Climate Change in the Himalayas is a major topic of worry for climate watchers in the Subcontinent and across the world. The Himalayas have the largest deposits of snow and ice in the world outside the Polar Regions and is often referred to as the ‘Third Pole’ and also as the ‘Water Tower of Asia’.
Climate Change in the Himalayas: The Basic Possible Impacts
The issue of Climate Change in the Himalayas is drawing forward many observations, with observations of warming in the Himalayas indicating that mean temperatures are rising with a higher rate in the Nepalese as well as the Chinese side of the Himalayas, which is accompanied with higher warming in the Himalayas overall relative to some other regions of the world. Experts are worried over what climate change might entail for the Himalayan region.
In the western Indian Himalayas, a declining trend has also been observed for the monsoons with an increasing trend in the eastern Indian Himalayas. In many parts of the Tibetan Plateau, increased stream flow and precipitation have been observed. Glaciers in both the eastern and the western Himalayas however, are mostly retreating, although for now the majority of glaciers such as the Karakoram are stable or are advancing at a slow pace. The expansion of glacial lakes is also being reported, most notably in Nepal and Bhutan.
With predictions for increases in overall temperature and monsoon precipitation due to Climate Change, with reduced winter precipitation in the future, it is expected that glacial discharge will eventually lessen, leading to long term shortages in water supply in glaciated basins. This could lead to shortages of water for example for irrigation and hydro-power generation. In the short term devastating economic losses could entail from more intense flooding – the most common natural calamity in the Subcontinent.
Xu et al. (2009) analyzed Climate Change trends and concluded that they indicate that the impacts of Climate Change in the Himalayas could lead to an eventual cascading effect on all regions affected by the Himalayas. There are indications that Climate Change in the Himalayas could entail a number of effects, including the availability of water in terms of the amounts of water withheld or discharged, that could also be dependent on altered seasonality.
Biodiversity could also be affected, in terms of effects on endemics species populations and their distribution and also in terms of altered relationships between predator and prey. Ecosystem boundary shifts could also be observed, especially in the case of changes in the ecosystems at high elevation and in movements and alterations to tree-lines. Global feedback systems could also be affected, and monsoonal shifts and losses in terms of soil carbon could for example be observed. Climate Change in the Himalayas could also have socio-economic impacts such as changes due to altered water supplies and changes in agricultural production.
Observations and Projections
Although the most frequently reported impact of Climate Change in the Himalayas is glacial retreat, and its implications for the flow of water downstream, there can be numerous other possible impacts due to Climate Change in the Himalayas. As described above, Climate Change can have numerous other cascading effects on the Himalayas and its connected regions if we factor in other concomitant effects of Climate Change in the Himalayas such as changes in precipitation, habitats, the carbon cycle, etc.
In a major prediction in terms of Climate Change in the Himalayas, the IPCC is reported to have controversially stated that Himalayan glaciers are receding faster than in any other part of the world and predicted that they would disappear by 2035 if the Earth keeps warming at the current rate. This was followed by a rebuttal by the Ministry of Environment & Forests, GoI that a large mountain glacier would take between 100 to 1000 years to respond to warming.
Observations of the wastage of Himalayan glaciers are difficult and as such of rate of Himalayan glacier retreat because of the considerable difficulties posed by the high altitudes and the remoteness of the Himalayan region. It is this lack of comprehensive observational data that has led to certain speculations based on in situ observations and simulated projections of climate change. The associations used are usually of well observed glaciers and their working under Euro-American climes. This method is inadequate in some site-specific queries and can be overlooked such as the impacts on surface albedo by the seasonal cycle of precipitation which can in turn impact the retreat of Himalayan glaciers.
It is observed that glaciers, snow and ice that cover over 17 per cent of the Greater Himalayas are receding at a faster rate than in the rest of the world. This rate has witnessed an increase in recent years, and if warming continues at the current rate, studies indicate that Climate Change in the Himalayas could entail as a possible long term effect, an 80 per cent shrinkage of glaciers in the Tibetan Plateau by 2030.
The processes in turn that determine their run off and flow downstream are complex, but some general predictions can be made when it comes to the question of discharge. It is most likely that increased warming and the corresponding melting will lead to increased discharge in the short term. However, over time as the retreat of glaciers and frozen material becomes more complete, it is expected that discharge will become more limited, particularly in the event that decreased precipitation takes place.
In terms of the impacts of Climate Change in the Himalayas on precipitation and moisture, there can be various influences depending on the location of sites in the Greater Himalayas and their distance from sources of moisture. A variety of other determinants have also to be taken into account however, such as global systems of atmospheric circulation, orographic influences, etc. More intense precipitation can increase the risk of water-related hazards such as landslides, flash floods and flow of debris in the Himalayas, and these are projected to increase in frequency as precipitation becomes more intense in certain locations. The decrease in frozen material in the long term is also expected to influence precipitation, with a shorter dry season expected to bring about massive changes to flora and fauna.
Biodiversity can also be a flag-point issue with biodiversity in the Himalayan region being higher than the global average. Changes in hydrological patterns can affect biodiversity, especially among plants in the eastern Himalayas, a region having the richest plant biodiversity. One of the earliest responses to Climate Change in the Himalayas could be changes in plant phenology, or the life cycle of plants and associated species. Plant reproduction for example, could be impacted by warmer temperatures in terms of the time in which leaf flush and flowering occur. Rhododendrons in the Himalayas for example, are flowering a month earlier than usual. Disruptions in relationships with pollinators could also adversely impact alpine plants and animal species dependent on these plants. The shortened length of the dry season could also become an issue and in some cases, flowering might fail to initiate, especially at the lower altitudes.
It is also very likely that pest populations such as those of locusts and grasshoppers could increase with the increase in temperatures. With the onset of more the more palpable effects of Climate Change in the Himalayas, changed predator-prey relations could also become a feature, with increases or decreases in the populations of multiple species, leading to changed equations in the food web. Apart from plants, observations show that existing species are tracking climactic shifts and are shifting in terms of their geographical distribution. However, broader geographical migration does not present as vast a scope in the Himalayas because of topographical limitations. Studies of Himalayan species must keep track of these shifts in populations, which are also expected to be influenced by plant adaptations.
With the composition and distribution of vegetation types in the Himalayas expected to change due to changes in the water cycle and plant phenology, the species most likely to be palpably affected by this shift are endemic species found mostly at the higher altitudes. Species endemism increases with an increase in altitude in the Himalayas. It is expected that with a 1oC rise in temperature, isotherms could shift by about 160 m in altitude, which could severely affect higher altitude alpine ecosystems. Between 1923 and 2003 photographs indicate that northwest Yunnan witnessed a rise in the tree line by 67 m and in tree limits by 45 m.
All these represent the tip of the iceberg of what could become the cascading effects of Climate Change in the Himalayas leading to certain fundamental alterations to ecosystems in the Himalayas. It is not possible at this time to enumerate all of the associated responses, and we have touched upon what could be the immediate cause and effect correlations that could be possible.
The Eastern Himalayas in the Present Scenario
The range of the eastern Himalayas extends from the Kaligandaki Valley in central Nepal to northwestern Yunnan in China. In India, the Eastern Himalayas comprise of parts of the north-eastern states, Sikkim and the Himalayan region of North Bengal.
The region in total consists of 3 global biodiversity hotspots. The difference in altitudes over short distances can exhibit ecosystems ranging from tropical lowlands to cold deserts in high mountains with an incredible biodiversity in vegetation. Out of this biodiversity, a high proportion of species of flora and fauna in the eastern Himalayas are endemic species. Many of these species are largely unique to their habitats, especially in India’s north eastern states.
Consistent warming trends have been observed in the eastern Himalayas in the last 100 years. It is observed that with the rise in temperatures, a decline is being observed in areas under permafrost and glaciers in the eastern Himalayas. The chief source of moisture is increasingly shifting from frozen matter to precipitation events. The problem however, is one of the remoteness of areas in the eastern Himalayas, especially in the Tibetan Plateau and many parts of India’s north eastern region, and there is a great shortage of observations of Climate Change in the Himalayas to form a most detailed analysis.
The Western Himalayas in the Present Scenario
The western Himalayas extend from Badakhshan in north eastern Afghanistan, onwards to Jammu & Kashmir till central Nepal. In India, the western Himalayas form the chief part of the land areas of the states of Jammu & Kashmir, Himachal Pradesh and Uttarakhand.
The Intergovernmental Panel on Climate Change (IPCC) agreed in its Fourth Assessment Report that there was a clear lack of adequate data to support complete assessments for the Hindu-Kush region of the western Himalayas. However, in the same report the IPCC claimed that Himalayan glaciers would disappear by 2035, which was subsequently refuted by many other sources. The statement was later retracted by the IPCC but spoke of how more detailed research was needed in the region if more complete and certain assessments of Climate Change in the Himalayas are to be made, given the remoteness of many locations in the western Himalayas.
If the eastern Himalayas is a global biodiversity hotspot, the western Himalayas is known as a global Climate Change hotspot. Glacial retreat is a massive issue in the western Himalayas and is garnering attention over possible downstream flows, with ramifications for ecosystems downstream beyond the Himalayas. Given how economies and populations in the Subcontinent are hugely dependent also on agricultural productivity, this is an issue that requires much more comprehensive data collection and research. The total area expected to be directly affected by Climate Change in the Himalayas is given below, with the mountainous regions and the river basins included.
Fig: Total area expected to be directly affected by Climate Change in the Himalayas
Source: Surender P. Singh et al.
In terms of possibilities, other than the impacts of Climate Change in the Himalayas on the environment, the effects are also likely to impact in concatenation on human life as well. Although Climate Change in the Himalayas could progress gradually and humans have the tendency to adapt, the costs might be immediate and unpredictable. For example, more frequent flash floods and landslides might result in irreversible loss of human lives and increase risks to living in the mountains. In the long term droughts might have more severe effects due to glacial retreat and impact agricultural production. The chances of the extinction of certain species and its cascading effects might subliminally bring about massive changes in how life is carried out on Himalayan slopes.