Women cover themselves with scarves and caps to beat the heat in Vijayawada. , Photo Credit: GN Rao
AAround 350 million Indians were exposed to extreme heat stress between April and May 2022. Between 1990 and 2019, summer temperatures increased by an average of 0.5–0.9 °C in districts of Punjab, Haryana, Uttar Pradesh, Bihar and Rajasthan; About 54% of the districts in India have also seen a similar increase in winter temperatures. Between 2021 and 2050, it is expected that the maximum temperature will increase by 2-3.5 °C in 100 districts and by 1.5-2 °C in about 455 districts. Similarly, about 485 districts will see an increase in winter temperatures between 1°C and 1.5°C. Such a rapid increase in urban temperature is rare. Although local weather patterns are worsening due to climate change, we expect April-May temperatures to reach record highs every three years.
weather variability
Our cities are beset by the urban heat island effect, where temperatures are 4-12 °C higher than in rural outlying areas. Meanwhile, the humidity has increased the felt temperature, with wet bulb temperatures often rising above 32 °C in many cities. More recently, significant variability in weather has been observed over northern India. Cold weather in January was followed by a heat wave in February and early March, and hailstorms and heavy rains in the last few weeks.
Weather variability has consequences, especially for agriculture. For example, 90% of India’s cumin production comes from Gujarat and Rajasthan. Recent weather variability has destroyed most of the cumin crop in Rajasthan. From agricultural crop loss, it is a small step towards drought and high mortality.
Rising temperatures have made cities increasingly unusable. According to one study, for laborers doing heavy work, 162 hours are lost per year from heat exposure. An increase in temperature directly affects labor productivity. Around 50% of India’s workforce is estimated to be exposed to heat during their working hours. This includes marginal farmers, laborers on construction sites and street vendors selling their produce on the streets; Increasingly, even gig economy workers are being affected.
reduce the problem
Greenery can help mitigate part of the problem. Ideally, there should be at least seven trees in the urban landscape for every urban citizen in India. However, leafy Delhi also lacks many urban areas. Development plans for Tier 2 and Tier 3 cities may establish a mandate to increase permeable urban surface area, with an emphasis on increasing the density and area of urban forests. Expansion of wetlands and restoration of dead and decaying ponds/lakes can help reduce urban heat as well as ensure ecological functioning.
We need to reduce the urban heat island effect. This will require greater use of permeable materials in civil infrastructure and residential construction, and an emphasis on enhancing the natural landscape in urban areas. Urban layouts such as brick grates for ventilation and terracotta tiles for letting hot air out, and curbing anthropogenic heat emissions from vehicles, factories, etc. can be considered. Urban building standards should be upgraded to avoid the use of heat-absorbing galvanized iron and metal roofing sheets. Additionally, using cleaner cooking fuels will reduce indoor air pollution, which can also help reduce urban heat. Streets with poor ventilation may require further expansion or an increase in natural vegetation.
The urban design of Chandigarh considered climate response as an important factor. The city was established at the foothills of the Shivaliks between two river beds, while natural green areas were included in the city’s master plan. A large green belt of mango trees was also planted around the city to reduce urban sprawl and serve as a buffer between the residential city and the industrial suburbs. Local architecture such as mud houses within the area were considered as a template for creating climate-responsive architecture. To help cool the city, a small creek was dammed to form Sukhna Lake, while smaller water bodies were developed near larger buildings. Parks were planned in every sector along with tree plantation along all major roads. Large forest areas were also reserved. Over time, such complementary urban design has been overlayed by modern building materials and affected by diverse factors such as climate change and traffic congestion. However, the underlying design principles apply across Indian cities.
Other measures can also be considered – from adopting public transport to reducing the use of private vehicles and, most importantly, reducing the size of landfills. Methane production from mountainous landfills can cause fires, which often exacerbate urban heat and weather variability in our cities. Emphasizing solid waste management at source as well as waste segregation can help. We need to improve our forecasting ability, including the potential impact of heat on food production. Current econometric models of food inflation mainly look at variability in monsoon, minimum support prices and vegetable prices. Looking at the impact of heat on food production, storage and sale, we also need to add local heating trends to the mix. We need detailed policies and guidelines on weather variability and urban heat management at the state, district, city and municipal ward levels.
An El Nino-influenced monsoon bodes ill for marginal farmers and urban migrants. Policy makers should take mitigative action as soon as possible, setting up structural infrastructure measures to help Indians adapt to these conditions.