Valerian Isaac, a traditional fisherman from Anchuthengu in Thiruvananthapuram, is deeply concerned about the impact of climate change on his livelihood and the overall quality of life. He used to enjoy his summer with the sea cooling down when folks in the town sweltered in the heat. The situation however has changed dramatically.
“The sea has warmed up significantly. Consequently, the fish have migrated to cooler waters away from the coast. Previously, we relied on good winds and occasional rains to alleviate the heat. But this summer has proven to be the toughest yet,” Isaac said.
With the dwindling catch, only a handful of fishermen dare to venture out into the sea in his area. And they are not the only ones suffering. Adverse weather has also affected autorickshaw drivers, tour operators, vegetable vendors and those in the construction sector.
As the government considers imposing further restrictions on operations between 11am and 3pm, the livelihoods of even more sectors hang in the balance.
Isaac, like many others, had not heard of the term ‘El Nino’, a climate phenomenon responsible for warming the sea surface temperature in the Pacific Ocean and often cited as a primary cause of harsh summers. However, he, along with the rest of the populace, has become acquainted with the term ‘heatwave’ in recent times. Its sudden appearance in the vocabulary coincided with its confirmation in Palakkad on April 26, the day of the general elections. Such weather was once considered unusual, mostly associated with the traditional hot regions of the country.
The India Meteorological Department first issued a heatwave alert in Kerala in 2016, the warmest year on record for the state, primarily focused on Palakkad. This year, the focus has again been on Palakkad which experienced scorching temperatures throughout April, with Thrissur following suit. Subsequently, heatwave alerts were issued for Kollam, Kozhikode and Alappuzha, as temperatures in these districts deviated from the norm significantly.
Weather experts assert the situation is similar across south and east India. An Asia-wide heatwave map published by international weather agencies depicts most countries in the region coloured in red. “The temperature rise is attributed to global warming induced by climate change. The impact of El Nino exacerbates the situation,” said D Sivananda Pai, senior scientist and ADGM of India Meteorological Department.
According to him, the dry weather in Kerala has increased the temperature.
“In Palakkad, the relative humidity is now in the 30-40% range in comparison to the normal 60-80%. That’s why the temperature remains high. The condition is worse for people living in more humid areas as high moisture content does not help reduce body temperature,” he said.
Like this year, 2016 too was an El Nino year. While it was the warmest year in recent history, the damage, technically, was limited to a heatwave alert in Palakkad. “What makes the conditions worse than 2016 is the absence of summer rain, especially in the northern districts, and the land use and land cover changes because of urbanisation,” said Rajeevan Erikkulam, a meteorologist with the Kerala State Disaster Management Authority.
Weather experts pointed out the situation is likely to improve by the second week of May when summer rains are expected to be more regular. The El Nino effect is expected to be neutral during the time of monsoon, but the experts have a warning — the next El Nino year could be much worse than 2024.
Qualitatively, heatwave is a condition of air temperature that becomes fatal to human body when exposed. Quantitatively, it is defined based on the temperature thresholds over a region in terms of actual temperature or its departure from normal.
Criterion for declaring heatwave
Heatwave is considered to be in effect if the maximum temperature of a station reaches at least 40°Celsius or more in the plains, at least 30°Celsius or more in hilly regions, and 37 °Celsius or more in coastal regions. The departure from normal is 4.5 to 6.4°Celsius. If the above criteria is met in at least two stations in a meteorological sub-division for at least two consecutive days, a heatwave is declared on the second day.
Heatwave prone states
Heatwave generally occurs over the plains of northwest India and central, east and north peninsular India from March to June. It covers Punjab, Haryana, Delhi, Uttar Pradesh, Bihar, Jharkhand, West Bengal, Odisha, Madhya Pradesh, Rajasthan, Gujarat, parts of Maharashtra and Karnataka, Andhra Pradesh and Telangana. Sometimes, it occurs over Tamil Nadu and Kerala too.
Impact of heatwave
Heatwave in Kerala
Reasons for heatwave