Impact of climate change on the Himalayas
If global warming increases 3°C by the end of the Century, 90% of the Himalaya region will face drought for more than a year, according to new research from the University of East Anglia, United Kingdom.
Climate change in the Himalaya region can be attributed to two main factors. Increased concentrations of long-lived greenhouse gasses in the atmosphere and Black carbon.
Climate Change Impacts on the Himalayas
Climate change has a number of impacts on the Himalayas, such as glaciers melting, changes in precipitation trends, treeline shift, and early flowering of plants.
Rising Temperature in the Himalayas
The fourth report of the IPCC said that there is a more than 90% probability that the observed warming since 1950 is due to emission of human-induced greenhouse gasses.
There will be a significant acceleration of warming in the 21st century as compared to the 20th century due to temperature rise and the warming will be significant in arid regions of Asia, Himalayas highlands including Tibetan Plateau.
Over the last 100 years, warming in the greater Himalayas has been much greater than the global average. For example, warming of .6°C per decade in Nepal as compared to .74°C global average over the last 100 years.
Changes in Precipitation Trends
Over the last few decades, both increasing and decreasing trends of precipitation have been observed in different parts of the Himalayas.
For example, a decrease in monsoon precipitation of up to 20% in the central Himalayas and an increase in precipitation between 20-30% in the western Himalayas by the end of the century, has been observed.
In many areas, a large part of precipitation falls as rain rather than snow when compared to previous times which results in that snowmelt starts earlier and this in turn affects the river regime and water supply, particularly in basins which are dependent on glacial melt for water supply in summer. Ex. Tarim basin.
Glaciers melting
Glaciers in the Himalayan region are melting faster than any part of the world due to increased emissions of human-induced greenhouse gasses and deposition of black carbon on the snow surface in the Himalayas.
The glaciers in the Greater Himalaya form the largest body of ice outside the polar caps, storing about 12,000 km³ of freshwater and are the source of water for the many rivers that flow across the Indo-Gangetic plains, which are large floodplains run parallel to the Himalaya mountains.
The Ganga, Indus, Brahmaputra, and other rivers that crisscross the northern Indian plain may soon become seasonal rivers as a result of climate change, which might have an impact on the economy of the region. This is predicted by observing the current trends of glacier melting.
95% of earth's water is Ocean saltwater and only remaining 5% is freshwater, out of which 80% is stabilised in solid forms such as ice caps, mountain glaciers and snow cover and remaining water (20% of freshwater) includes groundwater and freshwater lakes.
Forest Transition
The regions in the Himalayas are experiencing forest transition due to impacts of climate change.
In the Western Himalayas, upward movement of treeline species due to temperature rise has been reported. The Oak forest (a broadleaf evergreen forest) is being invaded by pine forests in the Garhwal Himalayan region.
In Eastern Himalaya, species in the transition zones between subalpine and alpine are especially vulnerable to climate change as they have limited scope to move further.
The Eastern Himalaya has richness in endemic species with restricted habitat distribution. These endemic species are also considered threatened by the IUCN.
Lowland species are primarily threatened by habitat loss while species in highland may have to extend their habitat or distribution range upward (toward North) due to warming temperature because the areas in high altitude are warming faster than those in lower altitude.
The apple cultivation has shifted to higher elevations and that apple yields from orchards at lower altitudes has declined due to inadequate and delay in snowfall.
Land Subsidence
People in the mountainous region have contributed least to climate change, but are at high risk of facing the worst effects of changing climatic conditions.
For example, Joshimath, a town situated on the mountain region of the Himalaya, began sinking in the year 2023 and residents had to relocate for a few days. This is one of the climate change-induced events that the mountainous communities felt.
Impacts on Phenology of Plants
Climate change impact on the flowering phenology of plants has also been clearly observed in the region. For example, early flowering of the Rhododendron arboreum has been attributed to increase in temperature and decrease in rainfall (and snowfall as winters have shrunk).
A study also predicted the possibility of the R. arboreum to move towards higher altitudes to cope with climate change. The Rhododendron tree might expand its distribution range in response to global warming under the scenario of rising winter-temperature.
Culturally and ecologically important the rhododendron tree occurs at an altitude of 1500-3000 metres. Rhododendron, a small evergreen tree, is listed as threatened in the western Himalayas and as endangered in southern India.
Earlier onset of flowering in several species of Rhododendron by about 1-2 weeks as compared to past has been reported in the Kumaon Himalaya (western Himalaya).
Similarly, flowering phenology of alpine plants was also impacted by the temperature rise in winter and spring seasons. Early flowering was recorded for 11 alpine/subalpine plants.
Phenological modification in the alpine ecosystem has been observed as the most serious effect of global warming, and snowmelt regime is a major determinant of the flowering structure of alpine ecosystems.
Temperature and precipitation changes have an impact on snowpack and snowmelt, which in turn affect the growing season of the environment in which plants grow.
Affect Pollination
Climate change could impact pollination as early flowering and ripening of fruits in plants due to climate change in turn affects the pollination and pollinator population, leading to changes in ecosystems productivity and species composition in the high altitude regions.
Impacts on the Alpine Ecosystem
In 2022, India has recorded the hottest March in the past 122 years. This high heating in March and April months led to warm and humid conditions in the alpine zone in the Himalaya resulting in early flowering of alpine plants in the Uttarakhand state. (Times of India).
Early flowering could result in many consequences including extinction of plant species (due to high temperatures) and flourishing weeds in the alpine zone. Warm and humid environment also creates suitable conditions for weeds to grow.
Range Shift or Treeline Shift
Plant species found in low- and middle-altitudes tend to move high altitude regions to cope with changing climate. The plant species in high-altitude areas will also tend to migrate upwards but slowly, as temperature increases, this may lead to interspecific competition, distribution range reduction and in the long run, high-altitude species will not find suitable areas for habitats effectively forcing them towards extinction.
More than 85% of the 124 endemic species have shifted their range as a result of warming during winter in the alpine zone of Sikkim Himalaya, increasing species richness in the zone. (Research gate).
Shifting of the treeline (upward) and encroachment of woody vegetation into the alpine meadows will lead to degradation of the alpine ecosystem, which is very sensitive to impacts of climate change.
Areas at higher altitudes have a faster warming rate than those at lower altitudes, making them more sensitive to climate change. Therefore, alpine plant species grown in high-altitude areas are more vulnerable to rapid temperature rise.
Alpine ecosystems are predicted to experience strong levels of temperature increase from global warming, this temperature rise will have indirect effects on alpine ecosystems by causing snowpack decline, earlier snowmelt, and early flowering of alpine trees.
Impact on food systems
Agriculture is the mainstay of people and is a rich repository of agro-biodiversity in the Himalaya region. Agriculture is mostly rainfed, nearly 85%, in the region.
In Uttrakhand state, mixed cropping of 12 crops (grown together in a single field), known as Barahnaja, is the best example of rich agri-diversity of the region. All these crops are cultivated and grown without use of fertilizers and pesticides as the region is resilient to crop diseases.
This traditional farming is suitable in ecologically fragile regions and prevents soil erosion. These crops are adapted to local climatic conditions and withstand the environment risks. They enhance soil health and fertility and provide many health benefits because all crops are chemical-free and also contribute to food and nutritional security for regional inhabitants. But due to the impact of climate change, the area cultivated with traditional crops has drastically decreased (around 60%).
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