Urban heat islands aggravate summer discomfort


The only reason why April 2022 was not the hottest April on record in the country is that northeast India experienced heavy rainfall, an event so unexpected that even the Indian department of Meteorology (IMD), which now prides itself on accurate forecasts, said he was wrong. . In northwestern and central India, April broke all heat records.

Early heat could have cascading effects. The melting of the Himalayan ice could start early, causing gallons of melt to rush down mountain rivers in quantities that could cause flooding and calamitous events.

Urban heat islands develop due to various factors, such as concretization, industrialization and high population density, often in combination with reduced vegetation cover.

The heat wave (which the meteorologist describes as a temperature above 40 degrees Celsius and 4.5 to 6.5 degrees Celsius above normal for this time of year) may flow back from parts of the land of the northwest and central, but the relief is temporary. April is technically late spring or early summer, May is the hottest month, while for the northern plains June is just as bad, if not worse. Forecasts gloomily indicate that May will see above normal temperatures.

The World Meteorological Organization noted that while it may be premature to pin blame for the extreme heat on climate change alone, it is consistent with what is expected in a changing climate – heat waves are more frequent and more intense, and start earlier.

Early heat could have cascading effects. Himalayan ice melt could start early, not only affecting glaciers more, but also causing gallons of melt to rush down mountain rivers in quantities that could cause flooding and catastrophic events. A very fine climatic balance, perfected over millennia, is on the verge of collapsing.

In the weeks to come, the extra water could be a blessing. The first heat has increased the demand for water and electricity, and interstate disputes are intensifying. With parched water bodies and groundwater at abyssal levels, India is likely to feel the impact of the extreme weather event in several ways. Just like last year the railways ran oxygen trains to deal with the wave of Covid-19, this year passenger trains are being sidelined to haul coal to produce fuel. ‘electricity. For every degree of temperature increase, the efficiency of electricity transmission drops by 1 to 2 percent, said Hem Dholakia, senior specialist (research) at the Coalition for Disaster Resilient Infrastructure (CDRI).

It’s no surprise that the PMO is calling meetings with state stakeholders to prepare for the weeks ahead. Following the IMD warnings, the Union Health Department has also contacted the states, asking them to issue daily heat bulletins and implement the national action plan on heat-related illnesses. heat. This includes ensuring an adequate water supply, warning people in advance and supplying medical centers to treat cases of dehydration and heatstroke.

Memories of 2015 have not gone away, when the country recorded more than 2,100 heat wave deaths, the highest since 1971. The unofficial toll must be several times higher. In 2015, the country labeled the heat wave a “disaster” under the National Disaster Management Act, considering its impact on human life and loss of productivity.

April also brought to light a phenomenon that experts often talk about: the urban heat island. In Delhi, for example, on April 29, when Safdarjung station (which is considered the norm for the city) recorded the second highest temperature on record in April of 43.5 degrees Celsius, another station at Akshardham recorded 46.4, a difference of three degrees. Urban heat islands develop due to various factors, such as concretization, industrialization and high population density, often in combination with reduced vegetation cover. Concrete surfaces and roads have greater heat reflectivity, causing temperatures in these pockets to be much higher than in surrounding areas. “The maximum impact of urban heat islands is on minimum temperatures,” said IMD Director General Mohapatra. So the nights bring little relief.

The coming summer is disastrous. And the summers of years to come will test our preparedness to mitigate the climate crisis. By 2050, 60 million Indians will live in urban areas. Climate-resilient urban planning is urgently needed, said Anjal Prakash, lead author of the sixth assessment report of the Intergovernmental Panel on Climate Change.

Climate change is the result of 200 years of human activities, and localized cosmetic measures may not stem the events caused by global changes. For example, the increase in temperature in India is not necessarily due to activities in India alone. However, as one of the most vulnerable countries to climate change-related events, India also needs to develop heat event mitigation measures.

Understanding why a particular locality has become an urban heat island may require scientific investigation. However, some interventions work regardless of the cause. “We need to build infrastructure for Indian needs and not imitate the west,” said Prakash, a critic of the use of glass as a building material. “In a country that enjoys such sunshine, we don’t need glass buildings, inside which the cost of cooling increases. We need to have passive cooling built into our architecture, for which we have enough mainstream examples. Take the Hawa Mahal in Jaipur, where temperatures are easily about four degrees cooler than outside. And we need to rebuild our green and blue infrastructure.”

Indeed, green cover and water bodies influence microclimates, lowering temperatures by just a degree or two, which could be the difference between life and death. Simply ensuring fountains are turned on on hot days is effective, as is keeping public parks and gardens open for people to take shelter, Dholakia said.

Ahmedabad was the first city in the country to have a heat health action plan, which has been replicated nationwide. Suggested actions are determined by local circumstances, the dry heat of northern India requires different measures than the moist heat of the coasts. Unfortunately, while the first stage of the plan, which involves the IMD giving short-term forecasts with a color-coded warning system, is in place, the actions that local authorities need to take on them remain sporadic. “There should be a system for declaring certain activities, such as construction, not to be done during the hottest hours. Or that school times be brought forward based on weather alerts,” Prakash said. With year-round weather events impacting school life – floods, smog, extreme cold – instead of declaring holidays, authorities will now have to circumvent these events.

Cool roofs are another initiative, which works well for high-end infrastructure as well as low-cost buildings. Rooftop gardens are one measure, just paint the tin roofs with reflective white paint instead of the heat-absorbing black paint, which again lowers the temperatures by a degree or two.

March was the hottest on record, April was cruel. Will India be able to ease the miseries of May? It is one thing to recommend that a continuous supply of electricity and water be maintained and quite another challenge to ensure that this happens.


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