The rewilding of urban centres could help to mitigate climate change and biodiversity loss, while improving the wellbeing of billions of city-dwellers and increasing society’s resilience to future virus outbreaks.

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The coronavirus pandemic has encouraged people across the globe to reconnect with local nature. Lockdown measures have highlighted our need for regular contact with the natural world, while drawing attention to the ecological depletion of many urban areas. As a result, there is a growing interest in urban rewilding, fuelled by evidence that the blending of nature with city life could not only foster healthier and happier human communities, but also tackle global environmental problems by transforming cities into thriving carbon sinks.

Urban Rewilding and Human Health

Our transition towards an ecological civilisation is being accelerated by the pandemic, at both the collective and the individual level. Travel restrictions, for example, have rooted us firmly, if not forlornly, in our local soil, and in many cases deepened our appreciation for our often-overlooked natural surroundings. Some of us have sought refuge from narrow domestic life in public parks and private gardens, while others have found even the modest sights beyond our windows to be a vital source of wonder and perspective.

While such tame encounters with nature may bring us brief moments of respite, they are, however, not enough to maintain our mental and physical health. Mounting scientific evidence demonstrates the importance of frequent visits to wild spaces for human wellbeing, linking what author Richard Louv has called Nature-Deficit Disorder to a range of illnesses and diseases, including depression, obesity, diabetes and poor immunity – some of which increase our vulnerability to viruses like COVID-19. Thus, for people who have been locked-down in small inner-city apartments – who have been cut off not only from the comfort of human community, but from the sustenance of the natural world – the months of isolation have been made ever-more difficult by their confinement within a largely manmade environment.

If we are to protect the sanity and wellbeing of city-dwellers, and at the same time address the various ecological crises that confront us, then the rewilding of urban areas is an urgent imperative. Fortunately, a growing number of cities are beginning to respond to these crises, ushering in a future where all aspects of sustainable urban life are interwoven with the textures and rhythms of nature.

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Sustainable Cities

Many of the world’s major cities are becoming more sustainable, from Vienna to Vancouver, Copenhagen to Curitiba, and Munich to Madrid. One particularly notable example is Singapore, which has blossomed into a “biophilic” garden city since gaining independence in 1965, having lost much of its native vegetation to colonial industrialisation after 1819. The Singapore Green Plan, which was announced in the 1990s, has served to restore the city-state’s degraded ecosystems, while reducing pollution and carbon emissions. In the last decade, over 100 buildings have also been retrofitted with vegetation – green roofs and walls and vegetable rooftop gardens have all helped to improve air quality throughout the city and to conserve energy by keeping streets cool. Thus, Singapore is proof that even the most depleted urban environments can be transformed into liveable, sustainable cities for the benefit of both people and planet.

Another major city which is rewilding design into urban planning is Barcelona. In 2016, it introduced a new “superblock” grid system, where traffic is restricted to major roads surrounding neighbourhoods of nine blocks, and inner streets are reserved for pedestrians and cyclists. In the central district of Eixample, a new ten-year plan will see 80% of each road lined with trees and 20% left unpaved, while no resident will be more than 200 metres from a green space. The project, which has a budget of €38m, aims to reduce the city’s carbon footprint while improving the health of residents.

Not every city, however, will be able to emulate the success of these pioneers. Urban centres in poorer countries, for example, might be unable to afford the requisite green infrastructure, while those with ill-designed grid systems may struggle to replicate Barcelona’s green zones. Indeed, every city is faced with a unique set of challenges, including those posed by the particular geography, climate and architectural framework it inhabits. In order to meet these challenges, it will require a combination of ingenuity, innovation and imagination.

Imagination

While Barcelona and Singapore have given us a glimpse of the future, they have by no means exhausted the potentialities for the wild city of tomorrow. Thus, to assist the conception of such a city, let us travel forward in time, and consider a wider and wilder range of possibilities…

The train wheezes to a halt, and the sliding doors open onto the cool platform. We stroll through the tranquil subway and climb the stairs leading up to the street, emerging at last into the open air. As our eyes adjust to the dazzling sunlight, we find ourselves immersed in a pulsing parade of green and gold – towering buildings line the road in both directions, tangled in wreaths of gleaming vegetation. Some way down the street, people are collecting apples from the boughs of bending trees, while a neighbouring band of deer casually browses in a clump of brambles, showered by a golden flurry of lilting butterflies. Between the two feasting parties, a fox darts furtively across the road, ignited for a moment by the orange afternoon light, before dipping into the gloom of a side-street.

Our ears are engulfed in a wave of luminous sounds, gradually attuning to the murmur of human voices and the singing of birds, to the whirring of bicycle wheels and the gentle clashing of branches. The very air itself is alive, electric with the scents of pine needles and wildflowers, vibrating with the hum of bees in their hives and the ringing of crickets in the verges.

Looking down the street, there isn’t a car in sight – the only sound missing is that familiar, incessant rumble of traffic. Where cars would be parked in contemporary cities, the spears of unmown grasses bend in the breeze, shaded by thick trees that plume from the pavement like puffs of green vapour. Behind them, spiralling into the azure sky, office and apartment blocks are cloaked in velvet mosses and veridian creepers. Sun-baked balconies burst with plants and vegetables, runner beans wind around the stems of street-lamps, and solar panels bloom in rooftop gardens. Overhead, a flock of honking wild geese flies towards the obscured horizon, gazing down on clouds of vegetation and clusters of concrete buildings, a rippling cityscape laced with ribbons of silver water.

Soon we’re approached by one of the locals, who is eager to inform us about life in this living, breathing city. She tells us that the entire human community here works to preserve the natural ecosystems on which it depends – indeed, this society has blended the blessings of Western science with indigenous knowledge, recognising that the health of each individual is entwined with the integrity of the encompassing biosphere. The city is nestled harmoniously within the wider earth community, and is therefore less vulnerable to virus outbreaks and diseases, to droughts, floods and even crime.

Daily life is nourished by clean water, green energy and locally-grown food. Streams and brooks flow with crystal water, brimming with fish; organic farms flourish on rooftops and spill down walls, while public transport is confined to silent routes along major roads and underground. At school, children are taught how to plant and harvest a garden, and nature is woven into the syllabus to nurture creativity and resilience. Education here is not restricted to the remembrance and reproduction of facts, but expanded and broadened into the study of the art of living.

As the evening shadows stretch out across the street, we thank our acquaintance and part ways. The voice of the wind is fading, and the sounds of the day are beginning to recede into the approaching darkness. The cool air soon falls silent, stirred intermittently by the blustering of owls and the rustling of rabbits in the thickets. Slowly, a pale moon climbs into view, glowing above the treetops. Warm lights ooze out of nearby windows like melted butter, and the moon’s rays drip down the walls like silver paint. Bats flit and swerve in circles overhead, dancing beneath a sea of stars that sweeps across the dome of the darkening sky, a stream of lights embedded in the swirling Milky Way like jewels in a resplendent rock. We look in wonder at the sparkling cosmic canopy, feeling we may have grasped the city’s secret. Humans cannot live in isolation from the living world: just as its plants, rivers and creatures feed our bodies, so do its shifting shapes, shades and songs feed our minds. By rewilding our urban centres, we can restore health to humanity and to the earth, and protect all life from further catastrophe. In doing so, we may also come to a deeper understanding of ourselves, and rediscover what it means to be human.

The post Urban Rewilding: A Solution To The World’s Ecological And Mental Health Crises? appeared first on Earth.Org.

Global warming is accelerating the spread of ivy in Europe’s deciduous forests, a recent study has found. While the vine’s proliferation is good news for wildlife, it could threaten the survival of young trees and disrupt woodland regeneration.

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Ivy (Latin name: Hedera, “to cling or grasp”) is a woody creeper commonly found in ecosystems which contain a mixture of light and shade. During its first ten years of life, it grows away from the sun in search of a shady host plant, displaying a behaviour called ‘negative phototropism’. Thus, in temperate forests, juvenile ivy often begins climbing on the sunny southern face of trees, before gradually reaching around, away from the light, and growing predominantly on the darker northern side. This tendency makes it a useful orientation tool for navigators lost in the woods.

Sinking its short, bristled roots into the soft bark, the creeper ascends several feet each year, weaving its way upwards through the gloom. After a decade, when it has fully matured, its waxy, triple-lobed leaves transform into the shape of upturned teardrops, and for the first time the vine begins to grow towards the sun. Soon, a wreath of emerald tendrils is densely draped around its host, some 30 metres from the forest floor, proffering shelter and food for over 50 species of wildlife.

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Study

A recent study carried out by Ghent University in Belgium investigated the effects of global warming on the abundance of common ivy and other woodland plants. The team, led by Dr Michael Perring, surveyed almost 2 000 plots within 40 temperate forest regions across Europe, assessing around 1 000 plant species – including lianas, the family of climbers to which ivy belongs. Their observations were compared with historical data from two rounds of surveys, conducted at the same plots between 1933-94 and 1987-2015 respectively. The average duration between the first survey and the follow-up survey at a given site was 38 years.

Their findings indicated that ivy had become, on average, 14% more prevalent over a 38-year period, its range extending by nearly 3% each year. Dr Perring says, “What we have done is highlight, to my knowledge for the first time in temperate, rather than tropical areas, the large geographic extent of this ivy spread in the understorey. What is also really marked is that no other species exhibits such a geographically coherent pattern of increase — this is really quite striking.”

The findings also suggested that global warming was a major factor behind ivy’s increased profusion. “There was a much higher probability of finding ivy at a resurvey where it was absent initially where there had been a greater rate of warming,” said Dr Perring. While rising air temperatures appear to be the primary cause of the plant’s accelerated growth, there may also be secondary factors, such as the management strategies employed in certain woodlands, or increased amounts of shade due to the presence of more or older trees.

The ecological implications of ivy’s proliferation are both positive and negative. An abundance of ivy means more food and shelter for birds and insects, especially during winter, as well as increased biomass accumulation and nutrient cycling in the understory, and, due to its evergreen nature, an extended period of carbon sequestration for temperate woodlands. On the other hand, trees are more vulnerable to windfall if large tangles of ivy converge in the canopy, and the chemicals released by ivy leaf litter can hinder the growth of seedlings (a phenomenon known as allelopathy), thereby disrupting forest regeneration.

In light of such threats, ivy’s quickening expansion should be monitored in order to protect other plant species and preserve ecosystem health. In addition, given the newly-discovered correlation between rising air temperatures and accelerated ivy growth, the speed of the creeper’s advancement across temperate forests could serve as a useful indicator for the rate of global warming.

The post Ivy Is Flourishing In European Forests Due To Rising Temperatures appeared first on Earth.Org.

A study comparing the environmental impacts of various single-use beverage containers has concluded that glass bottles have a greater overall impact than plastic bottles, primarily because they are heavier and require more energy to manufacture. The study also identified more environmentally-friendly alternatives to plastic bottles for a range of beverage types: recycled aluminium cans are the most sustainable containers for pressurised or ‘fizzy’ drinks, while Tetra-pak and milk cartons are the least impactful packaging for fruit juice and milk respectively. These findings could help to catalyse a shift towards more sustainable beverage packaging and mitigate the environmental harm caused by plastic pollution.

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Plastic bottles are the world’s most ubiquitous drinks containers. A million are sold each minute and their production is increasing every year; by 2021, 583 billion are expected to be consumed annually. But as these bottles are largely single-use, many of them are discarded and dumped in the earth’s ecosystems, where they constitute a significant portion of all environmental waste. Of the 32.5 million trash items collected in the Ocean Conservancy’s international beach cleanup in 2019, plastic bottles and plastic bottle caps were the third and fourth most prevalent items after food wrappers and cigarette butts, accounting for roughly ten percent (if not more) of all the litter plaguing the planet’s coastlines.

Study

Environmental experts at the University of Southampton have conducted a study in an attempt to address the ecological implications of this issue. Two fundamental questions underpinned their research: What attributes do plastic bottles possess which have led to them becoming so indispensable, yet so toxic? Are there any equally effective alternatives which do not incur the same environmental impact?

To answer the first question, the researchers examined the two most common types of plastic bottle, made from PET (polyethylene terephthalate) and HDPE (high density polyethylene), outlining a range of properties which make them highly effective liquid containers: they are lightweight, durable, cheap to produce, safe, convenient and versatile (capable of keeping liquids hot or cold).

However, they also identified drawbacks for both materials. For example, plastic bottles have a limited capacity for recycling, due to the fact that plastics consist of polymer chains which shorten each time they are recycled. For this reason, 91% of all plastics are not totally recycled – rather, they are usually remoulded or ‘downcycled’ into lower quality products.

Moreover, the manufacturing process requires high levels of energy and generates carbon dioxide emissions, while the extraction of raw materials like crude oil – which constitutes just one phase of production – creates large amounts of solid wastes, depletes the ozone layer and emits petroleum hydrocarbons into the atmosphere.

Having evaluated the environmental impacts of both PET and HDPE plastic bottles, the researchers proceeded to carry out a life cycle assessment of four other common beverage containers, measuring their ecological footprint at every stage of their existence. The environmental impact of glass bottles (new and recycled), Tetra-pak cartons, milk cartons, and aluminium cans (again, all both new and recycled) were all assessed while taking into account their suitability for storing three particular types of beverage: pressurised or ‘fizzy’ drinks, fruit juice and milk.

Given that each beverage type has particular storage requirements, the researchers expected certain containers to be more suitable for some drinks than others. For example, while fizzy drinks need packaging which can be pressurised, milk containers need to facilitate refrigeration and fruit juices are often unrefrigerated and hence have specific hygiene requirements.

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Results

The results of the life cycle assessment indicated that more sustainable alternatives to plastic bottles exist for all three types of beverage: recycled aluminium cans were found to be the most environmentally-friendly packaging for pressurised drinks, while Tetra-pak and milk cartons were the least impactful containers for fruit juice and milk respectively. Glass and recycled glass bottles were the most impactful packaging for every drinks category, with plastic bottles always the second-most impactful.

These findings support the results of many previous, smaller life cycle assessments, demonstrating that, while plastic bottles generally cause more environmental impact at the end of their life cycle, glass bottles have a more damaging overall effect, largely because they are heavier and require more energy for their production.

Future

The research team at the university hopes that the findings of this study will help to illuminate a more sustainable future for beverage packaging and society as a whole. Ian Williams, Professor of Applied Environmental Sciences at Southampton, said, “We hope our study will help inform public and commercial debate over the suitability of some types of packaging that we all use in our daily lives, and lead to swift and decisive changes in the drinks industry to find more environmentally-friendly alternatives as a matter of some urgency.”

Alice Brock, postgraduate researcher and co-author of the study, called for large-scale societal changes aimed at mitigating the ecological impacts of single-use drinks containers: “Based on the evidence, society needs to move away from single-use beverage packaging in order to reduce environmental harm and embrace the regular everyday use of reusable containers as standard practice.” 

She added, “Changes in infrastructure and potential incentives to use reusable packaging should be implemented and policies such as the proposed coffee cup tax should be adapted for single-use beverage packaging.”

While infrastructural changes certainly would help to reduce the amount of single-use plastic that is manufactured and then discarded, they address only one side of the issue. The key to solving the global plastic problem must be to target both production and disposal and to combine sustainable infrastructure with a strategy for eliminating the existing plastic waste that pollutes the planet.

Featured image by: Flickr

The post Glass Bottles Have a Larger Environmental Impact Than Plastic Bottles- Study appeared first on Earth.Org.

Numbers of Iberian lynx have risen from just 94 in 2002 to over 700 this year, thanks to an ongoing captive breeding programme.  In Andalucía, Spain, the largest population of lynx has expanded, while new populations have been established in Extremadura and Castilla-La Mancha, as well as Portugal, where the predator was previously extinct. As a result of the animal’s continued recovery, local reserves and communities are also benefiting from ecological restoration and economic growth.

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The Iberian lynx (Latin name: Lynx pardinus) was once common across much of Spain, Portugal and southern France.  But in the 20th century, hunting and agricultural and industrial development decimated its numbers and destroyed much of its habitat, causing its population to decline by almost 90%. At the turn of the 21st century, the lynx was the most endangered feline in the world.

In 1953, the extermination of thousands of lynxes and rabbits (the lynx’s main prey) under Spanish dictator Francisco Franco’s Vermin Law (“Ley de Alimañas”) pushed the species towards extinction. In addition, outbreaks of rabbit myxomatosis in the 1950s and hemorrhagic disease in the 1980s further depleted the predator’s primary food source.

Consequently, between 1985 and 2001, the lynx’s inhabited range shrank by 87% and the number of reproductive females fell by over 90%. By 2002, there were only two isolated populations left in the world, containing just 25 breeding females.

It was around this time that the European Union decided to intervene, partnering with Spanish administrations and environmental NGOs, including the WWF, in a bid to save the species. With the support of politicians, landowners and local communities, their efforts to protect and expand lynx populations through captive breeding and habitat restoration have so far been successful, with the animal’s numbers increasing more than sevenfold in the last 18 years, and its extinction status changing from ‘Critically Endangered’ to ‘Endangered’ on the IUCN Red List in 2015.

Ramón Pérez de Ayala, a coordinator at WWF Spain, believes that this trend must continue for at least another 20 years in order to secure a complete recovery for the lynx.  “If we carry on,” he said, “if we can maintain the population growth momentum, and if luck stays on our side, we’ll have at least 750 females of reproductive age – which means more than 3 000 lynxes in total – by 2040.”

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The Ecology of the Iberian lynx

The Iberian lynx is an elusive predator, native to the dense oak forests of the Mediterranean basin. It is the smallest of the four lynx species (which include the Canada lynx, the bobcat and the Eurasian lynx), and is characterised by a spotted coat, tufted ears, a forked beard and a short tail. It is most active at dawn and dusk, and prefers to stalk its prey on the borders of meadows and grasslands.

Rabbits form up to 90% of its diet. Males usually eat one rabbit per day, while females with kittens require up to three. When rabbit populations decline due to disease or hunting, lynxes turn to feeding on small rodents and birds, as well as young deer and sheep.

Like many apex predators, the Iberian lynx plays a crucial role in maintaining equilibrium within its ecosystem, and is therefore considered a keystone species. A healthy lynx population typically keeps the numbers of other medium-sized rabbit-eating predators (such as foxes and mongooses) in check through competition, helping to regulate a stable rabbit population; conversely, low numbers of lynx can see the populations of these other predators explode, placing immense pressure on the rabbit population and threatening their survival.

Threats

A range of factors threaten the survival of the Iberian lynx. Agricultural development and the construction of dams, motorways and railways represent one of the largest threats, as these are often the primary drivers of habitat destruction and fragmentation. The conversion of native forests into commercial plantations without dense undergrowth can also limit the lynx’s capacity to survive in previously inhabited areas. Other major threats include hunting (despite being illegal since the 1970s), road accidents (34 lynx were killed by cars in 2019), traps set for other predators and the decline of rabbit populations.

Since 2002, the lynx recovery programme has endeavoured to mitigate these threats by restoring lynx populations and habitats in Andalucía, Extremadura, Castilla-La Mancha and Portugal, and stimulating the growth of rabbit populations to enrich ecosystems. The latest phase of the programme is the 5-year Life Lynxconnect project, which began in 2019 and has a budget of €18.8 million, partially funded by the European Union. This project aims to create two new populations in Granada’s Sierra Harana, while geographically connecting existing populations in order to increase their genetic diversity.

Javier Salcedo, the project’s leader, believes that genetic problems which derive from inbreeding can be avoided by facilitating the flow of genes between isolated populations. “We need to see an exchange of animals that will give us an exchange of genes,” he says. It is hoped that genetically-viable, self-sufficient populations will be more resilient to the threats posed by human development and climate change in the future.

Conservation

The resurgence of the Iberian lynx continues to benefit the broader sphere of Mediterranean conservation.  Over the last 18 years, local ecosystems have been aided by habitat restoration, fund-raising and community education, while new jobs in tourism and leisure have been created and local economies have grown. But the conservation of the lynx is not just an ecological or economic necessity – it is also a moral one. As Pérez de Ayala points out, “Every species has an intrinsic value that can’t be lost – it would be like demolishing a cathedral. On a more emotional level, the lynx is a jewel and a thing of beauty to behold.”

The wider implications of the lynx’s recovery raise two important questions: Is enough being done to protect and restore the rest of the Earth’s endangered species? How much could both humans and nature profit from their prosperity?

The post The Iberian Lynx Bounces Back From The Brink Of Extinction appeared first on Earth.Org.

A recent study has found that rising winter temperatures have made lakes in the Northern Hemisphere over three times more likely to have an ice-free year compared with 80 years ago. Given the importance of lake ice cover for local communities and freshwater ecosystems, this could have significant socioeconomic and ecological implications.

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Over 50 million of the world’s 117 million lakes freeze each winter. In the Northern Hemisphere, lake ice is typically present for up to six months between December and May. As lakes are particularly sensitive to variations in weather conditions, the amount of ice cover seen each winter can serve as a useful indicator of climatic changes.

Years in which lakes do not have total ice cover for at least one day are known as ice-free years. These are considered extreme climatic events, as the loss of lake ice can alter the conditions of freshwater ecosystems irreversibly. Moreover, such years have become more frequent and more severe in recent decades. Since the 1970s, over 15 000 lakes in the Northern Hemisphere have seen ice-free years, and it is becoming increasingly common for lake ice to break up earlier, freeze later and last for a shorter duration.

Earlier this year, researchers at York University in Canada carried out a study to investigate the relationship between global levels of greenhouse gases and the frequency of ice-free years. They began by acquiring lake ice cover records from the National Snow and Ice Data Center in Colorado for 122 lakes across North America, Europe and Asia between 1939 and 2016. The sample included Lakes Suwa (Japan), Baikal (Russia), Geneva (Switzerland), Balaton (Hungary), Champlain (USA) and Michigan (USA).

These records showed a sharp rise in the frequency of ice-free years since 1939. In the years between 1939 and 1978, 31 ice-free years were recorded and nearly 1% of the lakes had at least one ice-free winter, while a maximum of four lakes did not fully freeze in a given year. By contrast, in the years between 1978 and 2016, the number of ice-free years more than trebled to 108, and the average number of ice-free lakes in a year increased fivefold, with as many as 10 lakes not fully freezing in a single season.

The researchers then compared these figures with historical data for local winter air temperature, cloud cover and total precipitation. Rising winter temperatures, correlated with increasing levels of greenhouse gases in the atmosphere, were found to be the most important predictor of ice-free years.

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In general, the lakes saw ice-free years when mean winter temperatures rose above -6oC (with the exception of Lake Balaton, which continued to freeze until temperatures exceeded 3oC). While the probability of having an ice-free winter had risen dramatically for all lakes, those in more southern and coastal regions were especially vulnerable due to higher average winter temperatures. 

Drawing on these results, Alessandro Filazzola, the lead author of the study, predicts that all 122 lakes will have more ice-free years in the future, regardless of whether greenhouse gas levels are kept in check. “Lake ice is becoming increasingly absent,” he said. “Even under low carbon emissions scenarios, we’re going to have continued ice-free events.”

If carbon emissions are curbed in the near future, the percentage of ice-free lakes is expected to continue increasing until around the year 2050, where it will plateau. However, if emissions rise, the rate of lake ice loss will increase until 2100 at least. For lakes with socioeconomic or ecological significance, higher carbon emissions would mean warmer winters, the loss of winter transport and recreational activities, and a greater risk of toxic algal blooms, which are harmful to marine life. It could also lead to the disappearance of winter traditions at culturally important lakes, such as Lake Suwa in Japan, where generations of Shinto priests have recorded and celebrated the formation of ice since 1443.

The results of this study demonstrate a clear causal relationship between climate change and lake ice loss. Limiting carbon emissions would be the most effective way to reduce the frequency of ice-free years in the future, and to minimise their cultural, economic and biological implications. Records of ice-free years and winter temperatures can help to predict further ice loss and assess the severity of climate change, and should therefore be continually maintained. Moreover, while it is important to continue monitoring the 122 lakes from this study, this range should be broadened to include many more across the Northern Hemisphere. Further research into the impact of ice loss on ecological communities within freshwater ecosystems is also required.

Featured image by: Flickr 

The post More Ice-free Years For Northern Hemisphere Lakes Are Predicted Due To Climate Change appeared first on Earth.Org.

The scientists who re-engineered PETase, an enzyme which has evolved to break down plastic, have now created an enzyme ‘cocktail’ which can digest plastic up to six times faster than previously possible. By combining PETase with a second enzyme called MHETase, they were able to break down PET, a common thermoplastic which takes centuries to biodegrade, in just days.

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Since it was first patented in the 1940s, PET (polyethylene terephthalate) has been used in the production of billions of plastic bottles and synthetic fabrics across the globe. Many of these products, once discarded, have ended up in the Earth’s ecosystems, polluting landscapes and waterways and threatening wildlife.

The global appetite for plastic is only increasing. At present, over 300 million tonnes are manufactured each year, 50% of which are single-use. And, as about 90% of this is not recycled, the need to transform the way it is produced and to protect the living world is becoming ever-more urgent.

PET bottles – among the most archetypal forms of plastic waste – are usually not fully recycled, but rather melted and remoulded into harder plastics. But the recently-created two-enzyme ‘cocktail’, which strips PET plastics down to their original structure, could enable them to be recycled infinitely. This has the potential to limit the amount of plastic that is manufactured and discarded, while also reducing our reliance on the fossil fuels used in its production.

Enzymes are produced by all living things to catalyse and regulate chemical reactions, such as digestion. Those with the ability to digest plastic were first discovered in 2016, when scientists from the University of Kyoto identified a microbe at a bottle-recycling facility which secreted two enzymes (PETase and MHETase) in order to break down plastic and use it as a primary source of energy and carbon. The microbe, named Ideonella sakaiensis, has evolved this behaviour in response to an environment rich in PET. Thus, it seems that, over the last few decades, nature has been developing a strategy for dealing with our increasingly prevalent plastic litter. 

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This discovery provided the basis for a second study in 2018, when Professor John McGeehan, Director of the Centre for Enzyme Innovation (CEI) at the University of Portsmouth, and Dr Gregg Beckham, Senior Research Fellow at the National Renewable Energy Laboratory (NREL) in the US, re-engineered the enzyme PETase and found that its activity could be accelerated by 20%. This was the first intimation that the global plastic problem could be solved by the industrial application of specialised enzymes. Then, earlier this year, the same scientists observed that mixing PETase with MHETase doubled the rate of PET disintegration, while physically connecting them further tripled this rate.

Professor McGeehan said: “Gregg and I were chatting about how PETase attacks the surface of the plastics and MHETase chops things up further, so it seemed natural to see if we could use them together, mimicking what happens in nature.

“Our first experiments showed that they did indeed work better together, so we decided to try to physically link them, like two Pac-men joined by a piece of string.

“It took a great deal of work on both sides of the Atlantic, but it was worth the effort – we were delighted to see that our new chimeric enzyme is up to three times faster than the naturally evolved separate enzymes, opening new avenues for further improvements.”

Indeed, while the speed at which the re-engineered PETase acts alone is not fast enough to make it a commercially viable solution, it seems that the PETase-MHETase ‘super- enzyme’ could hold the key to solving the problem of plastic pollution by being able to break it down quicker. The question is: how soon can it be harnessed on a large scale and applied to the ubiquitous piles of plastic that plague the planet?

Featured image by: Flickr 

The post Scientists Create Enzyme ‘Cocktail’ Able to Break Down Plastic Six Times Faster appeared first on Earth.Org.