Climate-driven Extreme Weather Events

Syllabus: GS3/Environment

Context

• A new study published in Nature Geoscience reveals that climate-driven extreme weather events in India’s summer monsoon could permanently disrupt the Bay of Bengal’s marine productivity.

About

• This study highlights the critical link between monsoon variability and marine ecosystem health in the Bay of Bengal over the past 22,000 years.
• Foraminifera microfossils were used to reconstruct past ocean conditions, revealing how monsoons and ocean chemistry evolved in response to global climate change.
  • Shells of foraminifera, tiny single-celled marine organisms record environmental data in their calcium carbonate shells. 
• The study is significant given that several climate models warn of significant disruption to the monsoon, under the impact of human-caused warming.

Major Findings

• Both abnormally strong and weak monsoons throughout history caused major disruptions in ocean mixing, leading to a 50% reduction in food for marine life.
  • Disrupted ocean mixing leads to plankton starvation.
• Marine Productivity: Marine productivity declined sharply during periods like Heinrich Stadial 1 (a cold phase between 17,500 and 15,500 years ago) and the early Holocene (about 10,500 to 9,500 years ago), when monsoons were either unusually weak or strong. 
• Climate Crisis:
  • Past collapses during Heinrich Stadial 1 and early Holocene show a clear link between extreme monsoons and productivity crashes.
  • Future climate models forecast warmer surface waters and unstable monsoon behavior—conditions that mirror historic downturns.
  • The ocean’s inability to support plankton would catastrophically undermine the marine food web.
• Concerns and Impacts:
  • Bay of Bengal has <1% of ocean surface, but contributes ~8% of global fishery production.
  • Hilsa fish, crucial for protein and income across South Asia, is especially at risk.
  • 150+ million people depend on Bay fisheries; Bangladesh’s artisanal sector, which provides 80% of the national marine catch, is already under stress from overfishing.

Recommendations

• Strengthen and refine climate models to better predict monsoon impacts.
• Enforce sustainable fisheries management, especially in vulnerable artisanal sectors.
• Accelerate action on emissions, as global warming is intensifying monsoon swings.
• Protect coastal communities with adaptive resource planning and conservation policies.

Source: TH