Four asteroids, including a stadium-sized one, speeding towards Earth

• Earth is set to witness the close, but safe, passage of several massive asteroids in the coming days. According to NASA’s Jet Propulsion Laboratory, four asteroids will fly by Earth between May 23 and May 25, 2025. The largest of the group is asteroid 387746 (2003 MH4), measuring approximately 1,100 feet, which is roughly the size of a stadium.
• On May 23, asteroid 2025 KC, which is almost the size of a house, will fly by Earth at a safe distance of 636,000 km, posing no threat to the planet. On May 24, two more asteroids – 2025 KL and 387746 (2003 MH4), will make their closest approaches, passing at 1,910,000 km and 4,150,000 km respectively. Finally, 2025 KM will skim past Earth on May 25, with its closest approach estimated at 960,000 km.
• Asteroids, also known as planetoids, are rocky objects that orbit the Sun. While many originate within our solar system, formed during its early years, some may come from interstellar space.
• Although these space rocks frequently pass Earth, most reside in the asteroid belt between Mars and Jupiter. While the majority of asteroids are harmless, a collision with a massive one could cause significant destruction.
• Asteroid spotting is a routine part of modern space observation. Owing to advanced telescopes and monitoring programs like NASA’s Near-Earth Object Observations, scientists regularly monitor thousands of space rocks to assess any potential threats.
• Most of these asteroids pass harmlessly, but spotting them early is important for planetary defence. This data also aids researchers in understanding the solar system’s history.
• Tracking these space rocks allows for precise orbital calculations, and in rare cases of potential impact. Most importantly, it gives us time to prepare or deflect the threat in advance.
• NASA reports that car-sized meteorites strike Earth roughly once a year. Meanwhile, football-field-sized asteroids pass by about once every 2,000 years. The damage from an asteroid impact depends on its mass, speed, angle of entry, and the location of impact. Fortunately, most space rocks are statistically more likely to fall into oceans or uninhabited regions

Export boost: Government restores RoDTEP scheme, allows leather exports from all ports

• The Ministry of Commerce and Industry has introduced several measures to enhance India''s export competitiveness, particularly in the leather sector

Key developments:

1. Removal of Port Restrictions for Leather Exports

• Previously, finished leather, wet blue leather, and East India tanned leather could only be exported from specific notified ports.
• Now, exporters can ship these leather products from any port or inland container depot, making the process more flexible and efficient.

2. Geographical Indication (GI) Tag for East India Tanned Leather

• Tamil Nadu’s vegetable-dyed leather has earned a GI tag, granting it exclusive branding similar to Darjeeling Tea and Kanchipuram silk sarees.
• This recognition boosts market value and authenticity, helping Tamil Nadu’s leather industry expand globally.

3. Removal of CLRI Certification Requirement

• The Central Leather Research Institute (CLRI) certification was previously mandatory for leather exports.
• The government has eliminated this requirement, simplifying export procedures and reducing compliance costs.

4. Restoration of the RoDTEP Scheme

• The Remission of Duties and Taxes on Exported Products (RoDTEP) scheme has been reinstated for:

5. Advance Authorization (AA) holders

• Export-Oriented Units (EOUs)
• Special Economic Zones (SEZs)
• This scheme reimburses exporters for embedded duties, taxes, and levies, making Indian exports more competitive.

Impact on India’s Leather Industry

• Boosts global competitiveness by reducing export restrictions.
• Encourages traditional craftsmanship, especially in Tamil Nadu’s vegetable-dyed leather sector.
• Simplifies export procedures, making it easier for businesses to expand internationally.

Bharat Forecasting System (BFS)

• The Bharat Forecasting System (BFS) is India''s high-resolution weather prediction model, developed by the Indian Institute of Tropical Meteorology (IITM), Pune, under the Ministry of Earth Sciences (MoES). It was officially launched by the India Meteorological Department (IMD) on May 26, 2025, marking a major advancement in India''s meteorological capabilities.

Key Features & Powers of BFS

• World’s Highest-Resolution Forecasting Model: BFS operates on a 6-kilometre grid, surpassing global models from the US, UK, and EU, which typically use 9–14 km resolution.
• Advanced Computing Power: The system relies on supercomputers ‘Arka’ and ‘Arunika’, enabling faster and more precise weather simulations.
• Improved Accuracy: BFS enhances forecasting accuracy by 30–64%, particularly for monsoons, cyclones, and extreme rainfall events.

How BFS Improves Weather Predictions

• Localized Forecasts: BFS provides panchayat-level predictions, allowing villages and small towns to receive precise weather alerts.
• Better Disaster Management: The system strengthens cyclone tracking, flood forecasting, and aviation safety, reducing economic losses.
• Enhanced Agricultural Planning: Farmers benefit from more reliable monsoon forecasts, improving crop planning and water management.

Impact of Weather on India’s Economy

• Agriculture: Monsoon variability affects crop yields, food prices, and rural livelihoods.
• Infrastructure & Transport: Extreme weather disrupts roads, railways, and air travel, impacting trade and logistics.
• Energy Sector: Accurate forecasts help power grids manage demand, especially during heatwaves and storms.

Role of the India Meteorological Department (IMD)

• National Weather Authority: IMD oversees weather forecasting, climate research, and disaster preparedness.
• Public Alerts: It issues warnings for cyclones, heatwaves, and floods, ensuring timely responses.
• Scientific Research: IMD collaborates with global meteorological agencies to improve forecasting models.

Challenges in Forecasting India’s Diverse Geography

• Varied Climate Zones: India has deserts, mountains, coastal regions, and tropical forests, making weather prediction complex.
• Monsoon Uncertainty: The Indian Ocean and Himalayas influence monsoon patterns, requiring advanced modeling.
• Urban Heat Islands: Cities experience localized temperature spikes, affecting forecast accuracy.
• The Bharat Forecasting System positions India as a global leader in precision weather forecasting, ensuring science serves communities from the national level down to the last village

How BFS Compares to Global Forecasting Models

• Highest Resolution in the World:
• BFS operates on a 6-kilometre grid, surpassing global models from the US, UK, and EU, which typically use 9–14 km resolution.
• This allows for more precise local forecasts, especially for monsoons, cyclones, and extreme rainfall events.

Advanced Computing Power:

• BFS relies on supercomputers ‘Arka’ and ‘Arunika’, enabling faster and more detailed weather simulations.
• The system improves forecasting accuracy by 30–64%, making it one of the most reliable models worldwide.

Localized Forecasting Advantage:

• BFS provides panchayat-level predictions, ensuring villages and small towns receive accurate weather alerts.
• In contrast, global models often focus on large-scale weather patterns, making them less effective for hyper-local forecasts.

BFS’s Role in Climate Change Adaptation

Disaster Preparedness:

• BFS strengthens cyclone tracking, flood forecasting, and aviation safety, reducing economic losses.
• It helps governments and farmers prepare for extreme weather events.

Agricultural Planning:

• Farmers benefit from more reliable monsoon forecasts, improving crop planning and water management.
• This is crucial for food security and rural economies.

Infrastructure & Energy Management:

• Accurate forecasts help power grids manage demand, especially during heatwaves and storms.
• BFS supports urban planning, ensuring cities adapt to changing climate conditions

UK hands over Chagos Islands to Mauritius

• UK Prime Minister Keir Starmer signed a deal transferring sovereignty of the Chagos Islands to Mauritius, including the key Diego Garcia military base. The base, which plays a central role in UK-US defence operations in the Indian Ocean, will now be leased from Mauritius under a new 99-year lease.

Key Takeaways :

• 1. Under the deal, the UK will pay Mauritius an average of £101 million ($129m) per year — amounting to a total of £3.4 billion ($4.35 billion) over the course of the lease. Starmer also claimed the arrangement would cost less than operating an aircraft carrier annually.
• A 2. The US, which co-operates the Diego Garcia base with the UK, will shoulder the base’s operational costs — which Starmer said exceed the UK’s financial contribution. US President Donald Trump voiced his support for the deal in February following a meeting with Starmer in Washington.

Chagos Archipelago

• 1. The Chagos archipelago comprises more than 60 low-lying islands in the Indian Ocean roughly 1,600 km to the northeast of the main island of Mauritius. Chagos has a land area of only 56.1 sq km, with Diego Garcia alone spread over 32.5 sq km — which is about the same as the land area of Lakshadweep.
• 2. Including the lagoons within its atolls, however, Chagos has a total area of more than 15,000 sq km. The Great Chagos Bank, spread over 12,642 sq km, is the world’s largest atoll structure.
• 3. The Chagos islands remained uninhabited until the late 18th century, when the French brought in enslaved laborers from Africa and India to work on newly established coconut plantations. In 1814, under the Treaty of Paris, France ceded Mauritius—including the Chagos Archipelago—to the British
• 4. In 1965, the UK constituted the British Indian Ocean Territory (BIOT), of which the Chagos Islands were a central part. The BIOT was meant to provide the British (and by extension their Cold War allies, the Americans) with an overseas base in the Indian Ocean.
• 5. Chagos was attached to Mauritius, another British colony in the Indian Ocean, for administrative purposes. But when Mauritius gained independence in 1968, Chagos remained with Britain. The UK government gave the newly-independent country a grant of 3 million pounds over the “detachment” of the Chagos archipelago.

BEYOND THE NUGGET: Diego Garcia

• 1. Diego Garcia is the largest island in the Chagos Archipelago, located in the Indian Ocean. In 1966, Britain signed an agreement with the US which made the BIOT available for the two countries’ defence needs. Land was acquired in 1967, and four years later, the plantation on Diego Garcia was shut down.
• 2. Diego Garcia became a fully operational military base in 1986. It has played a pivotal role in military operations, including US-UK strikes on Houthi targets in Yemen (2024–2025), humanitarian missions to Gaza, and earlier, bombing campaigns against the Taliban and al-Qaeda in Afghanistan in 2001.
• 3. “Diego Garcia is the site of a joint U.S.-UK military facility that plays a vital role in national, regional, and global security. It enables the United States to support operations that demonstrate our shared commitment to regional stability, provide rapid response to crises, and counter some of the most challenging security threats we face.” – Former U.S. President Joe Biden said this in October 2024.
• 4. Notably, Diego Garcia is a coral atoll and southernmost member of the Chagos Archipelago. It is located 7 degrees south of the equator.

India now the 4th largest economy: NITI CEO

•  India has officially surpassed Japan to become the fourth-largest economy in the world, according to IMF data and NITI Aayog CEO BVR Subrahmanyam. This marks a significant milestone in India''s economic trajectory.

Key Highlights from the IMF’s World Economic Outlook (WEO) Report

• India’s Nominal GDP (2025): Projected at USD 4.187 trillion, slightly ahead of Japan’s USD 4.186 trillion.
• Global Ranking: India now trails only the United States, China, and Germany.
• Growth Projection: India’s economy is expected to grow at 6.2% in 2025 and 6.3% in 2026, maintaining its position as the fastest-growing major economy.

Significance of India Surpassing Japan

• Economic Strength: India’s rise reflects strong domestic consumption, industrial expansion, and global trade integration.
• Manufacturing & Services Growth: The government is focusing on boosting exports, infrastructure, and digital economy, making India an attractive investment destination.
• Geopolitical Influence: As the fourth-largest economy, India gains greater leverage in global trade negotiations and economic policymaking.

Challenges in Becoming the Third-Largest Economy

• Infrastructure & Policy Reforms: India must modernize transport, energy, and digital infrastructure to sustain high growth.
• Income Inequality & Regional Disparities: Economic expansion must be inclusive, ensuring benefits reach rural and underdeveloped regions.
• Global Trade Uncertainty: Escalating trade tensions and supply chain disruptions could impact India’s export-driven sectors.

Impact on Domestic Consumption & Global Trade

• Rising Middle Class: Increased consumer spending is driving demand for automobiles, technology, and real estate.
• Export Competitiveness: India’s trade agreements and manufacturing incentives are strengthening its position in global markets.
• Investment Boom: Foreign direct investment (FDI) is expected to rise, particularly in technology, green energy, and infrastructure.
• India’s nominal GDP for 2025 (FY26) is expected to be USD 4.187 billion, marginally more than the likely GDP of Japan, which is estimated at USD 4.187 billion, the IMF had said.
• According to IMF data, India’s per capita income has doubled from USD 1,438 in 2013-14 to USD 2,880 in 2025.
  The IMF in its WEO report also said the Indian economy is projected to grow at 6.2 per cent in 2025-26, slower than the earlier estimated rate of 6.5 per cent, due to escalated trade tensions and global uncertainty.
• NITI Aayog’s approach paper titled “Viksit Rajya For Viksit Bharat @ 2047′ said from being considered a part of the ‘fragile five’ economies of the world, India rose to become the top five economies of the world in just a decade
• The World Bank defines high-income countries as those whose annual per capita income is more than USD 14,005 (2024- 25). India has the potential and aims to be a high-income country by 2047. The approach paper said a Viksit Bharat @ 2047 will be a USD 30 trillion economy.

All you need to know about: drug addiction

•  In a January advisory, the US Surgeon General urged cancer warnings for alcoholic drinks and called for guidelines on alcohol consumption limits to be reassessed. The General’s warnings are also important in light of the addictive effects of consuming alcohol, and how contemporary society perceives that addiction and how contemporary science treats it.
• Most of us know someone who has battled a drug addiction. It’s not unusual to hear the refrain: “it’s all in your mind, the day you decide you want to quit, you will come out of it”. In reality, addiction is not a moral failure. Like diabetes, hypertension, thyroid dysfunction, and coronary artery disease, addiction is also a medical illness.
• Drug addiction is characterised by a compulsive drive to imbibe the drug (e.g. alcohol) despite serious adverse consequences, loss of control over intake, and a negative emotional state during abstinence. Emerging lines of evidence have found that drug misuse changes the brain in profound ways, leading to disrupted behaviour.
• What starts as mere experimentation often turns into frequent use. Since a variety of brain circuits is affected, drug use turns into compulsive behaviour. Brain changes produced by addiction are progressive, long lasting, and persist even after years of drug use discontinuation.
• The evidence today suggests the brain areas governing reward, motivation, inhibitory control, and self-awareness, undergo progressive structural and functional changes.
• Addiction can be conceptualised as a cycle of three stages. Each stage represents the malfunctioning of a network of interacting brain circuits: the basal ganglia in the binge-intoxication stage, the extended amygdala in the withdrawal-negative affect stage, and the prefrontal cortex in the craving stage.

Addiction vis-à-vis neurodevelopment

• Adolescence is a period of experimentation and tumult. Normal adolescent behaviour such as risk taking, novelty seeking, and heightened sensitivity to peer pressure increase the likelihood of experimenting with drugs.
• Biologically, these risky behaviours reflect the immaturity of the neural systems governing executive control and emotional regulation. The frontal lobes and the connections between them don’t fully develop until the age of 25.
• Pre-clinical, animal, and human studies have all shown that drug exposure during adolescence results in different neuroadaptations from those that occur during adulthood. The adolescent period is uniquely sensitive to long-term alterations by chronic alcohol and drug exposure. Persons who start using alcohol and drugs early in life are thus more vulnerable to alcohol use disorder.

Binge intoxication

• The first stage of addiction is binge intoxication. Drug use triggers large surges of dopamine and opioid peptides, which has a reinforcing effect that surpasses the magnitude and duration of natural reinforcers like food and sex.
• Brain areas governing reward processing and emotional regulation essentially become hijacked.
• The dopamine neurotransmitter doesn’t only signal reward: it is a modifier of motivation and a predictor of reward. Based on the magnitude and duration of dopamine-mediated activity in the brain, information about learning, decision making, stimulus-response, and approach behaviour is conveyed to deeper brain structures.
• Large, abrupt and large increases in dopamine predict reward. Lower, slower increases sustain effort and attention. The brain responds even to aversive stimuli or to the absence of an expected reward by decreasing the amount of dopamine released. This influences subsequent behaviour to not dedicate efforts to non-rewarding stimuli.
• People addicted to cocaine show significant dopamine increases even in response to drug-conditioned cues, like the sight or smell of a drug or drug-related advertisements.
• Drug-conditioned cues can trigger a person to use drugs. This is called cue reactivity. Drug-conditioned cues work by associating a drug with a specific sight, smell or taste, causing a person to use drugs when they see, smell, or taste the associated cue.
•  Surprisingly, in people with an addiction (but not in  non-addicted individuals), drug-conditioned cues elicit greater dopamine release than the consumption of the drug itself.
• We don’t respond in this way to natural reinforcers like food and sex because drugs qualitatively and quantitatively enhance brain dopamine by a factor of five to 10 over natural reinforcers. The dopamine surge produced by natural reinforcers also reaches a point of satiety, unlike drugs of abuse. Overall, drug-seeking behaviour is entrenched through neuroadaptations that involve a host of neurotransmitters in key brain areas.

Fighting to withdraw

• The second stage of addiction is the withdrawal-negative affect stage. Say drug use starts off through impulsive experimentation and transitions to compulsive intake.
• The transition is aided by positive and negative reinforcement. Negative reinforcement strengthens drug-seeking behaviour by alleviating the negative emotional state, which in fact was in fact first precipitated by the absence of drug use.
• Neuroadaptations in the brain’s reward, executive, and stress systems drive drug intake despite adverse consequences.
• The dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, a key driver in the brain stress system, is widely implicated in addiction. Withdrawal from addictive drugs produces an activated HPA stress response. But repeated withdrawals blunt the stress response.
• Addictive drugs prime the brain to excessively release dopamine and opioid peptides. As a way to restore the internal milieu, the brain’s dynorphin system releases less dopamine, which then produces negative emotions. Addiction can thus be viewed as a reward-deficit disorder.
• Emerging research also links an individual’s compromised ability to process and learn from disappointments as being central to the addictive process.

Braving the craving

• The third stage of addiction is the preoccupation anticipation, a.k.a. craving, stage. The frontal brain circuits govern inhibitory control and executive function. Chronic intermittent drug use selectively damages these areas, resulting in poor decision-making that can then perpetuate the vicious addiction cycle.
• An imbalance between the brain circuits that underlie reward and conditioning and those that underlie emotional control and decision-making contributes to loss of control in addiction.
• Drug-induced dopamine increase inherently motivates the individual to procure more of the drug irrespective of whether the effects are perceived to be pleasurable. Many addicted persons have told this author they seek drugs even though they no longer get the ‘high’.
• This happens because stimuli or environmental changes that are arousing elicit an attentional behavioural switch, which affects the motivation to seek an anticipated reward. Neutral stimuli previously associated with a drug become salient and increase dopamine by themselves to elicit a desire for drug use.
• This explains why an addicted person is at a risk of relapse when exposed to an environment where they previously took the drug.
• Neuroadaptations occur across an array of neurotransmitters, including dopamine, glutamate, opioids, serotonin, and cannabinoids. They result in abnormal functioning of the frontal brain circuits, which further impair an individual’s judgement and cognition.
• Drug addiction engages key brain circuits across the three cycles of addiction. The aforementioned research together throws light on how the brain engages in self-destructive compulsive drug seeking, and thus the problem with characterising it as a moral failure

Science behind missiles: Newton’s laws, neural networks and algos

From ballistics to brains

• The earliest missiles were just arrows and spears—unguided projectiles. In fact, the word “missile” comes from the Latin missilis, meaning “that which may be thrown.” The science behind them is ballistics: the study of how objects move through the air under the influence of gravity and drag.
• Ballistic missiles still exist today, but modern ones are far from simple. A ballistic missile is one that is powered during only the early phase of its flight. After that, it coasts along a parabolic path—just like a rock thrown into the air, only faster and farther. 
• A typical intercontinental ballistic missile (ICBM) reaches altitudes of over 1,000 km and speeds of Mach 20 (20 times the speed of sound). Once launched, they are almost impossible to intercept. But pure ballistic paths are predictable — and that’s both their strength and their vulnerability. So modern missiles add another ingredient: guidance.

Guided missiles and the problem of precision

• To hit a moving target — a plane, a tank, even a ship — you can’t just aim and hope. You need to adjust in real time. That’s what guided missiles do. They carry sensors (like radar, infrared, or GPS) and control systems (gyroscopes, fins, internal thrusters) that steer them mid-flight.
• In the early days, this was done using analog computers. One famous story involves British engineer Barnes Wallis using bicycle chains and gears to model bombing trajectories.
• Today’s missiles use high-speed processors and AI-based prediction, but the challenge remains the same: predicting future motion in a world full of uncertainty.

A brief look at rocket science

• Every missile is, at heart, a rocket. Rocket propulsion follows Newton’s Third Law: for every action, there is an equal and opposite reaction. Burn fuel and expel gas out the back, and the missile is pushed forward. The real challenge isn’t just going fast — it’s controlling flight at those speeds. 
• When the Mach number crosses 1, the air surrounding the rocket undergoes a process called shocking, resulting in intense friction and heat. Missiles need special heat shields and materials that won’t melt at thousands of degrees Celsius. Their electronics must survive g-forces that would crush a human.
• Modern missiles push  into the realm of the hypersonic — speeds above Mach 5. These include hypersonic glide vehicles, which detach from rockets and surf the upper atmosphere while maneuvering unpredictably. Unlike traditional ballistic missiles, their path is hard to model, making them extremely difficult to intercept.
•  Both China and the U.S. have invested heavily in these next-generation systems. India’s DRDO is also testing hypersonic platforms. These weapons don’t just travel fast — they’re smart, maneuverable, and virtually impossible to defend against with today’s technology.
• What makes hypersonic missiles especially disruptive is not just their speed, but the shrinking response time they impose. A traditional ICBM may give its target 30–40 minutes to react; a hypersonic missile could cut that to under 10. That changes the calculus of deterrence and defense.
•  Even tracking these weapons is a challenge: at such speeds, air friction generates plasma that can block radar signals. As a result, militaries worldwide are racing not only to build hypersonic weapons, but also to develop new space-based sensors and directed-energy countermeasures to stop them.

Pigeons and missiles

• In World War II, American psychologist B.F. Skinner proposed a bizarre idea: use pigeons to guide missiles. He trained the birds to peck at an image of a target projected on a screen inside the missile’s nose cone. Their pecking movements would steer the missile toward its goal. 
• Though never deployed, Project Pigeon (and its later version, Project Orcon, for “organic control”) showed the creative lengths to which scientists would go in the early days of missile guidance. Today’s systems rely on microprocessors, not pigeons—but the principles remain the same: sense, compute, correct.

The science of predicting impact

• At its core, missile science is about solving a fundamental problem: how do you strike something that’s far away, possibly moving, and maybe trying to avoid you? The answer lies in physics, engineering, and increasingly, artificial intelligence.
• That challenge grows more complex as defenses improve. Missiles must now anticipate evasive maneuvers, adjust mid-course using real-time data, and sift through decoys or electronic jamming.
• A modern air-to-air missile might make hundreds of tiny course corrections per second, all while enduring intense heat, G-forces, and signal noise. The missile, in effect, becomes a high-speed problem-solver — guided not just by brute force, but by algorithms and sensors that mimic decision-making under pressure.
• It’s a blend of old and new — Newton’s laws and neural networks, calculus and code. And while the technologies have evolved dramatically, the underlying science has stayed remarkably consistent.
•  Even the most advanced missiles still obey the same principles as a stone flung from a slingshot. The only difference is that today, the stone flies at Mach 10, thinks for itself, and rarely misses.

Why has the monsoon come early this year? | Explained 

• The India Meteorological Department said the southwest monsoon set in over Kerala on May 24, a week ahead of its normal onset. Since 1975, the earliest monsoon onset over Kerala occurred on May 19, 1990, 13 days ahead of schedule.

Is there a secret sauce to the monsoon’s early arrival?

• The short answer to this question is: we don’t know. The onset date tends to be around June 1, give or take a few days. Early arrival is always a reason to celebrate but unfortunately it doesn’t always portend a bountiful monsoon. However, a late arrival by more than two weeks nearly always brings a deficit.
• Predicting the onset date is a great challenge and is eagerly awaited by the subcontinent.

Factors Behind the Early Monsoon Onset

• Natural Climate Variability: The monsoon onset has fluctuated over decades, with the earliest recorded arrival on May 19, 1990.
• Global Warming Influence: Studies suggest that climate shifts may be affecting monsoon patterns, though the exact mechanisms remain unclear.
• Cyclonic Activity: Late-season pre-monsoon cyclones may have influenced the monsoon trough’s movement, accelerating its arrival.
• El Niño & La Niña Uncertainty: While these climate phenomena impact monsoon strength, they don’t offer consistent predictability for onset timing.

Comparing Past & Present Early Onsets

• The last early onset occurred on May 23, 2009, during a mild El Niño year.
• 2009 saw a severe monsoon drought, raising concerns about whether 2025 will follow a similar pattern.
• Current global temperatures are over 1.2°C above pre-industrial levels, potentially influencing monsoon behavior.

Challenges in Predicting Monsoon Onset

• Complex Interactions: The monsoon trough moves from the northwestern Pacific to the Bay of Bengal, but multiple factors influence its final arrival in Kerala.
• Changing Rainfall Patterns: The withdrawal phase of the monsoon is also shifting, merging with the northeast monsoon in some regions.
• Erratic Seasonal Distribution: Floods and droughts are becoming more unpredictable, complicating long-term forecasting

What is the science of the monsoon onset?

• There are many theories as to the science of the onset. But this just means there is no consensus on a complete understanding of the processes leading to the onset. Even the famed El Niño and La Niña don’t offer systematic predictability to the onset.
• The march of the trough is watched carefully from its origin in the northwestern tropical Pacific into the Andaman Sea and the Bay of Bengal. But many players still tinker with the trough movement from the Bay of Bengal to Kerala.
• It has been reported that the monsoon onset has been systematically delayed by a few days since the 1970s. There have been many studies of a regime shift in the climate system as well as the ecosystems around the time but the shift’s causes are not entirely understood.
• If it is just a natural decadal timescale variability of the climate system, it will always be difficult to predict.
• Moreover, the impact of global warming on the regime shift poses further barriers to understanding and predicting shifts in the onset. Natural variability means that even with a systematic delay in the onset, we will still have some years with very early onsets, 2025 being a good example.

Are past and present early onsets similar?

• This year’s onset was the earliest in 16 years; the last was on May 23, 2009. Let’s examine some of the conditions underlying these events.
• 2008 was about 0.5°C warmer than the pre-industrial baseline and 2009 was a mild El Niño year. The summer of 2009 was noted to be warm across the tropical Pacific, which is unusual for an El Niño year.
• In an El Niño year, the east is expected to be warming in the summer and the west to be cooling. Was that an indication that global warming is now superimposing itself on El Niño? Other El Niño years since haven’t systematically shown any such patterns.
• Unfortunately, 2009 turned out to have a severe monsoon drought. We can only hope this year’s early onset will not repeat that piece of history.
• Global warming thus far in 2025 is already over 1.2°C and the world is riding the coattails of record warmth in 2023-2024, with a strong El Niño in 2023, and a failed La Niña in 2024.
• An unusual sea surface temperature anomaly pattern in the tropical Pacific occurred in 2024, with warm anomalies in the far east and far west but cooler anomalies in the centre. Even though it was called a La Niña, it’s prudent to wait for further analysis of the pattern to be reported soon.

How does the monsoon reach Kerala?

• Many external factors are now playing into the arrival of the monsoon trough to Kerala. More cyclones are occurring late into the pre-monsoon cyclone season, that is, close to the monsoon onset.
• Some have pulled the trough forward to deliver an early onset. During this year’s onset also, the northward pull on the western end of the trough indicates that the low-pressure system trudging along the west coast may have played a role in the earliness.
• Late season cyclones themselves are likely related to Arctic warming or recent wind shifts over the Arabian Sea.
• Typhoons in the Pacific have also pulled moisture away from the Indian Ocean during the onset phase to delay the onset. Considering the natural variability of the onset and all these local and remote drivers of the circulation affecting the trough, there are difficult challenges in understanding and predicting the onset.
• Even if onset predictions become very accurate, they won’t suffice unless we can also predict the fate of the monsoon for the rest of the season.

Will 2025 be like 2009?

• 2009 evolved to be warm across the tropics in the summer, had a mild El Niño in the winter, and rapidly transitioned to a La Niña in 2010. Even though these events occurred after the monsoon’s onset, the ocean heat content and the winds carry some signs of things to come. Indeed, the onset may be related to how the tropical Pacific sea surface temperatures are evolving during the onset.
• At present, the cool temperatures in the central Pacific are disappearing with the warm temperatures in the east and west persisting from 2024. But even if the summer of 2025 ends up behaving similar to that of 2009, we can’t know without further studies if this implies a connection to the early onset.
• The forecasts at present call for a neutral year as far as the El Niño and the Indian Ocean Dipole are concerned, which would make 2025 different from 2009. But some decadal climate variability indicators are favouring an El Niño to evolve this summer. Even if an El Niño does evolve, will that mean it has a role in the early onset? We need to wait and watch.

How is seasonal rainfall distribution changing?

• All this leaves us with no clear answers as to the causes of the monsoon’s early onset this year — or any year. If it is just natural variability, we need to understand how the variability is being influenced directly by global warming and indirectly through the impacts of global warming on cyclones, El Niño, and the polar regions.
• Even the monsoon’s withdrawal is changing, with the merger of the southwest monsoon with the northeast monsoon in some regions of the country. Rainfall distribution within the season also remains erratic, with floods and droughts strewn across the country.
• Numerous efforts keep producing advances in the potential drivers of the monsoon but this will be a slow march forward. We can only hope for an early onset of deep insights and better predictions.