Heatwaves, cold spells, wet days: Since last Aug, Delhi has broken weather barriers every month
NEW DELHI: Every month since August 2020, Delhi has broken at least one weather record, IMD data shows. Experts said that while these extreme weather recordings are the immediate result of temporary atmospheric events, the larger role of the climate crisis in the overall shifting of weather patterns is evident.
In August 2020, the city recorded the highest rainfall for the month since 2013. In September, Delhi saw the warmest month in almost two decades.
The next two months were colder, with Delhi breaking a 58-year-old record in October and November seeing mean minimum temperature drop to levels last seen in 1949. This trend continued into December and January.
February was the second warmest in 120 years; March recorded the hottest day in 76 years, but April saw the lowest minimum temperature for the month in at least a decade. May too broke several records, with Delhi seeing the highest single-day rainfall for the month.
Scientists acknowledged the role of temporary weather conditions, but said the role of climate crisis is clear. “Many all-time records are being broken in many parts of India... We are seeing that extreme weather events are increasing. All off this is also an impact of the climate crisis, ” said Mahesh Palawat of Skymet Weather.
WHILE THESE RECORDINGS ARE IMMEDIATE RESULT OF TEMPORARY ATMOSPHERIC EVENTS OVER (AND AROUND) DELHI, LARGER ROLE OF CLIMATE CRISIS IS EVIDENT
Every month since August 2020, Delhi has broken at least one weather record, India Meteorological Department (IMD) data shows. Met officials and scientists said that while these extreme weather recordings are the immediate result of temporary atmospheric events over (and in and around) the national capital, the larger role of the climate crisis in the overall shifting of weather patterns is evident.
In August 2020, the city recorded 236.5mm rainfall, the highest for the month since 2013. Met officials also observed that 50% of the total rainfall fell in just two days of precipitation, August 13 (68.2mm) and August 20 (54.8mm).
In September, Delhi went on to record the warmest month in almost two decades. The Capital’s average maximum temperature that month was 36.2 degrees Celsius, breaking the previous record of 36.1 degrees Celsius in 2015. The last time Delhi recorded higher average maximum temperature in September was in 2001, when the mercury soared to 36.3 degrees Celsius.
In October and November, the scenario was the opposite. They were colder.
In October, Delhi broke a 58-year-old record, clocking a mean minimum temperature of just 17.2 degrees Celsius. November broke an even older record, with the month’s mean minimum temperature dropping to 10.2 degrees Celsius, a level last seen in 1949. The mean minimum temperature of November was lower only in 1938 before that, at 9.6 degrees Celsius.
This trend of colder than usual record continued in the months of December and January as well, with December witnessing eight so-called cold wave days, the highest since 1965. January recorded the highest number of cold wave days since 2008 (at seven days) and also broke the record for the highest rainfall for the month in 21 years (56.6mm).
IMD’S criteria for a cold wave in the plains is that the minimum temperature should be 10 degrees or lower, and the departure from normal minimum temperature 4.5 degrees or less for two consecutive days.
Kuldeep Srivastava, head of IMD’S regional weather forecasting centre, said that these extreme weather recordings between October and January were the immediate impact of fewer western disturbances passing over Delhi.
Western disturbances are cyclonic storms originating over the Mediterranean that affect weather in north-west and north India.
“Last winter, we recorded lower than usual temperatures because of fewer western disturbance activities in the region. Usually, in the months of October, November, December and January, we get around five to six active western disturbances each month; last year we only got two to three.” Srivastava said.
He added: “A western disturbance results in cloud formation over a region, which traps heat during the day and helps increase night time temperatures. In the absence of these clouds, what we saw this winter was that heat was not getting trapped and Delhi was recording lower than normal temperatures.”
Then, in February the weather conditions changed again. This February was the second warmest in 120 years, with the mean maximum temperature in the month touching 27.9 degrees Celsius, falling marginally short of the all-time record of 29.7 degrees Celsius in 2006.
March recorded the hottest day in 76 years, with the mercury levels touching 40.1 degrees Celsius on March 29.
After a sweltering February and March, in April the conditions changed again and the lowest minimum temperature in at least a decade was recorded on April 4, at 11.7 degrees Celsius.
May broke several historic records, according to IMD. Under the impact of cyclonic storm Tauktae, Delhi on May 19-20 broke the record for the highest single-day rainfall for the month ever, with 119.3mm of precipitation.
This also pushed the month’s rainfall in the city to 144.8—the second highest in the month since 2008.
The gusty winds and the intense showers also successfully brought the temperatures down, breaking the record of the lowest maximum temperature ever.
While acknowledging the role of temporary weather conditions that led to these extreme recordings, weathermen said the trend of extreme weather has been especially evident in the region over the past three years. The role of the climate crisis is clear, they added.
Mahesh Palawat, vice-president of Skymet weather services, said that such extreme weather conditions are not just specific to Delhi but also being observed in several other parts of the country.
As for Delhi, May is usually marked by extreme dry heat and high temperatures, he added -and this year it hasn’t seen a single heat wave day, another record.
Meteorologists declare a heatwave when the maximum temperature for a location in the plains crosses 40 degrees Celsius.
In the hills, the threshold temperature is 30 degrees Celsius. Also, when the departure in the maximum temperature during the day is 4.5 degrees to 6.5 degrees above normal, a heatwave is declared.
“Many all-time records are being broken in many parts of India in the last two to three years. We are seeing that extreme weather events are increasing. Over the last three years, we have also been noticing that the intensity of cyclones that are hitting the coasts of India is also increasing. All this is also an impact of the climate crisis, ” Palawat added.
AP Dimri from the School of Environmental Sciences, Jawaharlal Nehru University, agreed that such extreme weather is a clear impact of the climate crisis at play.
“Imagine your free atmosphere as a sponge that soaks up water. In an ideal situation, it will release water uniformly when its capacity is saturated. Under the impact of global warming, pressure is created at one point, which causes extreme weather conditions in one area; exactly like a sponge would squeeze out water under pressure. This month is a typical example of how weather patterns as we understand it is changing. Delhi in May usually records at least a few days of temperatures reaching 40 degrees or above, but this time except for one or two days the temperature has not spiked. Increased warming of the land and of the seas is also altering weather patterns,” Dimri explained.