Study Finds Rising Number of Atmospheric Rivers Associated with Flooding in India

As the planet continues to grow warmer, a team of atmospheric scientists from the Indian Institute of Technology and the University of California have found that the number of atmospheric rivers (ARs) associated with flooding in India has been rising. In their study published in the journal Communications Earth & Environment, the group describes how they carefully analyzed data from multiple sources to track the number of ARs affecting India and how it has led to increased flooding in the country.

ARs and Flooding

ARs have been in the news of late because of several of them that caused flooding in California this past winter. However, ARs are not only affecting the US but other regions as well. ARs can form and cause increased amounts of rain in many parts of the world. They are channels of moisture-laden air that form when air pressure systems collide, pushing air with a lot of moisture in a stream-like fashion through the atmosphere. When they meet land, the air pressure relents, allowing the moisture to be released, often in dramatic fashion.

The Study

The researchers examined weather records from the European Reanalysis Version, the Dartmouth Flood Observatory, and the India Meteorological Department for the years 1951 through 2020, looking for evidence of ARs that have had an impact on India, particularly during monsoon seasons. They found that AR events impacted the country 596 times, with 95% of them occurring during a monsoon season. They also discovered that 54% of the biggest AR events happened over the past three decades, indicating that the ARs are not only forming more frequently but are also getting bigger as the planet grows warmer.

Warmer Ocean Surface Temperatures and Flooding

The researchers noted that warmer ocean surface temperatures over parts of the Indian Ocean have led to more evaporation, which, in turn, has led to more rain when ARs form. The increase in precipitation has led to massive floods that have destroyed property and killed thousands of people.

The study’s findings suggest that the impact of ARs on India is becoming more severe. The researchers urge policymakers to consider the study’s findings when planning for future natural disasters and climate change adaptation strategies.