Category: The Conversation

Source: The Conversation – UK – By Milan Klöwer, NERC Independent Research Fellow, University of Oxford

Air travel is famously one of the hardest sectors to decarbonise, and the number of air passengers keeps increasing. Electric planes and “sustainable” aviation fuels are still a long way off making a dent in the industry’s emissions – if they ever will.

But new research by me and my colleagues shows aviation could still cut its climate impact dramatically, simply by using planes more efficiently. In fact, rethinking cabin layouts alone could slash emissions by up to half.

From 1980 to 2019, the share of occupied seats in commercial air planes increased from 63% to 82%. Airlines already have strong commercial incentives to sell every seat – empty ones cost money as well as carbon.

For any given level of passenger travel, carrying more people on each flight means other planes can stay grounded and fewer flights are needed overall. It’s planes that make the big difference, not people – the additional weight of a passenger and their luggage is negligible relative to the aircraft and its fuel.

Aviation is responsible for 2%-3% of global CO₂, but its contribution to global warming is about 4% when secondary effects like condensation trails (which trap heat) are factored in. This impact is dominated by rich people flying frequently, often long-haul in business and first class or even private.

Efficiency in aviation is often thought of as an engineering challenge: how much thrust an engine generates for a given amount of jet fuel. But operational efficiency – the amount of passenger-kilometres per unit of CO₂ emitted – has received far less attention.

In our research, my colleagues and I calculated this operational efficiency for the year 2023, for every flight route, by airline, aircraft model and airport. We found that efficiency gains available in the short term could reduce aviation’s climate impact by more than half.

Short empty flights are the least fuel-efficient

On average, aviation emissions fell from around 260 grams of CO₂ per paying passenger-kilometre in 1980 to 90 grams in 2019. That’s a big difference, but for comparison, electrified rail powered by low-carbon energy can emit less than 5 grams.

Our analysis shows that CO₂ efficiency varies enormously across routes, regions, airports, airlines and aircraft models. Some flight routes emit more than 800 grams per passenger-kilometre, others less than 50. This variability is staggering but also yields a large potential to reduce emissions if efficiency across the industry increased towards that of the most efficient routes we analysed.

Among the highest emitting countries, many of the least efficient flights start or land in the US, followed by China, Germany and Japan. Inefficient flights are common elsewhere, particularly from or to smaller airports, and in Africa and Oceania, often exceeding 140g per passenger-kilometre.

By contrast, more efficient flights – below 100 grams per passenger-kilometre – are common in Brazil, India and south-east Asia, particularly on high volume routes. Europe contains a mix of both.

These differences can be explained by the share of occupied seats, the aircraft models used on a route and the cabin layout – especially the space allocated for business and first class.

Budget airlines tend to be more efficient as they seat as many passengers as possible. Spacious business or first class seats are often removed and revenue is instead generated through services such as baggage, food or booking flexibility – all of which add little to flight emissions.

We also found a few newer aircraft models to be the most efficient in operation (Boeing 787 Dreamliner and Airbus 320neo, both in several variants) averaging less than 65 grams of CO₂ per passenger-kilometre. However, they are not (yet) the most widely used, partly because aircraft typically remain in service for around 25 years.

Long-haul flights are on average more efficient than shorter flights. Take-off emissions only occur once, and larger aircraft with more seats are typically used on longer routes. For similar reasons, larger airports tend to have lower average emissions per passenger.

Increasing air travel efficiency

We modelled three hypothetical scenarios to illustrate the potential of certain operational changes, recalculating the total emissions after each change.

First, we increased the average passenger load factor from 80% to 95%. This alone would cut emissions by 16%, as fewer flights would be needed to carry the same number of passengers. While this is already in airlines’ interests, creating additional incentives – such as emissions-linked airport charges or fuel taxes – could encourage further gains.

Second, we imagined only the two most efficient aircraft (Boeing 787-9 and Airbus A321neo) were in operation. Aircraft cannot be replaced overnight, given their long service lives, and airlines haven’t built enough 787-9 or A321neo yet anyway. But choosing already existing aircraft highlights the potential of replacing older aircraft with newer and more efficient ones – in our calculations, it would save between 27% and 34% of global emissions. This would also require overcoming logical and commercial constraints, again potentially incentivised by airport or fuel charges.

Third, we analysed the impact of an all-economy cabin layout. Business and first class seats are up to five times more CO₂-intensive than economy seating because they occupy far more space per passenger. Operating all aircraft at the manufacturers maximum seating capacity would reduce global aircraft emissions by between 26% and 57%.

There are already large differences between airlines. Some chose to set up their Boeing 777-300 ERs with more than 400 economy seats, while others have as few as 200, despite a maximum seating capacity of 550.

Our findings highlight how strongly aviation emissions are shaped by travel inequality between occasional economy fliers and frequent business and first class travellers. Many of those may complain about the inconvenience of economy class. But perhaps that’s not a bad thing: it could create an even stronger incentive to reduce the number of non-essential journeys.

Milan Klöwer receives funding from the Natural Environment Research Council.

– ref. Scrapping business class could halve aviation emissions – new study – https://theconversation.com/scrapping-business-class-could-halve-aviation-emissions-new-study-275474

Source: The Conversation – UK – By Aishwarya Viswamitra, PhD Researcher, School of Applied Social Sciences, De Montfort University

Sanju Pal built a successful career in management consulting, winning major awards and working at a senior level. Then her health changed.

After being diagnosed with severe endometriosis and undergoing surgery, she returned to work but struggled with pain and fatigue. Months later, she was dismissed for not meeting performance targets. What followed was years of legal action, culminating in a January 2026 ruling that she had experienced discrimination arising from disability under the Equality Act 2010.

Her case may set an important precedent. It also highlights a wider issue: how many others are navigating chronic illness at work without recognition, flexibility or legal support?

Endometriosis is a long-term condition in which tissue similar to the lining of the womb grows elsewhere in the body. It can cause severe pelvic pain, fatigue, heavy bleeding and other debilitating symptoms. For many, the impact on daily life, including work, is significant.

Despite this, diagnosis is often slow. Endometriosis affects 1.5 million women in the UK (one in every ten), and yet the average diagnostic delay is around eight years. During that time, people may continue working while managing escalating symptoms without formal recognition or support.

Pain may be dismissed as normal. Fatigue may be hidden. Without a diagnosis, adjustments at work are difficult to request and even harder to secure.

Work and endometriosis – the research

Evidence consistently shows that endometriosis can shape working lives in significant ways. Some studies suggest that around 38% of people with the condition worry about losing their job because of it. Others report that roughly 35% experience reduced income linked to symptoms. Many describe working through severe pain to avoid triggering absence procedures or being seen as unreliable.

Research highlights a culture of presenteeism and overcompensation. Employees push themselves to meet productivity targets, conceal symptoms and avoid disclosure. Annual leave is often used to manage flare-ups. Some reduce hours, shift into part-time roles or move into self-employment seeking flexibility, sometimes at the cost of career progression and financial security.

Disclosure itself can feel risky. Endometriosis remains poorly understood and is often invisible. Symptoms such as pelvic pain or heavy bleeding can be difficult to discuss in professional settings. Some fear being seen as less capable or less committed.

Read more:
Endometriosis afflicts millions of women, but few people feel comfortable talking about it

Workplaces, meanwhile, are often structured around uninterrupted availability and consistent productivity. Performance models that rely on fixed timelines and metrics may struggle to accommodate fluctuating conditions. When absence policies, promotion criteria and workloads remain rigid, employees can be penalised for symptoms beyond their control.

Sanju Pal’s experience of being assessed against standard progression targets during illness reflects patterns described in this research.

Recognition and its limits

Endometriosis has gained increasing political and public attention in the UK over the past decade. Parliamentary debates, inquiries and awareness campaigns have highlighted the challenges around diagnosis, workplace support and education.

Yet recognition at policy level does not always translate into everyday practice. Under the Equality Act 2010, a formal diagnosis is not required for someone to be considered disabled. What matters is whether an impairment has a substantial and long-term impact on normal daily activities. In some cases, endometriosis may meet this threshold.

In reality, recognition often comes only after lengthy disputes. Tribunals can be stressful, time-consuming and emotionally draining. Not everyone has the resources or stamina to pursue one.

Work is more than income. It shapes identity, confidence and social connection. Research on chronic illness and employment shows that supportive environments can make a meaningful difference. Flexible schedules, understanding managers and open communication can help people stay in roles they value. Rigid systems, by contrast, can intensify stress and push people out of the workforce.

Where workplaces go from here

Endometriosis UK’s Employer Friendly Employer scheme works with organisations to improve awareness and workplace practice. Initiatives like this aim to close the gap between policy and experience.

At the same time, significant questions remain. We know a growing amount about how endometriosis affects employees. We know far less about how employers understand the condition, how they interpret their legal responsibilities and what prevents adjustments from being made.

Cases like Sanju Pal’s should not be seen as isolated disputes. They reveal structural tensions between chronic illness and contemporary work culture, where productivity is often measured through consistency and visibility rather than wellbeing and sustainability.

If workplace equality is to improve, two things are needed. Employers must design systems that anticipate fluctuating health and build flexibility into everyday practice. Researchers must continue producing evidence that highlights the realities of living and working with endometriosis.

The question is no longer whether the condition affects working lives. It is whether workplaces are prepared to adapt before the next employee has to fight a legal battle to be recognised.

Aishwarya Viswamitra receives funding from the Economic and Social Research Council (ESRC).

– ref. Endometriosis: how a court ruling could make workplaces better for those with the condition – https://theconversation.com/endometriosis-how-a-court-ruling-could-make-workplaces-better-for-those-with-the-condition-276356

Source: The Conversation – UK – By Daniel Kelly, Senior Lecturer in Biochemistry, Sheffield Hallam University

Shilajit is the latest supplement marketed online as a “natural testosterone booster”. Promoted by influencers, wellness brands and biohacking communities, this sticky black resin is advertised as a way to increase testosterone, improve energy and enhance male vitality.

Shilajit is a tar-like substance formed over centuries from decomposed plant material compressed within rock in high-altitude regions such as the Himalayas. It has a long history of use in traditional Ayurvedic medicine, where it has been described as a rejuvenator and as an anti-aging compound.

Chemically, it contains a mixture of fulvic acid and trace minerals. Its complex composition is part of its mystique and also part of the scientific challenge in studying it.

When it comes to testosterone specifically, the evidence for shilajit’s effect on testosterone levels in humans is limited to two small studies.

The most frequently cited study was published in 2016. In this trial of healthy men aged 45–55, half were given purified shilajit (250mg twice daily) and half were given a placebo for 90 days. Neither group knew which group they had been randomly assigned to. The shilajit group saw increases in both total and free testosterone – the form immediately available for the body to use – compared with the placebo group.

On the surface, this sounds encouraging. However, the study included just 38 participants treated with shilajit, was of a relatively short duration, and measured testosterone using methods that are not considered the most reliable.

Although testosterone levels were modestly higher at 90 days, measurements at 30 and 60 days fluctuated in both directions. And probably the most curious finding was that testosterone levels fell in the placebo group, possibly inflating any claimed direct effects of shilajit on hormone levels.

The study was also funded by the manufacturer of the shilajit preparation used. While that does not invalidate the findings, it does warrant caution and independent replication.

An earlier study in infertile men reported improvements in semen parameters and increases in testosterone after shilajit supplementation. But again, sample sizes were modest, with only 28 men taking part – and the population studied was specific to men attending a fertility clinic. These findings may not translate to otherwise healthy men.

Beyond these small trials, there is a lack of large, independent, long-term studies assessing whether shilajit meaningfully raises testosterone in a way that improves muscle mass, strength, metabolic health or quality of life.

It is also important to distinguish between “statistically significant” changes in hormone levels and “clinically significant” ones. Testosterone fluctuates naturally throughout the day and declines gradually with age. Small shifts within the normal physiological range are unlikely to transform body composition or vitality. In both the clinical studies, testosterone was always in this physiological reference range, despite the reported increases.

Another issue that receives less attention in promotional material is product quality and contamination. Because shilajit is harvested from natural rock formations and then processed, its composition can vary substantially. Several analyses of commercially available preparations have raised concerns about contamination with heavy metals such as lead, mercury and arsenic.

While reputable manufacturers may purify their products, the supplement market is not regulated to the same standard as prescription medicines. Consumers are often paying premium prices for products that may differ considerably in purity and potency.

What actually affects testosterone?

Against this backdrop, it is worth asking what actually influences testosterone levels in men.

Sleep is one of the most powerful regulators. Even short-term sleep restriction can reduce testosterone concentrations in healthy young men. Being overweight is linked to lower testosterone, partly because extra body fat can turn some testosterone into oestrogen.

Resistance training can temporarily increase testosterone and, more importantly, improve muscle mass and regulate blood sugar irrespective of hormone changes. Long-term stress and drinking too much alcohol can interfere with the system in your body, called the hypothalamic–pituitary–gonadal axis, that regulates testosterone production.

In other words, the foundations of hormonal health are behavioural and metabolic. No supplement has yet been shown to override the effects of poor sleep, inactivity, stress or obesity.

For men experiencing symptoms such as persistent fatigue, low libido, erectile dysfunction or reduced muscle strength, the appropriate first step is medical assessment. In clinical practice, testosterone deficiency is diagnosed only after consistent biochemical evidence on repeated morning blood tests, alongside symptoms.

Testosterone deficiency can be associated with underlying conditions including obesity, type 2 diabetes, chronic illness or pituitary disorders. Blood testing, performed correctly and interpreted in context, is essential before considering any intervention.

In men with confirmed hypogonadism (the medical term for low testosterone levels), doctors can safely prescribe testosterone treatment, and there’s good evidence it works in many cases. That is very different from taking supplements you buy online based on marketing claims.

The growing popularity of shilajit sits within a broader cultural moment. Testosterone has become a shorthand for masculinity, energy and success.

Social media algorithms amplify anxieties about “low T”, often without context about what constitutes a true deficiency. Ancient remedies packaged in minimalist jars offer an appealing narrative of being natural, traditional and potent. Add influencer endorsements and promises of optimisation, and the commercial potential is obvious.

The appeal of quick fixes is understandable, but hormonal health is rarely fixed by a resin scraped from a rock. Consumers should also weigh cost against benefit. High-quality shilajit supplements can be expensive, particularly when taken for months at a time. For many men, the same investment directed towards structured exercise programmes, dietary improvements or professional medical advice would probably yield far greater returns.

In the case of shilajit, as with many supplements that promise hormonal optimisation, the marketing has travelled much faster than the science. This does not mean shilajit is entirely without potential.

The preliminary trials justify further rigorous investigation. Larger, independently funded studies could help clarify whether it exerts meaningful endocrine or metabolic effects, and in which populations.

Until then, the current evidence supports curiosity rather than confidence. Hormonal health requires careful assessment. Attempts to manipulate it without proper diagnosis and clinical oversight are unlikely to deliver what the marketing promises.

Daniel Kelly does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. Can a tar-like substance that oozes out of Himalayan rocks really boost your testosterone levels? – https://theconversation.com/can-a-tar-like-substance-that-oozes-out-of-himalayan-rocks-really-boost-your-testosterone-levels-275633

Source: The Conversation – UK – By Raul Zepeda Gil, Research Fellow in the War Studies Department, King’s College London

The leader of the Jalisco New Generation (CJNG) cartel, Nemesio Oseguera Cervantes, died in custody on February 22, shortly after he was captured by the Mexican authorities. The operation, which came amid renewed US demands for “tangible results” against fentanyl trafficking, appears to have relied on American intelligence support.

This is the most significant intervention against the cartels since the capture of former drug lord Joaquín “El Chapo” Guzmán in 2016. The CJNG is one of the strongest criminal organisations in Mexico and, alongside the Sinaloa cartel, sits at the centre of US claims about fentanyl production and trafficking.

The killing of Oseguera Cervantes, who is better known as “El Mencho”, may have enabled Mexico’s authorities to secure a political win with Washington. But the operation should not be seen as a victory. What often comes next when the Mexican state removes a high-profile cartel figure like El Mencho is an extended period of violence and instability inside the country.

In my own research on criminal conflict in the Tierra Caliente region of western Mexico, I trace how earlier rounds of arrests and state killings have reshaped local criminal groups, broken alliances and created openings for new players and leaders. It was through this very cycle of state enforcement and cartel reorganisation that El Mencho rose to prominence.

El Mencho began as an operational figure linked to the Valencia cartel, an organisation based in the state of Michoacán. The group lost ground in the late 2000s following sustained pressure from the authorities. After key parts of the Valencia network were dismantled around 2010, El Mencho and other remnants of the group moved to Jalisco further north and founded the CJNG.

The conditions that allowed the CJNG to rise came from the same enforcement repertoire that the authorities have now deployed against it. This pattern matters because it undercuts a common assumption among policymakers, including in US agencies such as the Drug Enforcement Administration, that removing a “boss” equals dismantling a criminal market.

The removal of Mexican criminal leaders does not cause the market for drugs to vanish, nor does it cause trafficking routes to disappear. What changes is the balance of power among groups that already compete for territory, labour and access to ports, roads and local authorities.

Studies that track the so-called “kingpin” strategy, the deliberate targeting of cartel leaders by law enforcement, have found that detentions and killings often trigger short-term spikes in homicides and instability in Mexico. Some work suggests that violence rises for months after a leader’s removal, while other research shows that the killing of a kingpin can provoke a sharper increase than an arrest.

This happens because an affected cartel faces a sudden succession struggle and employs violence to prevent – or respond to – rivals testing the new leadership and trying to renegotiate areas of control. As criminal groups cannot use the formal court system to resolve disputes, they tend to do so through open violence or bargains enforced by coercion.

This logic of violence has already been seen following El Mencho’s death. Reports of cartel gunmen blocking roads, launching arson attacks and carrying out disruptions across multiple states fit a familiar script: an affected organisation signalling its capacity, punishing the state and warning local rivals not to seize the moment.

Even if the state contains this wave of violence, the deeper risk sits in what follows. A leadership vacuum invites internal fracture and external opportunism from rivals who have waited for an opening to test boundaries and settle scores.

The 2024 detention of Sinaloa cartel leader Ismael “El Mayo” Zambada, for instance, has provoked a wave of violence in Sinaloa state as different factions in the organisation battle for leadership.

US drug politics

Another cycle that keeps repeating across Latin America is that US drug politics shapes security agendas throughout the region. A surge in overdose deaths, for example, can lead to political panic in the US and the application of pressure on Latin American governments to take action, usually through militarised enforcement.

These governments respond with crackdowns, raids and high-profile captures. This is followed by rising violence as criminal organisations fragment and then, after a period of time, governments try to deescalate. The cycle starts again when concern over drug trafficking next arises in the US.

Drug prohibition keeps this cycle alive by ruling out any response other than force or criminal law, while failing to produce meaningful results. Most countries have criminalised drugs. But despite governments reporting rising drug seizures each year, deaths linked to drug use globally continue to climb.

Mexico’s security forces cannot end a transnational market that is financed largely by US demand, no matter how many high-profile arrests they make. Operations that result in the killing or detention of cartel figures instead redirect and reorganise the drug trade, while often intensifying violence.

If Mexico and the US want fewer cartel-related deaths, they need to stop treating kingpin killings as the main metric of success. While a high-profile strike temporarily satisfies US pressure, it is Mexican citizens who all-to-often have to live with the blowback of this approach.

Raul Zepeda Gil does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. Mexico may pay a steep price for the killing of Jalisco cartel leader El Mencho – https://theconversation.com/mexico-may-pay-a-steep-price-for-the-killing-of-jalisco-cartel-leader-el-mencho-276648

Source: The Conversation – UK – By Morag Rose, Senior Lecturer in Human Geography, University of Liverpool

I love walking, and think it can change the world, but I hate wellbeing walks. I’m more interested in how walking can connect us to the places we dwell and the people we dwell with.

As a disabled person, wellbeing narratives frequently ignore my needs. They assume a standard body and often have a moralistic or bossy tone. They can ignore individual access needs and structural inequalities.

My walking is slow and sometimes painful. It is made possible by the NHS, orthotics (specialised, removable shoe inserts) and wider social infrastructure: from benches to public transport. “Walking” must be inclusive of wheelchairs, orthotics and other assistive technology. I believe everyone should have the right to walk and take up space on the streets.

Walking together can be a powerful way to critically engage with our environment and feel a sense of belonging. I have been exploring this idea in my art, activism and academic research, which has been bought together in The Feminist Art of Walking.

On a monthly basis for almost 20 years I have stood in Manchester and waited to see who will join me for a walk. I share the invitation widely, it’s open to anyone and always free to join. There is a meeting point but scant other information.

I can’t tell anyone where we will go since I simply don’t know our destination. When folk arrive, and they always do, we drift, guided by paper planes or pigeons, DIY maps or culverted rivers, our senses or our hearts. Every month a different prompt or provocation to inspire our wandering.

My waiting, and walking, began as an activist experiment, a way to subvert city streets increasingly threatened by gentrification, homogenisation and privatisation. I believe public space, non-commercial open places, where people can gather, ask questions, start conversations, or simply just be, are vital. We need to expand what we mean by public space to include pavements, bus stops, plazas and the like. We must resist attempts to prescribe, prohibit or limit access to such places. This matters now more than ever.

Opening up, sharing stories, making, holding, extending space – walking together with respect for those we share that space with – is the opposite of planting a flag and claiming dominance.

I wanted to explore ideas around psychogeography, an idea originated by the Marxist theorist Guy Debord in 1955 that asked how different places make us feel and behave. In response, I co-founded the LRM (Loiterers Resistance Movement).

Loitering for me means slowing down, resisting the need for productivity. Not everything of worth can, or should, be measured, commercialised or turned into an “output”. That’s why our events have always been free for everyone. Loitering also celebrates playfulness and re-enchantment. The LRM’s manifesto says:

We believe there is magic in the Mancunian rain. Our city is wonderful and made for more than shopping.

The beautiful thing about walking this way is the serendipity, the conversations and encounters. Over the years a community has formed and together we share stories and walk ourselves into being part of the city.

One of the aims of the most recent LRM walk was to gently challenge fear. We used warning signs and prohibition notices as our catalyst. Snow on the pavements added a personal dimension as my navigation was also informed by minimising the risk of slipping. My world shrinks in the snow, so an additional guiding element was added, a heightened awareness of textures and shadows. I was struck by the care of the collective, everyone kept pace, tracing thaw patterns and seeking clear patches.

Psychogeography suggests using the body as a tool to investigate the urban landscape and better understand the invisible power lines of commerce and capitalism. The psychogeographer uses the drift to free themselves from the everyday and walk new routes, with the intention of providing an alternative vision of the city.

Historically, the psychogeographer became associated with the “flaneur”, a lone male wanderer who is able to move unheeded through the city. This romantic idyll doesn’t reflect the reality for many of us, and there are many barriers stopping folk.

In my own research, I have walked with women across Manchester whose movements are shaped or limited by gendered street harassment, or the justified fear of violence. This can be compounded by intersectional factors such as race, faith, age or sexuality.

Of course women resist and still walk despite threats. As well as everyday walking, this can be seen during protest walks such as Reclaim The Night or Slutwalk. These demonstrations often have a carnivalesque atmosphere as women and allies gather to challenge oppression, assert their right to walk and take up space. It can also be seen in women-led groups such as Black Girl Hike and The Wonderlust Women for Muslim women.

I’ve been working with, and learning from, women who have transformed walking into powerful works of art and community building. For instance, Clare Qualmann’s East End Jam includes foraging walks around her neighbourhood and communal cooking sessions. Elspeth “Billie” Penfold combines walking and weaving, honouring her Bolivian and Argentinian heritage.

These artists, like the LRM, create communal walks. It is the being together, the moving together, that makes these wanders so special.

Conviviality is at the heart of the LRM. A convivial walk means we are navigating shared space despite, and because of, our differences. It does not homogenise but values multiplicity.

The LRM manifesto also states “the streets belong to everyone” and although we recognise this is an aspiration, not reality, it is an idea we fully commit to. Being together on a walk demonstrates how shared space can be used peacefully and creatively.

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Morag Rose founded and facilitates the psychogeographical collective The LRM (Loiterers Resistance Movement) a not-for-profit / mutual aid collective.

– ref. Loitering without intent: how taking aimless walks can create community and help you feel part of a city – https://theconversation.com/loitering-without-intent-how-taking-aimless-walks-can-create-community-and-help-you-feel-part-of-a-city-273844