Disclaimer: Copyright infringement not intended.

Context :

• Recently, A study explored the behavior of the Indian Summer Monsoon for the last 15,000 years.
• The researchers studied ocean sediments (layers of material found at the bottom of oceans) from the Bay of Bengal & the Andaman Sea to understand how changes in the monsoon affected water conditions like salinity (salt levels) & marine productivity (the ability of oceans to support marine life).

Key Findings:

1. Monsoon Variability:

• The study found that the intensity of the monsoon has changed a lot over time. It is affecting both the ocean & land ecosystems.
• Fossil shells (remains of tiny marine organisms) were used to track these changes in the monsoon.

1. Impact on Bay of Bengal:

• Early Holocene Period (11000–7000 years ago): During this period, monsoon was strongest and it was causing heavy rainfall.
• This led to large amounts of freshwater entering the Bay of Bengal. So it lowered the salt content (salinity) in the water.
• Increased River Flow: The rainfall came from increased water flow from major rivers like the Ganga & Brahmaputra.
• This stopped the mixing of water in the ocean and it reduced the supply of nutrients from deeper waters. So it lowered the overall productivity.

1. Weakened Monsoon Phases:

• During colder periods when the monsoon weakened then the flow of water from rivers decreased.
• This allowed the ocean water to mix better. And bringing up nutrients from the ocean's deeper parts and it boosted marine productivity (more nutrients meant more marine life could thrive).

1. Solar Activity Influence:

• The study also showed that changes in solar activity played a big role in changing the monsoon
• This means that the Sun's radiation affected rainfall patterns for long periods.

Implications for Climate & Future Projections:

1. Effect of Global Warming:

• The researchers also pointed out that global warming can make the Indian Summer Monsoon stronger in the future. It may affect things like agriculture (farming), water resources, & biodiversity (variety of life forms in an ecosystem).

1. Climate Projections:

• If scientists did understand how the monsoon responded to changes in the past then they can make better predictions for the future & plan for changes in climate.

Source: TH