A large number of Indian cities experienced scorching heat over the past week. As per Indian Meteorological Department (IMD), approximately 70 per cent of India experienced a maximum temperature between 40 and 46°C. According to an article published in Down To Earth on April 20, 2023, India has witnessed a 34 per cent rise in heat-related mortalities in 2013-2022 from the previous decade (2003-2012).

While such high temperatures are normal for some states, the Himalayan region saw the worst levels of mercury. The states in the region have witnessed moderate (0-4°C) to high (4-6°C) departures from the normal maximum temperatures in the past week.

For instance, Karsingsa, Itanagar, Anni, Passighat and Namsai in Arunachal Pradesh recorded a 3-5°C departure from the normal on May 23, 2024, according to IMD. At the same time, Ladakh, Jammu and Kashmir, Sikkim, Nagaland, Mizoram, Manipur, Tripura and Meghalaya recorded a 1-4°C departure from the normal.

Also read: India should brace for dry and hot spring-summer, El Nino, say experts

The story does not end here; the IMD forecast on May 25 suggests that a 2-8°C departure will likely occur in Himachal Pradesh, Mizoram and parts of Ladakh in the coming days. This has several issues for people living in the hills.

First, people living in the hills have not experienced such high temperatures, so their tolerance to heat is limited. They are more susceptible to heat-related illnesses than someone living in the plains. Their exposure to heat is also high as most of the population works outdoors. 

The preferable ambient temperature for humans ranges from 17-24°C, according to an analysis published in The Lancet Planetary Health. Prolonged exposure to temperatures beyond this can result in physiological stress, cardiovascular disease and other heat-related illnesses. 

Secondly, hill states have not required active cooling infrastructure like fans and air conditioners. Increasing temperatures are forcing a switch to active cooling that would create a surge in electricity consumption and dent in people’s pockets.

If the electricity demand is not fulfilled via cleaner energy sources, this could lift the emission curve of the region. This means a vicious cycle awaits the Himalayan region wherein a warming environment means more anthropogenic heat due to cooling and more emissions.   

Even India’s coastal belt was not spared by the rising mercury. On May 23 and 24, IMD recorded a 2-5°C departure from the normal across Medinipur in West Bengal and Puri in Odisha. Additionally, the entire west coast of India suffered from a 2-4°C departure from the normal on May 24.

The increase in temperature over the coasts is accompanied by high humidity, which increases the feel-like temperature. Such conditions create sultry weather, making it unsuitable for mental or physical work. This leads to a loss in productivity while inducing heat stress and thermal discomfort amongst the dwellers. 

Most Indian cities fall under the plains, and the prevailing high temperatures here are leading to increased intensity of the Urban Heat Island (UHI) effect. On May 23, several cities in Rajasthan, Madhya Pradesh, Gujarat, Delhi, Punjab, Uttar Pradesh, Telangana, Andhra Pradesh, Maharashtra, Tamil Nadu, Jharkhand, Chhattisgarh, Odisha and West Bengal witnessed maximum temperatures above 40°C, according to IMD.

Hisar, Bhiwani and Mungeshpur in Haryana; parts of Delhi such as New Delhi and Najafgarh; Rajnandgaon in Chattisgarh; Mahabaleswar, Pune, Pimpri-Chinchwad in Maharashtra; Jamshedpur in Jharkhand; Baripada and Balasore in West Bengal; and a few other cities saw a 6-8°C departure from the normal temperatures. 

IMD declared heatwaves to severe heatwaves in Rajasthan’s Churu; Jhansi, Mathura-Vrindavan and Agra in Uttar Pradesh; Khajuraho in Madhya Pradesh; and parts of Delhi (Pitampura, Narela and Pusa) on May 23. Further, cities are also experiencing high nighttime temperatures (approximately 5-6°C departure from normal minimum temperatures) due to UHI effect. This happens when the environment traps heat all day and releases it at night. 

Also read: Climate crisis in North East India: Why are rainfall patterns changing?

With such shifting temperature normals, cities need to both adapt and mitigate the impact of warming. This will require measures to cool down the environment. Increasing and improving green infrastructure is one such measure. It not only cools down the surroundings but also prevents flooding.

Green infrastructure includes green spaces and water bodies like parks, gardens, green belts, green roofs, ponds, lakes, etc. Green infrastructure restricts heat gain in urban areas via evapotranspiration and therefore plays a crucial role in regulating the micro-climate.

A 10 per cent increase in tree canopy cover can bring down afternoon temperatures by 1-1.5°C; active and passive water systems can lower the temperature by 3-8°C, according to the Ministry of Housing and Urban Affairs.

Further cooling materials for roofs and facades can reduce the indoor temperature by 2-5°C. Integrating such measures with master plans and building by-laws would bring a mandated implementation and enable cities to act for heat resilience and mitigation. 

As cities grow and heat up, it’s time to get rid of your air-conditioner and have more plants in your homes.

Ever wonder what’s the most cost-effective solution to cool the temperature? Simple. Planting more trees or incorporating more vegetation/plants in city design. It puts a new slant on the idea of the ‘urban jungle’.

Climate change is one of the most serious risks to urban life. Our cities are heating up. The dangers of the urban heat island — when concrete buildings, asphalt roads and other urban infrastructure absorb and re-emit solar radiation more than natural landscapes — are well documented, increasing temperatures in built-up areas which can increase the risk of heat-related illnesses. 

Poorly planned city development increases this risk. According to the Secretariat of the Convention on Biological Diversity, only 40 percent of the urban areas expected to exist by 2030 exist, meaning significant further urban development will occur over the next decade.

“Nature-based solutions” refer to a wide range of strategies with the potential to curb greenhouse gas emissions. They can improve an ecosystem’s capacity to absorb carbon dioxide or reverse degradation to the point where an ecosystem once again becomes a “net sink” of carbon (storing more carbon than it emits). 

Of all the methods for reducing the heat island effect, those involving plants have proven to be the most successful. There is still disagreement in the scientific community over how much green space people need and whether current systems adequately address this issue, despite the importance of urban green space to the layout and impact of today’s dense urban centres. The World Health Organization advocates for easy access to green space, suggesting everyone lives no more than 300 metres from a green area covering at least half a hectare.

Vegetation can mitigate the effects of extreme climate, reduce energy use, and improve people’s physical and physiological well-being, all of which go a long way towards making urban living more bearable.

In tropical regions, buildings exposed to more sunlight increase energy demand. Using plants for shade can reduce solar radiation, cool the building and improve energy efficiency. While trees have been planted to shade homes for generations, there has been substantial innovation in the application strategy in recent years.

Tree canopies cool the ground below by blocking sunlight and controlling how much heat a building radiates into the environment. For tropical cities,  Ceylon Ironwood trees have dense branching, and high leaf coverage provides excellent shading. Due to the shade, less absorbed heat is radiated to the air, encouraging evapotranspiration, reducing the surrounding temperature and increasing people’s thermal comfort. Indoor and outdoor temperatures can be lowered by more than 3 degrees when plants are used to modify the microclimate.

The shading performance of each species is different, resulting in varying scales of effectiveness on microclimate alterations, making living walls with climbers and creepers a suitable alternative when there is no space for trees.

Living walls 

A “living wall” is a system that irrigates and sustains a vertical garden. Living walls can influence the microclimate by reducing surrounding temperature and may also be part of a water treatment system.

Vegetation incorporated into a building’s exterior has two purposes: it lowers the heat transferred inside and improves the building’s look. A green facade is one in which plants such as vines and creepers are grown directly on the building’s exterior, while green walls are one in which a system is used to cultivate different species of plants along the wall surfaces.

Green facades and green walls are two common living wall systems that increase a building’s energy efficiency. Green facades have vegetation either planted directly in the ground or planters climbing onto building surfaces or light framework, and green walls have vegetation growing on a different system then attached to the wall instead of being planted directly. A green wall uses materials and innovative technology to cultivate various plants along the wall surfaces. A continuous green wall, also known as a “vertical garden,” usually instils lightweight and permeable frames where plants would be planted individually.

Climbing plants like Double Rangoon for a green façade are essential for optimal performance and a sustainable living environment. Climbers like the Yellow Trumpet vines create a more pleasant microclimate, while the Curtain Creeper lowers the surrounding temperature and cleanses the air.

Growing food

Urban farming is not as cutting edge as you think; people have been doing so for centuries at Machu Picchu and the ancient Hanging Gardens of Babylon. People all across the world have always had gardens in their homes. They shaped their surroundings to enhance their quality of life. Today’s urban garden integration has progressed, emphasising their ability to reduce greenhouse emissions and greening cities.

Green infrastructure could help the city coordinate the revitalisation of unused, abandoned, or underutilised spaces. Small-scale farming in these areas might offer urban residents food while reducing carbon emissions. Spaces between buildings (interstices) in the city can be used for urban farming, which also helps modify the city’s microclimate. Rooftops, balconies, and vacant lots are all excellent places to start an urban farm.

The presence of vegetation significantly influences a building’s microclimate. It has been demonstrated that vegetation can reduce temperatures by 1.32 to 5 degrees Celsius compared to a hard surface area. Because of evapotranspiration, vegetation can lower local temperatures, hence altering microclimates.

Urban greening can mitigate the urban heat island effect, especially in the spaces between buildings. Using plants to moderate the heat and reduce dependency on artificial cooling can be the seed of a solution to the dangers of rapidly heating cities.

Ts Dr Tamil Salvi Mari is a senior lecturer in architecture at Taylor’s University, Malaysia. Salvi’s research area revolves around investigating humane design — the interaction between humans, the built environment and the natural environment, focusing on current societal and environmental needs. 
This article was originally published March 13, 2023.
Originally published under Creative Commons by 360info™.

More than 30 large lakes in India have recorded a drying trend from 1992 to 2020, a new analysis published in journal Science revealed.

Of them,16 are the major lakes of southern India. Some of these include Mettur, Krishnarajasagar, Nagarjuna Sagar and Idamalayar. Recent droughts may have contributed to reservoir storage declines in southern India, noted the research published on May 18, 2023.

“Except for few lakes, most of the peninsular India lakes are declining in lake levels and storage,” Balaji Rajagopalan, professor of engineering at the University of Colorado Boulder and co-author of the study, told Down To Earth.

Lakes, which cover three per cent of the global land area, play a key role in regulating climate through carbon cycling.

“While rivers get all the attention rightfully, lakes have and continue to provide more of the water supply and sustain societies, across the world and, are often not well managed,” Rajagopalan added.

Satellite observations have recorded a loss of 90,000 square kilometres (km2) of permanent water area across the world. However, the factors driving such losses are not clear.

Red dots indicate lakes that are drying. Source: Yao et al / Science.

Rajagopalan and his colleagues used satellite observation from 1992-2020 to create a global database of lake water storage. They covered 2,000 of the world’s biggest lakes and reservoirs that contribute to 95 per cent of the total lake water storage on Earth.

They then used models to quantify and attribute trends in lake storage globally to natural changes, climate change and human consumption.

Overall, 53 per cent of the world’s largest lakes have been losing water and 24 per cent have seen an increase. Nearly 33 per cent of the global population resides in a basin with a large, drying lake. 

“The analysis also reveals a declining trend in reservoir water storage in both arid and humid regions,” Sarah W Cooley from the University of Oregon wrote in a related article. She was not involved in the study.

Also read: Earth has lost one-fifth of its wetlands since 1700 — but most could still be saved

The drying trend in Arctic lakes is also more pronounced than previously thought, the researchers highlighted. Climate change has some role to play in driving these changes, they said. “The contributions from temperature, precipitation and runoff indirectly indicate the potential role of climate change,” the author explained.

In about 100 large lakes, climate change and human water consumption were identified as the main drivers of water losses and a decline in lake volume.

The climate is linked to factors contributing to the decline of lakes, such as temperature and potential evapotranspiration (combined loss of water through the plant’s process of transpiration and evaporation of water from the Earth’s surface), precipitation and runoff, and human consumption.

The researchers hope to further understand the role of climate in these factors. They also plan to model the variability of paleo-lakes [old lakes] over the Indian subcontinent and how they potentially impact human migration.

Rajagopalan said it is important to understand the approaches to managing lakes in an integrated manner. “This will elevate the status of lakes to their rightful place,” he said.

Long-term droughts such as the one going on in the Horn of Africa region, especially in its southern parts, have been made 100 times more likely by climate change, according to a report by the World Weather Attribution (WWA) group.

The WWA is a collaboration of climate scientists from around the world who work on attributing extreme weather events such as droughts, heatwaves, extreme rainfall, floods and cold spells to the effects of anthropogenic greenhouse gas emissions-induced global warming and resultant climate change.

Such droughts are a result of a combination of impacts from low rainfall and high temperatures and can be categorised as meteorological (lack of rainfall) as well as agricultural (decrease in soil moisture content, increase in transpiration from plants and reduction in crop yields).

The southern parts of the Horn of Africa, which includes southern Somalia, southern Ethiopia and eastern Kenya, witnessed below-normal rainfall from 2020-2022, the study found. 

There are two kinds of rainfall periods in this region known as the short rains, which occur from October to December, and long rains, which occur from March to May. 

While scientists observed below-normal short rains in 2020, 2021 and 2022, they observed below-normal long rains in 2021 and 2022. 

The scientists analysed all rainfall events that occurred in the region from January 2021-December 2022 and also the short rains and long rains periods separately. 

They found that below-normal rainfall in the long rains period occurred once in a decade, while the same for short rains period occurred was once in five years. 

They also noticed a trend of low rainfall during the long rains period, while an opposite trend of more rainfall was noticed for the short rains period. 

For the 24-month period, there was only a 5 per cent chance of below-normal rainfall every year without a major trend. 

To quantify the contribution of climate change in the above occurrences, they used climate models and looked for similar less rainfall events in the model data. 

They found that the actual observations of low rainfall events matched the model data and that low rainfall during the long rains period has been made twice as likely by human-induced climate change.

The fact that during this entire period a La Niña event was also occurring in the equatorial Pacific Ocean made the trend of increased rainfall during the short rains periods attributable to climate change. 

During La Niña, the cooler-than-normal phase of the El Niño Southern Oscillation phenomenon, the drought occurrence is enhanced in the Horn of Africa region. 

To understand the contribution of climate change in the occurrence of agricultural drought, which accompanied the low rainfall periods in the region, the scientists also looked at how evapotranspiration changed during the 24 month period. 

During an agricultural drought, the decreased rainfall reduces the moisture content of the soil that is essential for the growth and productivity of crops. High temperatures increase the chances of this happening as they increase the evapotranspiration from plants. 

Evapotranspiration is the process through which plants lose water to the atmosphere to maintain their water content and temperature. 

The authors of the report found that in a world without the current global warming of 1.2 degrees Celsius, the combined impact of low rainfall and high evapotranspiration would not have led to drought at all. 

But in a warmed up world grappling with climate change, the events lead to an exceptional drought. 

“Climate change has made events like the current drought much stronger and more likely; a conservative estimate is that such droughts have become about 100 times more likely,” the scientists noted in the report.

The three-year drought in the region has had wide-ranging impacts on people’s food and water security, their livelihoods and health. Around four million people in the region are suffering from acute food insecurity. 

This is mainly because most of the people in the region are still dependent on rain-fed agriculture, agro-pastoralism and pastoralism which are extremely vulnerable to drought conditions.

Prolonged drought conditions are not the only factors which are caging the region’s people in a cycle of poverty that would be difficult to get out of. 

“State fragility and conflict, as well as the length of the drought played a significant role in worsening outcomes, especially for people in Somalia,” the study showed.

“Further, the severity of impacts linked to the long duration of the drought also raises serious questions about the length of droughts that government drought management systems and the international aid infrastructure should be prepared to handle in the future,” the researchers observed.