Climate Shifts in Kaas Plateau | 17 Jul 2023

Source: PIB

Why in News?

A recent study conducted by the Agharkar Research Institute (ARI) and the National Centre for Earth Sciences has shed light on significant climate shifts in the Kaas Plateau during the Early-Mid-Holocene and late Holocene Periods.

• The researchers studied the sediments of a seasonal lake to understand and decipher the past climate of the Kaas Plateau.

What is Kaas Plateau?

• The Kaas Plateau, located in Maharashtra's Satara district, is a UNESCO World Natural Heritage Site and a designated biodiversity hotspot.
• Known as Kaas Pathar in Marathi, its name is derived from the Kaasa tree, botanically known as Elaeocarpus glandulosus (rudraksha family).
• The plateau have various seasonal flowers forming a floral carpet over the entire lateritic crust during August and September.

What are the Key Findings of the Study?

• Ancient Lake and Environmental Preservation:
  • The present "Flower Wonder" of the Kaas Plateau is located on an ancient lake that dates back to the Early-Mid-Holocene period, approximately 8000 years ago.
  • The seasonal lake has been preserved over a long time and provided valuable insights into the past climate of the region.
• Climate Shifts during the Early-Mid-Holocene:
  • Around 8664 years ago, there was a change in the climate from freshwater to drier conditions with low rainfall.
  • Pollen and diatom data indicated a major shift in the Indian summer monsoon activity during this time.
  • Despite the drier conditions, there were intermittent humid periods suggested by a significant rise in the number of diatoms.
• Late Holocene Climate Changes:
  • During the late Holocene, approximately 2827 years ago, there was a decrease in rainfall and a weakened Southwest Monsoon.
• Recent Environmental Impact:
  • Over the last 1000 years, there is evidence of lake Eutrophication, indicated by the presence of high numbers of planktonic and pollution-tolerant diatom taxa.
    • Eutrophication is the process of a water body becoming overly enriched with minerals and nutrients which induces excessive growth of algae or algal bloom, thereby, leading to oxygen depletion of the water body.
  • Human activities, including agriculture and cattle/livestock farming in the catchment area, likely contributed to this environmental impact.
• Monsoon Intensity and Duration:
  • The southwest monsoon intensified during the Early Holocene, around 8000 years ago.
  • The northeast monsoon relatively weakened around 2000 years ago.
  • It is likely that the 'Flower Wonder' of the Kaas Plateau existed for a longer duration, up to March-April, during the early–mid-Holocene (8000–5000 years), when the monsoon rainfall was more abundant, with more than 100 rainy days.