UPSC CURRENT AFFAIRS – 28th May 2025

Home UPSC Current Affairs Why has the monsoon come early this year?

Why has the monsoon come early this year?

Why in News?

The 2025 southwest monsoon onset over Kerala was unusually early, but the reasons behind early or delayed monsoon onset remain uncertain due to complex natural variability and climate influences.

Introduction

The southwest monsoon arrived over Kerala on May 24, 2025, marking an onset a week earlier than normal.
While early onset typically raises expectations of good rainfall, it does not guarantee a productive monsoon season.
The complexities of monsoon dynamics — influenced by local, regional, and global climatic variables — make prediction and understanding a significant scientific challenge.

Understanding the Onset of the Indian Monsoon

Normal Onset Window

The monsoon normally sets in around June 1, with slight variations each year.
Since 1975, the earliest onset was recorded on May 19, 1990.

Why Onset Prediction Is Difficult

No single model or theory can comprehensively explain monsoon onset.
Multiple climatic systems interact to affect onset — including:
- Low-pressure systems over the Bay of Bengal
- Westerlies and Easterlies
- Tropical Pacific Sea Surface Temperatures (SSTs)
- Cyclonic systems forming in the Arabian Sea and Pacific

Role of El Niño, La Niña, and Global Warming

Do ENSO Events Predict Onset?

ENSO (El Niño-Southern Oscillation) phases, including El Niño and La Niña, do not offer systematic predictability of monsoon onset.
For instance:
- 2009 had a mild El Niño and early monsoon, yet saw severe drought.
- 2023-24 experienced a strong El Niño, followed by a failed La Niña in 2024.
- SST anomalies in 2024 were unusual — warm in the far east and west Pacific, and cool in the center.

Impact of Global Warming

The planet has warmed by over 1.2°C above pre-industrial levels (as of 2025).
Global warming is believed to alter traditional ENSO patterns, cyclogenesis, and monsoon variability.
The combined effect of warming and decadal variability makes monsoon prediction harder.

Is 2025 Similar to 2009?

Key Comparisons

2009: Warm tropical oceans, early monsoon, drought year.
2025: Early onset, post-El Niño SST patterns, but currently neutral ENSO forecast.

Differences

In 2025, El Niño and Indian Ocean Dipole (IOD) are neutral, unlike 2009.
However, decadal climate indicators suggest a possible El Niño development later in the year.

Local and Remote Drivers of Monsoon Onset

Influences on the Monsoon Trough

The monsoon trough’s advance is influenced by:
- Pre-monsoon cyclones (increasing in frequency and intensity)
- Arabian Sea low-pressure systems
- Typhoons in the Pacific, which may siphon off moisture

2025 Case Study

The northward pull on the trough this year suggests that a low-pressure system along the west coast played a role in early onset.

Cyclones and Arctic Warming

Increasing cyclone activity close to onset is potentially linked to Arctic warming and shifting wind patterns.

Changing Patterns in Monsoon Withdrawal and Rainfall

Withdrawal Patterns

The withdrawal of the southwest monsoon is now merging with the northeast monsoon in some regions, altering regional climatic calendars.

Erratic Intra-Seasonal Distribution

Floods and droughts occur simultaneously across regions.
The monsoon is increasingly uneven in both space and time due to:
- Local topography
- Land-use changes
- Anthropogenic emissions
- Shifts in oceanic and atmospheric currents

What Does the Future Hold?

Scientific Understanding Still Evolving

Progress is being made, but no definitive model exists to:
- Predict the onset
- Forecast the seasonal spread
- Anticipate the withdrawal

Need for Enhanced Research

Key areas for deeper study:
- Impact of climate change on regional monsoon circulations
- Role of Arctic and polar processes
- Influence of decadal variability and teleconnections