Extreme weather events order of the day?

Chennai: In the first week of December when Cyclone Michaung ravaged Tamil Nadu’s capital city, some localities received the season’s total rainfall in just 36 hours. This week, Kayalpattinam in Thoothukudi district registered a record 110 cm rainfall in just 48 hours, much more than the amount of rains the small town receives for the whole of a year.

Weather experts and environmentalists say such one -day extremely heavy rainfall events are likely to become a normal affair due to the effects of Climate Change. They said the average rainfall is likely to be the same, but the number of rainy days might reduce drastically as experienced in Chennai and in Thoothukudi this north-east monsoon (NEM) season.

Perungudi in Chennai received over 70 cm rainfall in 36 hours on December 4 and 5, inundating the entire locality, which is much more than the season’s rainfall. In 2021, the city received more than the average rainfall for November in just eight days as it recorded 41.5 cm between November 1 and 8 as against 37.4 cm.

S Balachandran, Additional Director-General of Meteorology, Chennai told DH that the short period of intense rains occur very often due to the effects of Climate Change and Global Warming.

“The more the oceans get warmer, the more we will see such incidents. It is said that one degree of increase in temperature leads to 7 per cent more water vapor. The warmer the atmosphere is, the more we might see such weather events,” he said.

The phenomena of more rainfall, which should ideally be spread over days, occurring just in a few hours is increasing, Balachandran added.

Environmental activist G Sundarrajan, who runs an NGO Poovulagin Nanbargal, too said such events can be expected frequently and local governments should focus on adapting to the new normal and build resilience capabilities, besides mitigation efforts.

“Short duration extreme rainfall isn't a new phenomenon. But the gap between two such events is narrowing down and that is the cause of concern. If we stop emitting carbon today, such weather events won’t stop immediately because the temperature has already overshot by 1.5 degree Celsius. We need to find ways to come out of such events as quickly as possible,” he told DH.

He said the governments should keep the natural drains encroachment free which will ensure that the water drains out easy and fast.

“We need to decentralize development as well. We need a lot of plains and that is when water will flow easily. In places like Chennai, it is difficult for the water to drain because there is no way for it to do so as there are encroachments everywhere,” Sundarrajan added.

Weather blogger K Srikanth, who tweets under Chennai Rains on X platform, said it is believed that warmer oceans lead to extreme weather events – excess rainfall and heat waves – and this is likely to be the order of the day.

“The number of rainy days may reduce but the average rainfall is likely to be the same. But we are fairly well alerted now on weather events but sometimes the rainfall exceeds beyond the estimated levels. Such predictions help put in place several safety protocols which minimize damage during such weather events,” Srikanth told DH.

Balachandran said it is not possible to predict the exact amount of rainfall that a weather event can bring. “We can only predict whether it will be heavy rainfall, very heavy rainfall, or extremely very heavy rainfall,” he said.