Monsoon Mayhem: Are Record-Breaking Floods the New Normal?

The monsoon season in India has been particularly brutal this year, with extreme weather events wreaking havoc across the country. From flash floods and landslides in Himachal Pradesh to the heaviest rains in 40 years in Delhi, the effects of climate change are becoming increasingly evident.

The year 2023 started with record-breaking temperatures in February, breaking a 123-year-old record. In April and June, the East and Central regions of India experienced a humid heatwave that was 30 times more likely due to climate change. Furthermore, Cyclone Biparjoy formed in the Arabian Sea, lasting for 13 days and becoming the longest-lasting cyclone since 1977.

Currently, Northwest India is being ravaged by relentless heavy rainfall, triggering devastating flash floods and landslides in Himachal Pradesh. Delhi has recorded the highest rainfall in the past 40 years. Meteorologists and climate scientists attribute these extreme weather events to the escalating levels of global warming.

The ongoing spell of extremely heavy rains is a result of the convergence of three weather systems: the Western Disturbance over the Western Himalayas, cyclonic circulation over the northwestern plains, and the Axis of Monsoon trough across the Indo-Gangetic Plains. While this alignment is a typical pattern during the Monsoon, the impact of climate change has altered this scenario. Rising land and sea temperatures have increased the moisture-holding capacity of the air, intensifying the role of climate change in India's growing extreme weather events, according to Mahesh Palawat, Vice-President of Meteorology and Climate Change at Skymet Weather.

Numerous reports and studies have already established the influence of climate change on Indian Monsoon patterns. However, it has also disrupted atmospheric and oceanic phenomena, amplifying the repercussions of global warming. Factors such as El Nino, larger wildfires releasing more carbon into the atmosphere, a warmer North Atlantic Ocean, exceptional warming of the Arabian Sea, and unusual upper-level circulation patterns contribute to the unique weather events of 2023, as explained by Dr. Raghu Murtugudde, Earth System Scientist and Visiting Professor at IIT-Bombay.

The Ministry of Earth Sciences report titled 'Assessment of Climate Change over the Indian Region' projects that monsoonal rainfall will become more intense and affect larger areas due to increased atmospheric moisture content with rising temperatures. The frequency of localized heavy rain events has significantly increased over central India, attributed in part to changes in moisture availability caused by greenhouse gas-induced warming, aerosols, atmospheric stability, and urbanization. Both global and regional models indicate an increase in seasonal mean rainfall over India while projecting a weakening monsoon circulation.

Since the mid-twentieth century, India has witnessed rising average temperatures, decreased monsoon precipitation, increased occurrences of extreme temperatures, rainfall events, droughts, rising sea levels, and intensified severe cyclones, among other changes in the monsoon system. Scientific evidence strongly suggests that human activities have contributed to these regional climate changes.

The rising global surface and ocean temperatures have accelerated evaporation, exacerbating rainfall. The Indo-Gangetic plains receive ample moisture from both the Bay of Bengal and the Arabian Sea, providing continuous moisture supply to weather systems, resulting in increased rainfall and extreme weather events, according to Krishnan Raghavan, Scientist-G, Director of the Indian Institute of Tropical Meteorology (IITM).

Dr. Raghavan said that the necessity of researching other global factors influencing circulations that impact Indian weather. One such factor is Arctic amplification, where the rapid heating of polar regions and glacial ice melt affect atmospheric circulation patterns in mid-latitude and tropical regions. Further research on this factor is crucial as it could contribute to changing weather patterns in India.

The Intergovernmental Panel on Climate Change (IPCC) has warned that extreme weather events are becoming more frequent and intense, and India is no exception. The IPCC's Sixth Assessment Report, released in 2021, found that the Indian subcontinent will experience a 20% surge in extreme rainfall events by the end of the century.

These extreme rainfall events can lead to a number of problems, including floods, landslides, and droughts. Floods are the most common extreme weather event in India, and they can cause widespread damage to property and infrastructure. Landslides are also a major problem, particularly in mountainous areas. Droughts can lead to crop failure and water shortages.

The IPCC report also found that the warming of the western Indian Ocean is associated with an increase in moisture surges on the low-level monsoon westerlies towards the Indian subcontinent. This can lead to an increase in the occurrence of precipitation extremes over central India.

In addition to the IPCC report, there is also evidence to suggest that the frequency and intensity of extreme weather events in India have been increasing in recent years. A study by the Council on Energy, Environment and Water (CEEW) found that the Indian subcontinent has witnessed more than 478 extreme events since 1970, with an acceleration in their frequency after 2005.

The CEEW study also found that the weakening of the monsoons is coinciding with the increase in extreme weather events. This is because the monsoons are essential for rainfall in India, and their weakening can lead to droughts and other problems.