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Challenging the Myth: Trees Are Not the Ultimate Solution for Overheating Cities

The cooling effects of trees are complex and vary significantly depending on the context in which they are planted, says researchers

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A new study led by the University of Cambridge offers fresh insights into how urban tree canopies, while effective at cooling cities during the day, may inadvertently trap heat at night.

As global temperatures continue to rise, many cities are grappling with the effects of urban heat stress, which is linked to increased illness, energy consumption, and social inequality. Excessive heat can also damage urban infrastructure, highlighting the urgent need for effective mitigation strategies. Among these, tree planting has become a central component of efforts to cool down cities.

However, a recent study led by the University of Cambridge warns that not all tree species or planting methods are equally effective in reducing urban temperatures. According to Dr. Ronita Bardhan, Associate Professor of Sustainable Built Environment at the University of Cambridge’s Department of Architecture, “Trees have a crucial role to play in cooling cities down but we need to plant them much more strategically to maximize the benefits they can provide.”

New Insights on Tree Cooling and Heating Effects

Published in Communications Earth & Environment, the study offers the first comprehensive global assessment of urban tree cooling. By analyzing 182 studies from 110 cities worldwide, the research reveals how tree planting can lower pedestrian-level air temperatures by up to 12°C, with 83% of cities studied achieving temperatures below the “thermal comfort threshold” of 26°C. However, the study also shows that the cooling effects of trees can vary dramatically depending on species, climate, and urban design.

Dr. Bardhan noted, “Our study busts the myth that trees are the ultimate panacea for overheating cities across the globe. The cooling effects of trees are complex and vary significantly depending on the context in which they are planted.”

Cooling Benefits Vary by Climate Type

The study found that urban trees tend to be more effective in cooling cities in hot, dry climates compared to those in humid, tropical areas. In hot and dry climates like Nigeria’s savanna, trees can lower city temperatures by as much as 12°C during the day, but can also increase nighttime temperatures by up to 0.8°C. In arid climates, trees were shown to cool cities by just over 9°C but also raise nighttime temperatures by 0.4°C. Conversely, in tropical rainforest climates, daytime cooling was limited to about 2°C, with nighttime warming reaching 0.8°C.

“Trees perform best in dry, hot climates, but in tropical regions with high humidity, their nighttime warming effect can negate their daytime cooling benefits,” said Dr. Bardhan.

Strategic Tree Planting: The Key to Maximizing Cooling

The study underscores the importance of planting trees in a way that aligns with a city’s specific urban form and climate conditions. Cities with open layouts, for instance, benefit from a mix of evergreen and deciduous trees of varying sizes, leading to more effective cooling across different seasons. In contrast, compact urban layouts, like those in Cairo or Dubai, favor evergreen species that are better suited to dry, hot conditions.

The researchers found that mixed-species planting could provide up to 0.5°C more cooling than monoculture tree planting, as different trees offer varying levels of shade and sunlight penetration at different heights. Furthermore, larger green spaces allow for bigger tree canopies, leading to better overall cooling in dry climates.

“Our study provides context-specific greening guidelines for urban planners to more effectively harness tree cooling in the face of global warming,” Dr. Bardhan said. “Urban planners need to plant the right mix of trees in optimal positions to maximize cooling benefits.”

Looking to the Future: Planning for Warmer Climates

The study also stresses that as climate change progresses, it is essential for cities to choose resilient tree species that will continue to thrive under hotter conditions. “Urban planners should plan for future warmer climates by choosing resilient species which will continue to thrive and maintain cooling benefits,” Dr. Bardhan emphasized.

Furthermore, the researchers note that trees alone cannot solve the issue of urban heat. To complement tree planting, solutions like solar shading and reflective materials should continue to play a vital role in mitigating the heat effects in cities.

A Tool for Urban Planners

In an effort to make these findings more accessible, the researchers have developed an interactive database and map that allows users to estimate the cooling efficacy of different tree planting strategies based on the climate and urban characteristics of cities worldwide. This tool will help urban planners design more effective, climate-specific tree planting schemes.

Society

When Pollinators Vanish, Children Go Hungry—Here’s the Proof

A landmark study has, for the first time, traced a direct line from the collapse of wild insect pollinators to the malnutrition and poverty of farming families — reframing biodiversity loss as a global public health emergency.

Dipin Damodharan

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Pollinator Decline Threatens Nutrition, Farm Incomes: Study
Image credit: Tom Timberlake

Two billion. That is how many people on this planet eat what smallholder farmers grow. Not what agri-industrial combines harvest, not what commodity markets trade — what families with small plots of land pull from the soil, season after season, with the tools and seeds and knowledge they have. Two billion people. And a significant share of what keeps those harvests coming, what puts vitamins into the food and income into the household, has no name on any payroll, files no tax return, and has never once been thanked.

It is insects. Wild insects — bees, hoverflies, moths, beetles — moving flower to flower across millions of smallholder fields, doing work that no machine replicates and no subsidy replaces. Pollinator decline is dismantling that system quietly, field by field, season by season. A study published today in Nature, led by researchers at the University of Bristol, has for the first time traced exactly what that loss costs — not in abstracted ecosystem valuations, but in the vitamin A missing from a child’s diet, in the folate a pregnant woman never gets, in the farm income that does not arrive at the end of a harvest. The number at the end of that calculation is not a projection or a model. It is a measurement. And it is arresting.

Insect pollinators, the study found, are responsible for 44% of the farming income of the households tracked, and contribute more than 20% of dietary intake of vitamin A, folate and vitamin E — three nutrients whose deficiency is already linked to stunted child growth, weakened immunity and higher rates of disease. When pollinators vanish, the families don’t just grow less food. They grow less nutritious food, earn less money and become more vulnerable to illness. The cycle reinforces itself, downward.

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Ten Villages, One Year, and a Chain of Evidence

The study centred on ten smallholder farming villages and their surrounding landscapes in Nepal. Over the course of a year, the research team — drawn from universities and non-governmental organisations across Nepal, the United Kingdom, the United States and Finland — tracked three things simultaneously: which insects were visiting which crops, what those crops yielded and how nutritious they were, and what the farming families were actually eating and earning.

The impact of pollinator decline on food production and nutrition is high
Nepal’s smallholder farming communities are highly dependent on diverse range of pollinator-dependent crops. Image credit: Tom Timberlake

It is, in structural terms, the kind of study that is very hard to pull off. Most research on pollinators stops at the field boundary — counting bee visits, measuring fruit set, estimating yield differentials. This one kept going, all the way to the dinner table and the household ledger. That continuity of evidence is what makes it significant.

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The picture that emerged was not abstract or statistical. It was human. Over half the children in the study villages were too short for their age — a condition that goes by the clinical name of stunting and signals not just poor growth but compromised brain development, reduced immunity and diminished life prospects. The underlying cause, as the researchers documented it, was diet. And that diet depended, in ways the families could not easily see or control, on the insects working their fields.

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Pollinator Decline: The Hidden Hunger Nobody Is Counting

There is a term in public health circles for the condition that the Nepal families illustrate: hidden hunger. It describes not the obvious, acute starvation that makes headlines, but the chronic, silent insufficiency of vitamins and minerals that undermines health even when enough calories are being consumed. A quarter of the global population currently suffers from it. It is, by most measures, one of the largest sources of preventable illness on the planet, and it is almost entirely invisible in the way society keeps score of environmental damage.

When a species goes extinct, when a forest is cleared, when an insect population crashes — the accounting of loss is typically measured in biodiversity metrics, in ecosystem service valuations, or in the emotional register of what is no longer there to see. It is almost never measured in folate deficiency, in children’s height-for-age charts, in the likelihood of a farming family falling into debt after a bad harvest.

That is what this study changes. It is not the first to establish that pollinator decline matters for nutrition in the abstract. But it is the first to demonstrate, with tracked data from real communities over a real year, the size and mechanism of the effect — and to show that the effect flows not just through calories but through the specific micronutrients that are hardest to replace.

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Biodiversity as Medicine

Planetary Health — the field Dr Myers directs at Johns Hopkins — proceeds from a deceptively simple premise: human health and ecological health are not separate subjects. They are the same subject, studied from different ends. The degradation of natural systems is not a background condition to human development; it is one of the primary mechanisms by which human health is undermined.

That claim has long had intuitive force. What the Bristol study on pollinator decline provides is something more demanding: empirical evidence at the household level. It is one thing to argue that biodiversity loss will eventually compromise food security in a generalised way. It is another to show, village by village, season by season, that the decline in the bee community visiting a particular set of crops reduces particular vitamins in particular families’ diets by a measurable amount.

Bee on a flowering crop showing the impact of pollinator decline on food production and nutrition
Image credit: Tom Timberlake

The phrasing matters. Biodiversity is not a luxury. In policy conversations, the language of luxury — or alternatively, of long-term concern — has frequently served to push ecological questions down the agenda. If the relationship between pollinator health and child health is as direct as this study finds, that framing becomes harder to sustain.

What Goes When the Bees Go

It is worth being specific about the nutritional stakes. Vitamin A deficiency impairs vision, particularly in low light, and compromises the immune system’s ability to fight infections that would otherwise be routine. Folate deficiency during pregnancy causes neural tube defects in developing foetuses, among other effects. Vitamin E is a key antioxidant, and its deficiency is associated with neurological damage and weakened immune function. These are not marginal health concerns. They sit near the top of the global burden of preventable disease.

The crops most dependent on animal pollination — fruits, many vegetables, pulses — are also, not coincidentally, among the most concentrated sources of these particular nutrients. A diet from which pollinator-dependent produce has been reduced or removed can look adequate in calorie terms while being profoundly inadequate in micronutrient terms. The families studied in Nepal were, in effect, already living that deficit, in a context where pollinator diversity is declining.

Globally, insect populations have been under sustained pressure for decades. Pesticide use, habitat loss, monoculture farming, climate change and artificial light at night have all been implicated in declines that researchers have called, in some cases, ecological collapse. The mechanisms are various; the direction of travel is consistent.

The Good News: Reversible by Design

The research is, in its implications, genuinely alarming. But the researchers are also at pains to emphasise something that is easy to miss in the headline findings: the relationship between pollinators and nutrition runs in both directions. If pollinator decline causes nutritional harm, pollinator recovery can produce nutritional gains. And the actions required are not exotic.

Planting wildflowers at field margins. Reducing pesticide inputs. Keeping native bee colonies. These are the kinds of changes that do not require new technology or large capital investment. They require farmers to understand what is happening in their fields at a level of detail most have not previously been given reason to consider. The researchers are already working on that — translating their findings into practical guidance and working with local organisations, government partners and farmers in Nepal to implement changes on the ground.

The approach is now informing Nepal’s emerging National Pollinator Strategy, an effort to make pollinator-friendly practices a standard part of everyday agriculture rather than a specialist conservation concern. The researchers report that farmers who have adopted even modest changes are already seeing improvements in crop yields, income and nutrition — a feedback loop that runs in the direction of health rather than away from it.

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A Framework That Travels

Nepal is not an isolated case. Two billion people around the world depend on smallholder farming. Many of them face the same combination of circumstances: high dependence on pollinator-sensitive crops, limited dietary alternatives, micronutrient deficiencies that are already entrenched and ecosystems under stress. The findings from ten Nepali villages do not translate automatically to every agricultural context, but the framework — the method of tracing connections from insects to income to nutrition — does.

Diets even in industrialised countries still depend on pollinators and the ecosystems that sustain global agriculture. The buffer of wealth — the ability to import, substitute, supplement — is larger in wealthy countries, but it is not unlimited, and it does not protect the most economically vulnerable people even within those countries.

The lesson from this research on pollinator decline is less a specific warning about Nepal and more a methodological call to arms: to start measuring the connections that have, until now, been assumed or asserted but rarely demonstrated. When those connections are demonstrated, the case for protecting what remains of insect diversity becomes something different — not a moral preference or an aesthetic value, but a documented precondition for human health.

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The Stakes

A quarter of the world’s people are living with hidden hunger. Over half the children in ten Nepali villages are stunted. Forty-four percent of the farming income in those communities flows, invisibly, through the wings of insects that nobody counted or protected until researchers started looking. The insects are in decline.

The study’s authors are careful, as scientists should be, to describe what they found and what it implies rather than what must be done. But the shape of the implication is not obscure. The fabric of life — the phrase Dr Myers uses — is not an abstraction. It is the thing that puts vitamins in a child’s diet and money in a family’s pocket. Tear large enough holes in it, and the consequences are not primarily ecological. They are medical. They are economic. They are, in the most direct sense, human. That’s why the new findings on pollinator decline matter.

The bees were always doing the work. We just weren’t watching closely enough to see it — or to understand what we stood to lose.

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Society

Lost in Your Twenties? You’re Not Behind—You’re Becoming

Feeling lost in your twenties? You’re not behind—you’re becoming. Here’s why confusion, doubt and delay are part of growth.

Glenda Fernandes & Dr. Aiswarya V R

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Quarter-Life Crisis? Why Feeling Lost in Your 20s Is Normal
Image: Sasha Freemind/Unsplash
Authors

The quarter-life crisis is one of the most widely felt yet least talked-about experiences of early adulthood. Two psychologists explain why the pressure to have everything figured out is making an already difficult decade harder – and how self-compassion could be the most important skill a young person develops.

In recent years, conversations about mental health have become more visible, yet one experience faced by many young adults often remains unspoken: the quarter-life crisis. Across universities, workplaces, and homes, many individuals in their twenties quietly struggle with feelings of uncertainty about their future. They may have completed their education, secured a job, or be actively searching for one, yet a persistent question lingers: Is this the life I really want?

What many describe as a quarter-life crisis is often this exact feeling—uncertainty, comparison, and the quiet fear of falling behind. It’s a phase increasingly common among young adults, where expectations collide with reality, leaving many questioning their choices, direction, and sense of purpose.

The twenties have long been viewed as a time of opportunity, exploration, and independence. However, for many young adults today, this stage is also marked by intense pressure. Decisions about career paths, financial stability, relationships, and personal identity often converge during this period. At the same time, social comparisons — particularly through social media — can create the impression that everyone else seems to have their lives perfectly planned.

What Is a Quarter-Life Crisis, Really?

A quarter-life crisis isn’t just “being dramatic.” It is a period of uncertainty and emotional stress marked by feeling stuck or directionless, comparing yourself constantly to others, doubting your choices, anxiety about the future, and the pressure to have it all figured out. In a world where everyone seems to be thriving online, it is easy to feel like you are the only one struggling. But behind those curated posts, many are just as confused.

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Psychologists describe this as a phase of emotional and psychological uncertainty that typically occurs in early adulthood. Unlike the widely discussed mid-life crisis, the quarter-life crisis often emerges when individuals are expected to transition into stable adult roles. The pressure to make the “right” decisions about career, relationships, and life direction can make this period particularly stressful. While these challenges can feel overwhelming, psychological research suggests that certain factors can help young adults navigate this phase more effectively.

Why Are We So Hard on Ourselves?

When things don’t go as planned, most of us turn inward with criticism.

“I should be doing better.” “I’m already behind.” “Everyone else has their life together.”

This inner voice can be harsh, unforgiving, and exhausting. And instead of helping, it makes the crisis feel heavier. That is where self-compassion comes in.

Self-Compassion: The Skill No One Taught Us

Self-compassion is not about being lazy or making excuses. It is about treating yourself with the same kindness you would offer a friend. Think about it: if your friend said they felt lost, would you tell them they were a failure? Probably not.

Psychologist Kristin Neff identifies three elements at the heart of self-compassion: self-kindness — being gentle with yourself instead of critical; common humanity — recognising that struggle is part of being human; and mindfulness — acknowledging your feelings without overreacting. It is not about ignoring your problems; it is about facing them without tearing yourself down.

What many call a quarter-life crisis—that overwhelming feeling of being lost in your twenties
Image: Toni Reed/Unsplash

How Self-Compassion Helps During a Crisis

When you practise self-compassion, something shifts. Instead of panicking, you pause. Instead of judging, you understand. Instead of spiralling, you ground yourself.

Research shows that people who are more self-compassionate experience lower anxiety and stress, better emotional resilience, greater clarity in decision-making, and improved overall wellbeing. Self-compassion does not solve a crisis overnight — but it changes how you go through it.

Small Ways to Be Kinder to Yourself

You do not need a complete life overhaul. Start small. Change your inner dialogue: replace “I’m failing” with “I’m figuring things out.” Take breaks without guilt — rest is productive too. Limit comparison; social media shows highlights, not reality. Celebrate small wins, because progress is not always loud. And ask for help. You do not have to do this alone.

A quarter-life crisis can feel like everything is falling apart. But sometimes, it is actually everything falling into place — just not in the way you expected. In the end, a quarter-life crisis is not a sign that you are failing. It is a sign that you are evolving, and with self-compassion, you can navigate this uncertainty with greater strength, clarity, and trust in your own journey.

Reference

>> Neff, K. (2003). Self-Compassion: An Alternative Conceptualization of a Healthy Attitude Toward Oneself. Self and Identity, 2(2), 85–101.

>> Robinson, O. C. (2019). A Longitudinal Mixed-Methods Case Study of Quarter-Life Crisis During the Post-university Transition: Locked-Out and Locked-In Forms in Combination. Emerging Adulthood, 7(3), 167–179. Scopus.

Glenda Fernandes is a researcher at Christ (Deemed to be University), Bangalore, with a focus on the psychological experiences of young adults, including quarter-life crisis, meaning in life, and self-compassion. Dr. Aiswarya V R is Assistant Professor at Christ (Deemed to be University), Bangalore, specialising in health and developmental psychology. She holds an MSc in Applied Psychology from the University of Calicut and a doctorate in Child Psychology from the University of Kerala.

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The Sciences

Scientists Crack the Genetic Code Behind Seedless Grapes

Indian researchers reveal how genetic mutations create the popular seedless varieties consumers love, opening doors to better grape breeding

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Scientists have finally unlocked the mystery behind one of our favourite fruit features – seedless grapes. A study by Indian researchers has decoded the genetic mechanisms that create seedless grapes, potentially revolutionizing how we breed these popular fruits.

The Science Behind Seedless Success

The research, led by Dr. Ravindra Patil at the Agharkar Research Institute (ARI) in Pune, India, examined why some grapes develop without seeds while others don’t. Published in BMC Plant Biology, the study focused on a seedless mutant derived from the high-yielding grape variety ARI-516.

Using advanced genomic tools, the team discovered that pollen sterility is the key culprit behind seedlessness. The seedless grapes showed:

  • Abnormal pollen structure with very low viability
  • Complete inability of pollen grains to germinate
  • Smaller female reproductive structures compared to seeded varieties
  • Disrupted fertilization processes leading to seedless berry formation

Genetic Detective Work

The researchers employed cutting-edge techniques to crack the code:

Transcriptomic Analysis: RNA sequencing revealed that genes crucial for pollen development, cell division, and hormone signaling were significantly “switched off” in seedless varieties.

Whole-Genome Sequencing: This identified multiple insertion-deletion mutations (InDels) in genes responsible for pollen development, essentially breaking the normal seed formation process.

The evidence points to parthenocarpy – a natural process where fruits develop without fertilization due to reproductive defects.

Why This Matters

This discovery isn’t just academic curiosity. Seedless grapes represent a massive global market, with consumers strongly preferring them for:

  • Fresh consumption
  • Raisins and dried products
  • Juices and processed foods

The research provides molecular markers that grape breeders can use to:

  • Develop new seedless varieties faster
  • Improve fruit quality and yield
  • Create grapes better adapted to different climates

Impact on Agriculture

Dr. Patil’s team has conducted one of the most comprehensive studies on grape seedlessness using modern genomic tools. This breakthrough could significantly accelerate breeding programs worldwide, benefiting both grape growers and consumers who enjoy these convenient, seed-free fruits.

The study represents a perfect example of how understanding nature’s genetic mechanisms can lead to practical agricultural improvements, potentially transforming grape cultivation and meeting growing global demand for high-quality seedless varieties.

The research was conducted in collaboration with Savitribai Phule Pune University and represents a significant advancement in horticultural genomics.

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