What does IMD’s latest report say?
As per the IMD report released, maximum temperatures in northwest and central India are predicted to fall gradually by 2-3 degrees C in the next three days.
Maximum temperatures in most parts of Delhi, Haryana, and Chandigarh, as well as large parts of Rajasthan, and isolated pockets over eastern Madhya Pradesh, Uttar Pradesh, Bihar, Jharkhand, and Odisha were recorded in the range of 45-48 degrees C.
How do heatwaves arise?
Some experts believe that post El Niño warming has contributed to higher-than-usual temperatures in north India this year.
The IMD, said that weak El Niño conditions are currently observed over equatorial Pacific and are likely to weaken further and convert into ENSO neutral
The two opposing patterns (El Niño and La Niña) occur in an irregular cycle called the El Niño Southern Oscillation (ENSO) cycle, with a neutral period in between
During El Niño, surface temperatures in the equatorial Pacific rise, and trade winds — east-west winds that blow near the Equator — weaken.
Normally, easterly trade winds blow from the Americas towards Asia.
Due to El Niño, they falter and change direction to turn into westerlies.
ENSO, however, does not cause extreme heat in isolation.
Teleconnections, which are the relationships between global weather and wind patterns, impact each other.
The Walker circulation, which involves the trade winds that blow from east to west along the Equator, are affected by ENSO due to teleconnections.
El Niño is associated with a shift in Walker circulation, causing a large-scale redistribution of heat and moisture.
Heat redistribution on the surface impacts airflows above the ocean.
It is known that El Niño diminishes Indian monsoon since the weakened Walker circulation disrupts the flow of moist air from the Indian Ocean towards the Indian subcontinent, reducing the moisture available in the winds, hence creating drier conditions.
El Niño also creates high-pressure areas over the Indian subcontinent, which suppress cloud formation and precipitation.
The absence of clouds is also contributing to the current heatwave in north and central India.
What’s the cause of North India’s heat?
Delhi and most parts of north and central India that are currently under a heatwave spell, are far from the influence of oceans that can regulate temperatures and air moisture.
Continental air, which is a large volume of dry air over a land mass, greatly affects the weather in Delhi because of its inland location.
Tropical air masses that originate in the Thar Desert and other hotter, drier regions to the west and northwest of India bring increased heat to Delhi and surrounding areas, contributing to heatwave conditions.
Another important factor exacerbating heatwave conditions in India is loss of tree cover.
In urban areas, the urban heat island (UHI) effect is also at play and contributes to hot conditions
Is the Delhi Heat Action Plan enough?
Delhi has a Heat Action Plan in place for 2024-2025, but at this stage, it is more like a set of guidelines.
While the Heat Action Plan of Delhi is a fantastic first step, what is needed is building of capacity across the ecosystem, and the access to funds and facilities that could be utilised without too much bureaucratic hurdles.
More importantly, a more disaggregated approach to looking at the problem, applying the demographic and socio-economic lens is a must, as many of the generic solutions may not really serve the underprivileged lower economic strata of people
Delhi has to play catch-up over the next couple of years, as implementing the ideas mentioned in the HAP takes time
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