Climate change may end up greening the Thar Desert

Climate change may end up greening the Thar Desert

Subject: Geography

Section: Physical Geography

Context: A study of rainfall and climate data portends the end of the Indian subcontinent’s arid northwestern swathes.

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• Two researchers have postulated that the demise of the Thar Desert is a distinct possibility due to global warming.
• It is based on their theory on rainfall and climate data, with a focus on what is known as the ‘Indian ocean warm pool’, or IOWP.
• The existence of this warm region in the Indian Ocean has been known for decades and is a source of monsoons. And now, with global warming, the IOWP is expanding westwards.
• With the IOWP expanding westward, the ‘length of the rainy season’ would result in “a 50-100 per cent increase in the mean summer rainfall over the semi-arid northwest of India”.
• As global warming is likely to continue at least till the end of the century, westward expansion of the Indian monsoon will continue. The length of the monsoon season is expected to increase from about 70 days to about 90 days and annual rainfall to increase from about 45 cm to about 70 cm by that time. The increased rainfall spread over a longer season will help grow taller vegetation.
• However, during the dry winter season, the plants may die unless water is made available through irrigation or uplift of the water table. So, greening could be accelerated if the run-off during the monsoon season could be harvested.
• In the long term, the increased rainfall has the potential to green the desert and significantly increase food productivity in the region. But in the short term, it is necessary to plan for harvesting the excess water to increase groundwater reserves.

Indian Ocean Warm Pool

• The Indian Ocean Warm Pool (IOWP) is a region of the Indian Ocean that is characterized by sea surface temperatures of more than 28°C throughout the year.
• The Indian Ocean Warm Pool is located in the western part of the Indian Ocean, primarily in the region bounded by the eastern coast of Africa, the northern coast of Madagascar, and the southern coast of India.
• IOWP Formation: Atmospheric winds cool the ocean surface through evaporation, sometimes forcing colder, deep waters to come up — a phenomenon known as ‘upwelling’. This happens near the Somalia coast in the western Arabian Sea during summers. The waters in the region are cooler, leaving a ‘warm pool’ elsewhere.
• The Indian Ocean Warm Pool plays an important role in the global climate system, as it influences the monsoon climate of the Indian subcontinent and the surrounding regions. The high sea surface temperatures in the IOWP lead to increased evaporation, which in turn contributes to the formation of the monsoon rains.
• The warm temperatures and high levels of sunlight promote the growth of phytoplankton, which forms the base of the marine food chain. The region is also home to a diverse range of marine life, including coral reefs, fish, and marine mammals.

Thar Desert

• The Thar Desert, also known as the Great Indian Desert, is a large arid region in the northwestern part of India and the eastern part of Pakistan.
• The Thar Desert is located in the northwestern part of the Indian subcontinent, covering an area of approximately 200,000 square kilometers. It spans across the states of Rajasthan, Gujarat, Haryana, and Punjab in India, and the eastern part of Pakistan.
• The Thar Desert is characterized by extreme climatic conditions, with high temperatures during the day and low temperatures at night. The region experiences very little rainfall, with an average annual rainfall of less than 250 mm. The climate is also marked by strong winds, dust storms, and sandstorms.
• Thar Desert Formation
  • The amount of rain falls from east to west. The western region of Rajasthan receives little to no rainfall. This is because of the following factors.
    • The Arabian Sea branch of the southwest monsoon blows through Gujarat’s Kathiawar area and escapes to the north-west.
    • There are no towering mountains to keep these winds at bay. The Aravalli range in Rajasthan runs parallel to the path of the monsoon winds and cannot prevent them from moving north.
    • The region’s high temperatures improve the water retention capacity of the winds and diminish the likelihood of rainfall.
  • Despite the harsh climatic conditions, the Thar Desert is home to a diverse range of flora and faun The region is known for its unique desert vegetation, including thorny bushes, shrubs, and cacti. The desert is also home to several species of reptiles, birds, and mammals, including the Indian gazelle, the Indian wolf, and the desert fox.
  • The Thar Desert is sparsely populated, with a few scattered human settlements. The region is home to several indigenous communities, including the Rajputs, the Jats, and the Meghwals. Thar Desert has the highest population density of any desert on the planet.
  • Water is a scarce resource in the Thar Desert. The Luni River is the only large river in this area. The region relies heavily on groundwater reserves. However, overexploitation of groundwater has led to a depletion of the water table, posing a threat to both human and animal populations in the region.
  • The Thar Desert is a rich source of minerals and other natural resources, including coal, gypsum, and marble. The region is also known for its handicrafts, particularly embroidery and weaving. Tourism is another important economic activity in the region, with several desert safaris and camel rides attracting visitors from around the world.
  • The Thar Desert faces several environmental challenges, including soil erosion, desertification, and loss of biodiversity. Climate change is exacerbating these challenges, with rising temperatures and changing rainfall patterns affecting the desert ecosystem.