The story so far: At least five people in Bihar’s Aurangabad city reportedly died on Thursday due to a sunstroke, news agency Reuters reported. Parts of north and central India continued to reel under a severe heatwave on Thursday, even as the India Meteorological Department (IMD) predicted a gradual fall in temperature over the next five days. On Wednesday, an automatic weather station in Delhi recorded a maximum temperature of 52.9 degrees Celsius, the highest temperature on record in the capital. The IMD, however, said that this could be due to “an error in sensor or local factors”, since the recorded temperature was an outlier. The IMD is said that it is examining the data and sensors.

Ten more people were reported dead government hospital in Odisha’s Rourkela region on Thursday due to the heat. A 40-year-old labourer in Delhi died due to a heatstroke (a condition in which the body temperature increases beyond 40 degrees C) on Thursday, The Indian Express reported. Despite these reports, it must be noted that heat-related deaths are widely underreported.

What does IMD’s latest report say?

As per the IMD report released Friday afternoon, maximum temperatures in northwest and central India are predicted to fall gradually by 2-3 degrees C in the next three days.

Maximum temperatures on Thursday in most parts of Delhi, Haryana, and Chandigarh, as well as large parts of Rajasthan, and isolated pockets over eastern Madhya Pradesh, Uttar Pradesh, Bihar, Jharkhand, and Odisha were recorded in the range of 45-48 degrees C.

Parts of western Madhya Pradesh, Chhattisgarh, and coastal Andhra Pradesh, and isolated pockets over Gujarat, Telangana, and Rayalaseema recorded maximum temperatures in the range of 42-45 degrees C.

How do heatwaves arise?

Some experts believe that post El Niño warming has contributed to higher-than-usual temperatures in north India this year.

El Niño and La Niña are atmospheric patterns that influence the warming and the cooling of sea surface temperatures in the Central and Equatorial Pacific. The two opposing patterns occur in an irregular cycle called the El Niño Southern Oscillation (ENSO) cycle, with a neutral period in between.

In March 2024, the World Meteorological Organisation (WMO) announced that even though the 2023-24 El Niño, which peaked as one of the strongest on record and has declined since, will continue to impact climate for the coming months. This exacerbates the heat captured by anthropogenically produced greenhouse gases, causing higher temperatures.

The IMD, in its May bulletin, said that weak El Niño conditions are currently observed over equatorial Pacific and are likely to weaken further and convert into ENSO neutral (the Australian Bureau of Meteorology had already announced on April 16 that the ENSO cycle is now in neutral).

A study published in 2016 had predicted that if El Niño activity increases in the future, heatwaves in India were likely to intensify.

During El Niño, surface temperatures in the equatorial Pacific rise, and trade winds — east-west winds that blow near the Equator — weaken. Normally, easterly trade winds blow from the Americas towards Asia. Due to El Niño, they falter and change direction to turn into westerlies.

ENSO, however, does not cause extreme heat in isolation. Teleconnections, which are the relationships between global weather and wind patterns, impact each other. The Walker circulation, which involves the trade winds that blow from east to west along the Equator, are affected by ENSO due to teleconnections.

El Niño is associated with a shift in Walker circulation, causing a large-scale redistribution of heat and moisture. Heat redistribution on the surface impacts airflows above the ocean. It is known that El Niño diminishes Indian monsoon since the weakened Walker circulation disrupts the flow of moist air from the Indian Ocean towards the Indian subcontinent, reducing the moisture available in the winds, hence creating drier conditions.

El Niño also creates high-pressure areas over the Indian subcontinent, which suppress cloud formation and precipitation. The absence of clouds is also contributing to the current heatwave in north and central India.

What’s the cause of North India’s heat?

Delhi and most parts of north and central India that are currently under a heatwave spell, are far from the influence of oceans that can regulate temperatures and air moisture. Continental air, which is a large volume of dry air over a land mass, greatly affects the weather in Delhi because of its inland location. Tropical air masses that originate in the Thar Desert and other hotter, drier regions to the west and northwest of India bring increased heat to Delhi and surrounding areas, contributing to heatwave conditions.

Another important factor exacerbating heatwave conditions in India is loss of tree cover. “The vast expanses of open areas with very little or no trees increase the impact of direct sunlight,” Indu K. Murthy, head of Climate, Environment and Sustainability at CSTEP, told The Hindu. According to the Global Forest Watch, India lost 2.33 million hectare 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.

In urban areas, the urban heat island (UHI) effect is also at play and contributes to hot conditions. In the UHI effect, urban areas are significantly warmer than their surroundings because building materials like concrete, asphalt, bricks, etc. have higher thermal inertia and absorb and retain more heat than natural landscapes, causing a localised increase in temperature. Densely packed buildings lack proper airflow that allows for cooling.

A study published in Nature journal on May 15, 2024 found that urbanisation alone has led to a 60% enhancement in warming in Indian cities. The UHI effect contributes to global warming as it is associated with an increased demand for energy which leads to a higher production of greenhouse gases. The UHI effect can also impact climate factors other than heat, like rainfall, pollution, etc.

A report by the Centre for Science and Environment, published in May 2024, found that cities are not cooling down at night at the same rate that they used to, not giving people a chance to recover from the daytime heat. “Hot nights are as dangerous as midday peak temperatures,” the study noted. In Delhi, nights are slightly cooler by just 11.2 degrees C, which is 9% down from 2001-2010.

The CSE report also said that the UHI effect is stronger at night than daytime in Delhi.

Is the Delhi Heat Action Plan enough?

Delhi has a Heat Action Plan in place for 2024-2025, but at this stage, it is more like a set of guidelines.

“While the Heat Action Plan of Delhi is a fantastic first step, what is needed is building of capacity across the ecosystem, and the access to funds and facilities that could be utilised without too much bureaucratic hurdles. More importantly, a more disaggregated approach to looking at the problem, applying the demographic and socio-economic lens is a must, as many of the generic solutions may not really serve the under-privileged lower economic strata of people,” Dr. Murthy from CSTEP said.

The Hindu tried reaching out to the Delhi Disaster Management Authority to inquire about the steps it has undertaken to implement the Heat Action Plan, but did not receive a response.

Aditya Valiathan Pillai, a fellow at Sustainable Futures Collaborative, said if we don’t start now, we won’t be able to beat the heat in 10 years. “Delhi has to play catch-up over the next couple of years, as implementing the ideas mentioned in the HAP takes time. My concern with this plan is it doesn’t talk about financing. [The government] needs to figure out how it is going to finance this long list of solutions it has proposed,” Mr. Pillai said.

He added that the plan needs to be grounded in some legal structure for it to “have weight within the bureaucracy and the government”.

A La Nina would have significant consequences for global agriculture because it typically brings wetter weather to eastern Australia and southeast Asia and drier conditions to the Americas.
| Photo Credit: Ritu Raj Konwar/The Hindu

There are early signs that a La Nina weather event may form in the Pacific Ocean later this year, Australia’s weather bureau said on Tuesday.

A La Nina would have significant consequences for global agriculture because it typically brings wetter weather to eastern Australia and southeast Asia and drier conditions to the Americas.

The bureau said it had declared a “La Nina Watch”.

“When La Nina Watch criteria have been met in the past, a La Nina event has subsequently developed around 50% of the time,” it said.

Also Read | El Niño, La Niña and changing weather patterns 

La Nina events result from cooler sea surface temperatures in the Pacific. Warmer sea surface temperatures can cause an opposite weather phenomenon called El Nino, which occurred last year and lasted into early 2024.

“Sea surface temperatures in the central Pacific have been steadily cooling since December 2023,” the bureau said.

“The Bureau’s modelling suggests that ENSO will likely remain neutral until at least July 2024,” it said, using the formal name, the El Niño Southern Oscillation, that describes the switch between the two phases.

Japan’s weather bureau has said there is a 90% chance that the El Nino phenomenon will dissipate by the end of May.

Other forecasters have also heralded a La Nina later this year. Last week, Japan’s weather bureau said there was a 60% chance it would occur by November, and a U.S. government forecaster said there was a 69% chance that it would develop during July-September.

An area is uncovered by the lowering of the water level from the Magdalena river, the longest and most important river in Colombia, due to the lack of rain, in the city of Honda, January 14, 2016. While flooding and intense rain wreak havoc on several countries in Latin America, El Nino brings other harmful effects to Colombia with severe drought.
| Photo Credit: Reuters

Japan’s weather bureau said on Friday there was a 90% chance that the El Nino phenomenon will dissipate by the end of May, while there was a 60% chance of the La Nina phenomenon occurring in the months up until November.

El Nino is a warming of ocean surface temperatures in the eastern and central Pacific. La Nina is characterised by unusually cold ocean temperatures in the equatorial Pacific region and is linked to floods and drought.

Around five and half millenia ago, northern Africa went through a dramatic transformation. The Sahara desert expanded and grasslands, forests and lakes favoured by humans disappeared. Humans were forced to retreat to the mountains, the oases, and the Nile valley and delta.

As a relatively large and dispersed population was squeezed into smaller and more fertile areas, it needed to innovate new ways to produce food and organise society. Soon after, one of the world’s first great civilisations emerged – ancient Egypt.

This transition from the most recent “African humid period”, which lasted from 15,000 to 5,500 years ago, to the current dry conditions in northern Africa is the clearest example of a climate tipping point in recent geological history. Climate tipping points are thresholds that, once crossed, result in dramatic climate change to a new stable climate.

Our new study published in Nature Communications reveals that before northern Africa dried out, its climate “flickered” between two stable climatic states before tipping permanently. This is the first time it’s been shown such flickering happened in Earth’s past. And it suggests that places with highly variable cycles of changing climate today may in some cases by headed for tipping points of their own.

Whether we will have any warnings of climate tipping points is one of the biggest concerns of climate scientists today. As we pass global warming of 1.5˚C, the most likely tipping points involve the collapse of ice sheets in Greenland or Antarctica, tropical coral reefs dying off, or abrupt thawing of Arctic permafrost.

Some say that there will be warning signs of these major climate shifts. However, these depend very much on the actual type of tipping point, and the interpretation of these signals is therefore difficult. One of the big questions is whether tipping points will be characterised by flickering or whether the climate will initially appear to become more stable before tipping over in one go.

620,000 years of environmental history

To investigate further, we gathered an international team of scientists and went to the basin of Chew Bahir in southern Ethiopia. There was an extensive lake here during the last African humid period, and deposits of sediment, several kilometres deep, underneath the lake bed record the history of climate-driven lake level fluctuations very precisely.

Today, the lake has largely disappeared and the deposits can be drilled relatively cheaply without the need for a drill rig on a floating platform or on a drillship. We drilled 280 metres below the dry lake bed – almost as deep as the Eiffel Tower is tall – and extracted hundreds of tubes of mud around 10 centimetres in diameter.

By putting these tubes together in order they form a so-called sediment core. That core contains vital chemical and biological information which records the past 620,000 years of eastern African climate and environmental history.

We now know that at the end of the African humid period there was around 1,000 years in which the climate alternated regularly between being intensely dry and wet.

In total, we observed at least 14 dry phases, each of which lasted between 20 and 80 years and recurred at intervals of about 160 years. Later there were seven wet phases, of a similar duration and frequency. Finally, around 5,500 years ago a dry climate prevailed for good.

Climate flickering

These high-frequency, extreme wet-dry fluctuations represent a pronounced climate flickering. Such flickering can be simulated in climate model computer programs and also happened in earlier climate transitions at Chew Bahir.

We see the same types of flickering during a previous change from humid to dry climate around 379,000 years ago in the same sediment core. It looks like a perfect copy of the transition at the end of the African humid period.

This is important because this transition was natural, as it occurred long before humans had any influence on the environment. Knowing such a change can occur naturally counters the argument made by some academics that the introduction of livestock and new agricultural techniques may have accelerated the end of the last African humid period.

Conversely, humans in the region were undoubtedly affected by the climate tipping. The flickering would have had a dramatic impact, easily noticed by a single human, compared to the slow climate transition spanning tens of generations.

It could perhaps explain why the archaeological findings in the region are so different, even contradictory, at times of the transition. People retreated during the dry phases and then some came back during the wet phases. Ultimately, humans retreated to the places that were consistently wet like the Nile valley.

Confirmation of climate flickering as precursors to a major climate tipping is important because it may also provide insights into possible early warning signals for large climate changes in future.

It seems that highly variable climate conditions such as rapid wet–dry cycles may warn of a significant shift in the climate system. Identifying these precursors now may provide the warning we need that future warming will take us across one of more of the sixteen identified critical climate tipping points.

This is particularly important for regions such as eastern Africa whose nearly 500 million people are already highly vulnerable to climate change induced impacts such as drought.

Martin H. Trauth, Professor, University of Potsdam; Asfawossen Asrat, Professor, Addis Ababa University, and Mark Maslin, Professor of Natural Sciences, UCL

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Over the last 25 years, the ozone hole which forming over Antarctica each spring has started to shrink.

But over the last four years, even as the hole has shrunk it has persisted for an unusually long time. Our new research found that instead of closing up during November it has stayed open well into December. This is early summer – the crucial period of new plant growth in coastal Antarctica and the peak breeding season for penguins and seals.

That’s a worry. When the ozone hole forms, more ultraviolet rays get through the atmosphere. And while penguins and seals have protective covering, their young may be more vulnerable.

Why does ozone matter?

Over the past half century, we damaged the earth’s protective ozone layer by using chlorofluorocarbons (CFCs) and related chemicals. Thanks to coordinated global action these chemicals are now banned.

Because CFCs have long lifetimes, it will be decades before they are completely removed from the atmosphere. As a result, we still see the ozone hole forming each year.

The lion’s share of ozone damage happens over Antarctica. When the hole forms, the UV index doubles, reaching extreme levels. We might expect to see UV days over 14 in summers in Australia or California, but not in polar regions.

Luckily, on land most species are dormant and protected under snow when the ozone hole opens in early spring (September to November). Marine life is protected by sea ice cover and Antarctica’s moss forests are under snow. These protective icy covers have helped to protect most life in Antarctica from ozone depletion – until now.

Unusually long-lived ozone holes

A series of unusual events between 2020 and 2023 saw the ozone hole persist into December. The record-breaking 2019–2020 Australian bushfires, the huge underwater volcanic eruption off Tonga, and three consecutive years of La Niña. Volcanoes and bushfires can inject ash and smoke into the stratosphere. Chemical reactions occurring on the surface of these tiny particulates can destroy ozone.

These longer-lasting ozone holes coincided with significant loss of sea ice, which meant many animals and plants would have had fewer places to hide.

What does stronger UV radiation do to ecosystems?

If ozone holes last longer, summer-breeding animals around Antarctica’s vast coastline will be exposed to high levels of reflected UV radiation. More UV can get through, and ice and snow is highly reflective, bouncing these rays around.

In humans, high UV exposure increases our risk of skin cancer and cataracts. But we don’t have fur or feathers. While penguins and seals have skin protection, their eyes aren’t protected.

Is it doing damage? We don’t know for sure. Very few studies report on what UV radiation does to animals in Antarctica. Most are done in zoos, where researchers study what happens when animals are kept under artificial light.

Even so, it is a concern. More UV radiation in early summer could be particularly damaging to young animals, such as penguin chicks and seal pups who hatch or are born in late spring.

As plants such as Antarctic hairgrass, Deschampsia antarctica, the cushion plant, Colobanthus quitensis and lots of mosses emerge from under snow in late spring, they will be exposed to maximum UV levels.

Antarctic mosses actually produce their own sunscreen to protect themselves from UV radiation, but this comes at the cost of reduced growth.

Trillions of tiny phytoplankton live under the sea ice. These microscopic floating algae also make sunscreen compounds, called microsporine amino acids.

What about marine creatures? Krill will dive deeper into the water column if the UV radiation is too high, while fish eggs usually have melanin, the same protective compound as humans, though not all fish life stages are as well protected.

Four of the past five years have seen sea ice extent reduce, a direct consequence of climate change.

Less sea ice means more UV light can penetrate the ocean, where it makes it harder for Antarctic phytoplankton and krill to survive. Much relies on these tiny creatures, who form the base of the food web. If they find it harder to survive, hunger will ripple up the food chain. Antarctica’s waters are also getting warmer and more acidic due to climate change.

An uncertain outlook for Antarctica

We should, by rights, be celebrating the success of banning CFCS – a rare example of fixing an environmental problem. But that might be premature. Climate change may be delaying the recovery of our ozone layer by, for example, making bushfires more common and more severe.

Ozone could also suffer from geoengineering proposals such as spraying sulphates into the atmosphere to reflect sunlight, as well as more frequent rocket launches.

If the recent trend continues, and the ozone hole lingers into the summer, we can expect to see more damage done to plants and animals – compounded by other threats.

We don’t know if the longer-lasting ozone hole will continue. But we do know climate change is causing the atmosphere to behave in unprecedented ways. To keep ozone recovery on track, we need to take immediate action to reduce the carbon we emit into the atmosphere.

Pea plants are damaged by drought, due to the El Nino weather phenomenon in Madrid municipality near Bogota, Colombia, January 17, 2016.
| Photo Credit: Reuters

Latin American nations must be on high alert as the weather phenomenon known as El Nino rapidly switches over to La Nina, experts said on Thursday, leaving populations and crops little time to recover.

El Nino and its abundant rains could soon turn into droughts caused by La Nina as well as an intense hurricane season across South America, experts said at a panel organized by the United Nations’ Food and Agriculture Organization (FAO).

The full weather pattern involving El Nino, La Nina and a neutral phase typically lasts between two to seven years. But experts said that the transition period from El Nino to La Nina is getting shorter.

“We just saw it happen,” said Yolanda Gonzalez, director of the International Research Center for the El Nino Phenomenon. “A year ago we came out of a Nina, and in March there were already signs of a Nino.”

“Now in March, April there are signs of a Nina,” she added. “We haven’t been able to recover from the impact.”

In South America, the weather patterns can hit key crops such as wheat and corn, denting commodity-dependent economies.

The phenomenon is not caused by climate change, FAO’s technical team told Reuters, but experts have seen that the effects of the weather pattern, such as rainfall, heat waves and drought, have become more extreme.

The rapid transitions between El Nino and La Nina could also be correlated with climate change, FAO said, though scientists have yet to establish definitive causation.

“These abrupt changes, and the fact that these cycles are now almost overlapping, ultimately decreases the ability to adapt to the changes,” said Marion Khamis, FAO’s regional risk management specialist. “This implies a huge challenge.”

Untimely rains have left wheat-growing farmers worried as they anticipate a drop in yield, output and quality. File picture of a farm worker harvesting wheat in Gurugram
| Photo Credit: PTI

The story so far: The unusual rise in mercury in February this year, followed by an untimely spell of widespread rain accompanied by gusty winds and hails during the month of March in parts of the country’s key grain-producing States — Punjab, Haryana, Madhya Pradesh, Uttar Pradesh, Rajasthan, Bihar and Gujarat — have left wheat-growing farmers worried as they anticipate a drop in yield (productivity), output (production) and quality.

How will the rains affect wheat crop?

According to the India Meteorological Department (IMD), fairly widespread rains along with stormy winds between 40-50 kilometers per hour lashed several parts of the major wheat-growing States in the country during March, under the influence of consecutive western disturbances. Rain spells accompanied by winds are not considered to be a good sign for the crop’s health if they are close to the ripening and harvesting stage, especially if there are instances of water logging in the fields. Unfortunately, there have been instances of crop flattening in fields, besides water logging, which could be detrimental for the ready-to-harvest wheat crop. Wheat, a key rabi (winter) crop is sown between late October till December; it nears the ripening stage in the month of mid-March, and harvesting of the early sown varieties usually commences by the end of March itself. The IMD data suggests that between March 1 and April 9, large excess rains (40% more rain than normal) were received in several States.

How much output would be affected?

Agriwatch, an agri-commodity research firm, in its latest report has stated that owing to the recent untimely rains, the country’s wheat production in the agriculture year 2022-23 is likely to be 102.9 MT which is less than the Union government’s estimate of 112 MT. The Centre, however, is optimistic that wheat production would be close to 112 MT on account of an increased acreage (area) of wheat and better yield this season, despite a slight production loss due to recent adverse weather conditions. As per the government, the average wheat acreage this year (2022-23) has been 14,86,240 hectares more in comparison to the last five years (2017-2021) which stood at 30,382,010 hectares.

What are agri-experts saying?

A sizable section of farmers assert that the inclement weather has adversely damaged the standing wheat crop.

Indu Sharma, former director of the Indian Institute of Wheat and Barley Research (IIWBR), based in Haryana’s Karnal, says, “It’s not just the untimely rains in March, but the unusually higher temperature in February this year that has also been detrimental for the wheat. Now, after the rains and winds, wherever the crop has flattened, it will be difficult to recover it, eventually hurting the crop’s yield. ”

Moreover, if the country’s wheat production drops below the government estimate it could lead to a hike in prices of wheat and wheat-based products in the domestic market, says Rajesh Paharia Jain, a New Delhi-based trader and wheat exporter. He adds that any decline in wheat production can also lead to a potential foodgrain security issue.

An agriculture domain expert and a former member of the Uttar Pradesh Planning Commission, Sudhir Panwar says if the government asserts that wheat production is not going to be severely impacted due to inclement weather then it means that the policy of wheat purchase would remain the same as that of the last year. “In such a scenario, the private player will purchase wheat on Minimum Support Price (MSP) or with some incentive. The wheat price for the consumer in the domestic market should hardly be impacted as the government’s first priority would be to replenish its foodgrain stock. If the production is less, then the possibility of market intervention by the government is also quite bleak as its priority would be to maintain the buffer stock,” he says.