Chennai floods: Extreme weather here to Stay?

Chennai has been battered by record-breaking rainfall that continues to pound the city. The deluge has raised many questions about the catastrophe and the increasing incidence of such extreme weather phenomena. ET answers some of these questions.



WHY IS IT HAPPENING?
Weather scientists say that southern India receives heavier winter rain in El Nino years. The El Nino phenomenon usually disrupts the June-September monsoon but it often intensifies the winter monsoon in southern India. It has been observed that threatening weather systems over the Bay of Bengal tend to move towards southern India is El Nino years.



IS THIS DUE TO CLIMATE CHANGE?
Extreme precipitation events are increasing across the world, particularly in Asia. Scientists say this is due to global warming and climate change.



HOW DOES GLOBAL WARMING LEAD TO EXTREME RAINFALL?
Simply put, higher temperature increases water evaporation and cloud formation. Further, it is scientifically established that heat increases the atmosphere’s capacity to hold water in line with mathematical formulations contained in the Clausius-Clapeyron equation.

WHY IS ITS IMPACT SO BAD?
Emergency response systems and drainage facilities are often inadequate even for relatively moderate rainfall or extreme rainfall for a day or two. Experts say that perhaps no Indian city is geared to face record-breaking cloudbursts and torrential rainfall that goes on for many days.

WHAT ARE THE LESSONS FOR OTHER INDIAN CITIES?
They have to prepare for catastrophic rainfall. There may be some debate on how many such catastrophes are lurking in the years ahead but climate change is taking alarming proportions.

SOME EXTREME EVENTS IN RECENT YEARS:

Kashmir valley was rattled this year by record rainfall that drowned urban areas and villages

Ladakh, a desert area, was devastated by unprecedented torrential rain and mudslides in 2010

Kedarnath and adjoining areas of Uttarakhand were devastated by a lethal cloudburst in 2013

Mumbai was stunned by a killer cloudburst that coincided with high tide in 2015

Pakistan was rattled in 2010 by the worst flood in the nation’s history

Monsoon failed in 2014 and 2015. Failure in two consecutive years is very, very rare

September rain has jumped in the past decade as monsoon withdrawal gets delayed almost every year