Heatwave In India : What Is The Reason For High Temperature In India? - The HNT
Heatwave In India : While India typically experiences heatwaves during the spring and early summer, the country has recently grappled with an exceptional one. May 2024 set records as the hottest May ever recorded, and the heatwave that began earlier this year has proven relentless. This intense heat, coupled with the effects of climate change, has caused significant stress on the population and infrastructure. Let's delve deeper into the recent heatwave in India, exploring its impact and the ongoing challenges it presents.
Heatwave In India
Do you remember the summer season 2 years ago? Year 2022. Look at this article, it was called the Hottest Summer Ever. That year, it was so hot in India that it broke the 122 year old record. But then came the Summer of 2023. In 2023, the summer season was so scorching hot that scientists said that it was the hottest summer in the last 2,000 years in the northern hemisphere of Earth.
But then we come to the year 2024. January 2024: Hottest January Ever Recorded. February 2024: Hottest February Ever Recorded. March 2024: Hottest March Ever Recorded. April 2024: Hottest Month Ever Recorded. The last 11 months on Earth, have been record breaking in terms of heat. The scorching heat that you have to bear today is not normal.
And you are not alone. Last month, in South India and in the entire Southeast Asia, record-breaking heat waves have been seen. Vietnam, Singapore, Malaysia, Indonesia everywhere, there was such unbearable temperatures. In the Philippines, the heat index had crossed 53°C.
In Uttarakhand, there were forest fires. In the first week of May, forest fires were seen in Odisha, Chhattisgarh, Madhya Pradesh and Jharkhand. Heat wave warnings are being issued all over the country, even in places like Kerala, where there aren't heat waves usually. And now temperatures have been soaring above 46°C in North India.
Global warming and climate change are the main reasons behind all this. But are they the only reasons? No. In this video, come let's understand the two other reasons that are causing this and what is the solution at the local level. What can we do to avoid this heat?
What Is The Reason For High Temperature In India?
First, we need to understand that such extreme weather events are not only seen in India or Southeast Asia, but also in every corner of the world. What happened in South America this month? Watch this news. "At least 83 people are de@d after days of heavy rain in Southern Brazil and more than hundred are missing.
Another 123,000 people that have been displaced by floods." There were devastating floods in Brazil in which more than 150,000 people were displaced. Entire cities was submerged.
What is happening in South Africa? We are witnessing a terrible drought. "The Southern African region is experiencing a severe drought with many families unable to cater for their daily needs like food." "I just spoke with some of the elders from the community and the last time they can remember this type of drought is 1947.
So this is not a normal circumstance." A drought unparalleled in the past several decades. That's why many southern African countries have requested $5.5 billion from the rest of the world. To prevent a situation of starvation. There is one weather event behind all this destruction which is considered the biggest cause. El Niño. It is a natural cycle of the Earth's climate that is seen every 5-7 years.
But due to climate change, it is becoming more extreme year after year. The full name of this cycle is El Nino Southern Oscillation. In short, it is called ENSO. According to the World Health Organization, this is the second biggest cause that changes the climate of the Earth.
And in the first place is the relationship between the Earth and the Sun, Earth's revolution around the Sun, which causes the seasons to change. Winter following summer and summer following winter. But after that effect, El Niño has the second biggest impact.
What is El Niño?
It's something that can be seen in the Pacific Ocean. The Pacific Ocean is the world's largest and deepest ocean, lying is between Asia and the Americas. Imagine, this ocean is like a tub, a bathtub, water keeps moving from one side to another.
When you move your hand in the tub, the water sloshes from one side to another and then gets back to the first point. Similarly, winds blow over the Pacific Ocean flowing from east to west. These winds are called Trade Winds and most of the time, they move from the Americas to the direction of Asia and Australia.
Because it's based on Earth's rotation. You must have read about the Coriolis effect in school. Since Earth rotates from West to East, due to this Coriolis effect, the Trade Winds flow in the opposite direction. Due to this, normally, the water on the surface of Pacific Ocean starts flowing towards West. It means it starts flowing towards Australia.
And when the water on the surface starts flowing in that direction, in the east, the water below the surface level of the sea starts rising to the surface. That is, near South America, the water from the depths of the sea rises towards the surface. This is called Upwelling.
The water that rises from the depths of the ocean, is much colder comparatively, and has more nutrients. Because of this, fish and marine life also benefit. So in this normal situation, the hot water goes to Australia, and the cold water came to South America. When water is hot, it evaporates more easily. And because of that evaporation, clouds are formed and more rain is seen near Australia.
But now friends, imagine that these trade winds have weakened. These winds are not flowing as strongly over the Pacific Ocean.
What will happen?
The upwelling will be weak, it will be almost non-existent. The hot water on the surface will consistently remain hot. The clouds that were supposed to bring rain to Australia can rain anywhere over the Pacific Ocean. So the Australia region will become very dry. This is the phenomenon of El Niño which is like a regular cycle.
But this is not a regular cycle. Sometimes it happens every 4 years, sometimes after 5 years, sometimes after 7 years. But when El Niño happens, it lasts for 6 to 12 months. But during the El Niño, the weather patterns of the world change. In Australia and Southeast Asia, it causes higher temperatures and drier weather conditions.
The risk of heat waves increases. And the wildfires that took place in Australia, you might remember the violent Australian wildfires of 2020, even that was caused by this El Niño. The last El Niño event was in 2018-19 Which lasted till January 2020. This is why the bushfires in Australia happened in December 2019.
Since then, today, from January 2023 till now, another El Niño is in effect. The interesting thing here is that in South America, El Niño has the opposite effect as it has in Asia and Australia. That is, it rains more there. The risk of floods increases. This is why today we see many devastating floods in Brazil.
Now, apart from this, there is an opposite phenomenon of El Niño which is La Niña. Both these words are from Spanish.
El Niño means the boy and La Niña means the girl. The normal conditions of the Pacific Ocean, as I told you, normally, if they go to extremes, then the La Niña effect is seen.
What does this mean?
The Trade Winds blowing towards the west start moving strongly in that direction. Because of this, colder water flows to South America and hotter water flows towards Australia and it starts raining more in Australia due to La Niña.
La Niña's events usually last longer. They can last for 1-4 years. After the El Niño of 2018-19, when La Niña came in 2020-21, it became so extreme that it caused flooding in Australia. It rained so heavily in Australia. You can see the news from March 2021, Floods in Australia.
You can see this interesting chart on the screen. This graph depicts the El Niño and La Niña events that took place over the last 30 years. The red peaks are the El Niño events and the higher it is, the stronger the El Niño event was. The strongest El Niño event till date was seen in 2015-16. After that, was the 1997-98 event followed by the current 2023-24 event. On the other hand, the blue trenches are the La Niña events.
The latest was in 2020-21 which went on all the way up to January 2023. Before this, the strongest La Niña was in 1999-2000. If you zoom in on the latest time, you will see that the graph of El Niño is going down again. Scientists believe that La Niña can start by July-August.
How will this impact India? India's monsoon can be better than average this year. Last year, in the rainy season of 2023, there wasn't a lot of rain because of El Niño. El Niño is a big reason why the summers of 2023 and 2024 were very hot. Because of which, droughts were seen in Southern African countries. Even the heavy rains and floods in Dubai were caused by it to some extent.
Scientists believe that climate change caused by humans is making the El Niño effect more extreme. That is, floods caused by El Niño are becoming more dangerous. Heat waves are becoming more and more violent. This is why in Kerala, a heat wave warning has been issued only twice. The first time was in 2016 and the second time was in 2024. Both times, during an El Niño event.
The Indian Meteorological Department has a basic criteria to declare a heat wave. They say that if the temperature in the plains is above 40°C, above 37°C in the coastal areas, and above 30°C in the mountains, apart from this, if for two consecutive days, the temperature is 4.5°C above normal, then a Heat Wave will be declared. And if it is 6.4°C above normal for two consecutive days then a Severe Heat Wave will be declared.
But if the temperature crosses 45°C then without checking any other condition a Heat Wave is declared. This was about the temperatures. But, in itself, temperature is not a very useful metric. Because, if you have ever noticed, in May, it is easier to tolerate 45°C in Delhi as compared to 38°C in Mumbai. 38°C in Mumbai seems more unbearable compared to 45°C in Delhi.
Why is this? It is because of the humidity. The more humidity there is in the air, the more difficult it is to tolerate higher temperatures. But what really is humidity? Relative Humidity means the maximum moisture content in the air at a particular temperature.
100% relative humidity means that air is completely saturated at a certain temperature. It is holding as much moisture than it possibly can and cannot hold any more. The thing is the hotter the air is, the more is its capacity of retaining mositure. Hot air can hold more moisture as compared to cold air. This means that if the relative humidity of cold air and hot air is at 100%, hot air will have more moisture.
And as the humidity increases, the more difficult it becomes for our body for the sweat on our body to evaporate. And sweating, as you know, is the number one way for our body to keep us cool. If it's really hot and there's high humidity, we will not be able to sweat and our body will not be able to keep itself cool. That can be lethal for us. This is why, it is important to consider both temperature and humidity.
And one metric that considers both of these things together is the Heat Index. Heat index tells us how hot the weather outside will feel for us. On your phone's weather app, you would have noticed, the temperature in Mumbai might be written as 31°C, with the "feels like 37°C" beside it. In some apps, it is written as Real Feel.
This Feels Like indicator is computed from the heat index. On this chart, you can see the various temperature levels, and various relative humidity, and their corresponding Heat Index. If the temperature is 35°C and the relative humidity is 50%, then it will feel like 41°C. But if at the same temperature, the relative humidity is at 75% then it will feel like a dangerous 53°C.
And this comes under the Red category. which means extreme danger. On this heat index, you have a high chance of getting a heat stroke or a sunstroke. This is why, the latest heat wave in the Philippines was so dangerous and deadly. Because the heat index there had reached 53°C. Those who do not know this, may look at the actual temperature of "only" 40°C or 41°C, thinking that it's not very high.
But it is very important to pay attention to the Heat Index. Because even for the heat index of 32°C to 41°C, you need to take extreme caution. If you spend a lot of time in the sun or do any physical activity, it is possible to get a heat stroke. We hear cases where people lose their lives due to the heat. Due to a heat wave. And this is why, temperature wise, Delhi is hotter right now.
But heat index wise, how bearable is it to stay outside? It becomes intolerable by June end. Because by then the rainy season is about to start and the humidity increases. Although, the situation has worsened to an extent that in Delhi, the Heat Index is touching 50°C. And according to this report, over the next few days, it can reach as high as 56°C.
Now apart from this there is another effect which increases the impact of heat waves impact on a local level. An effect whose solution is much easier than all other effects. The Urban Heat Island Effect. In different areas of a city, some places are hotter and some are colder.
You must have noticed this too. At places with more trees, like parks or any other place, the temperature is relatively more comfortable there compared to other areas. And the areas with only big concrete buildings, tall glass buildings, 8-lane highways, asphalt covered ground, these places are way hotter. These places are known as Urban Heat Islands and there is a very simple reason behind it.
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This effect was studied in Delhi and it was found that the places where this urban heat island effect is present like Connaught Place, Sitaram Bazar, Bhikaji Cama Place, these places were 3°C to 8°C hotter as compared to the places with more trees. Like the Hauz Khas District Park, Buddha Jayanti Park. Think about it, friends. 7°C to 8°C. It's such a huge difference! This tells you the importance of trees.
And this is why I say that having a web of roads in any city should not be an indicator of development. I said this in an old video, and it was clipped and shared on Twitter by many, claiming that I am against development. "Do we really need more highways? Do we really need double highways? Do we need double airports? Because to build these highways many forests need to be cut down.
There are many such highways that go through the middle of national parks and wildlife sanctuaries." Laying down concrete and asphalt in cities and broadening the roads is not real development in my opinion. In my opinion, development means that people have proper walkable places. Cities should be designed where the temperature outside is comfortable there is enough greenery that people can walk to where they need to go. Cars should be used as little as possible.
Urban Heat Island effect
Because cars also release heat which increases the Urban Heat Island effect. I talked about this in this video in a city if there are more places where cars are completely banned it would be better for people. This is something that most developed countries are starting to understand.
Look at the transformation in Paris. The government there has banned cars from the city on a large scale. Removed the asphalt and planted trees. Promoted cycling. All this to reduce the intensity of the Urban Heat Island effect. And people have a comfortable temperature to live in the city so that people can walk from one place to another.
Promoting public transport as an alternative is very important. Using air conditioners. Another thing that raises the intensity of the Urban Heat Island effect. When it gets hot outside people use ACs in their homes. Using ACs in the house means that heat will be released outside. And the area or the environment outside will get hotter. One alternative to this is to use natural methods.
Ventilation should be incorporated into the design of the building in a way that there is minimum need of an AC. Historically, our ancestors used to design such buildings. Look at these old buildings in Dubai. A tower is built in the buildings this is the ventilation area so that air can circulate inside the house.
Apart from this, in many places, the roofs are actually painted white so that the sunlight can be reflected. Look at this article on Yale University's website. If you paint your roof of your house white, then it will make a difference of 2°C to 3°C. Because dark colours absorb sunlight and white colour reflects sunlight.
And this isn't applicable only for cities it is equally applicable for rural areas too. Apart from white paint, another alternative can be to plant greenery on the roof. Plant grass or grow trees. You will ask what else can we do instead of installing AC in houses?
What is its alternative in this modern world?
The straight answer is Radiant Cooling. This is a new technology which saves a lot of money in comparison to AC. What happens in this is, you install pipes in the walls through which cold water flows. And this cold water flowing through the walls, keeps your house cool without an AC.
This technology is being used in many new buildings, but in reality, it's an old technology. In the olden days, the forts built by kings and emperors, monuments like Taj Mahal, how did they keep them cool? By using water channels. Small channels of water used to flow around the building and since water passed through the area, it made the surrounding area cooler.
This is the same concept. By promoting this technology, not only will the city remain cooler, but it will save money too. Electricity bill will be reduced. And apart from this, obviously, governments will need to focus on making cities greener. More trees, more parks, so that the impact of heat waves can be minimised.
But we will have to implement all these solutions as soon as possible, because in the near future, these heat waves are going to get more dangerous and more impactful. In a recent Future Projections for the Tropical Indian Ocean study it showed that in a few years, we will see almost permanent marine heat waves in the Indian Ocean.
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