remain stable or perhaps decrease in some valleys, due to increased cloudiness, which in turn causes a flow of moisture.
“These areas of the Karakoram are one of the few places in the world where the positive mass balance of the glaciers is taking place. But generally, temperatures are rising rapidly. In part it is due to the increase in greenhouse gases, as in other parts of the world, but in another part the increase in temperature is due to the absorption of sunlight in the 'brown cloud' of pollution. Air pollution is another big effect, but climatologists do not reach an agreement on what is happening in particular, "says Kargel.
On the other hand, Kargel explains that the increase in meltwater that comes from glaciers in a short time is similar to a bank account that has an increase in liquidity in the short term, but that will be depleted in the long run. “The water that the rivers have stored in the form of ice can produce a great increase in the supply of water in the short term, as the climate warms; but in the long run the situation becomes more precarious, because eventually the ice 'savings account' is emptied. This is an issue that water managers must take into account,” adds Kargel.
Preparing for changes in the water current
The findings of the international study are also based on a review of the main reports on the area, with the aim of highlighting the issues related to glaciers and climate change in the HK region and their impact on hydrology, as well as identify gaps in glaciology and hydrology research. Since millions of people depend on the three river basins, the authors argue that these gaps in research on the effect of warming on glaciers in this region need to be addressed.
“Precipitation is a key factor that needs to be studied. It varies from valley to valley, and currently available information on precipitation is largely for the lower altitudes, around 1,000 meters. The HK region exhibits high topographic variability with different precipitation regimes. And this is not captured well in the models”, explains Azam.
Some of the recommendations made by the study are the extension of observation networks to higher altitudes, the establishment of fully automatic meteorological stations at higher altitudes to monitor temperatures and precipitation, and the development of projects to analyze the surface and the volume of glaciers. An international collaboration equivalent to NASA's Icebridge mission, which surveys the poles through an aerial survey of polar ice, is also suggested.
Article originally published on IndiaSpend.
Nikhil Ghanekar is a special correspondent for IndiaSpend reporting on the environment, climate change, water resources, wildlife and politics.
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