Lilly P. Harvey– PhD Researcher, Environmental Science, Nottingham Trent University
New research suggests the extinction crisis may be even worse than we thought. More than half of species that have so far evaded any official conservation assessment are threatened with extinction, according to predictions by researchers from the Norwegian University of Science and Technology.
Conservation resources are limited and it is not feasible or logical to protect every square kilometre of land and sea. So to mitigate the rapid loss of biodiversity, where should our conservation resources go? To answer this question we first need to know which species to protect.
The International Union for Conservation of Nature coordinates a network of scientists who have assessed biological information available for all sorts of species worldwide for more than 50 years, publishing their findings in the Red List of Threatened Species. Its goal has been to identify species that need protection with an assigned conservation category of extinction risk.
It’s the Red List that confirmed tigers are officially endangered, for instance, or that giant panda populations have recovered enough to move from endangered to merely vulnerable.
However, while species like pandas and tigers are well studied, researchers don’t know enough about some species to properly assess their conservation status. These “data deficient” species make up around 17% of the nearly 150,000 species currently assessed.
When analysing conservation data it is common for researchers to remove or underestimate assumptions of threat for these species, in order to control for unknown variations or misjudgements. Now, these researchers in Norway have tried to shed light on the black hole of unknown extinction risk by designing a machine learning model that predicts the threat of extinction for these data deficient species.
Machine learning for extinction assessment
When thinking of artificial intelligence and machine learning it is easy to imagine robots, computer-simulations and facial recognition. In reality, at least in ecological science, machine learning is simply an analytical tool used to run thousands of calculations to best represent the real-world data we have.
In this case, the Norwegian researchers simplified the Red List extinction categories into a “binary classifier” model to predict a probability of whether data deficient species are likely “threatened” or “not threatened” by extinction. The model algorithm has “learned” from mathematical patterns found in biological and bioclimatic data of those species with an already assigned conservation category on the Red List.
They found more than half (56%) of the data deficient species are predicted to be threatened, which is double the 28% of total species currently evaluated as threatened in Red List. This reinforces the concern that data deficient species are not only under-researched, but are at risk of being lost forever.
On land, these likely threatened terrestrial species are found across all continents, but live in small geographically restricted areas. This finding supports previous research with similar conclusions that species with small range sizes are particularly vulnerable to anthropogenic habitat degradation, such as deforestation or urbanisation.
At risk amphibians
Amphibians are the most at-risk group, with 85% of those data deficient species predicted as threatened (compared to 41% of those currently evaluated on the Red List). Amphibians are already a poster-child for the extinction crisis and are a key indicator for ecological health, as they depend on both land and water. We don’t know enough about what causes such catastrophic extinction of amphibians, and I am part of a science initiative trying to address the problem.
It’s a slightly different, but still tragic, story at sea. Data deficient marine species that are predicted to be facing extinction are concentrated along coasts, particularly in south-eastern Asia, the eastern Atlantic coastline and in the Mediterranean. When data deficient species are combined with fully-assessed species on the Red List, there is a 20% increase in the probability of extinction along the eastern coastlines of tropical Latin America.
What this means for global conservation
Though it is likely that the need for conservation has actually been underestimated worldwide these probability predictions are highly variable across different areas and groups of species, so don’t be fooled into overgeneralising these findings. But these broad results do highlight why it is so important to further investigate data deficient species.
The use of machine learning tools can be a time-and-cost-effective way to enhance the Red List and help overcome the challenging decision of where and what to protect, aiding targeted conservation action and expanding protected areas in these black holes of biodiversity.
For those of us without access to outside green space, houseplants are a stylish and affordable way of getting a nature fix. Alongside looking nice, indoor plants actually have several other perks – the biggest benefit of which could be improving your mental health. And the good news is you don’t need to be a self-professed “plant parent” to experience these benefits either.
One in eight UK households don’t have access to any kind of garden. Young people and those from minority ethnic backgrounds are among those least likely to have a garden.
Not having access to nature can have a number of effects on our health. It’s been linked to symptoms of depression and anxiety, as well as other health conditions, such as asthma, cardiovascular disease, and poor immune function. For many of us, houseplants are an essential link to nature.
While there’s not yet a robust body of research on the mental health benefits of houseplants specifically, plenty of studies have shown how beneficial green space and gardening are for mental health. For instance, one study found that people who garden daily have better wellbeing and lower stress levels compared to those who don’t.
A recent review of 42 studies demonstrates that even just being in the presence of indoor plants can improve mental and physical health. These experiments compared participants doing various activities in rooms with or without plants.
The presence of plants saw better performances on cognitive tasks involving focus, sorting or memory recall, greater pain tolerance when holding hands in ice cold water, and lower levels of physiological stress. Interestingly, the aesthetic appearance of plants is important too, with separate research showing that people tend to react more positively to lush, green plants with rounded and denser foliage.
There are plenty of other reasons owning houseplants is beneficial for you.
Plants can remove pollutants such as carbon dioxide, nitrogen dioxide (from nearby traffic), fine particles (from dust) and volatile organic compounds (from air fresheners, cooking and cleaning). For people indoors for the majority of the day, indoor air quality is hugely important.
High concentrations of carbon dioxide can reduce cognitive performance (such as concentration and memory recall) while prolonged exposure to other indoor pollutants can cause long-term health problems – ranging from minor eye or throat irritations to respiratory problems and cancer.
But removing a meaningful quantity of indoor pollutants would require a lot of plants in a very bright room – something unrealistic for most people. If you do want to give it a try, plants with a high leaf area – such as an India rubber tree (Ficus elastic) or devil’s ivy (Epipremnum aureum) are your best bet.
In theory, plants can also help increase indoor air humidity. Most of our buildings are too dry. Keeping humidity in an optimal range can prevent the spread of viruses, fungal growth, as well as eye, skin and nose dryness. Though dependent on other conditions in the room like size, light, and airflow, some of the best plants for increasing humidity are English ivy (Hedera helix), Devil’s ivy (Epipremnum aureum) and Peace Lily (Spathiphyllum).
You don’t need a green thumb to enjoy success with houseplants. Gardening is all about learning through trial and error, and even the most seasoned gardeners make mistakes. Indeed, not all plants will thrive everywhere – and some may struggle through infestations, won’t adapt to light or water conditions, and die. Try not to get hung up on this setback. It’s always worth trying again, perhaps with a different species and armed with more botanical knowledge.
Each plant has different requirements, so look for plants that are suited to the conditions in your home. You may even want to find plants that actually thrive on neglect. Some of the best options for beginners are the spider plant (Chlorophytum comosum), the parlour palm (Chamaedorea elegans), and anything in the cactus and succulent families, such as the zebra cactus (Haworthia) or the jade plant (Crassula ovata).
Growing herbs is also a cheap and useful starting point for beginners. There are also apps out there that can help make it easier for you to care for your plants, by giving you advice, reminders and a forum to ask questions.
Owning houseplants can have a range of benefits for our health – especially mental health. It can also be a great hobby that always teaches you something new, encourages self-expression – choosing and caring for plants –, and gives you a tangible sense of fulfilment.
Lindsay Bottoms– Reader in Exercise and Health Physiology, University of Hertfordshire
Have you ever noticed people out walking with poles even on flat surfaces and wondered why they are doing it? This is known as Nordic walking, which is a little bit like cross country skiing but without the snow.
Walking with poles was first developed in Scandinavia and came to central Europe about 20 years ago. For some reason, it has not become particularly popular even though it has many health benefits.
Here’s why – alongside a few good reasons to give Nordic walking a try.
1. You burn more calories
As far back as 1995, researchers noticed that Nordic walking burned more calories than regular walking did. In fact, they found it burned up to 18% more calories than ordinary walking did.
Numerous studies have confirmed these findings since – which is why it’s suggested that Nordic walking could be a great form of exercise for those looking to lose weight. One study from Italy even found that overweight people lost weight faster doing Nordic walking compared to ordinary walking.
While Nordic walking doesn’t burn more calories than other, more intense forms of exercise – such as running – it can be a great low-impact exercise option, or a way to boost the benefits of your regular daily walks.
2. It may reduce limb pain
Using poles while you walk can distribute your weight through the arms and torso, placing less strain on your back, knees and hips. In theory, this has the potential to improve back pain while walking.
If you’re someone who suffers from lower back, hip or knee pain, Nordic walking could be helpful to you since it redistributes your weight somewhat. But it’s worth discussing with your doctor first before giving it a try, and stopping if your pain still persists even while using the poles.
3. Improves upper body strength
Nordic walking engages your arms and shoulders more than regular walking does, and that could improve your strength. Research has shown that Nordic walking can not only increase hand grip strength but also increases muscle activity in the shoulders.
Upper body strength – including how strong your grip is – is important for many of the things we do everyday, from carrying our shopping to filling up the kettle. Increasing muscle strength is also important to help prevent injury as it helps stabilise the joints and protects them when moving under impact like carrying heavy shopping bags.
Nordic walking also engages the core muscles (including those in the abdomen and your back) more than ordinary walking does.
Greater engagement of the core muscles will help strengthen them, which may in turn improve posture. Better core strength can also improve your balance as well as your ability to move.
5. Reduce risk of falling
Unfortunately as we get older we are more likely to trip and fall when we are walking. This is mainly because of a decrease in muscle strength, balance issues and problems with the way we walk.
The benefit of Nordic walking is that you are placing the poles into the ground at the same time as you’re using your legs. This improves balance and makes you less likely to fall.
In fact, one study even showed that people who followed a Nordic walking training programme for three weeks had improved balance – even when walking without poles. It’s no wonder Public Health England recommends Nordic walking for improving balance in older people.
Another study on obese women also showed Nordic walking was able to improve blood pressure, though only to a similar extent as ordinary walking. In addition, Nordic walking has been shown in postmenopausal women to improve resting blood sugar levels, which is important in preventing diabetes as well as improving cholesterol levels in the blood.
7. You can walk faster
Nordic walking can help you get where you want to be faster than ordinary walking can. In fact, a review showed Nordic walking increased average walking speed by up to 25% compared to ordinary walking. As a consequence of walking faster, you can then burn more calories. So if you went for a 30-minute Nordic walk, you’d be able to walk further and burn more calories than you might on a regular walk.
There seem to be clear advantages to doing Nordic walking. It may especially be good for people who don’t like other types of exercise – such as running – but still want to do something of a higher intensity than brisk walking.
James Lovelock, the maverick scientist and inventor, died surrounded by his family on July 27 2022 – his 103rd birthday. Jim led an extraordinary life. He is best known for his Gaia hypothesis, developed with the brilliant US biologist Lynn Margulis in the 1970s, which transformed the way we think of life on Earth.
Gaia challenged the orthodox view that life simply evolved and adapted to the ever-changing environment. Instead, Lovelock and Margulis argued that species not only competed but also cooperated to create the most favourable conditions for life.
Earth is a self-regulating system maintained by communities of living organisms, they claimed. These communities adjust oxygen and carbon dioxide levels in the atmosphere, salinity in the ocean and even the planet’s temperature to keep them within the acceptable bounds for life to thrive.
Just like Charles Darwin before him, Lovelock published his new, radical idea in a popular book, Gaia: A new look at life on Earth (1979). It was an instant hit that challenged mature researchers to reassess their science and encouraged new ones. As my friend and colleague Professor Richard Betts at the Met Office Hadley Centre put it:
He was a source of inspiration to me for my entire career, and in fact his first book on Gaia was a major reason why I chose to work on climate change and Earth system modelling.
Not only did the book challenge the classical Darwinism notion that life evolved and prospered through constant competition and dogged self-interest, it founded a whole new field: Earth system science. We Earth system scientists study all the interactions between the atmosphere, land, ocean, ice sheets and, of course, living things.
Lovelock also inspired the environmental movement by giving his ideas a spiritual overtone: Gaia was the goddess who personified the Earth in Greek mythology.
This antagonised many scientists, but created a lot of fruitful debate in the 1980s and 1990s. It is now generally accepted that organisms can enhance their local environment to make it more habitable. For example, forests can recycle half the moisture they receive, keeping the local climate mild and stabilising rainfall.
But the original Gaia hypothesis, that life regulates the environment so that the planet resembles an organism in its own right, is still treated with scepticism among most scientists. This is because no workable mechanism has been discovered to explain how the forces of natural selection, which operate on individual organisms, birthed the evolution of such planetary-scale homeostasis.
This matchbox-sized device could measure tiny traces of toxic chemicals. It was essential in demonstrating that chlorofluorocarbons (CFCs) in the atmosphere, which originated in aerosols and refrigerators at the time, were destroying the ozone layer. It also showed that pesticide residues exist in the tissues of virtually all living creatures, from penguins in Antarctica to human breast milk.
The money he earned from the electron capture detector gave him his freedom because, as he was fond of telling people, the best science comes from an unfettered mind – and he hated being directed. The detector was just the start of his inventing career and he filed more than 40 patents.
He also wrote over 200 scientific papers and many popular books expanding on the Gaia hypothesis. He was awarded scientific medals, international prizes and honorary doctorates by universities all around the world.
Dr Roger Highfield, the science director at the London Science Museum, summed Jim up perfectly:
Jim was a nonconformist who had a unique vantage point that came from being, as he put it, half-scientist and half-inventor. Endless ideas bubbled forth from this synergy between making and thinking. Although he is most associated with Gaia, he did an extraordinary range of research, from freezing hamsters to detecting life on Mars … He was more than happy to bristle a few feathers, whether by articulating his dislike of consensus views, formal education and committees, or by voicing his enthusiastic support for nuclear power.
Jim was deeply concerned by what he saw humanity doing to the planet. In his 1995 book The Ages of Gaia, he suggested that the warm periods between ice ages, like the current Holocene, are the fevered state of our planet. Because over the last two million years the Earth has shown a clear preference for a colder average global temperature, Jim understood global warming as humanity adding to this fever.
Jim did despair at humanity’s inability to look after the environment and much of his writing reflected this, particularly his book The Revenge of Gaia in 2006. But at the age of 99, he published Novacene: The Coming Age of Hyperintelligence (2019), an optimistic view which envisaged humanity creating artificially intelligent life forms that would, unlike us, understand the importance of other living things in maintaining a habitable planet.
His dwindling faith in humanity was replaced by trust in the logic and rationality of AI. He left us with hope that cyborgs would take over and save us from ourselves.
Len De Nys– PhD researcher, Stress, Healthy Ageing and Physical Exercise, University of Stirling Anna Catriona Whittaker– Professor of Behavioural Medicine, University of Stirling
When you’re suffering from stress, it can affect almost every aspect of your life – even down to how well you sleep at night. While it’s normal to experience stress over things every now and again, if it continues to affect your sleep in the long-term it can lead to poorer quality sleep and even insomnia.
But our recent review suggests that physical activity may be key to improving both stress levels and sleep.
To conduct our review, we looked at all possible studies ever published on this topic. Around 60% of the studies we looked at happened to be done on women with breast cancer, while the other 40% were done on a more diverse range of participants, including men and women without breast cancer. It’s uncertain why so many studies in this area looked at women with breast cancer, but it may be to do with the fact that chemotherapy causes a lot of side effects – such as stress and poor sleep.
Our findings suggest that, in general, exercise was effective for reducing stress levels and improving sleep. Other studies that have looked at a more diverse group of participants have also shown that physical activity can help lower stress and can help people get a better night’s sleep. Research also suggests exercise may be beneficial for people with other health conditions such as depression or sleep disturbances.
Cortisol is an essential hormone in the body. It works with our brain to regulate a number of important body processes including mood, immune system function and metabolism. It also triggers our “fight-or-flight” response when we encounter things that are scary or stressful – hence why it’s often called our “stress hormone”.
Cortisol also plays an important role in sleep. Cortisol levels change throughout the day, but are generally at their peak in the morning, around 30-45 minutes after waking up, helping us feel alert and ready to take on the day. But gradually these levels decline throughout the day, which helps us feel tired and fall asleep at night.
According to our review, physical activity counterbalances this negative spiral by regulating cortisol levels – which simultaneously improves sleep quality. We found that light-to-moderate intensity exercise (such as running and yoga) seem to be the most beneficial in improving stress and sleep. But our study also suggests that exercise works best at reducing stress and improving sleep when it’s tailored to each person’s preference.
Why exercise works
Previous research suggests a couple of possible reasons why exercise is so good for reducing stress and improving sleep.
First, exercise can be seen as a “hormetic” stressor. Hormesis is that sort of good stress that keeps your body alert. During exercise, your body is exposed to various forms of stress – such as the stress your muscles experience because of the extra demand placed on them. These stressors simulate existing mechanisms that your body uses to withstand greater stress.
Either too little or too much exposure to exercise stressors can lead to poor health. It’s that sweet spot that regulates cortisol and improve sleep (and overall health). But this sweet spot differs from person to person – and may even be affected by your own mental state when you exercise.
Second, it’s important to consider the type of exercise you do – as this can determine whether or not it makes you feel relaxed or more stressed. This is why it’s essential that you enjoy the exercise you do. You may also want to change the intensity of the exercise you do depending on the time of day.
Since exercise releases cortisol (especially more intense types of exercise, such as weightlifting or high-intensity interval training), morning exercise can help your body feel more energised during the day and help you feel more tired in the evening. For this same reason, if you’re someone who likes to exercise in the evening it’s best to choose exercises – such as yoga or tai chi – that help you wind down and don’t spike cortisol levels too much.
But of course, not everyone can exercise first thing in the morning. The good news is that exercise almost any time of day can help reduce your stress levels and improve sleep – and this is true of almost every type of exercise, too.
Urban beautification campaigns are usually sold to local residents as a way to improve their daily lives. Design elements – from lighting systems to signs, benches, bollards, fountains and planters, and sometimes even surveillance equipment – are used to refurbish and embellish public spaces.
Designers refer to these elements as “urban furniture”. And the projects they’re used in are usually aimed at increasing social interaction, heightening safety, improving accessibility and generally making life in the city better.
Cities aren’t only identified by their monuments or signature buildings. You can tell New York City and Palermo apart just by looking at what people are doing in public. A New York scene is more likely to feature someone on a skateboard eating a burrito, while a Palermo image might include a group of men in a street watching a football match on television through a shop window.
Urban space is where city children learn and play, students read and people work, walk and relax. It is through these different activities that any single city’s urban culture is created.
Architects, infrastructural and spatial designers carefully configure the built environment – the constructed fabric of our cities – and this has a lasting effect on how we use or inhabit them.
In cities around the globe – from Algiers, Auckland and Chicago to Hanoi, Mexico City and Seoul – research shows that transforming public spaces markedly affects the diversity of what people do in them, and whether they use them.
In Algiers, the Algerian capital, neighbourhoods were formally designed in the 1970s in a rigid modernist style. Design elements including shady trees, benches and lights at night made people feel comfortable carrying out activities such as playing cards or gathering to chat, but huge buildings, wide streets and large spaces also caused people to feel insecure and lost. Further, the land was landscaped in the kind of homogenous way characteristic of other big cities including Los Angeles, Auckland and Sydney. These large-scale and non-contextual designs have also been linked to antisocial behaviour.
After the area was transformed in 2013, there was a notable decline in the diversity of the activities people undertook there (family and religious gatherings; street art; music; informal vendors). Instead, the law now prioritises touristic activity over local people’s everyday needs and allows the authorities to operate a zero-tolerance approach towards anything deemed disruptive. Vendors have become nomadic, packing up and hiding as soon as the police are nearby.
In the Cheonggyecheon-Euljiro area of Seoul, South Korea, meanwhile, redevelopment led to 50-year-old workshops being torn down. This in turn has threatened the historical and cultural values of the local population and disrupted social networks.
How cities are co-created
In his 1968 book, The Right to the City, the French Marxist philosopher and sociologist Henri Lefebvre described the city as a co-created space. This contrasts with the more capitalist definition in which urban space is a commodity to be bought and sold, Lefebvre saw it as a meeting place where citizens collectively built urban life.
This idea that public space is a public good that belongs to everybody has been increasingly challenged in recent years, with the rise of privately owned public space. Most of the parks in London (roughly 42 kilometres squared) of green space in total) are owned by the City of London Corporation, the municipal body that governs the City of London, but increasingly squares within new developments are owned by corporations.
Urban theorists have long noted the connection between how a city is designed and how life is conducted within it. The US scholar Jane Jacobs is famous for highlighting that cities fail when they are not designed for everyone. And Danish architect Jan Gehl’s output has consistently focused on what he has termed the “life between buildings”.
As Gehl has explained, for a city to be good to its residents, those in charge of designing it have to be aware of how it is being used: what people are doing in its spaces. To be successful, urban designs have to be focused on and geared towards people’s daily lives. Gehl has explained that designing a city for pedestrians – at a walkable scale – is how you make it healthy, sustainable, lively and attractive.
Research has also highlighted how democratic this can be. But it is contingent on those spaces being designed in consort with residents. When a public space, by contrast, is overly designed without people’s needs being taken into account, it does not get used.
Abi Gazzard– PhD in Ecology and Conservation, University of Reading
When large patches of woodland are swallowed by urban sprawl or when households replace long grass with artificial turf or refurbish buildings to repair cracks and crevices, wildlife populations are robbed of potential places to rest, breed and hibernate. That’s why conservation groups urge homeowners, where possible, to create wildlife-friendly habitats on their own land.
One artificial refuge that has long adorned gardens is the bird box. It is estimated that there are 4.7 million of them in gardens across the UK. Some studies have reported that nest boxes (or bricks) can help birds to produce more chicks and boost their populations compared with birds nesting in areas without artificial refuges.
But whether and how animals actually use these refuges depends on their design, where they are placed and the conditions of the wider landscape. In the wrong setting – or with the wrong design – wildlife can suffer harm or an increased risk of being captured by predators.
Relatively little is known about what makes a house a home for species other than birds, or how effective artificial refuges are for conserving a species. Even so, garden centres and other retailers offer a wide variety, ranging from ceramic houses for toads to wood and concrete roosts for bats. Many of these are made and installed with mammals in mind.
One such mammal is the nocturnal, ground-dwelling hedgehog. Hedgehogs have undergone a long-term decline and are listed as vulnerable on Britain’s red list of mammals: some parts of the countryside may have seen numbers crash by up to 75% over the past 20 years. Where populations persist, hedgehogs often make use of residential gardens, and it is here where the public – by providing nest boxes (or “hedgehog houses”) – could play a significant role in their conservation.
In a new study, I found that you might be able to improve the chances of a hedgehog taking up residence in your garden nest box by, among other things, thinking carefully about where you position it and leaving out food and bedding material.
The hedgehog housing census
Charming images and videos of hedgehogs using nest boxes (both homemade and shop-bought) abound on social media. Yet very little is known about how best to choose, make or install these refuges. That’s partly because people are advised to avoid disturbing nesting hedgehogs.
To resolve this, researchers at the University of Reading (including myself) and specialists at the conservation campaign group Hedgehog Street launched the hedgehog housing census: an online questionnaire which gathered information on how nest boxes are used across the UK.
More than 5,000 surveys were returned. Using this data we examined how hedgehogs use boxes for different types of nesting. Hedgehogs typically build distinct nests for somewhere to rest during the day, somewhere to rear young and somewhere to hibernate over winter, and may move between more than one nest in each instance. For each type of nesting, we modelled how the use of a nest box appeared to have been influenced by its design and dimensions, plus features of the garden and environment.
For most seasons, the study showed that hedgehogs were more likely to have used a nest box where food – such as meaty pet food – and bedding were provided. Some gardeners left piles of dry leaves in a corner of the garden which hedgehogs could gather and drag into the box.
Hedgehogs were also more likely to use nest boxes where there was access between the front and back gardens, highlighting the importance of connections between habitats. This may be possible by cutting a hole in the bottom of a fence or leaving a gap beneath a gate to form a hedgehog highway. Additionally, the likelihood of a hedgehog inhabiting a box tended to increase when they were placed under shelter such as shrubs, or on hard surfaces such as patios, and with the entrances oriented away from wide open spaces.
The presence of dogs seemed only to have a negative effect during the vulnerable period of hibernation, which typically occurs between November and April. Surprisingly, badgers or foxes did not seem to deter hedgehogs from nesting in a box, though few people reported having seen either species in their garden. We also found that, during hibernation, nest boxes were more often used when the boxes were south-facing and within five metres of a building. This may be because these spots were warmer, and cosier nesting chambers help hibernating hedgehogs burn less energy. Too warm and hedgehogs could wake up more frequently, though. The optimum nest box temperature for hedgehogs – and the design features that might influence this – are not well understood.
The census also revealed where hedgehogs might prefer to make their own nests in gardens. Survey respondents reported evidence of 2,546 other nests used by hedgehogs in their gardens, including nests built under vegetation, such as long grass or shrubs, (46%), sheds (21%), woodpiles (15%), compost heaps (6%) and decking (6%).
Nest boxes – and gardens more broadly – provide important nesting habitats for the declining hedgehog. But there is still much we don’t know about how these artificial refuges compare to natural nests. This a field in which researchers must delve deeper, by untangling how nest box design affects occupancy and by trying to understand the consequences of using artificial refuges on hedgehog health, behaviour and abundance. For now, it’s clear that simple actions can improve the chances of a hedgehog using a nest box – a potentially critical part of nurturing the recovery of this species.
Joanne Bentley– Postdoctoral Researcher in Molecular Ecology, African Climate & Development Initiative, University of Cape Town Alex Pigot– Research Fellow, Genetics, Evolution & Environment Division of Biosciences, UCL Andreas L. S. Meyer– Postdoctoral Research Fellow in Ecology & Evolutionary Biology, University of Cape Town Christopher Trisos– Senior Research Fellow in Climate Change Risks, University of Cape Town
The history of climate change is one of people slowly coming to terms with the truth. None but a small minority still question whether it’s real and caused by humans. Now most grapple with the reality of trying to slow down catastrophic warming, and the difference between solutions and false hope. The concept of climate overshoot is the next thing we will need to get to grips with.
Unless urgent action is taken, emissions are expected to cause the planet to continue heating rapidly over the next few decades, prompting the global average temperature to overshoot the Paris agreement’s target, which aimed to limit warming to between 1.5°C and 2°C. A period of higher temperatures will occur in the middle of this century as a result. Then, the idea goes, new but yet unproven technologies and techniques for pulling greenhouse gases from the atmosphere will eventually bring temperatures back down to a safer level.
Until now, scientists were unsure what temporarily overshooting (and then boomeranging back below) the Paris agreement’s temperature target would entail for nature. So, for the first time, we studied the consequences of allowing Earth’s temperature to exceed these precautionary limits, then fall below them again, for marine and land-based life. In other words, we looked at how damaging the journey of overshooting the 2°C temperature target would be, and not just the destination itself.
The results suggest that a temporary overshoot would cause waves of irreversible extinctions and lasting damage to tens of thousands of species. This is what the world can expect if humanity fails to make deep emission cuts this decade, and relies instead on future technologies to remove emissions later.
Harm arrives fast and leaves slowly
Our study modelled the impact of global temperatures exceeding 2°C for around 60 years between 2040 and 2100 on over 30,000 species that live on land and in the sea. We looked at how many of them would be exposed to temperatures that could hinder their reproduction and survival, and how much time they would be exposed to this risk.
Harm would be fast to arrive and slow to disappear for nature, even after temperatures fall again. Just a few years of global temperatures above 2°C could transform the world’s most important ecosystems. Take the Amazon basin, for example. Some species would remain exposed to dangerous conditions long after the global average temperature stabilised – with some remaining exposed as late as 2300. This is because some species, especially those in the tropics, live closer to the limit of heat they can tolerate and so are sensitive to relatively small changes in temperature. And while global average temperatures may return to safer levels eventually, local temperature changes might lag behind.
The consequences of this exposure could be irreversible and include the tropical forest turning into savanna. The world would lose a critical global carbon sink, leaving more planet-warming gases in the atmosphere.
The Coral Triangle in the western Pacific Ocean is one of the most species-rich marine ecosystems and home to many reef-building corals, sea turtles, reef fish and mangrove forests. Our modelling showed that in some communities, all or most of the species would be exposed to dangerous conditions simultaneously for at least a few decades and as much as two centuries. As well as disrupting a source of food for millions of people, disappearing corals and mangroves would remove a natural barrier protecting coastal towns and villages from rising seas and worsening storms.
No way home
The consequences of overshooting 2°C for the survival of species have been neglected by policymakers. Our analysis indicates that it cannot be assumed that life will simply recover once temperatures fall below 2°C again. We found that 3,953 species will have their entire population exposed to temperatures outside the range they evolved in for more than 60 consecutive years. The Philippine porcupine will be exposed for 99 years, and the Mawa clawed frog for an astonishing 157 years. Surviving this length of exposure is a stern challenge for any species.
Relying on carbon dioxide removal and so-called negative emissions technologies to lower greenhouse gases in the atmosphere over several decades is too risky to contemplate. Some of this technology, like carbon capture and storage, hasn’t yet been shown to work at the scale needed. Other techniques have negative effects on nature, such as bioenergy, where trees or crops are grown and then burned to generate electricity. Rolling out vast plantations at the same time as temperatures overshoot the internationally agreed “safe” limit would leave species reeling from a hotter climate and shrinking natural habitat.
Delaying drastic cuts to emissions will mean the world overshooting 2°C is a best-case scenario. This overshoot would come at an astronomical cost to life on Earth that negative emission technologies will not reverse. The effort to stop temperatures rising isn’t an abstract attempt at bending curves on a graph: it’s a fight for a liveable planet.
Answer: the vehicles on our streets, primarily the not-so-humble passenger car.
Despite the (slow) migration to electric-powered cars, consumer trends are making driving even more wasteful and unequal. A recent analysis found the emissions saved from electric cars have been more than cancelled out by the increase in gas-guzzling Sport Utility Vehicles (SUVs). Around the world, SUVs alone emit more carbon pollution than Canada or Germany, and are causing a bigger increase in climate pollution than heavy industry.
While cars are sometimes necessary for people’s mobility and social inclusion needs – not least those with disabilities – car-centric cities particularly disadvantage the already-marginalised. In the UK, women, young and older people, those from minority communities and disabled people are concentrated in the lowest-income households, of which 40% do not have a car. In contrast, nearly 90% of the highest-income households own at least one car.
So the driving habits of a minority impose high costs on society, and this is especially true in cities. Copenhagen, for example, has calculated that whereas each kilometre cycled benefits society to the tune of €0.64 (53 pence), each kilometre driven incurs a net loss of -€0.71 (-59p), when impacts on individual wellbeing (physical and mental health, accidents, traffic) and the environment (climate, air and noise pollution) are accounted for. So each kilometre travelled where a car is replaced by a bicycle generates €1.35 (£1.12) of social benefits – of which only a few cents would be saved by switching from a fossil-fuelled to an electric-powered car, according to this analysis.
Reducing car use in cities
Half a century ago, the Danish capital was dominated by cars. But following grassroots campaigns to change policies and streets, including replacing car parking with safe, separated bike lanes, Copenhagen has increased its biking share of all trips from 10% in 1970 to 35% today. In 2016, for the first time, more bicycles than cars made journeys around the city over the course of that year.
But while many other car-limiting initiatives have been attempted around the world, city officials, planners and citizens still do not have a clear, evidence-based way to reduce car use in cities. Our latest research, carried out with Paula Kuss at the Lund University Centre for Sustainability Studies and published in Case Studies on Transport Policy, seeks to address this by quantifying the effectiveness of different initiatives to reduce urban car use.
Our study ranks the 12 most effective measures that European cities have introduced in recent decades, based on real-world data on innovations ranging from the “carrot” of bike and walk-to-work schemes to the “stick” of removing free parking. The ranking reflects cities’ successes not only in terms of measurable reductions in car use, but in achieving improved quality of life and sustainable mobility for their residents.
In all, we have screened nearly 800 peer-reviewed reports and case studies from throughout Europe, published since 2010, seeking those that quantified where and how cities had successfully reduced car use. The most effective measures, according to our review, are introducing a congestion charge, which reduces urban car levels by anywhere from 12% to 33%, and creating car-free streets and separated bike lanes, which has been found to lower car use in city centres by up to 20%. Our full ranking of the top 12 car-reducing measures is summarised in this table: https://datawrapper.dwcdn.net/NDMp4/12/
The inequality of car use
Cars are inherently inefficient and inequitable in their use of land and resources. On average, they spend 96% of their time parked, taking up valuable urban space that could be put to more beneficial uses such as housing and public parks. In Berlin, car users on average take up 3.5 times more public space than non-car users, primarily through on-street parking.
And it is overwhelmingly richer people who drive the most: in Europe, the top 1% by income drive nearly four times more than the median driver, accounting for some 21% of their personal climate footprint. For these highest emitters, climate pollution from driving is second only to flying (which, on average, generates twice as many emissions).
Prioritising cars as a means of transport also favours suburban sprawl. City suburbs typically possess larger homes that generate higher levels of consumption and energy use. North American suburban households consistently have higher carbon footprints than urban ones: one study in Toronto found suburban footprints were twice as high.
Electric vehicles are necessary, but they’re not a panacea. Since cars tend to be on the road for a long time, the migration to electric vehicles is very slow. Some studies anticipate relatively small emissions reductions over the coming decade as a result of electric vehicle uptake. And even if there’s nothing damaging released from an electric car’s exhaust pipe, the wear of car brakes and tyres still creates toxic dust and microplastic pollution. However a car is powered, can it ever be an efficient use of resources and space to spend up to 95% of that energy moving the weight of the vehicle itself, rather than its passengers and goods?
COVID-19: a missed opportunity?
Our study assesses urban mobility innovations and experiments introduced before the pandemic was declared. In response to COVID-19, travel habits (to begin with, at least) changed dramatically. But following large reductions in driving during the spring of 2020, road use and the associated levels of climate pollution have since rebounded to near pre-pandemic levels. Indeed, in Sweden, while public transport use declined by around 42% during the first year of the pandemic, car travel declined by only 7% in the same period, leading to an overall increase in the proportion of car use.
While entrenched habits such as car commuting are hard to shift, times of disruption can offer an effective moment to change mobility behaviour – in part because people forced to try a new habit may discover it has unexpected advantages. For such behaviour to stick, however, also requires changes in the physical infrastructure of cities. Unfortunately, while European cities that added pop-up bike lanes during the pandemic increased cycling rates by a stunning 11-48%, we are now seeing a return to car-centric cities, with extra car lanes and parking spaces once again displacing cycle lanes and space for pedestrians.
Overall, the opportunities to align pandemic recovery measures with climate targets have largely been squandered. Less than 20% of government spending on pandemic measures globally were likely to also reduce greenhouse gas emissions.
The extent to which workers resume driving to their offices is another key issue determining future car use in cities. Thoughtful travel policies to reduce unnecessary travel, and opportunities for faraway participants to fully participate in meetings and conferences digitally, could slash emissions by up to 94% – and save time to boot. Those who work remotely three or more days per week travel less overall than their peers. But long car commutes can quickly wipe out such emissions savings, so living close to work is still the best option.
No silver bullet solution
The research is clear: to improve health outcomes, meet climate targets and create more liveable cities, reducing car use should be an urgent priority. Yet many governments in the US and Europe continue to heavily subsidise driving through a combination of incentives such as subsidies for fossil fuel production, tax allowances for commuting by car, and incentives for company cars that promote driving over other means of transport. Essentially, such measures pay polluters while imposing the social costs on wider society.
City leaders have a wider range of policy instruments at their disposal than some might realise – from economic instruments such as charges and subsidies, to behavioural ones like providing feedback comparing individuals’ travel decisions with their peers’. Our study found that more than 75% of the urban innovations that have successfully reduced car use were led by a local city government – and in particular, those that have proved most effective, such as congestion charges, parking and traffic controls, and limited traffic zones.
But an important insight from our study is that narrow policies don’t seem to be as effective – there is no “silver bullet” solution. The most successful cities typically combine a few different policy instruments, including both carrots that encourage more sustainable travel choices, and sticks that charge for, or restrict, driving and parking.
So here are the 12 best ways to reduce city car use:
1. Congestion charges
The most effective measure identified by our research entails drivers paying to enter the city centre, with the revenues generated going towards alternative means of sustainable transport. London, an early pioneer of this strategy, has reduced city centre traffic by a whopping 33% since the charge’s introduction by the city’s first elected mayor, Ken Livingstone, in February 2003. The fixed-charge fee (with exemptions for certain groups and vehicles) has been raised over time, from an initial £5 per day up to £15 since June 2020. Importantly, 80% of the revenues raised are used for public transport investments.
Other European cities have followed suit, adopting similar schemes after referenda in Milan, Stockholm and Gothenburg – with the Swedish cities varying their pricing by day and time. But despite congestion charges clearly leading to a significant and sustained reduction of car use and traffic volume, they cannot by themselves entirely eliminate the problem of congestion, which persists while the incentives and infrastructure favouring car use remain.
2. Parking and traffic controls
In a number of European cities, regulations to remove parking spaces and alter traffic routes – in many cases, replacing the space formerly dedicated to cars with car-free streets, bike lanes and walkways – has proved highly successful. For example, Oslo’s replacement of parking spaces with walkable car-free streets and bike lanes was found to have reduced car usage in the centre of the Norwegian capital by up to 19%.
3. Limited traffic zones
Rome, traditionally one of Europe’s most congested cities, has shifted the balance towards greater use of public transport by restricting car entry to its centre at certain times of day to residents only, plus those who pay an annual fee. This policy has reduced car traffic in the Italian capital by 20% during the restricted hours, and 10% even during unrestricted hours when all cars can visit the centre. The violation fines are used to finance Rome’s public transport system.
4. Mobility services for commuters
The most effective carrot-only measure identified by our review is a campaign to provide mobility services for commuters in the Dutch city of Utrecht. Local government and private companies collaborated to provide free public transport passes to employees, combined with a private shuttle bus to connect transit stops with workplaces. This programme, promoted through a marketing and communication plan, was found to have achieved a 37% reduction in the share of commuters travelling into the city centre by car.
5. Workplace parking charges
Another effective means of reducing the number of car commuters is to introduce workplace parking charges. For example, a large medical centre in the Dutch port city of Rotterdam achieved a 20-25% reduction in employee car commutes through a scheme that charged employees to park outside their offices, while also offering them the chance to “cash out” their parking spaces and use public transport instead. This scheme was found to be around three times more effective than a more extensive programme in the UK city of Nottingham, which applied a workplace parking charge to all major city employers possessing more than ten parking spaces. The revenue raised went towards supporting the Midlands city’s public transport network, including expansion of a tram line.
6. Workplace travel planning
Programmes providing company-wide travel strategies and advice to encourage employees to end their car commutes have been widely used in cities across Europe. A major study, published in 2010, assessing 20 cities across the UK found an average of 18% of commuters switched from car to another mode after a full range of measures were combined – including company shuttle buses, discounts for public transport and improved bike infrastructure – as well as reduced parking provision. In a different programme, Norwich achieved near-identical rates by adopting a comprehensive plan but without the discounts for public transport. These carrot-and-stick efforts appear to have been more effective than Brighton & Hove’s carrot-only approach of providing plans and infrastructure such as workplace bicycle storage, which saw a 3% shift away from car use.
7. University travel planning
Similarly, university travel programmes often combine the carrot of promotion of public transport and active travel with the stick of parking management on campus. The most successful example highlighted in our review was achieved by the University of Bristol, which reduced car use among its staff by 27% while providing them with improved bike infrastructure and public transport discounts. A more ambitious programme in the Spanish city of San Sebastián targeted both staff and students at Universidad del País Vasco. Although it achieved a more modest reduction rate of 7.2%, the absolute reduction in car use was still substantial from the entire population of university commuters.
8. Mobility services for universities
The Sicilian city of Catania used a carrot-only approach for its students. By offering them a free public transport pass and providing shuttle connections to campus, the city was found to have achieved a 24% decrease in the share of students commuting by car.
9. Car sharing
Perhaps surprisingly, car sharing turns out to be a somewhat divisive measure for reducing car use in cities, according to our analysis. Such schemes, where members can easily rent a nearby vehicle for a few hours, have showed promising results in Bremen, Germany and Genoa, Italy, with each shared car replacing between 12 and 15 private vehicles, on average. Their approach included increasing the number of shared cars and stations, and integrating them with residential areas, public transport and bike infrastructure.
Both schemes also provided car sharing for employees and ran awareness-raising campaigns. But other studies point to a risk that car sharing may, in fact, induce previously car-free residents to increase their car use. We therefore recommend more research into how to design car sharing programmes that truly reduce overall car use.
10. School travel planning
Two English cities, Brighton & Hove and Norwich, have used (and assessed) the carrot-only measure of school travel planning: providing trip advice, planning and even events for students and parents to encourage them to walk, bike or carpool to school, along with providing improved bike infrastructure in their cities. Norwich found it was able to reduce the share of car use for school trips by 10.9%, using this approach, while Brighton’s analysis found the impact was about half that much.
11. Personalised travel plans
Many cities have experimented with personal travel analysis and plans for individual residents, including Marseille in France, Munich in Germany, Maastricht in the Netherlands and San Sebastián in Spain. These programmes – providing journey advice and planning for city residents to walk, bike or use (sometimes discounted) public transport – are found to have achieved modest-sounding reductions of 6-12%. However, since they encompass all residents of a city, as opposed to smaller populations of, say, commuters to school or the workplace, these approaches can still play a valuable role in reducing car use overall. (San Sebastián introduced both university and personalised travel planning in parallel, which is likely to have reduced car use further than either in isolation.)
12. Apps for sustainable mobility
Mobile phone technology has a growing role in strategies to reduce car use. The Italian city of Bologna, for example, developed an app for people and teams of employees from participating companies to track their mobility. Participants competed to gain points for walking, biking and using public transport, with local businesses offering these app users rewards for achieving points goals.
There is great interest in such gamification of sustainable mobility – and at first glance, the data from the Bologna app looks striking. An impressive 73% of users reported using their car “less”. But unlike other studies which measure the number or distance of car trips, it is not possible to calculate the reduction of distance travelled or emissions from this data, so the overall effectiveness is unclear. For example, skipping one short car trip and skipping a year of long driving commutes both count as driving “less”.
While mobility data from apps can offer valuable tools for improved transport planning and services, good design is needed to ensure that “smart” solutions actually decrease emissions and promote sustainable transport, because the current evidence is mixed. For instance, a 2021 study found that after a ride-hailing service such as Uber or Lyft enters an urban market, vehicle ownership increases – particularly in already car-dependent cities – and public transport use declines in high-income areas.
Cities need to re-imagine themselves
Reducing car dependency is not just a nice idea. It is essential for the survival of people and places around the world, which the recent IPCC report on climate impacts makes clear hinges on how close to 1.5°C the world can limit global warming. Avoiding irreversible harm and meeting their Paris Agreement obligations requires industrialised nations such as the UK and Sweden to reduce their emissions by 10-12% per year – about 1% every month.
Yet until the pandemic struck, transport emissions in Europe were steadily increasing. Indeed, current policies are predicted to deliver transport emissions in 2040 that are almost unchanged from 50 years earlier.
To meet the planet’s health and climate goals, city governments need to make the necessary transitions for sustainable mobility by, first, avoiding the need for mobility (see Paris’s 15-minute city); second, shifting remaining mobility needs from cars to active and public transport wherever possible; and finally, improving the cars that remain to be zero-emission.
This transition must be fast and fair: city leaders and civil society need to engage citizens to build political legitimacy and momentum for these changes. Without widespread public buy-in to reduce cars, the EU’s commitment to deliver 100 climate-neutral cities in Europe by 2030 looks a remote prospect.
Radically reducing cars will make cities better places to live – and it can be done. A 2020 study demonstrated that we can provide decent living standards for the planet’s projected 10 billion people using 60% less energy than today. But to do so, wealthy countries need to build three times as much public transport infrastructure as they currently possess, and each person should limit their annual travel to between 5,000 kilometres (in dense cities) and 15,000 kilometres (in more remote areas).
The positive impact from reducing cars in cities will be felt by all who live and work in them, in the form of more convivial spaces. As a journalist visiting the newly car-free Belgian city of Ghent put it in 2020:
The air tastes better … People turn their streets into sitting rooms and extra gardens.
Cities need to re-imagine themselves by remaking what is possible to match what is necessary. At the heart of this, guided by better evidence of what works, they must do more to break free from cars.
David Williams– Lecturer in Sustainability and the Environment, University of Leeds
The world’s governments will this year negotiate a series of targets in response to the global biodiversity crisis that has already led to a massive loss of the planet’s wildlife. While none of the previous round of targets agreed in 2010 have been met, the one that gained the most publicity, and arguably the one we got closest to achieving was target 11. Its aim was that:
By 2020, at least 17% of terrestrial and inland water areas and 10% of coastal and marine areas … are conserved through effectively and equitably managed, ecologically representative and well-connected systems of protected areas.
These “protected areas” can range from enormous, strictly-protected areas like US national parks, through the heavily-used landscapes of UK national parks, to tiny urban nature reserves. Protected areas can stop or slow many of the forces threatening biodiversity such as habitat loss, hunting and pollution, and have been a mainstay of global conservation for decades.
By August 2020, some 15% of the world’s land had been protected. This was below the target, but there were enough specific commitments in place to drag the world over the line slightly late. In many ways this is an incredible achievement and perhaps the largest and fastest coordinated change in land management ever.
But the devil is in the detail. For protected areas to be effective they need to be in the right place, and big enough to keep populations of wild species alive. Hundreds of tiny reserves separated by inhospitable farmland may help us reach the 17% target, but they won’t stop extinctions. So, how does our current network stack up? Is it enough to stop species going extinct?
Most animals are underprotected
Colleagues and I recently tackled this question in a study now published in the journal PNAS.
We looked at 3,834 species of terrestrial mammals (all those with available data) and estimated how large a population every protected area in the world could theoretically support (technically, we also grouped adjacent protected areas, as animals can move between them). Understanding how many individuals could survive in each area is vital because small populations just don’t last very long: below a certain size they are much more vulnerable to being wiped out by disease, inbreeding, fires, poaching, or even just falling victim to natural fluctuations in numbers.
To do this, we combined global databases on where animal species live and where the world’s protected areas are located, with site and location specific estimates of population density (how many rhinos – or shrews – do you get per square kilometre).
Worryingly, we found that thousands of species do not appear to be adequately protected. Depending on the exact criteria used, we estimated that at least 1,536 species (40% of those we looked at), and maybe as many as 2,156 (56%) had ten or fewer protected populations that were likely to survive in the long run.
These under-protected species were found across all continents, across all species groups we looked at, and included some of the world’s smallest mammals, as well as some of the largest. Perhaps most concerning, 91% of the world’s threatened mammals – many of which are already the focus of conservation efforts – were under-protected, and hundreds of these species appear to have no viable protected populations at all. These species are at serious risk of population declines or extinctions as habitat outside protected areas comes under increasing pressure.
What is more, these numbers represent a best-case scenario. In reality, protected areas are only effective if they are well-managed, and most simply don’t have the resources.
Our work suggests that what matters is not the total percentage of the world that is protected, but whether protection is in the right places and whether protected areas are large enough, or well enough connected to other areas, to support populations that will survive in the long term. If not, then they are just delaying the inevitable, and species will continue to be lost from them, whether or not targets have been met.
Expanding or relocating the world’s protected areas comes fraught with very real risks to human wellbeing. These areas are based on stopping people from doing things: from chopping down trees, from hunting certain species, from mining, or from farming.
This is what makes them so valuable to biodiversity, but imposes a huge cost on the local population. Many protected areas have a history of colonialism, forced removals, and the impoverishment or disenfranchisement of local and particularly indigenous people. Any future expansion has to be fair to these people.
Expansion is also only going to be possible if we reduce human demand for land. Protected areas are going to be ever more important as growing human consumption puts unprotected land under increasing pressure.
But they are like treating the symptom of a disease, and we also have to treat the root cause. Without rapid shifts towards healthier, plant-rich diets, reductions in food waste, and sustainable yield increases, there simply won’t be enough spare land to protect.
The world’s biodiversity is in serious trouble, and our current system of protected areas appears unlikely to save it. To prevent a wave of extinctions in coming decades, we need to greatly reduce humanity’s global footprint and to couple this with protected areas that are well managed, well located and large enough.