Temperature Rise in India

Context (IE | TH): The North, Central, & NE India are experiencing record-breaking high temperatures.
Delhi recorded a maximum temperature of 52.9°C, the highest on record in the capital. However, the IMD suggested this might be due to a sensor error or local factors, as it was an outlier.

Factors Behind the Severe Temperature Rise

The rise in temperatures is primarily due to increased emission of heat-trapping GHGs from human activities like burning fossil fuels, leading to global warming.
Since the Industrial Revolution, these emissions have made the Earth at least 1.1°C warmer than the 1850-1900 average.
The Indian subcontinent has seen a 0.7°C rise in annual mean temperatures since 1900.

Greenhouse Gas	Sources (% contribution to Global Warming)	Average Lifetime in the Atmosphere	Possible Added Heat Over a 100-Year Period
Carbon Dioxide	Human sources (100%): Mostly the burning of fossil fuels (such as coal, oil, and natural gas), deforestation/land-use change, and wildfires/biomass (plant material) burning Natural sources (0%)	Hundreds to thousands of years (about 25% lasts effectively forever)	CO₂ is used as the reference point for other GHGs, so its possible added warming (or global warming potential, GWP) is 1.
Methane	Human sources (60%): Leaks from fossil fuel production and transportation, landfills, livestock digestion and manure, rice farming, natural gas, wildfires/biomass burning Natural sources (40%)	About a decade	1 metric ton can trap about 30 times the heat of 1 metric ton of CO₂.
Nitrous Oxide	Human sources (40%): Production and use of organic and commercial fertiliser, burning of fossil fuels and vegetation Natural sources (60%)	About 110 years	1 metric ton can trap about 273 times the heat of 1 metric ton of CO₂.
Chlorofluorocarbons (CFCs, namely CFC-11, CFC-12, CFC-113)	Human sources (100%): Refrigerants; solvents (a substance that dissolves others); spray-can propellants Natural sources (0%)	52 to 93 years	1 metric ton can trap thousands to tens of thousands of times the heat of 1 metric ton of carbon dioxide

El Niño, an abnormal warming of surface waters in the equatorial Pacific Ocean, also contributed to the record-breaking temperatures.
El Niño weakens the Walker Circulation, which disrupts the flow of moist air from the Indian Ocean towards the Indian subcontinent. This diminishes Indian Monsson and creates drier conditions.
El Niño also creates high-pressure areas over the Indian subcontinent, suppressing cloud formation and precipitation, contributing to the current heatwave in north and central India.

Walker Circulation involves air rising over the Maritime Continent in the tropical western Pacific, travelling eastward high in the atmosphere, and sinking over the eastern Pacific Ocean.

The vast expanses of open areas with very little or no trees increase the impact of direct sunlight.
India has lost 2.33 million hectares of tree cover from 2001 to 2023, which is equivalent to a 6% decrease in tree cover since 2000 and 1.20 billion tonnes of CO₂e emissions.

The UHI effect causes urban areas to be warmer than their surroundings because materials like concrete and asphalt absorb and retain more heat than natural landscapes. Densely packed buildings also reduce airflow, preventing cooling.
The UHI effect contributes to global warming by increasing demand for energy, which leads to a higher production of GHGs.
Urbanisation alone has led to a 60% enhancement in warming in Indian cities.
The UHI effect can also impact climate factors other than heat, like rainfall, pollution, etc.

Increase in drought conditions: High temperatures increase evaporation rates, which, coupled with reduced precipitation, can exacerbate drought conditions. E.g. in North India.
Rainfall-related disasters: With every 1°C rise in average temperature, the atmosphere can hold about 7% more moisture. This intensifies storms by increasing precipitation intensity, duration and frequency, which ultimately can cause severe flooding. E.g., in NE India.
Deaths due to sunstrokes: Heatstroke or sunstroke is the most severe form of hyperthermia (heat-related illness). Heatstroke can lead to brain damage, organ failure or death.

HAPs usually include a combination of measures such as using forecasts and early warnings, public education campaigns on heatwave risks, building heat shelters and cooling centres, and providing clean water to prevent dehydration.
Delhi has a HAP in place for 2024-2025.