COP15: three visions for protecting nature on the table at the UN biodiversity conference

Harriet Bulkeley– Professor of Geography, Durham University

Kurit Afshen/Shutterstock

With the dust still settling on the UN climate change summit in Egypt, another round of international talks is beginning in Montreal, Canada. The UN biodiversity conference, otherwise known as COP15, will assemble world leaders to agree on new targets for protecting nature.

The loss of biodiversity – the dizzying variety of life forms from microscopic viruses, bacteria and fungi to towering trees and enormous whales – is accelerating. The last agreement in 2010 yielded the 20 Aichi targets which included halving the rate at which species were being lost and expanding protected habitats on land and in the sea by 2020. Governments failed to meet a single one.

global assessment in 2019 showed that nature was declining globally at rates unprecedented in human history. The forces driving more and more species towards extinction – climate change, habitat destruction and pollution – are all trending in the wrong direction. Nothing less than a transformation of how societies work and the relationship between people and the rest of nature will get us on track.

Read more: ‘Revolutionary change’ needed to stop unprecedented global extinction crisis

After two years of delay due to the pandemic and difficulties negotiating a new venue with the country that holds the conference presidency, China, many are relieved that COP15 is happening at all. That relief may prove short-lived as there is much to be done in these two short weeks. The grand objective is the approval of a new global biodiversity framework, essentially a plan for how the world’s nations expect to halt the loss of biodiversity and ensure that, by 2050, society is living in harmony with nature.

Bare ground strewn with branches and tree stumps with tropical forest in the distance.
Deforestation in the Brazilian Amazon broke records in the first half of 2022. Paralaxis/Shutterstock

30% by 2030

One debate which has dominated discussions so far is how much land and sea should be set aside for conservation. The current text aims for 30% by 2030. Some scientists believe this is insufficient, and that preserving half the Earth for nature is necessary. Others are wary of reviving failed ideas which have tried to boost wildlife by expelling people and erecting walls to keep them out.

Negotiators will debate whether a 30×30 target should be met at the national level or globally. The former would mean each country meeting this standard within its own borders. The latter would prioritise Earth’s most important areas of biodiversity (such as tropical rainforests) but oblige countries with large remaining wildernesses (overwhelmingly in developing countries) to shoulder the lion’s share of conservation work. Many poorer countries foresee this stopping their economic development.

There is also disagreement over what level of protection should be given to these areas and how the rights of people living within them should be recognised. These plans would require a doubling of protected areas on land and perhaps as much as a tenfold increase in the oceans. But they could exclude indigenous people and those who make their living from cultivation, forestry and fishing.

Two rangers look out over a lake in a sandy plain.
Protected areas can have insidious consequences. EPA-EFE/Paolo Pena/Peru Mineria

Less emissions, less meat, less waste

Instead of concentrating on the total area reserved for nature, recent research highlights the importance of addressing the underlying causes of extinctions and habitat loss, such as greenhouse gas emissions, meat consumption and plastic pollution.

Targeting the processes driving biodiversity loss would shift attention away from where nature is being destroyed to the places where these processes are guided and sustained: boardrooms, trading floors, local planning offices and supermarkets.

The framework under negotiation includes several targets that would restrain the destruction, from eliminating policies subsidising the conversion of forest to cow pasture to halving food waste. These have failed to attract the momentum behind flashier goals like the 30×30 target. Changing how economies and societies function is more contentious and asks more from rich countries with more influence over the drivers of biodiversity loss.

Safeguard nature’s services

Yet another approach would safeguard the services nature generates, including flood protection, wood fuel, climate regulation and food provision. And it would identify the natural assets (wetlands, forests, coral reefs and mangroves to name a few) that must endure for these services to continue. This would mean protecting nature close to where it is most needed. A staggering 6.1 billion people live within one hour of such assets.

Good COP or bad COP?

While everyone gathering in Montreal agrees that a breakthrough is needed, there are different ideas about what that should look like. For many seasoned conservationists, a good outcome will mean more stringent targets for protecting and restoring nature and more expansive protected areas, plus the money and other resources necessary to enforce them.

Businesses, investors, cities, regional governments and the communities they represent want an agreement that mobilises the whole of society. Some companies have asked that all businesses be forced to report the impacts their activities have on nature. Cities and regions have their own pledges and have asked COP15 to formally recognise their role in delivering national plans.

A coral reef with an island visible above the ocean surface.
Coral reefs offer food and protection from storms in the tropics. Ethan Daniels/Alamy Stock Photo

This could bring the protection and restoration of nature into mainstream thinking around how economies develop and societies are organised, and make the case that much of what is important about nature is not to be found on the other side of a fence. This trend is evident in growing enthusiasm around nature-based solutions to climate change.

The recent UN climate summit in Egypt heralded the potential of such solutions, which include restoring peatlands and seagrass beds. These actions tackle the climate and biodiversity crisis together by expanding refuge for wildlife and drawing carbon from the air. Cities, businesses and investors smell an opportunity to meet multiple measures of sustainable development at once.

Some conservationists worry these supposed solutions are greenwashing and allow companies to exploit indigenous people and communities. Other experts argue that, with the right safeguards in place, these fears can be put to rest.

With much at stake, in seeking to straddle different agendas, COP15 risks achieving none.


We found Britain’s greenest city centre – and its least green

Jake M Robinson– Ecologist and Researcher, Flinders University

Paul Brindley– Senior Lecturer, Department of Landscape Architecture, University of Sheffield

Meet the winner: Exeter. Panoptic Motion / shutterstock

Some of Britain’s city centres are filled with trees and parks, while others have little vegetation to break up the bricks, tarmac and concrete. Such differences aren’t just aesthetic: they affect whether animals can move around, and they have implications for human health and social equity.

That’s why we wanted to properly assess how green these cities are. In our latest research, now published in the open-access journal PLOS ONE, we looked at all 68 municipalities in Great Britain with populations of at least 100,000. City centres were defined using Consumer Data Research Centre spatial datasets, which use complex statistics to demarcate retail boundaries. You can think of the boundaries as similar to “central business districts”. In Sheffield, for instance, the city centre is the entire area within the central ring road. London is a special case; because it is so large, it has several of these areas.

satellite map of a city
Sheffield has plenty of green space – but not within the city centre ring road. Google EarthCC BY-SA

For each of these cities, we assessed three metrics of “greenness”: 1) tree cover using an algorithm to randomly sample recent aerial imagery, 2) the presence of green spaces using open-source data from Ordnance Survey (Great Britain’s national mapping agency), and 3) the normalised difference vegetation index (NDVI), which uses satellite observations of light absorption and reflection to measure vegetation cover in a given area.

Exeter greenest, Glasgow least green

Combining all three metrics into a single greenness score, we found that Exeter’s urban centre ranks highest, followed by Islington in London, Bristol, Bournemouth and Cambridge.

Glasgow’s urban centre is the least green, with Middlesbrough, Sheffield, Liverpool and Leeds also in the lowest five. Tree coverage is probably the most relatable way to describe the differences: trees cover 12% of the total land area of Exeter city centre, but just 2% of Glasgow’s.

City centre buildings, grey sky
Greenless Glasgow. leppäkerttu/pixabayCC BY-SA

Exeter, a small city in England’s remote south-west, largely avoided the rapid industrial growth of better-connected cities. This is apparent today in its leafy streets and the meadows along the River Exe. In contrast, places like Glasgow and Sheffield were massive industrial powerhouses with considerable urban sprawl, though they do still have luscious parks outside of their city centres.

North-south green divide

It is worth noting that the top five urban centres are all in the south of England, while the bottom five are ex-industrial areas in the north or Scotland. In fact, only 25% of all northern cities are in the top half of the greenness table. Further analysis uncovered a statistical link between a lower greenness score and higher levels of deprivation, as measured according to crime risk, health, economics, education, and other related metrics. In addition, areas with larger populations had lower tree coverage and vegetation index scores.

City greenness infographic
The top and bottom five. Anne-Lise Paris / PLOS, Author provided

Sheffield – where the study was conducted – is often billed as having one of the highest densities of trees out of all European cities. But this is due to the vast swathes of trees in the suburban areas and surrounding fringe of the Peak District national park. Our work shows that Sheffield actually has the lowest city centre tree cover out of all the cities included in the study.

The reasons for the north-side divide are complex and can depend on decisions made centuries ago and development since. Clearly, some urban centres invested in parks and tree-lined avenues more than others in the past. Industry and war efforts then contributed to urban sprawl and reduced natural features in certain urban centres, particularly in northern England and Scotland.

In the 19th century, city planners often incorporated street trees, particularly in affluent areas. These decisions were influenced by an admiration of continental European boulevards and the wellbeing benefits of “garden cities” and “spa towns”. This is exemplified by the “luxury effect” whereby affluent neighbourhoods record higher biodiversity in cities around the world, often dictated by structural classism and racism.

Differences in historical development have therefore left us with leafy urban centres like Exeter’s, and others with far less greenness. The question remains why over time such imbalances have not been addressed.

It’s an important question as around 70% of the world’s population will soon live in urban environments. In the UK, 84% of people already do. This rapid rise in urbanisation has led to a disconnect between humans and nature as we often fail to create healthy and biodiverse spaces, especially in city centres.

But there is at least one reason to be hopeful. Urban centres in Great Britain and other areas of the world are changing, especially as digital shopping means many retail outlets are closing. This is a problem in many ways, but it’s also an opportunity. The decline of in-person shopping gives us a chance to re-envision and redevelop urban centres to enhance their green spaces.


Cohousing is empowering people to fight back against a global housing crisis

Johannes Novy– Senior Lecturer in Urban Planning, School of Architecture and Cities, University of Westminster

Cohousing developments provide ample outdoor space for children to play in. Gary Calton | Alamy

The debate around how to fix the global housing crisis usually hinges on whether more market or more state is required. Some people stress the need for additional housing stock and less regulatory red tape, so that the market can create it. Others claim that stricter government measures – against ruthless developers and landlords, more rent control, and more public housing – are crucial.

Increasingly, policymakers are paying attention to what lies between the public and private sectors. The United Nations’ New Urban Agenda – a key international policy framework to promote sustainable urban development – highlights the benefits of “cooperative solutions, such as cohousing, community land trusts and other forms of collective tenure”. A slew of recent community-led housing projects across Europe and beyond show how this can work.

Cohousing includes all kings of edifices, new and existing. It is not tied to a particular type of tenure. And the groups of people it involves can vary considerably in size. At its heart are two key principles. Residents do not only live next to each other, but with each other, in buildings that comprise communal spaces and facilities. And they take the lead, or at least are involved in, the design and management of their communities.

Communal life

German sociologist Anja Szypulski has lauded the “abundant potential” cohousing proffers for sustainable housing and neighbourhood development. The first way it does this is by promoting an ethos of participation and sharing.

Residents are involved throughout the building process. When, in the wake of the 2008 financial crash, a developer pulled out of a state-owned site in Cambridge, the city council opted for a cohousing initiative to build on the land instead, precisely because of the social and community benefits that would bring.

The resulting Marmalade Lane project opened in 2018 after four years, during which the cohousing members developed the architectural brief, sought planning permission and contracted builders.

Residents also often take part in actually building their homes too. The Church Grove project in Lewisham, south London, is a community-led housing development on a old derelict school and industrial site. When completed it will count 36 homes designed to be permanently affordable. To keep the costs low, future residents are involved in this construction process. They have already built a communal hall on the site.

Communality also shapes daily life in a cohousing project. Marmalade Lane residents share 42 homes – houses and flats, both – organised around a common house with a shared kitchen, refectory and fireplace, a pedestrianised lane, outdoor play area and garden, a laundry, a gym and a workshop.

Similarly, La Borda, in Barcelona, is a cooperative housing block comprising 28 apartments, organised around a communal, open-plan atrium. Residents share a kitchen-dining area, a laundry room, guest rooms and generous outdoor spaces. Their flats were deliberately designed small, with movable walls, so that a room belonging to one flat could become part of another, as the need arose.

A building facade with columns, large windows and bikes out front.
The facade of the La Borda cohousing development in Barcelona. VELKEJ LED | WikimediaCC BY-SA

Socially and architecturally sustainable

The La Borda project contributes to the wider community, too, by organising events and sourcing goods from local cooperatives. It is based on a participatory planning process and costs have been kept low through the use of smart low-tech solutions and a lot of self-help during construction by its future users, who are also responsible for the maintenance and management of the project. Decisions are made collectively in a general assembly and all adults participate in various committees that deal with different issues, from financial matters to communal dinners

While the idea of committee meetings and doors facing each other won’t appeal to everyone, the benefits of knowing you’re not alone are clear. Residents at Marmalade Lane have spoken about children playing together, stay-at-home mothers not feeling isolated and retirees being engaged and occupied.

The UK Cohousing network describes cohousing as a “way of resolving the isolation many people experience today, recreating the neighbourly support of the past”. And research bears this out. A recent study on the way cohousing dwellers in the UK coped with lockdown found that many residents experienced a level of mutual support and care that went well beyond the general good neighbourliness of the early days of the pandemic.

Cohousing projects also encourage sustainability by typically being built for the long term. The Marmalade Lane buildings used environmentally-friendly materials and designs that promote low-energy use for a small carbon footprint.


Seasonal depression: small things you can do every day to cope

Jolanta Burke– Senior Lecturer, Centre for Positive Psychology and Health, RCSI University of Medicine and Health Sciences Annie Curtis– Senior Lecturer, School of Pharmacy and Biomolecular Sciences (PBS), RCSI University of Medicine and Health Sciences

Daylight is important, so try to get outside for a walk in the morning and afternoon. Dasha Petrenko/ Shutterstock

Many of us tend to feel sad or not like our usual self as autumn and winter approach. But for some, these feelings persist until spring arrives.

Known as seasonal affective disorder (or Sad), it’s a type of depression that occurs only during specific seasons. Alongside persistent low mood, some people may find they feel more lethargic than usual, have difficulty getting up in the morning and crave more carbs than normal.

If you’re someone who has Sad (or think you might), here are a few things you can do to improve your mood during the colder months.

What to do every day

Since Sad happens during seasons when the days are shorter and we get less sunlight, it’s thought to be caused by a disruption of our body clocks (also known as circadian-rhythm disturbance). We all have a “master clock” in the brain that uses daylight to control all of our body’s processes – from hunger to when we feel ready for bed.

Circadian rhythm disturbance has been linked to sleep disturbances, changes in mood and our eating patterns and metabolism, all of which are affected by Sad.

This is why getting outside and into natural daylight can be so important for people who have Sad.

In the morning, aim to get outside for at least a few minutes. Since light sends direct signals to your master body clock to tell it it’s time to wake up, morning light will help you feel more alert throughout the day. It may also help you fall asleep earlier in the evening.

At lunch, try again to get outside and get more natural light exposure. But if you can’t get outside or it’s overcast, you may want to try bright-light therapy. This exposes people to bright fluorescent light using a special lamp or mask. Research shows that 30 minutes of bright light therapy daily can help reduce symptoms of Sad.

A woman uses a fluorescent lightbox in her home to help treat her seasonal depression.
Light therapy may help on days that are overcast. Image Point Fr/ Shutterstock

If you find it difficult to convince yourself to get away from your desk at lunchtime, try to organise some activities to do that may help you get outside. For example, try to organise a daily lunchtime group walk with your colleagues or neighbours. Alongside getting you out into the daylight, exercising in a group can also boost positive emotions and connectedness, which is good for wellbeing and mental health.

Another activity you could try during your lunchtime walk is the “three good things in nature” task. The aim of this activity is to boost mindfulness and appreciation of nature by taking note of at least three things from the natural environment while you’re on your daily walk. Not only will this get you outside, it may also help improve your mood and wellbeing.

In the evenings, aim to set aside time to do things you enjoy. This may help to improve your mood and may ease some symptoms of Sad.

Other things you can do during winter months to improve your mood include:

Practise humour
Introducing more humour into your life may help balance out your negative emotions and could even improve sleep quality, mood and reduce symptoms of depression.

In the evening, take ten minutes to think of some funny things that happened during the day. Or think of a challenging situation you faced and instead try to think about how you’d deal with it in a funny way in the future. Making the time to watch something funny on TV three or four times a week may also help to boost your mood.

Find a hobby
Start a new hobby or pick up one you haven’t practised for a while. Engaging in a hobby will keep your mind less idle and more engaged, leaving you with less time to ruminate, if that’s something you tend to do. Perhaps try learning to knit. This is associated with increased mindfulness, calmness and a boost of positive emotions. Mastering new recipes may also be a great way of boosting wellbeing.

It doesn’t matter what hobby you choose, as long as it stretches your skills and helps you get into a state of flow. This is the feeling of “losing yourself” in what you’re doing and is a major component in experiencing subjective happiness. You might not feel better while you are doing your hobby (as it requires concentration), but as soon as you complete your task, you will experience a sense of accomplishment and a boost of positive emotions.

Keep your body clock in rhythm
Since Sad is thought to be caused by circadian-rhythm disturbance, keeping your circadian rhythm in time may help to reduce symptoms of Sad.

Sleep plays a big role in keeping your body clock in check. So in the evenings, try to avoid too much bright light as this will delay your sleep. You should also try to keep similar times for going to sleep and waking up both during the week and on weekends. Alongside proper sleep, eating your meals at regular times may also help to keep your body clock in time.

While it may be normal to feel a dip in your mood after the clocks first change, if you’re finding that symptoms are lingering for many weeks or are having a big effect on your life, you may want to speak to your doctor. In the meantime, remember that even just a few small changes every day may help keep Sad symptoms at bay.


Coastal erosion is unstoppable – so how do we live with it?

Sophie A. Day– Senior Research Associate in Environmental Sciences, University of East Anglia Robert James Nicholls– Professor of Climate Adaptation, University of East Anglia

Sophie Day, Author provided

A record storm surge in 1953 devastated much of eastern England’s coast, prompting prolific investment in concrete sea walls, wooden groynes and other engineered structures designed to protect the coastline from erosion. These measures brought a reassuring sense of permanence for people in previously risky locations. Houses atop sandy cliffs and tucked behind or among sand dunes went from being holiday homes to permanent residences, and new homes were built nearby.

But decades later, the east coast and other parts of England are still eroding – rapidly in some places – despite efforts to hold the coastline in place.

England has some of the fastest eroding coastline in Europe, particularly along the Norfolk and Yorkshire coasts. Historical records show that England’s soft and sandy east coast has always been subject to retreat. The numerous lost villages beneath the North Sea are testament to this.

A beach lined with wooden groynes and other structures.
Sea walls and other structures cannot hold the coastline together forever. Sophie Day, Author provided

Back in 2018 the Committee on Climate Change, which advises the UK government, calculated that around 9,000 properties in England are located in areas likely to be lost to coastal erosion by 2025. This number is projected to increase 15-fold by the end of the century, disrupting whole communities as more buildings, roads and farmland inevitably slip into the danger zone.

Unstoppable – and necessary?

A growing body of research warns that the speed of coastal erosion will be compounded by sea-level rise and other effects of climate change, such as more extreme storms and prolonged wet weather, as waterlogged soils increase the likelihood of sandy cliffs collapsing. Rates of erosion can be roughly but not precisely estimated, due to the complexity of coastal systems and uncertainty regarding how the effects of climate change will manifest.

A paved road ending in a sheer cliff edge.
Life in an eroding community can be unpredictable. Sophie Day, Author provided

Since the early 1990s, scientists have collected huge amounts of data in order to understand how the wind, waves, tides and storms shape coastlines. The evidence indicates that it is not possible or prudent to stop or delay coastal erosion forever and that in some places, it may even be necessary.

This is because when soft cliffs such as those along the east of England retreat, they release a lot of sand which is deposited on nearby beaches, making them higher and wider. High and wide beaches absorb the energy of waves, giving some protection to cliffs, dunes and sea walls from coastal erosion and flooding.

The chief executive of the UK Environment Agency recently said it is inevitable that at some point communities will have to move back from the coast. So what does this mean for people who live in places where coastal erosion is accelerating, or where it can no longer be stopped?

At Happisburgh in north Norfolk for example, a section of old and damaged sea defences had to be removed in the 1990s to avert dangerous collapse. Rapid erosion of the beach and cliffs since the early 2000s has meant homes in this village being steadily demolished as the coastline retreats. As yet there are no arrangements to compensate people here, or other government policies to help them adapt.

A series of collapsed houses along a sandy outcrop.
Uprooted. Sophie Day, Author provided

Living with coastal erosion

It is important to be realistic: homes, roads and other things which knit some coastal communities together will need to be relocated inland away from danger – and soon. But doing this is far from simple, and will certainly be costly.

Ideally, the kind of investment which erected coastal defences in the aftermath of the 1953 storm surge would be mobilised today to help these places move. This is a pressing issue – letting crisis and despair characterise life for coastal communities on the edge is unsustainable and unfair.

Slowly, things are changing. A network of coastal communities, local authority officers and politicians, academics and others have worked since the early 2000s to argue for what is needed to cope with and prepare for coastal erosion around England and Wales. Now, a new pulse of government funding could test these ideas so that in future, no community feels abandoned to the sea.

An abandoned building behind a metal fence.
Eroding coastal communities need reassurance and support. Sophie Day, Author provided

Part of this work will be to begin the transition in eroding towns and villages on England’s east coast from a state of crisis to one in which people can begin to live feeling safe and confident. It must be systematically worked out how communities can move away from risky areas while maintaining homes, utilities and services, as well as preserving local heritage, culture and each place’s unique character.

As academics working alongside government agencies, our next challenge will be ensuring these time-limited projects translate into robust national policy and funding. Coastal erosion cannot be stopped, so we must help everyone relearn how to live with it.


Climate tipping points could lock in unstoppable changes to the planet – how close are they?

David Armstrong McKay– Researcher in Earth System Resilience, Stockholm University

Continued greenhouse gas emissions risk triggering climate tipping points. These are self-sustaining shifts in the climate system that would lock-in devastating changes, like sea-level rise, even if all emissions ended.

The first major assessment in 2008 identified nine parts of the climate system that are sensitive to tipping, including ice sheets, ocean currents and major forests. Since then, huge advances in climate modelling and a flood of new observations and records of ancient climate change have given scientists a far better picture of these tipping elements. Extra ones have also been proposed, like permafrost around the Arctic (permanently frozen ground that could unleash more carbon if thawed).

Estimates of the warming levels at which these elements could tip have fallen since 2008. The collapse of the west Antarctic ice sheet was once thought to be a risk when warming reached 3°C-5°C above Earth’s pre-industrial average temperature. Now it’s thought to be possible at current warming levels.

In our new assessment of the past 15 years of research, myself and colleagues found that we can’t rule out five tipping points being triggered right now when global warming stands at roughly 1.2°C. Four of these five become more likely as global warming exceeds 1.5°C.

These are sobering conclusions. Not all of the news coverage captured the nuance of our study, though. So here’s what our findings actually mean.

Uncertain thresholds

We synthesised the results of more than 200 studies to estimate warming thresholds for each tipping element. The best estimate was either one that multiple studies converged on or which a study judged to be particularly reliable reported. For example, records of when ice sheets had retreated in the past and modelling studies indicate the Greenland ice sheet is likely to collapse beyond 1.5°C. We also estimated the minimum and maximum thresholds at which collapse is possible: model estimates for Greenland range between 0.8°C and 3.0°C.

A vast wall of blue and white ice with ocean in the foreground.
Greenland’s ice sheet is showing signs of destabilising at current warming levels. David Dennis/Shutterstock

Within this range, tipping becomes more likely as warming increases. We defined tipping as possible (but not yet likely) when warming is above the minimum but below the best estimate, and likely above the best estimate. We also judged how confident we are with each estimate. For example, we are more confident in our estimates for Greenland’s ice sheet collapse than those for abrupt permafrost thaw.

This uncertainty means that we do not expect four climate tipping points to be triggered the first year global temperatures reach 1.5°C (which climate scientists suggest is possible in the next five years), or even when temperatures averaged over several years reach 1.5°C sometime in the next couple of decades. Instead, every fraction of a degree makes tipping more likely, but we can’t be sure exactly when tipping becomes inevitable.

This is especially true for the Greenland and west Antarctic ice sheets. While our assessment suggests their collapse becomes likely beyond 1.5°C, ice sheets are so massive that they change very slowly. Collapse would take thousands of years, and the processes driving it require warming to remain beyond the threshold for several decades. If warming returned below the threshold before tipping kicked in, it may be possible for ice sheets to temporarily overshoot their thresholds without collapsing.

For some other tipping points, change is likely to be more dispersed. We estimate that both tropical coral reef death and abrupt permafrost thaw are possible at the current warming level. But thresholds vary between reefs and patches of permafrost. Both are already happening in some places, but in our assessment, these changes become much more widespread at a similar time beyond 1.5°C.

Elsewhere, small patches of the Amazon and northern forests might tip and transition to a savannah-like state first, bypassing a more catastrophic dieback across the whole forest. Model results that are yet to be published suggest that Amazon tipping might occur in several regions at varying warming levels rather than as one big event.

An aerial view of burning Amazon rainforest surrounded by bare fields.
The Amazon may not collapse from forest to grassland all at once. Paralaxis/Shutterstock

There may also be no well-defined threshold for some tipping elements. Ancient climate records suggest ocean currents in the North Atlantic can dramatically flip from being strong, as they are now, to weak as a result of both warming and melting freshwater from Greenland disrupting circulation. Recent modelling suggests that the threshold for the collapse of Atlantic circulation depends on how fast warming increases alongside other hard-to-measure factors, making it highly uncertain.

Into the danger zone

There are signs that some tipping points are already approaching. Degradation and drought have caused parts of the Amazon to become less resilient to disturbances like fire and emit more carbon than they absorb.

The front edge of some retreating west Antarctic glaciers are only kilometres away from the unstoppable retreat. Early warning signals in climate monitoring data (such as bigger and longer swings in how much glaciers melt each year) suggest that parts of the Greenland ice sheet and Atlantic circulation are also destabilising.

These signals can’t tell us exactly how close we are to tipping points, only that destabilisation is underway and a tipping point may be approaching. The most we can be sure of is that every fraction of further warming will destabilise these tipping elements more and make the initiation of self-sustaining changes more likely.

This strengthens the case for ambitious emissions cuts in line with the Paris agreement’s aim of halting warming at 1.5°C. This would reduce the chances of triggering multiple climate tipping points – even if we can’t rule out some being reached soon.


Me, myself and nature

The biodiversity stripes I shared recently have been very popular. This follow-up post shares another set of stripes that help show why the human-…

Me, myself and nature

We studied 40,000 pieces of litter to find out where it all comes from – here’s what we discovered

  1. Thomas Stanton– Loughborough University Doctoral Prize Fellow, Loughborough University
  2. Antonia Law– Lecturer in Physical Geography, Keele University
  3. Guaduneth Chico– Lecturer in Environmental Sciences and GIS, Nottingham Trent University
  4. Matthew Johnson– Associate Professor, Department of Geography, University of Nottingham

Litter is perhaps the most tangible of all environmental problems. And it’s not just a disrespectful few who are responsible for it. Litter, defined in its broadest terms, includes any solid material present in the environment that was made or processed by people. It may have arrived there from an accidental spillage, as debris washed ashore, or because of the irresponsible management of industrial waste.

How some types of litter enter and travel through the environment cannot be traced. Litter breaks down beyond recognition, identifying marks such as branding wear away and rivers can transport it far from where it originated. But some litter has clear sources and pathways, discernible from its function and packaging labels, from which the brand that made the item can be easily identified.

The community interest company Planet Patrol created an app for people to record the litter they find and remove. We used it to map the location, materials, type and, where possible, brands of 43,187 items of litter collected across the UK in 2020. Our research was recently published in the Journal of Hazardous Materials.

Two maps of the UK depicting total app entries and total litter found by region.
App users submitted the litter they found throughout the UK. Stanton et al. (2022), Author provided

Plastic was the most common material recorded, accounting for 63.1% of all items. Metal was second (14.3%), followed by composite materials (pieces of litter made from more than one material, like Tetrapak cartons) at 11.6%. Bottles, lids, straws and other items from the drinks industry made up 33.6% of the total, of which metal cans were the most common.

Our citizen scientists identified brands for 16,751 items (38.8% of the total), with 50% of these belonging to just ten brands. The Coca-Cola Company was the most frequently identified brand (11.9% of branded litter), followed by Anheuser-Busch InBev (7.4%) and PepsiCo (6.9%). The top three brands were all drinks manufacturers.

A Sankey diagram showing how brands, parent companies and materials comprise total litter found.
Despite taking up most space in the statements of packaging manufacturers, plastic comprised a third of total litter found. Stanton et al. (2022), Author provided

Plastic policies

Surprisingly, our findings do not vindicate one of the EU’s most important orders on litter: the 2019 Single-Use Plastics Directive. This identified the top ten types of plastic litter based on beach surveys around Europe, and legislated to reduce their production and sale in the EU while the UK was still a member.

These ten items, which include cotton buds, plastic bags and plastic bottles, were not all common in our results, which came from sampling inland areas as well as some beaches. Though this directive applies to the whole of the EU, we suspect its focus on coastal environments alone does not accurately reflect the nature of most litter found across Europe.

Two disposable coffee cups immersed in sand on a beach.
Common litter on beaches may not represent what’s typically found elsewhere. Henk van Dijk/Shutterstock

Throughout the 2020s, the UK government and its devolved powers will introduce or reform legislation to tackle litter. These include a plastic tax (introduced in April 2022), a tax on the production of plastic packaging containing less than 30% recycled plastic, a deposit return scheme for drink containers (limited to plastic containers only in England) and reforms which will make packaging producers pay for action including litter picking and education campaigns. Over the same decade, the top ten companies identified by our study plan to change the materials they use in their packaging.

Our analysis of these corporate and legislative policies concluded that they disproportionately favour solutions based on recycling, with little consideration of how to reduce waste and allow people to reuse items. This approach fails to address plastic pollution’s root cause: selling things people don’t really need.

Should we name (and shame)?

Since most litter in the environment cannot be traced back to its origins, naming the people and organisations responsible may seem futile. But litter that can be linked with an industry or a company is some of the easiest to address. This is particularly true for packaging, which made up 59.1% of the items logged in our study.

Given how common this type of waste appears to be, expanding opportunities for people to refill containers with goods (where appropriate), removing or reducing the need for new packaging as zero-waste shops do, is a good idea. This will require collaboration between companies, industries and governments. Small-scale efforts to achieve this are underway, with Wales pledging to become the first refill nation (where people can easily refill water bottles, making bottled water obsolete), some supermarkets introducing or trialling refill aisles and The Coca-Cola Company’s various small-scale efforts to allow consumers to refill bottles with beverages, most notably in Latin America.

A person fills a mason jar with red lentils.
Zero-waste shops allow customers to fill containers brought from home. Reshetnikov_art/Shutterstock

Making it easier for people to refill packaging would also reduce demand for raw packaging materials, lower transportation costs and emissions and reduce waste. It will also help people reckon with their own environmental footprints.

Tracing and curbing litter requires foresight and collaboration, which is currently lacking among companies that profit from the waste-generating consumption of single-use products, and the legislators that fail to properly govern it. Naming them is the start of holding them accountable.


Drought: why some UK trees are losing their leaves in August

Stuart Thompson– Senior Lecturer in Plant Biochemistry, University of Westminster

Leaf fall in London, July 2022. Matthew Chattle / Alamy

Britain is suffering its worst drought since the 1970s, with dry weather expected until October. Many parks and lawns are now more straw than grass, but some trees and other plants have responded in a more surprising way: by losing their leaves.

It is likely that this exceptionally dry weather is due to climate change. But are trees turning brown or dropping their leaves because they have lost track of the seasons, and behaving as if it is autumn?

Leaf fall is a carefully controlled process in which the junction between the leaf and the stem is precisely dissolved without damaging surrounding parts of the plant. Given this, you might think that it could only happen now if the trees and other plants are confused.

But this is not the case. Instead, it is an emergency response to protect the plant from dehydration.

The reason becomes clear if we think about what leaves do: they are solar panels, collecting sunlight and capturing its energy through the process of photosynthesis. Carbon dioxide is one of the key ingredients in this process and plants obtain it from the atmosphere, initially dissolving it in water coating the inside surfaces of each leaf.

To give the leaf the largest possible area to capture carbon dioxide, these interiors are folded and folded until they are typically 20 times the area of the leaf’s outside surface. This is good for harvesting carbon dioxide, but means water can be lost through evaporation across all of this huge area.

As much as 99% of water taken up by plants just passes through them and evaporates into the air in this way. Rain forests are rain forests because the trees release so much water vapour that they change the climate around them. Some large trees take up and evaporate a metric tonne of water in a day.

Leaves left useless

This is fine if water is plentiful, but what if it is not? In a drought, plants initially close the pores in their leaves that allow carbon dioxide in and through which water escapes. This reduces water loss but also slows or stops photosynthesis, since the supply of carbon dioxide is cut off.

Furthermore, closing the pores traps the oxygen produced as a by-product of photosynthesis inside the leaf. Oxygen is necessary for most living things, but is an aggressive and destructive substance which damages leaves if it builds up. The light energy a leaf captures can also become dangerous if it cannot be used to convert carbon dioxide to sugars. Leaves are left useless and accumulate damage when their supply of carbon dioxide is cut off to save water.

Large tree, turning slightly brown
Early autumn colours in Richmond Park, London, August 2022. Malcolm Park / Alamy

Lack of water can also do more fundamental harm. Leaves need a continuous supply to replace the water lost during photosynthesis and to remain hydrated. Otherwise they will slowly dry out even when their pores are closed.

Water molecules stick to one another, which is why pond skaters can run across a pond without breaking the surface. Plants use this phenomenon on a much larger scale to transport water up to their leaves in narrow, water-filled tubes. As water evaporates from the leaves, each water molecule in the tube pulls on the next, drawing the whole column of water upwards without the plant having to do any work.

An elegant trick, but as it gets harder and harder to pull water out of dry soil, the tension in the water can become so great that these columns break, blocking the tubes with bubbles and preventing water reaching the leaves for long periods. Shedding leaves reduces this risk too.

Not all species lose their leaves to cope with lack of water, but most will have had to reduce or stop photosynthesis in one way or another. Without photosynthesis, ecosystems will shrink. Less photosynthesis means less plant growth and therefore less food for herbivores – and, in turn, fewer herbivores for carnivores to feed on. It will also affect UK food production unless water is diverted to farms to protect crops, a particular concern at present because of disruptions to grain supplies due to the war in Ukraine.

Although drought-induced leaf fall may not be due to a jumbling of the seasons, climate change is disrupting ecosystems in other ways. Different species use different cues to calibrate their annual cycles and as the world warms, organisms are slipping out of sync as their individual interpretations of changing temperatures and weather patterns shift.

This can easily disturb delicate networks of interactions and interdependencies. For example, plants may produce flowers at the wrong time for bees to pollinate them. Disruption of patterns of bird migration may mean that fruit-bearing plants have no way to spread their seeds. If they set off at the wrong time, migratory species may arrive at their destination to find they have missed a key food source, or that it isn’t available yet.

This drought seems likely to be a taste of more extreme and chaotic weather patterns to come, in which we and the living world will frequently have to scramble for solutions in the face of new and unpredictable climatic conditions.


Castlefield Viaduct: Manchester’s new park in the sky could transform the city – but who will benefit?

Ian Mell– Reader in Environmental & Landscape Planning, University of Manchester

An urban park as a slice of history. PA Images | Alamy

In July 2022, Manchester welcomed the newest addition to its roster of urban parks. Owned by the National Trust, the Castlefield Viaduct is a Grade II-listed, 19th-century railway bridge that has been redevelopped into a new 330m-long sky park.

The project is part of a wider repurposing of brownfield and former industrial space in Manchester with several other projects promoting the city as a go-to place for innovative urban development in housing and green and open space. Under construction, in particular, is Victoria North, a new neighbourhood of 15,000 new homes across a 155-hectare site in the north of the city. This includes City River Park, a huge new “recreational corridor”, according to the proposals, along the River Irk.

For now, the National Trust is operating Castlefield Viaduct as a 12-month trial. Entry is free but ticketed and limited to 100 visitors per day on allocated one-hour slots each afternoon. Due to the extensive publicity campaign, high demand has led to the National Trust website crashing.

Colourful plants in a plant bed along a walkway.
3,000 plant species greet visitors on the new walkway. Ian Mell, Author provided

The idea behind the trail is to generate political and financial support to create a longer park extending westwards (the current layout only covers a proportion of the total viaduct area) and make it permanent.

Initial reactions to the Castlefield Viaduct have been positive. Local charity Castlefield Forum, which is set to have its own community plot on the bridge, has launched a podcast to tell the area’s stories.

Access to green and open space is urgently needed in central Manchester. However, as my research on access to nature and regeneration shows, there is no guarantee that simply having green space makes people use it. Location, access routes and amenities all influence usage. Exactly who stands to benefit from a project like Castlefield Viaduct becoming a permanent feature of the city skyline is a crucial question.

Steel beams cross over a planted walkway on a bridge platform.
The Castlefield Viaduct brings a new, industrial aesthetic to Manchester’s green spaces. Ian Mell, Author provided

A Victorian structure revisited

Built in 1892, the bridge was left derelict after 1969, when Manchester Central Station, now the Manchester Central Convention Complex, was taken out of service. Repurposing an abandoned site with little access, socio-economic worth or ecological value into a public park is a sign that Manchester city council, the landowner of the viaduct, is willing to test new approaches to urban greening.

Initial designs for the site were drawn up by London studio Twelve Architects. Founding director Matt Cartwright explained in 2021 that the brief included creating “moments of joy”. On a recent visit, I found the site is divided into three distinct zones linking the viaduct’s past, present and future journeys.

Seats, planted beds and a light coloured pathway on a bridge.
Motifs of the bridge’s structure are repeated in the landscaping of the park. Ian Mell, Author provided

The opening section draws on the railway motifs of trellis architecture to guide people into the site. The second introduces the 3,000 planted species – from cotton grass and ferns to fennel, Broom and fleabane – in a range of planters, highlighting the biodiversity of the local environment.

The third, meanwhile, which you can currently see, but not acccess, from the visitors centre, offers views on to where the site may go physically and conceptually. These various spaces blend with the sound of the passing trams. You are keenly aware of being in both a park and in a layer of the city’s history. The linear nature of the site underscores the notion of travel between the zones – as a visitor, you walk there and back again.

How Mancunians need more green

Castlefield is thus doted with a unique conceptual motif and a novel industrial aesthetic, as compared to other parks in Manchester. It remains to be seen, though, whether the design and the fact that it is located in an area of largely privately rented and owned flats will attract locals or serve primarily as a tourist attraction for visitors.

When the 606 linear park opened in Chicago in 2015, local residents reportedly expressed fears they would be priced out of their neighbourhoods. Reports in 2020 revealed that the park had indeed triggered luxury developments and long-term local residents being displaced. Research shows how similar developments, including New York’s High Line, can lead to what economists have dubbed eco-gentrification.

Research has also shown how much need there is for green space in Manchester. The city centre currently has very few public green spaces, and even fewer that provide play facilities or access to nature. According to Friends of the Earth, over 73% people across Manchester have poor or limited access to a personal garden or a communal green space. Covid lockdowns highlighted how significant this lack of access to green space is, especially for those with families.

The redevelopment of the Castlefield Viaduct presents an interesting conundrum for Manchester and other UK cities. High-quality and potentially exclusive locations that are inaccessible can nonetheless act as a catalyst for green-space investment linked to regeneration programmes like Grosvenor’s Living Cities. This strategy provides increased certainty for investors but primarily serves specific communities, that is, those who can afford market-rate apartments.

We also need look beyond the financing of high-end projects towards a more locally attuned approach to green space provision. Urban planning expert Meredith Whitten has shown how this would focus on local provision for meeting people’s everyday needs to interact with nature, play outside and live in a biodiverse landscape.

This requires sufficient public funding to be allocated to local government to support capital and revenue spend on public parks –- something not seen in the UK over the last 12 years.

By drawing on the industrial heritage of the city, Castlefield Viaduct makes strong links to its fabled Cottonopolis heritage. The park also sets out a bold statement of intent, that redundant spaces in Manchester can be meaningful, accessible and interactive. Of course, integrating industrial chic with urban regeneration is nothing new. But it is new in Manchester. This could be the start of something beautiful.