A contemporary study on fossil leaves announces intriguing revelations about the Indian climate 25 million years ago, haughtily asserting its resemblance to modern-day Australia’s. Scrutinizing these past climatic dynamics facilitates accurate forecasting of future monsoon patterns.
Fossil Leaves and Their Story
The study zeroes in on fossil leaves from various geological eras, unearthed from East Garo Hills of Meghalaya, Deccan Volcanic Province, Gurha mine in Rajasthan, and Makum coalfield in Assam. These fossils were selected specifically due to their distinct morphological characteristics such as apex, base, and shape, which are ecologically calibrated with the prevailing weather conditions. This signifies their adaptation to all the annual seasons. The findings inferred these fossil leaves were acclimatized to an Australian type of monsoon, not the existing Indian monsoon system.
The Geological Journey of India
Following its detachment from Gondwana, India embarked on a 9000 km northward expedition from the Southern Hemisphere over a span of 160 million years before reaching its current alignment with Eurasia. The temperature data drawn from this historical voyage demonstrates that all fossil sites endured warm (tropical to subtropical) climates, with temperatures ranging from 16.3 to 21.3 degrees Celsius. This journey was also marked by copious rainfall, varying from 191.6 cm to 232 cm at different fossil locations.
Gondwana and Its Dissolution
About 140 million years ago, India was a constituent of the supercontinent Gondwana, alongside present-day South America, Africa, Antarctica, and Australia. The vast Tethys Ocean separated Gondwana from Eurasia. With the fragmentation of Gondwana, a tectonic plate, now comprising India and Madagascar, started drifting away. Eventually, India separated from Madagascar, drifting in the north-east direction. It then collided with Eurasia to form the Himalayas approximately 50 million years ago. India continuously inches in the same direction, albeit at a reduced pace of around 4 cm/year.
Understanding the Indian Monsoon
Characterized as the ‘monsoon’ type, the Indian climate echoes similar weather patterns found in south and southeast Asia. The southwest monsoon season (June – September) and the retreating monsoon season (October – November) are two crucial divisions of the four seasonal demarcations in India.
Factors Shaping Southwest Monsoon
Several components influence the formation of this monsoon. These include the differential heating and cooling of land and water, leading to lower pressure on the Indian landmass while the surrounding seas encounter relatively high pressure. Additionally, the Inter Tropical Convergence Zone’s shift over the Ganga plain during summer and the presence of a high-pressure area east of Madagascar significantly impact the Indian Monsoon. The Tibetan plateau’s intense heating during summer results in strong vertical air currents leading to the formation of low pressure. Lastly, the movement of jet streams and periodic change in the pressure conditions are also instrumental in affecting the monsoon patterns.
Last Modified: February 13, 2024