Syllabus:
GS1: Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc., geographical features and their location- changes in critical geographical features (including water bodies and ice-caps) and in flora and fauna and the effects of such changes.
Context:
A new study shows that fossil leaves from Nagaland link the formation of Antarctic ice 34 million years ago with the early evolution of the Indian monsoon system.
About the Study
- Researchers from the Birbal Sahni Institute of Palaeosciences (Lucknow) and Wadia Institute of Himalayan Geology (Dehradun) studied fossilised leaves from Nagaland’s Laisong Formation.
- The study, published in Palaeogeography, Palaeoclimatology, Palaeoecology, employed the Climate Leaf Analysis Multivariate Programme (CLAMP) to analyse the size, shape, and structure of the fossilised leaves.
- This study aids in understanding the past climate influences and improving future monsoon forecasts.
Key Findings of the Study
- Antarctic Glaciation and Monsoons Shift: The growth of Antarctic ice reshaped global wind and rainfall patterns by shifting the Intertropical Convergence Zone (ITCZ) northwards.
o This shift brought intense monsoonal rains to Northeast India, enabling dense forests to thrive. - Cause of Global Shift: Nagaland once experienced much warmer and wetter conditions than today, leading scientists to trace the cause to a global shift that coincided with the first massive ice formations in Antarctica.
- Global Interconnectedness of Earth’s Climate System: Changes in one part of the planet for instance, the growth or melting of Antarctic ice sheets can influence conditions thousands of kilometres away, such as rainfall over the forests of Nagaland.
- Warnings for Future: As modern climate change accelerates Antarctic ice melt, the ITCZ may shift further southward, potentially disrupting monsoon patterns across the tropics.
Intertropical Convergence Zone (ITCZ)
- ITCZ is a low-pressure zone located at the equator where trade winds from both hemisphere converge, and therefore it is a zone where air tends to raise lading to rainfall.
- In July, the ITCZ is located around 20°N-25°N latitudes (over the Gangetic plain), sometimes called the monsoon trough.
o This monsoon trough encourages the development of A thermal low area over north and northwest India. - Because of the ITCZ shift, southern hemisphere trade winds cross the equator between 40°–60° E and turn southwest–northeast to form the southwest monsoon, deflected by the Coriolis force.