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Ants at lower elevations influence bird diversity in mountain ecosystems

Here is a surprising factor influencing bird diversity at mid-elevations: the presence of ants from the Oecophylla genus.

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Mountains, which cover only 25% of the Earth’s surface, are home to a staggering 85% of the world’s amphibian, bird, and mammalian species, making them a crucial area for biodiversity and conservation efforts. While the relationship between species diversity and elevation has long been linked to environmental factors like climate, a new study from the Centre for Ecological Sciences (CES) at the Indian Institute of Science (IISc) uncovers a surprising factor influencing bird diversity at mid-elevations: the presence of ants from the Oecophylla genus.

“In mountains, you often see hump-shaped patterns of species diversity, and for a long time, people have been curious about the causes. One mechanism that hasn’t been thoroughly explored is biotic interactions, like competition,” said Kartik Shanker, Professor at CES and co-author of the study, which was published in Ecology Letters, in a press statement issued by IISc.

Oecophylla ants, which are aggressive insect predators, dominate the lower elevations of mountains in the paleotropics, a region covering Africa, Asia, and Oceania. The researchers investigated how these ants affect the diversity of insect-eating birds at various elevations.

Earlier research by co-author Trevor D. Price, Professor of Ecology and Evolution at the University of Chicago, had found that Oecophylla ants significantly reduced insect populations at the base of the eastern Himalayas, which likely influenced the presence of insect-eating birds. The current study aimed to determine if this pattern extended to other bird species across different mountain ranges.

Led by Umesh Srinivasan, Assistant Professor at CES, the researchers analyzed datasets that documented bird species at different elevations. They categorized the birds into dietary guilds, such as insectivores and omnivores, and compared mountain ranges that had Oecophylla ants at their base to those that did not.

“We looked at the ranges of these bird species at different elevations, starting from 100 meters and moving upwards in increments. Then, we compared bird species diversity between mountain ranges with and without Oecophylla ants,” explained Srinivasan, according to IISc statement.

The results were striking. The researchers found that insect-eating birds, in particular, were most diverse at mid-elevations, peaking around 960 meters. This pattern suggested that the presence of Oecophylla ants at lower elevations forced the birds to move higher up the mountains to avoid competition for food. In contrast, bird groups such as nectar and fruit eaters, which did not compete with Oecophylla ants, showed declining species diversity as elevation increased.

The study highlights the critical role biotic interactions play in shaping species diversity in mountain ecosystems. The findings also raise concerns about how climate change could further disrupt these patterns. “With climate change, if the ants shift their ranges towards higher elevations, this might impact bird species at those elevations as well,” Srinivasan warned.

The research offers valuable insights into the complex dynamics that govern biodiversity in mountainous regions and underscores the importance of considering biotic factors, such as competition, in conservation planning.

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Society

Hormuz Crisis Exposes Global Fertiliser Dependency Risks

Hormuz disruption highlights risks of fertiliser dependency as experts warn of food security threats and call for agroecology shift.

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Hormuz crisis highlights risks of fertiliser dependency as experts warn of food security threats and call for agroecology shift.
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Fertiliser dependency has come under sharp global scrutiny as tensions around the Strait of Hormuz highlight how geopolitical disruptions can ripple through food systems, raising concerns over food security and farm resilience.

The Strait of Hormuz, a critical chokepoint for global energy supplies, plays a central role in fertiliser production due to its link to fossil fuel exports. Any disruption threatens to push up fertiliser costs—directly impacting agricultural production worldwide, according to an analysis by Zero Carbon Analytics (ZCA).

How Fertiliser Dependency Shapes Global Food Systems

Experts warn that modern agriculture’s heavy reliance on fossil fuel-based fertilisers has created a fragile system vulnerable to geopolitical shocks.

“This vulnerability is a choice, and one that we all pay for,” says Raj Patel, economist and food systems expert at the University of Texas. “Nearly 90 percent of the $540 billion in annual agricultural support goes to the same chemical-intensive production that depends on them. We didn’t stumble into this dependency. We funded it.”

The reliance is deeply embedded in global subsidies and production models, making rapid transitions difficult but increasingly necessary.

Farmers Face Rising Costs Amid Hormuz Tensions

Farmers across Asia are already feeling the pressure of rising fertiliser prices as geopolitical tensions escalate.

“With fertiliser prices rising—and the planting season soon to begin—Asia’s farmers are once again being forced to choose between rising costs and falling yields,” says Shamika Mone, President of the Inter-Continental Network of Organic Farmer Organisations.

She adds that consumers are also likely to face further food price hikes, underlining the broader socio-economic impact.

A Fragile System Under Stress

The current crisis is being described as more than just a supply issue—it is a structural problem in global agriculture.

“What we are seeing is not just a fertiliser and commodity crisis, it is a stress test to a fragile food system that is not designed to be resilient,” says Belén Citoler of the World Rural Forum.

The disruption has exposed how interconnected energy markets and food systems have become, with shocks in one quickly cascading into the other.

Agroecology and Organic Farming as Alternatives

Across continents, experts and farmers are calling for a shift toward more resilient agricultural practices that reduce fertiliser dependency.

“The conflict in Iran highlights the vulnerability of an agriculture system that is overly reliant on fossil fuel fertilisers,” says Oliver Oliveros of the Agroecology Coalition.

He points to growing efforts by countries such as Brazil, Kenya, and Vietnam to support agroecological practices that use natural fertilisers and nitrogen-fixing plants.

Farmers themselves are also adapting.

“Geopolitical conflicts… show how vulnerable our agricultural system has become,” says German farmer Olivier Jung, who has been experimenting with crop diversity and reduced external inputs to build resilience.

Similarly, Brazilian farmer Thales Bevilacqua Mendonça warns that global supply chains are increasingly unstable, urging a shift toward ecological farming practices.

Policy Shift Seen as Key to Reducing Fertiliser Dependency

Experts argue that reducing fertiliser dependency will require systemic policy changes, particularly in how agricultural subsidies are allocated.

“To speed up the transition, we need to redirect billions in agriculture subsidies… and invest in approaches that safeguard farmers and consumers from energy price volatility and climate shocks,” Oliveros adds.

Organic farming advocates also stress that proven alternatives already exist.

“If we really want to take food security seriously, policymakers must support the most resilient models… organic farming must become a pillar,” says French farmer Olivier Chaloche.

A Turning Point for Global Food Security?

The Strait of Hormuz disruption may prove to be a wake-up call for governments worldwide.

As fertiliser dependency becomes increasingly tied to geopolitical instability, the push toward agroecology, organic farming, and resilient food systems is gaining urgency.

The question now is whether policymakers will act fast enough to transform a system many experts say is no longer sustainable.

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Society

South Asia’s $107 Billion LNG Expansion Faces Risk Amid Middle East War: Report

A new report warns South Asia’s LNG infrastructure expansion could face economic and energy risks as Middle East tensions disrupt global gas markets.

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South Asia is investing $107 billion in LNG infrastructure — but a new report warns geopolitical tensions could make this strategy risky.

South Asia’s ambitious expansion of liquefied natural gas (LNG) infrastructure could expose the region to significant economic and energy security risks as geopolitical tensions disrupt global energy markets, according to a new report by Global Energy Monitor.

The report warns that escalating conflict in the Middle East, particularly attacks on Iran and disruptions to shipping routes in the Strait of Hormuz, could sharply affect LNG prices and supply chains, putting pressure on energy-importing economies such as India, Bangladesh, and Pakistan.

Data from the Asia Gas Tracker, compiled by Global Energy Monitor, shows that the three South Asian countries have about $107 billion worth of LNG terminals and gas pipelines either announced or currently under construction.

Together, these projects represent a major share of global gas infrastructure expansion. Southern Asia accounts for 17% of global LNG import capacity under development—about 110.7 million tonnes per year—and 17% of global gas pipelines by length, totalling 34,146 kilometres, according to the report.

India’s expanding gas infrastructure

India is pursuing one of the largest gas infrastructure expansions in the world. The report notes that the country is developing the second-largest LNG terminal expansion globally and the third-largest gas pipeline buildout.

A chart in the report indicates that India ranks among the top countries worldwide for pipeline construction, with nearly three-quarters of its planned gas pipeline network already under construction.

Meanwhile, Bangladesh and Pakistan each have enough LNG import capacity in development to roughly double their existing capacity, highlighting the scale of the region’s dependence on imported gas.

Price volatility and project risks

Despite projections that global LNG supply could increase later in the decade, the report warns that the market remains highly sensitive to geopolitical disruptions. Even relatively balanced markets can experience price spikes if shipping routes or production are affected.

The ongoing conflict in the Middle East demonstrates how quickly a promising growth market can shift into an affordability crisis, potentially delaying or cancelling major infrastructure projects.

“We’ve seen this story before, and South Asian economies that import LNG will struggle with these price shocks. It’s a reminder of the risks of building new gas infrastructure, and that domestic alternatives like renewable power are more affordable and reliable in the long run..” said Robert Rozansky, global LNG analyst for Global Energy Monitor.

History of cancelled LNG projects

The report also highlights a pattern of stalled or cancelled gas infrastructure projects across the region.

Over the past decade, India, Bangladesh, and Pakistan have shelved or cancelled two to three times more LNG import capacity than they have successfully brought online, reflecting the financial and market risks associated with LNG development.

According to the report, India cancelled or shelved 49 million tonnes per annum of LNG capacity, compared with 23 million tonnes that entered operation between 2016 and 2025. Bangladesh and Pakistan show similar trends.

Renewables gaining ground

At the same time, renewable energy is increasingly competing with natural gas in the region’s power sectors.

Solar generation in Pakistan has more than tripled over the past three years, while India is projected to meet over 40% of its electricity demand with renewable energy by 2030.

The report also notes that improvements in energy storage technologies are enhancing grid flexibility, potentially reducing the role of gas as a backup power source.

Emerging alternatives such as green hydrogen could also help reduce reliance on imported fossil fuels for industrial use in the future.

The Asia Gas Tracker, developed by Global Energy Monitor, is an online database that maps and categorises gas infrastructure across the continent, including pipelines, LNG terminals, gas-fired power plants, and gas fields. The tracker is updated annually and documents projects through detailed data pages.

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Climate

Weather, Not Just Emissions, Driving PM2.5 Pollution in Indian Cities: Study

A new Climate Trends report finds weather conditions can alter PM2.5 levels in Indian cities by up to 40%, calling for season-specific reforms in India’s National Clean Air Programme (NCAP).

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A new analysis of India’s urban air quality has revealed that weather conditions can significantly influence pollution levels, sometimes masking the real health burden faced by residents. The report, released by Climate Trends, argues that India’s clean air policies must account for seasonal and meteorological factors to effectively tackle particulate pollution across major cities.

The study analysed Central Pollution Control Board (CPCB) monitoring data from 2024–2025 across six major cities — Delhi, Patna, Kolkata, Mumbai, Chennai, and Bengaluru — and found that meteorological conditions alone can shift pollution levels by up to 40 percent even without changes in emissions.

Researchers say the findings highlight a major gap in India’s National Clean Air Programme (NCAP) and recommend that the upcoming Phase-III reforms include season-specific targets, weather-adjusted evaluation metrics, and dynamic action plans triggered by atmospheric conditions.

Delhi’s extreme winter pollution

The report highlights Delhi as continuing to experience the most severe pollution crisis in the country. The capital recorded the highest annual average PM2.5 levels among the cities analysed and experienced prolonged periods of “Severe” and “Emergency” air quality days.

A particularly alarming finding is that Delhi recorded zero clean air days during winter, despite apparent annual improvements in pollution metrics.

According to the researchers, this discrepancy arises because annual averages can hide seasonal pollution spikes that occur during unfavourable weather conditions such as low wind speeds and high humidity.

“This study shows that a 20–30% reduction in annual PM2.5 does not translate into winter air-quality compliance in stagnation-prone cities like Delhi and Patna, where over 70% of days fall under low-wind, high-humidity meteorological regimes. NCAP Phase-III must therefore adopt season-specific targets, meteorology-triggered interventions, and airshed-level management frameworks to achieve meaningful public-health gains,” Aarti Khosla, Founder and Director of Climate Trends, said in a statement.

Weather plays a decisive role

The report emphasises that air pollution is not simply an “emissions-only” problem. Instead, it is strongly shaped by how emissions interact with atmospheric conditions.

Periods of atmospheric stagnation — characterised by low wind speeds and high humidity — prevent pollutants from dispersing, allowing them to accumulate near the ground and intensify exposure levels for urban populations.

Sagnik Dey, Head of the Centre for Atmospheric Sciences at IIT Delhi, explained the scientific basis for this pattern.

“The persistence of PM2.5 exceedances is strongly associated with sub-1 m/s wind regimes and elevated relative humidity across northern cities, where stagnation episodes sustain disproportionately high exposure levels. Ventilation efficiency emerges as the dominant determinant of inter-city variability. However, current NCAP evaluation frameworks primarily assess observed concentration changes without explicitly accounting for meteorological modulation, potentially leading to distorted interpretations of policy effectiveness. Integrating meteorological regime analytics is therefore essential to ensure a scientifically robust and equitable Phase-III evaluation.”

The study also estimates that simply shifting from stagnant atmospheric conditions to well-ventilated ones could reduce PM2.5 levels by 35–40 percent, demonstrating the powerful role of weather in shaping urban air quality.

Emerging patterns across Indian cities

Beyond Delhi, the report identifies several emerging trends across India’s major urban centres.

Southern cities such as Bengaluru and Chennai, historically considered less polluted, are beginning to show signs of winter-time air quality deterioration, signalling a new vulnerability. Meanwhile, Mumbai and Chennai recorded increases in annual pollution levels in 2025, suggesting that pollution challenges are expanding beyond seasonal spikes into year-round concerns.

Patna continues to face an intensifying crisis, emerging as the second-most polluted city after Delhi, driven in part by persistent atmospheric stagnation across the eastern Indo-Gangetic Plain.

In contrast, Bengaluru stands out for maintaining relatively stable and lower pollution levels, reflecting what researchers describe as “structural air-quality resilience.”

Kolkata’s complex pollution dynamics

Kolkata presents a unique case where meteorology interacts strongly with local pollution sources.

Dr. Abhinandan Ghosh of IISER Kolkata said meteorological conditions play a key role in winter pollution episodes in the city. “As a community of atmospheric scientists, we have long cautioned against a simplistic rat race to replicate Western PM₂.₅ benchmarks, for the Indian subcontinent is endowed with its own meteorological idiosyncrasies, complex topography, and friable alluvial soils that elevate baseline particulate concentrations. The report vindicates this standpoint: in Kolkata, it is not emissions alone but the capricious tyranny of winter boundary-layer dynamics – attenuated mixing heights and enfeebled dispersion – that engenders the most deleterious pollution episodes.”

Professor Abhijit Chatterjee of the Bose Institute pointed to biomass and waste burning as major contributors to winter pollution in the city.

“Amongst several sources, at the current scenario, biomass and waste burning are the major concern in Kolkata especially in winter. The high load of PM2.5 exceeding national standards in winter, primarily due to these two sources which accumulate near the surface because of low dispersion and ventilation coefficients.”

Need for season-specific policies

The study concludes that India’s clean air strategy must move beyond a uniform annual target system and instead adopt seasonally calibrated and meteorology-aware policies.

Experts argue that incorporating weather dynamics into pollution management would help policymakers better assess the effectiveness of interventions and design more realistic mitigation strategies.

Without such reforms, the report warns, improvements in annual averages may continue to mask severe seasonal pollution episodes that pose serious health risks to millions of urban residents.

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