How glacier algae are challenging the way we think about evolution

Wirestock Creators/Shutterstock

People often underestimate tiny beings. But microscopic algal cells not only evolved to thrive in one of the most extreme habitats on Earth – glaciers – but are also shaping them.

With a team of scientists from the UK and Canada, we traced the evolution of purple algae back hundreds of millions of years and our findings challenge a key idea about how evolution works. Though small, these algae are having a dramatic effect on the glaciers they live on.

Glaciers are among the planet’s fastest changing ecosystems. During the summer melt season as liquid water forms on glaciers, blooms of purple algae darken the surface of the ice, accelerating the rate of melt. This fascinating adaptation to glaciers requires microscopic algae to control their growth and photosynthesis. This must be balanced with tolerance of extreme ice melt, temperature and light exposure.

Our study, published in New Phytologist, reveals how and when their adaptations to live in these extreme environments first evolved. We sequenced and analysed genome data of the glacier algae Ancylonema nordenskiöldii. Our results show that the purple colour of glacier algae, which acts like a sunscreen, was generated by new genes involved in pigment production.

This pigment, purpurogallin, protects algal cells from damage of ultraviolet (UV) and visible light. It is also linked with tolerance of low temperatures and desiccation, characteristic features of glacial environments. Our genetic analysis suggests that the evolution of this purple pigment was probably vital for several adaptations in glacier algae.

We also identified new genes that helped increase the algae’s tolerance to UV and visible light, important adaptations for living in a bright, exposed environment. Interestingly these were linked to increased light perception as well as improved mechanisms of repair to sun damage. This work reveals how algae are adapted to live on glaciers in the present day.

Next, we wanted to understand when this adaptation evolved in Earth’s deep history.

The evolution of glacier algae

Earth has experienced many fluctuations of colder and warmer climates. Across thousands and sometimes millions of years, global climates have changed slowly between glacial (cold) to interglacial (warm) periods.

One of the most dramatic cold periods was the Cryogenian, dating back to 720-635 million years ago, when Earth was almost entirely covered in snow and ice. So widespread were these glaciations, they are sometimes referred to by scientists as “Snowball Earth”.

Scientists think that these conditions would have been similar to the glaciers and ice sheets we see on Earth today. So we wondered could this period be the force driving the evolution of glacier algae?

After analysing genetic data and fossilised algae, we estimated that glacier algae evolved around 520-455 million years ago. This suggests that the evolution of glacier algae was not linked to the Snowball Earth environments of the Cryogenian.

As the origin of glacier algae is later than the Cryogenian, a more recent glacial period must have been the driver of glacial adaptations in algae. Scientists think there has continuously been glacial environments on Earth up to 60 million years ago.

We did, however, identify that the common ancestor of glacier algae and land plants evolved around the Cryogenian.

In February 2024, our previous analysis demonstrated that this ancient algae was multicellular. The group containing glacier algae lost the ability to create complex multicellular forms, possibly in response to the extreme environmental pressures of the Cryogenian.

Rather than becoming more complex, we have demonstrated that these algae became simple and persevered to the present day. This is an example of evolution by reducing complexity. It also contradicts the well-established “march of progress” hypothesis, the idea that organisms evolve into increasingly complex versions of their ancestors.

Our work showed that this loss of multicellularity was accompanied by a huge loss of genetic diversity. These lost genes were mainly linked to multicellular development. This is a signature of the evolution of their simple morphology from a more complex ancestor.

Over the last 700 million years, these algae have survived by being tiny, insulated from cold and protected from the Sun. These adaptations prepared them for life on glaciers in the present day.

So specialised is this adaptation, that only a handful of algae have evolved to live on glaciers. This is in contrast to the hundreds of algal species living on snow. Despite this, glacier algae have dramatic effects across vast ice fields when liquid water forms on glacier surfaces. In 2016, on the Greenland ice sheet, algal growth led to an additional 4,400–6,000 million tonnes of runoff.

Understanding these algae helps us appreciate their role in shaping fragile ecosystems.

Our study gives insight into the evolutionary journey of glacier algae from the deep past to the present. As we face a changing climate, understanding these microscopic organisms is key to predicting the future of Earth’s icy environments.The Conversation

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This blog is written by Dr Alexander Bowles, Postdoctoral research associate, University of Bristol

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Alexander Bowles
Alexander Bowles

Wisdom of Generations: Learning from the Hills and Valleys of the Northeast India

A tea garden in Dibrugarh, Assam
A tea garden in Dibrugarh, Assam. Image credit: Nborkakoty at English Wikipedia.

Northeast (NE) India is more than just a region on the map; it is a treasure trove of beautiful
natural landscapes and ecological wealth that plays an essential role in our planet’s health. As
we celebrate World Environment Day 2024 with the theme of restoration, let us highlight the
ecological richness of Assam and the other Northeastern states of India. From the slopes of
Arunachal Pradesh to the lowlands of Assam, the NE region is a biodiversity hotspot, home to
unique species found nowhere else on Earth. The more we explore this ecological richness,
the more we discover the wonders and mysteries it holds, sparking our curiosity and interest.

The scenic landscapes of the NE region exemplify a dynamic and harmonious relationship
between humans and nature. Indigenous communities here have cultivated a profound
repository of traditional ecological knowledge passed down through generations. The Bodos,
Mishings, Karbis, Nyishis, Angamis, Khasis, and many others have developed a deep-rooted
understanding of their natural surroundings through intimate interactions with forests, rivers,
and mountains.

One of the most remarkable aspects of this traditional wisdom is the extensive knowledge of
local plants and their uses. These communities have identified and utilized numerous plant
species for food, medicine, shelter, and rituals, demonstrating a profound understanding of
the ecological roles of each species. For instance, the Bodos have long made use of medicinal
plants like Bhut Jolokia (ghost chili) for their therapeutic properties, contributing to the
preservation of traditional healing practices. This knowledge not only highlights the ecological
and cultural diversity of the region but also supports sustainable development and
conservation efforts.

Beyond plant knowledge, these communities have developed sophisticated ecosystem
management practices. Indigenous forest management practices in NE India have
significantly contributed to maintaining biodiversity hotspots and preserving wildlife habitats.
Traditional agroforestry systems, such as jhum cultivation practiced by the Karbi and Khasi
tribes, have shown resilience to climate variability while supporting local livelihoods. According
to a recent United Nations report, indigenous peoples’ territories encompass about 80% of the
world’s remaining biodiversity, underscoring the importance of their stewardship in
conservation efforts.

The wisdom of the hills and valleys also embodies resilience—a capacity to adapt and thrive
amidst changing circumstances. Indigenous communities have overcome challenges like
floods, droughts, and shifting climates by drawing on their deep ecological knowledge.

Panimur Waterfalls, Dima Hasao

According to the Indian State Forest Report 2021, Assam’s forest cover is around 35% of its
geographical area, highlighting its critical role in biodiversity conservation and carbon
sequestration. However, this forest cover is declining, and the region faces environmental and
climate challenges, including deforestation, riverbank erosion, and climate change impacts.

Preserving and promoting traditional ecological knowledge is crucial in the face of the global
climate crisis. According to UNESCO, indigenous communities’ traditional knowledge
significantly contributes to the sustainable management of natural resources, benefiting both
local communities and global biodiversity. Recognizing, valuing, and supporting these
practices are essential for environmental conservation, cultural identity, and community
resilience.

Celebrating the wisdom of Assam and Northeast India’s hills and valleys on World
Environment Day reminds us of the transformative power of indigenous knowledge.
Integrating their insights into broader restoration efforts can contribute to building a sustainable
future for all. By embracing the wisdom passed down through generations and augmenting it
with contemporary research and statistics, we, the #GenerationRestoration, can pave the way
toward ecological harmony and resilience in the years to come.

Let us change gears to the tea communities of the NE region. Assam also plays a vital role in
India’s tea production, boasting over 312 210 hectares of tea cultivation. These tea plantations
not only fuel the state’s economy but also hold significant cultural and ecological value. Assam
is among the world’s largest tea-producing regions, with an annual production of 500-700
million kilograms (Mkgs) of tea leaves. The tea industry employs a vast workforce and
supports livelihoods throughout the region, contributing significantly to India’s overall tea
production. The tea plantations in Assam are not only unique but also serve as a prime
example of the harmonious blend of agriculture and biodiversity conservation. The lush green
tea bushes are seamlessly intertwined with shade trees, providing a habitat for various birds
and insects. Assam’s tea is globally renowned for its robust flavor and represents a heritage
deeply rooted in the land and its ecosystems. However, climate and environmental changes
threaten these lush industries, impacting the ecological and socio-economic balance in the
region.

View to Guwahati city
View to Guwahati city

The government has launched several key initiatives to promote development, ecological
conservation, and socio-economic growth across the state. Notable initiatives include the
Assam Budget for Sustainable Development, Assam Tea Tribes Welfare Board, Jal Jeevan
Mission (Har Ghar Jal), Assam Arunodoi Scheme, Assam Green Mission, Assam Skill
Development Mission, and Assam Startup. Effective implementation of these programs aims
to address climate change, promote environmental conservation, and improve the overall
quality of life for the people of Assam. However, the success of these programs depends on
thorough execution at the grassroots level.

What unfolds in the remote corners of Assam reverberates across continents. The lessons
gleaned from this region—on biodiversity conservation, traditional knowledge integration, and
community-led resilience—are universal. They inform global discussions on sustainable
development, emphasizing the need for inclusive approaches that prioritize both people and
the planet.

This World Environment Day, let us heed the call of Northeast India—a call to action for
environmental engagement and climate action involving youth, communities, government
agencies, and non-profit organizations. The region’s youth must understand the challenges
facing their environment and take action to safeguard their communities and natural
surroundings amidst infrastructural growth and development for their own and future
generations. Climate mitigation and adaptation strategies tailored to the region’s unique
context are critical, including afforestation, sustainable agriculture, and flood management
solutions. Youth can lead the way in developing context-specific climate adaptation and
environment restoration strategies that respect local cultures and ecosystems. By immersing
themselves in environmental education, research, and activism, young students can amplify
their voices and influence decision-makers at all levels.

Assam and its neighboring states in India stand out as a distinctive and valuable addition to
the mosaic of Earth’s landscapes. They serve as a beacon of hope and possibility in our
collective journey toward planetary stewardship. The region’s unique natural heritage,
combined with its rich cultural and ethnic diversity, makes it an important site for scientific
research and cultural exchange. As we strive to better understand and protect our planet,
regions like Northeast India offer invaluable insights and opportunities for collaboration.

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This blog is written by Dr Jagannath Biswakarma, School of Earth Sciences, University of Bristol, UK. jagannath.biswakarma@bristol.ac.uk.

Jagannath Biswakarma
Jagannath Biswakarma

‘Foul and loathsome’ or jewels of the natural world? The complicated history of human-frog relations

Shutterstock

When was the last time you saw a frog? Perhaps you came across one in your garden and wondered at its little hands, glossy skin and what looked very much like a contented smile.

Maybe you regularly see them on Instagram or TikTok, where “frog accounts” have proliferated in recent years. People share adorable cartoon frogs, coo over crocheted frogs or go gaga for frogs dressed in cute hats.

In fact, our fascination with frogs isn’t new. As our research has found, the history of human-frog relations is long and complicated – and not all of it is nice.

Why we love frogs

There is a rich history of people really loving frogs.

This is interesting, because many people much prefer mammals and birds over reptiles and amphibians.

But the frog is an exception – for a lot of reasons. People tend to be attracted to baby-like faces. Many species of frog have the large eyes characteristic of young animals, humans included.

Having no teeth and no sharp claws, they also do not seem to be immediately threatening, while many of them have beautiful skin colouring and some are improbably tiny.

Frogs are truly among the jewels of the natural world, unlike toads which – with their more mundane colours and “warty skins” – do not usually inspire the same sense of enchantment.

Their beauty connects us to the wider riches of a vibrant nature hidden from most people’s sight in the dense rainforests of the tropical regions.

And they also connect us to nature in our own backyards. At certain times of the year, they spontaneously appear in our gardens and ponds. They can feel like special visitors from the natural world.

Dissecting human feelings for frogs

Yet relationships between people and frogs haven’t always been so positive. In fact, frogs occupy complicated places across cultures all over the world.

In the Western tradition, the legacy of biblical and classical sources was both negative and longstanding.

References to frogs in the Bible rendered them the instrument of divine anger as a swarming plague.

An etching from the late 1700s shows a plague of frogs.
An etching from the late 1700s shows a plague of frogs.
Wellcome Collection

Frogs challenged early modern zoological taxonomies, moving between classification as serpent, insect or reptile.

Perhaps their resistance to easy placement by humans explains the strong emotional language about them used by Swedish naturalist (and “father of modern taxonomy”) Carl Linnaeus.

When he considered the Amphibia in his 1758 Systema Naturae, he noted:

These foul and loathsome animals are abhorrent because of their cold body, pale colour, cartilaginous skeleton, filthy skin, fierce aspect, calculating eye, offensive smell, harsh voice, squalid habitation, and terrible venom.

In modern science, they sit in a branch of zoology, herpetology, that brings frogs together as “creeping animals” with snakes and lizards.

Frogs have also (or perhaps consequently) suffered in the service of science since at least the eighteenth century because it seemed to be possible to easily replicate experiments across multiple frog specimens.

Frogs were particularly crucial to the study of muscles and nerves. This led to ever more violent encounters between experimenters and frog bodies. Italian scientist Luigi Galvani, for example, did experiments in the late 18th century on legs of frogs to investigate what he thought of as “animal electricity”.

Legs of dissected frogs, and various metallic apparatus used to measure what was thought to be electricity flowing in animals
Scientist Luigi Galvani’s 18th-century diagrams of dissected frog legs and various metallic apparatus he used to measure what was thought to be electricity flowing in animals.
Library of Congress

In this sense, frogs were valued as significant scientific objects, their value lying in their flesh, their nervous systems, rather than in their status as living, feeling beings in the world.

In time, experiments with frogs moved beyond the laboratory into the classroom. In the 1930s, schoolchildren were expected to find frogs and bring them to school for dissection in biology classes.

This practice was, however, somewhat controversial, with opponents expressing sentimental attachment to frogs and concerns that such animal cruelty would lead to barbarism.

Recognising the fragility of frogs

So, our relationship with frogs is complicated. From the frogs of Aesop’s Fables to the meme Pepe the Frog, we have projected our own feelings and frustrations onto frogs, and exploited them for science and education.

Frogs have also borne the brunt of our failures as environmental stewards.

By 1990, the world was seeing a global pattern of decline in frog populations due to destruction and degradation of habitat for agriculture and logging, as well as a global amphibian pandemic caused by the chytrid fungus.

Climate change is also making life hard for many species. In 2022, over 40% of amphibian species (of which frogs and toads are by far the largest group) were threatened with extinction. Their vulnerability has seen the frog – especially the red-eyed tree frog – become a symbol for the environment more generally.

So we should delight in frogs and marvel at how beautiful and special they are while we still can, and consider how we might help save them.

Something to reflect on next time you are lucky enough to spot a frog.The Conversation

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This blog is written by Susan Broomhall, Director, Gender and Women’s History Research Centre, Australian Catholic University; Andrea Gaynor, Professor of History, The University of Western Australia, and Cabot Institute for the Environment member, Dr Andy Flack, Senior Lecturer in Modern and Environmental History, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

UK peatlands are being destroyed to grow mushrooms, lettuce and houseplants – here’s how to stop it

Peat is a natural carbon sink but is often found in house plants and other retail products, particularly within the food and farming industry.
New Africa/Shutterstock

During the long, solitary days of lockdown, I found solace in raising houseplants. Suddenly stuck at home, I had more time to perfect the watering routine of a fussy Swiss cheese plant, and lovingly train our devil’s ivy to delicately frame the bookcases.

But I started noticing that these plants, sourced online, often arrived in the post with a passport. Most had travelled from all over Europe, with one common tagline: contains peat.

As a peatland scientist, these labels instantly filled me with horror. Hidden Peat, a new campaign launched by The Wildlife Trusts, is now highlighting the presence of peat in all sorts of consumer products, including house plants.

Peatlands, such as bogs and fens, store more carbon than all of the world’s forests combined. They trap this carbon in the ground for centuries, preventing it from being released into the atmosphere as greenhouse gases that would further warm the climate.

Peatlands have multiple environmental benefits. They are havens for wildlife, providing habitat for wetland birds, insects and reptiles. They supply more than 70% of our drinking water and help protect our homes from flooding.

So why on earth is peat being ripped from these vital ecosystems and stuffed inside plant pots?

From sink to source

Despite their importance, peatlands have been systematically drained, farmed, dug up and sold over the last century. In the UK, only 1% of lowland peat remains in its natural state.

Instead of acting as a carbon sink, it has become one of the largest sources of greenhouse gas emissions in the UK’s land use sector. When waterlogged peat soils are drained, microbes decompose the plant material within it and that results in the release of greenhouse gases such as methane into the air.

Most of the peat excavated, bagged up and sold in the UK is used as a growing medium for plants. Gardeners have become increasingly aware of this problem. Peat-free alternatives have been gaining popularity and major retailers have been phasing out peat-based bagged compost in recent years.

Indeed, the UK government announced they would ban sales of all peat-based compost by 2024. But this legislation has not yet been written and it seems unlikely it will be enacted before the end of the current parliament.

Even if brought in to law, this ban would only stop the sales of peat-based bagged compost of the type you might pick up in the garden centre. Legislation for commercial growers is not expected until 2030 at the earliest. So the continued decimation of the UK’s peatlands could remain hidden in supply chains long after we stop spreading peat on our gardens.

Hide and seek peat

For consumers, it’s almost impossible to identify products that contain peat or use peat in their production. All large-scale commercial mushroom farming involves peat and it is used for growing most leafy salads. It gives that characteristic peaty aroma to whisky, and, as I found out, is a popular growing medium for potted plants.

But you’d struggle to find a peat-free lettuce in the supermarket. The Hidden Peat campaign asks consumers to call for clear labelling that would enable shoppers to more easily identify peat-containing products. Shoppers are also encouraged to demand transparency from retailers on their commitment to removing peat from their supply chains.

You can ask your local supermarket about how they plan to phase out peat from their produce. Some supermarkets are actively investing in new technologies for peat-free mushroom farming.

Make informed purchases by checking the labels on garden centre potted plants or source plants from peat-free nurseries. The Royal Horticultural Society lists more than 70 UK nurseries dedicated to peat-free growing.

You can write to your MP to support a ban on peat extraction and, crucially, the sale of peat and peat-containing products in the UK. That ensures that peat wouldn’t just get imported from other European countries.

Pilots and progress

The UK government recently announced £3.1m funding for pilot projects to rewet and preserve lowland peat, with peat restoration seen as a cornerstone of net zero ambitions. This campaign calls for further acceleration of peatland restoration across the UK.

As a research of the science behind peatland restoration, I see firsthand the enormous effort involved in this: the installation of dams to block old agricultural drainage ditches, the delicate management of water levels and painstaking monitoring of the peat wetness.

I spend a lot of time taking samples, monitoring the progress, feeding results back to the land managers. Like many other conservationists, I work hard to find ways to preserve these critical habitats.

But sometimes, there may be a digger in the adjacent field doing more damage in a day than we could undo in a lifetime. That’s the reality, and the insanity, of the UK’s current peatland policies.

We heavily invest in restoring peatlands, yet fail to ban its extraction – the one action that would have the most dramatic impact. By demanding that peat is not only eradicated from garden compost, but weeded out of our supply chains, we can keep peat in the ground, not in pots.

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This blog is written by Cabot Institute for the Environment member, Dr Casey Bryce, Senior Lecturer, School of Earth Sciences, University of Bristol.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Casey Bryce
Casey Bryce

The clam before the storm

Cornish mussels

How can you not love a bivalve? I certainly spent seaside holidays picking long, thin razor shells out of the sand on the beach, marvelling at their sharp edges and brown and cream patterned growth lines. I still love clambering over rocky shorelines thick with the blue-black ovals of mussels, encrusted with limpets and rough barnacles, layered with salty strands of seaweed.

Bivalves are a keystone part of a rich ocean fauna, interlocked with the ecology of the marine environment and intertwined with lives of both ancestral and modern humans. Seafood, and particularly shellfish such as mussels, oysters, cockles, scallops and clams have long been part of the human diet. The European market for mussels alone topped 600,000 kg last year (FAO.org), the majority of which are consumed in France, Spain and Italy. Just take a moment to imagine the delicious fragrance of a seafood paella, and you will appreciate why they are so popular. Unfortunately, the future of shellfish is becoming more uncertain as the climate heats up. The days when oysters are used to fire the passions of young lovers, or indeed for lovers to gift each other nacre jewellery or pearls, may be coming to an end. Climate change is likely to lead to a scarcity of oysters and an inability for them to thrive, meaning much smaller individuals, which will make such tokens harder to obtain, more expensive or simply not available anymore.

Aside from being a food source, bivalves are an essential part of the ecosystem in both marine and freshwater habitats. One important task that bivalves do is to filter the water, collecting particles of microalgae, phytoplankton, bacteria and silt. The indigestible particles are packaged with mucus and excreted as a sandy deposit that sinks to the sea floor. In this way, bivalves help to clean murky, turbid water. Some bivalves do this at an incredible rate; green mussels (Perna analiculus) or sea scallops (Placopecten magellanicus) can filter in excess of 10 gallons of water every day. Removing and digesting the algae reduces the number of algal blooms that occur, and sticking sediment particles together so they sink, clears the water. This allows light to penetrate deeper into the ocean, benefitting photosynthetic organisms attached to the seabed.

The structure of the seabed is altered by the presence of bivalves. Some bivalves, such as Venus clams (Veneridae) bury themselves in soft sediments, helping to stabilise the sand. Others attach themselves to rocks using strong root-like threads. Reefs are reinforced by encrusting bivalves, which help to reduce shoreline erosion. This feature is becoming more important as the frequency and intensity of severe weather events is set to increase.

The shells of bivalves are made from either calcite or aragonite, which are different forms of calcium carbonate. The two forms are found in different species and at different stages of the life cycle. They have slightly different chemical properties but they both contain carbon in the form of carbonate, which molluscs extract from seawater. When the shellfish die, the shells drift to the ocean floor to begin the transition into rock such as limestones, ultimately locking carbon away and becoming an important carbon sink. Increasing carbon dioxide in the atmosphere means more carbon dioxide is dissolving in the oceans. Although this might seem like a bonus for the shell-building fauna, the carbon dioxide forms a weak solution of carbonic acid, and this is altering the pH of seawater. Acid reacts with carbonate, dissolving it, so that shelly sea creatures have to work harder to build and maintain their shells.

The complexity of reefs and other underwater habitats is enhanced by bivalves, not just with structural strength, but with complex architecture, which provides niches, refuges and points of attachment for other species. Plenty of creatures apart from humans enjoy munching on bivalves. Squid and octopods can prise the hinged shells apart using the suckers on their tentacles to get at the tasty meat inside. Bivalves also contribute to the food web by spawning large volumes of eggs and larvae. These drift on the ocean currents, providing an essential food source for pelagic fish and other hunters, such as baleen whales.

Having convinced you that bivalves are amazing, what does the future hold for hinged molluscs? Many studies have looked at how different conditions affect bivalves, with some coming to positive, and some to negative conclusions. Cherry picking the answer you want does not necessarily reflect the overall trend and can be quite misleading. One way that scientists use to get an overview of multiple studies is to carry out a meta-analysis. This is a way of combining all the studies to give a statistical probability to each value being tested.

We gathered data on how well bivalves grow under different conditions predicted to change by climate change models. Growth rate can be altered by temperature, pH, oxygen availability and salinity. Ocean temperature is increasing, and this will affect the metabolism of cold-blooded organisms, who rely on the external environment for internal temperature regulation. The pH of the oceans is becoming more acidic, causing the thinning of shells in some shelled sea creatures.

Areas of the ocean are becoming periodically, or permanently short of oxygen. This is happening in two ways. There are widespread dead zones spreading out from the estuaries of major rivers (e.g the Ganges or Mississippi) where nitrates and other pollutants are causing eutrophication, which uses up all the dissolved oxygen. Across water courses as a whole, less oxygen is present in water at higher temperatures because oxygen doesn’t dissolve as well in warm as opposed to cold water. Recent summer heat-waves have left a raft of dead, floating, aquatic organisms, both in marine settings and in inland lakes and rivers. Last summer I caught the fire-brigade pumping air into a local fishing pond, trying, mostly unsuccessfully, to prevent the fish from suffocating.

The last climate stressor that we included in our meta-analysis was salinity. As the planet warms, leading to the melting of ice-caps and glaciers, the sea level will rise with the influx of fresh water. This will alter the salinity, especially in the areas of melt-water run-off around coasts where most species of bivalves tend to live. We wanted to see if salinity changes would be problematic for bivalves, and how that would interact with the other climatic changes. One of the interesting things about meta-analyses is that the effect not only of individual stressors can be evaluated, but also the effect of the interaction of stressors. Do they combine to become more than the sum of their parts, or do they counteract each other to have an overall negligible effect?

What we found was that each of the environmental stressors individually reduced bivalve growth, but that combinations of stressors – such as a temperature increase coupled with an increase in acidity – acted together to reduce growth in a more pronounced way. If climate changes in the way that most models are predicting, then they are also predicting fewer, smaller bivalves that take longer to mature. This may disproportionally affect low-income, island nations, such as the Maldives, where a large proportion of the diet is sourced directly from the sea. For the fishing industry, this means sustainable harvesting limits will need to be adjusted over time to allow time for bivalves to grow to maturity.

This is particularly pertinent because the types of bivalves that have been studied are nearly all either commercial or easy-to-collect reef-building species. They come predominately from the northern hemisphere, and there is a distinct lack of studies on African and tropical species. There are over 100 families of bivalves, of which just 18 have had quantitative growth studies carried out. In the studies we used, 81% of them were on just four families: oysters (Ostreidae), mussels (Mytilidae), scallops (Pectinidae) and Venus clams (Veneridae). There are an awful lot of families we know nothing about, and it isn’t necessarily true that how one species responds informs us accurately about what another species might do. Temperature, for example, really slows down the growth of oysters, scallops and mussels, but can increase the growth of Venus clams and pen shells (Pinnidae). I can see you throwing your hands in the air and asking “Why??”

In this case, the answer seems to lie in the habitat or mode of life that the bivalve inhabits. The families that grow faster in warm waters are the type that bury themselves deep in the soft sand or mud of the seabed. This seems to act as a protective buffer against temperature changes, whereas bivalves attached to the surface are exposed to temperature extremes and so they show reduced growth.

The data became even more interesting when we looked at how different life stages responded to environmental stressors. Nearly all (84%) of the studies we could include in our meta-analysis had been carried out on eggs/larvae or juveniles. This of course, makes perfect sense if you are studying growth, as young organisms do an awful lot more growing than adults. It does, however, leave a hole in the data, and that can lead to biased conclusions.

Very young bivalves, which are generally a free-living part of marine plankton, grow less well in warm, acidic or low oxygen conditions. Low salinity doesn’t seem to be an issue. Adults, on the other hand, can tolerate warm, acidic or low oxygen conditions singly, but struggle when these occur in combination. Adults are also strongly affected by low salinity (in the very few studies that have tested this). Again, this makes reasonable sense. Adults are fixed to whichever rock they settled on, and so survival depends far more on metabolic tolerance to environmental extremes. Mobile, free-swimming larval forms have a greater ability to move away from uncomfortable conditions, searching for somewhere they can flourish.

However, larval vulnerability indicates that in the future bivalve populations (as opposed to individuals) will grow more slowly and may suffer from recruitment and settlement problems. It may be difficult, slow or impossible for bivalve colonies to regenerate after disturbance or harvesting, leading to major population crashes.

Climate change is going to pose some challenges to the populations of bivalves. Bivalves supply the seafood industry, filter our water, stabilise our shorelines and produce planktonic larvae, which bolsters the ocean food web. Minimising the effects of climate change will help to protect this keystone fauna and enable them to continue to form such an essential part of the natural world. I hope my children’s children can still delight in finding ropes of mussels and living pearls.

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This blog is written by Rachel Kruft Welton. With thanks to George Hoppit for proof-reading and suggestions. Read more about their research.

Rachel Kruft Welton
Rachel Kruft Welton

Are you a journalist looking for climate experts for COP28? We’ve got you covered

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We’ve got lots of media trained climate change experts. If you need an expert for an interview, here is a list of our experts you can approach. All media enquiries should be made via Victoria Tagg, our dedicated Media and PR Manager at the University of Bristol. 

Email victoria.tagg@bristol.ac.uk or call +44 (0)117 428 2489.

Climate change / climate emergency / climate science / climate-induced disasters

Dr Eunice Lo – expert in changes in extreme weather events such as heatwaves and cold spells, and how these changes translate to negative health outcomes including illnesses and deaths. Follow on Twitter/X @EuniceLoClimate.

Professor Daniela Schmidt – expert in the causes and effects of climate change on marine systems. Dani is also a Lead Author on the IPCC reports.

Dr Katerina Michalides – expert in drylands, drought and desertification and helping East African rural communities to adapt to droughts and future climate change. Follow on Twitter/X @_kmichaelides.

Professor Dann Mitchell – expert in how climate change alters the atmospheric circulation, extreme events, and impacts on human health. Dann is also a Met Office Chair. Follow on Twitter/X @ClimateDann.

Professor Dan Lunt – expert on past climate change, with a focus on understanding how and why climate has changed in the past and what we can learn about the future from the past. Dan is also a Lead Author on IPCC AR6. Follow on Twitter/X @ClimateSamwell.

Professor Jonathan Bamber – expert on the impact of melting land ice on sea level rise (SLR) and the response of the ocean to changes in freshwater forcing. Follow on Twitter/X @jlbamber

Professor Paul Bates CBE – expert in the science of flooding, risk and reducing threats to life and economic losses worldwide. Follow on Twitter/X @paul_d_bates

Dr Matt Palmer – expert in sea level and ocean heat content at the Met Office Hadley Centre and University of Bristol. Follow on Twitter/X @mpclimate.

Professor Guy Howard – expertise in building resilience and supporting adaptation in water systems, sanitation, health care facilities, and housing. Expert in wider infrastructure resilience assessment.

Net Zero / Energy / Renewables

Dr Caitlin Robinson – expert on energy poverty and energy justice and also in mapping ambient vulnerabilities in UK cities. Caitlin will be virtually attending COP28. Follow on Twitter/X @CaitHRobin.

Professor Philip Taylor – Expert in net zero, energy systems, energy storage, utilities, electric power distribution. Also Pro-Vice Chancellor at the University of Bristol. Follow on Twitter/X @rolyatlihp.

Dr Colin Nolden – expert in sustainable energy policyregulation and business models and interactions with secondary markets such as carbon markets and other sectors such as mobility. Colin will be in attendance in the Blue Zone at COP28 during week 2.

Professor Charl Faul – expert in novel functional materials for sustainable energy applications e.g. in CO2 capture and conversion and energy storage devices.  Follow on Twitter/X @Charl_FJ_Faul.

Climate finance / Loss and damage

Dr Rachel James – Expert in climate finance, damage, loss and decision making. Also has expertise in African climate systems and contemporary and future climate change. Follow on Twitter/X @_RachelJames.

Dr Katharina Richter – expert in decolonial environmental politics and equitable development in times of climate crises. Also an expert on degrowth and Buen Vivir, two alternatives to growth-based development from the Global North and South. Katarina will be virtually attending COP28. @DrKatRichter.

Climate justice

Dr Alix Dietzel – climate justice and climate policy expert. Focusing on the global and local scale and interested in how just the response to climate change is and how we can ensure a just transition. Alix will be in attendance in the Blue Zone at COP28 during week 1. Follow on Twitter/X @alixdietzel.

Dr Ed Atkins – expert on environmental and energy policy, politics and governance and how they must be equitable and inclusive. Also interested in local politics of climate change policies and energy generation and consumption. Follow on Twitter/X @edatkins_.

Dr Karen Tucker – expert on colonial politics of knowledge that shape encounters with indigenous knowledges, bodies and natures, and the decolonial practices that can reveal and remake them. Karen will be in attending the Blue Zone of COP28 in week 2.

Climate change and health

Dr Dan O’Hare – expert in climate anxiety and educational psychologist. Follow on Twitter/X @edpsydan.

Professor Dann Mitchell – expert in how climate change alters the atmospheric circulation, extreme events, and impacts on human health. Dann is also a Met Office Chair. Follow on Twitter/X @ClimateDann.

Dr Eunice Lo – expert in changes in extreme weather events such as heatwaves and cold spells, and how these changes translate to negative health outcomes including illnesses and deaths. Follow on Twitter/X @EuniceLoClimate.

Professor Guy Howard – expert in influence of climate change on infectious water-related disease, including waterborne disease and vector-borne disease.

Professor Rachael Gooberman-Hill – expert in health research, including long-term health conditions and design of ways to support and improve health. @EBIBristol (this account is only monitored in office hours).

Youth, children, education and skills

Dr Dan O’Hare – expert in climate anxiety in children and educational psychologist. Follow on Twitter/X @edpsydan.

Dr Camilla Morelli – expert in how children and young people imagine the future, asking what are the key challenges they face towards the adulthoods they desire and implementing impact strategies to make these desires attainable. Follow on Twitter/X @DrCamiMorelli.

Dr Helen Thomas-Hughes – expert in engaging, empowering, and inspiring diverse student bodies as collaborative environmental change makers. Also Lead of the Cabot Institute’s MScR in Global Environmental Challenges. Follow on Twitter/X @Researchhelen.

Professor Daniela Schmidt – expert in the causes and effects of climate change on marine systems. Dani is also a Lead Author on the IPCC reports. Also part of the Waves of Change project with Dr Camilla Morelli, looking at the intersection of social, economic and climatic impacts on young people’s lives and futures around the world.

Climate activism / Extinction Rebellion

Dr Oscar Berglund – expert on climate change activism and particularly Extinction Rebellion (XR) and the use of civil disobedience. Follow on Twitter @berglund_oscar.

Land / Nature / Food

Dr Jo House – expert on land and climate interactions, including emissions of carbon dioxide from land use change (e.g. deforestation), climate mitigation potential from the land (e.g. afforestationbioenergy), and implications of science for policy. Previously Government Office for Science’s Head of Climate Advice. Follow on Twitter @Drjohouse.

Professor Steve Simpson – expert marine biology and fish ecology, with particular interests in the behaviour of coral reef fishes, bioacoustics, effects of climate change on marine ecosystems, conservation and management. Follow on Twitter/X @DrSteveSimpson.

Dr Taro Takahashi – expert on farminglivestock production systems as well as programme evaluation and general equilibrium modelling of pasture and livestock-based economies.

Dr Maria Paula Escobar-Tello – expert on tensions and intersections between livestock farming and the environment.

Air pollution / Greenhouse gases

Dr Aoife Grant – expert in greenhouse gases and methane. Set up a monitoring station at Glasgow for COP26 to record emissions.

Professor Matt Rigby – expert on sources and sinks of greenhouse gases and ozone depleting substances. Follow on Twitter @TheOtherMRigby.

Professor Guy Howard – expert in contribution of waste and wastewater systems to methane emissions in low- and middle-income countries

Plastic and the environment

Dr Charlotte Lloyd – expert on the fate of chemicals in the terrestrial environment, including plasticsbioplastics and agricultural wastes. Follow on Twitter @DrCharlLloyd.

Cabot Institute for the Environment at COP28

We will have three media trained academics in attendance at the Blue Zone at COP28. These are: Dr Alix Dietzel (week 1), Dr Colin Nolden (week 2) and Dr Karen Tucker (week 2). We will also have two academics attending virtually: Dr Caitlin Robinson and Dr Katharina Richter.

Read more about COP on our website at https://bristol.ac.uk/cabot/what-we-do/projects/cop/
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This blog was written by Amanda Woodman-Hardy, Communications and Engagement Officer at the Cabot Institute for the Environment. Follow on Twitter @Enviro_Mand and @cabotinstitute.

Watch our Cabot Conversations – 10 conversations between 2 experts on a climate change issue, all whilst an artist listens in the background and interprets the conversation into a beautiful piece of art in real time. Find out more at bristol.ac.uk/cabot/conversations.

Bats are avoiding solar farms and scientists aren’t sure why

The common pipistrelle. Rudmer Zwerver/Shutterstock

As our planet continues to warm, the need for renewable energy is becoming increasingly urgent. Almost half of the UK’s electricity now comes from renewable sources. And solar accounts for one-fifth of the energy capacity installed since 2019.

Solar farms are now a striking feature of the British landscape. But despite their growth, we’re still largely in the dark about how solar farms impact biodiversity.

This was the focus of a recent study that I co-authored alongside colleagues from the University of Bristol. We found that bat activity is reduced at solar farms compared to neighbouring sites without solar panels.

This discovery is concerning. Bats are top predators of nighttime insects and are sensitive to changes in their habitats, so they are important indicators of ecosystem health. Bats also provide valuable services such as suppressing populations of insect pests.

Nonetheless, our results should not hinder the transition to renewable energy. Instead, they should help to craft strategies that not only encourage bat activity but also support the necessary expansion of clean energy sources.

An aerial shot of a solar farm in south Wales.
Solar farms are now a striking feature of the British landscape. steved_np3/Shutterstock

Reduced activity

We measured bat activity by recording their ultrasonic echolocation calls on bat detectors. Many bat species have distinctive echolocation calls, so we could identify call sequences for each species in many cases. Some species show similar calls, so we lumped them together in species groups.

We placed bat detectors in a solar farm field and a similar neighbouring field without solar panels (called the control site). The fields were matched in size, land use and boundary features (such as having similar hedges) as far as possible. The only major difference was whether they contained solar panels.

We monitored 19 pairs of these sites, each for a week, observing bat activity within the fields’ centre and along their boundaries. Field boundaries are used by bats for navigation and feeding.

Six of the eight bat species or groups studied were less active in the fields with solar panels compared to the fields without them. Common pipistrelles, which made up almost half of all bat activity, showed a decrease of 40% at the edges of solar panel fields and 86% in their centre. Other bat species or groups like soprano pipistrelles, noctules, serotines, myotis bats and long-eared bats also saw their activity drop.

Total bat activity was almost halved at the boundaries of solar panel fields compared to that of control sites. And at the centre of solar panel fields, bat activity dropped by two-thirds.

Why are bats avoiding solar farms?

Conflict between clean energy production and biodiversity isn’t just limited to solar farms; it’s an issue at wind farms too. Large numbers of bats are killed by colliding with the blades of wind turbines. In 2012, for example, one academic estimated that around 888,000 bats may have been killed at wind energy facilities in the United States.

The way solar farms affect bats is probably more indirect than this. Solar panels could, in theory, inadvertently reduce the abundance of insects by lowering the availability of the plants they feed on. We’re currently investigating whether there’s a difference in insect numbers at the solar farm sites compared to the control sites.

Solar panels may also reflect a bats’ echolocation calls, making insect detection more difficult. Reduced feeding success around the panels may result in fewer bats using the surrounding hedgerows for commuting, potentially explaining our findings.

However, bats are also known to collide with smooth vertical flat surfaces because they reflect echolocation calls away from bats and hence appear as empty space. Research has also found that bats sometimes attempt to drink from horizontal smooth surfaces because they interpret the perpendicular echoes as coming from still water. But, given the sloped orientation of solar panels, these potential direct effects may not be of primary concern.

Improving habitats

An important lesson from the development of wind energy is that win-win solutions exist. Ultrasonic acoustic deterrents can keep bats away from wind turbines, while slightly reducing the wind speed that turbines become operational at (known as “cut-in speeds”) has reduced bat fatality rates with minimal losses to energy production. Research suggests that increasing turbine cut-in speeds by 1.5 metres per second can reduce bat fatalities by at least 50%, with an annual loss to power output below 1%.

A slightly different approach could be applied to solar farms. Improving habitats by planting native trees along the boundaries of solar farm fields could potentially increase the availability of insects for bats to feed on.

Research that I have co-authored in recent years supports this theory. We found that the presence of landscape features such as tall hedgerows and even isolated trees on farmland has a positive effect on bat activity.

Carefully selecting solar sites is also important. Prior to construction, conducting environmental impact assessments could indicate the value of proposed sites to bat populations.

More radically, rethinking the siting of these sites so that most are placed on buildings or in areas that are rarely visited by bats, could limit their impact on bat populations.

Solar power is the fastest-growing source of renewable energy worldwide. Its capacity is projected to overtake natural gas by 2026 and coal by 2027. Ensuring that its ecological footprint remains minimal is now particularly important.

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This blog is written by Gareth Jones, Professor of Biological Sciences, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Why are neonicotinoids so polarised?

Bee on yellow flower

The use of neonicotinoid insecticides has been, and still is, a topic of huge controversy and dispute. To use an appropriate analogy, stakeholders appear to fall into one of two neighbouring fields, distinctly fenced off from one another.

In one field, there are those that believe that the scientific evidence revealing the impacts of neonicotinoid compounds on pollinators and the wider environment is more than sufficient to strictly ban their use as a pest management tool. In the other field, interested parties argue that the evidence is convoluted and context specific, and that in some circumstances neonicotinoid use can be a safe, and environmentally resourceful strategy.

But why has this topic become so polarised? And why is there increasingly less space for those that wish to ‘sit on the fence’? This blog summarises the research published in a recent paper by Hannah Romanowski and Lauren Blake. The paper investigates the causes of controversy, and analyses the viability of alternatives in the UK sugar beet system.

What are neonicotinoids?

Neonicotinoids (neonics) are a group of synthetic compounds used as the active ingredient in some insecticides. They are neuroactive, which means that they act on the nervous system of the insect, causing changes in behaviour. They specifically bind to receptors of the nicotinic acetylcholine (nAChRs) enzyme, which are specific to insects, meaning neonics have low toxicity to vertebrates, such as mammals. They are used to control a variety of pests, especially sap-feeding insects such as aphids. Neonics are a systemic pesticide, meaning that they are absorbed by the whole plant (either by seed coating or spraying) and distribute throughout all the plants tissue.

Are neonics legal in the UK?

That’s where things get confusing… the answer is both yes and no. In 2018, the UK prohibited the outdoor use of neonics following a review of the evidence about their risk to pollinators, published by the European Food Safety Authority. However, the UK and many other EU member states have since granted emergency authorisations, which allows the use of neonics under a set of specific circumstances and conditions. The best-known example of this in the UK is the emergency authorisations granted in 2021, 2022 and 2023 for the use of thiamethoxam, one of the banned neonicotinoid compounds, on sugar beet.

However, even if an emergency authorisation is approved by UK Government, the predicted virus incidence (forecasted by Rothamsted Insect Survey) in a given year must be above a decided threshold before authorisation is fully granted. If the threshold is not met, neonicotinoids use remains prohibited. In 2021 for example, Defra set the threshold at 9%, and since the forecast of the virus was only 8.37%, the neonicotinoid seed treatment was not used. The crop went on to grew successfully unscathed by the virus.

Why is sugar beet an exception?

The Expert Committee on Pesticides (ECP) produced a framework in 2020 that laid out a list of requirements for an emergency authorisation of a prohibited pesticide. Requirements include not having an alternative, adequate evidence of safety, limited scale and control of use, and evidence of a permanent solution in development. In essence, the long-term economic and environmental benefits of granting the temporary emergency authorisation must outweigh any potential adverse effects resulting from the authorisation.

Sugar beet farm in Switzerland
Sugar beet farm. Source: Volker Prasuhn, Wikimedia.

Sugar beet is extremely vulnerable to a yield-diminishing group of viruses known as yellows virus (YV). YV are transmitted by an aphid vector, Myzus persicae, which are effectively controlled by neonic seed treatment. Compared to other crop systems, sugar beet is also considered low risk and ‘safer’ as it does not flower before harvest and is therefore not as attractive to pollinator insects. As was found during the research of this paper, there are currently no alternatives as effective as neonics in this system, but long-term solutions are in development. Since sugar beet produces 60% of white sugar consumed in the UK, the economic and environmental impacts of yield loss (i.e. from sugar imports) would be serious. In 2021, the government felt that sugar beet sufficiently met the requirements outlined by the ECP, and emergency authorisation was granted.

What were the aims of this paper?

The main aim of this study was to identify the key issues associated with the debate surrounding the emergency authorisation of neonics on sugar beet, and evaluate and compare current policy with potential alternatives.

Most of the data for this study was collected through semi-structured interviews with nine respondents, each representing a key stakeholder in this discussion. Interviews took place in 2021, just after the announcement that neonics would not be authorised, despite granting the emergency authorisation, as the threshold was not met.

What did this research find?

The main take-home from this research was that uncertainty around the scientific evidence was not the biggest concern to respondents, as was predicted. Instead, respondents were alarmed at the level of polarisation of the narrative.  It was broadly felt that the neonicotinoid debate illustrates the wider issues around environment discussions, that are falsely perceived as a dichotomy, fuelled by media attention, and undermining of science.

The organisation of the sugar beet industry was also considered an issue. In east England, where sugar beet is grown, local growers supply only one buyer, British Sugar. This means that for British Sugar to meet demand they use a contractual system, whereby growers are contracted each year to meet a particular yield. This adds pressure to growers, and means that British Sugar controls the seed supply and therefore the treatment of seeds with synthetic pesticides. One respondent in the study said, “At one time you couldn’t order seed that wasn’t treated with neonicotinoid’.

The study also found that alternatives such as Integrated Pest Management (IPM) and Host Plant Resistance (HPR) were not yet effective in this system. There were 3 reasons why IPM fails. Firstly, sugar beet has a very low yield diminishing threshold for the virus, meaning that it does not take much infection to significantly effect yield. Secondly, the system is extremely specific, meaning that general IPM practices do not work and research on specific methods of IPM (such as natural predators of Myzus persicae) are limited. HPR is in development, and some new varieties of plant with host resistance have been produced, but the virus has multiple strains and no HPR varieties are resistant to all of them. Finally, there is no incentivisation for farmers to take up alternative practices. Due to the contract system, the risk to growers of sugar beet to try new pest management strategies is too high.

What is the latest in 2023?

In 2023, another emergency authorisation was granted, however the threshold set by Defra was increased to 63% virulence. In March, the Rothamsted Virus Yellows forecast predicted an incidence of 67.51%, and so the neonicotinoid seed treatment was used. With this authorisation there are still conditions that growers are required to meet to mitigate any risk to pollinators. This includes no flowering crops being grown for 32 months after neonic treated sugar beet has grown, using herbicides to reduce the number of flowering weeds that may attract pollinators to the field growing treated sugar beet, and compliance with stewardship schemes such as monitoring of neonicotinoid residues in the environment.

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This blog is written by Hannah Romanowski, Biological Sciences, University of Bristol. The paper that this blog is based on can be found here: https://link.springer.com/article/10.1007/s13412-023-00830-z.

Hannah Romanowski

 

Climate change is threatening Madagascar’s famous forests – our study shows how serious it is

Urgent action is needed to protect Madagascar’s forests.
Rijasolo/AFP via Getty Images

Global climate change doesn’t only cause the melting of polar ice caps, rising sea levels and extreme weather events. It also has a direct effect on many tropical habitats and the animals and plants that inhabit them. As fossil fuel emissions continue to drive climate change, large areas of land are forecast to become much hotter and drier by the end of this century.

Many ecosystems, including tropical forests, wetlands, swamps and mangroves, will be unable to cope with these extreme climatic conditions. It is highly likely that the extent and condition of these ecosystems will decline. They will become more like deserts and savanna.

The island nation of Madagascar is of particular concern when it comes to climate change. Of Madagascar’s animal species, 85% cannot be found elsewhere on Earth. Of its plant species, 82% are unique to the island. Although a global biodiversity hotspot, Madagascar has experienced the highest rates of deforestation anywhere in the world. Over 80% of its original forest cover has already been cleared by humans.

This has resulted in large population declines in many species. For example, many species of lemurs (Madagascar’s flagship group of animals) have undergone rapid population decline, and over 95% of lemur species are now classified as threatened on the International Union for Conservation of Nature (IUCN) Red List.

Drier conditions brought about by climate change have already resulted in widespread bush fires throughout Madagascar. Drought and famine are increasingly severe for the people living in the far south and south-western regions of the island.

Madagascar’s future will likely depend profoundly on how swiftly and comprehensively humans deal with the current climate crisis.

What we found

Our study investigated how future climate change is likely to affect four of Madagascar’s key forest habitat types. These four forest types are the dry deciduous forests of the west, humid evergreen forests of the east, spiny bush forests of the arid south, and transitional forests of the north-west corner of the island.

Using computer-based modelling, we simulated how each forest type would respond to climate change from the current period up to the year 2080. The model used the known distribution of each forest type, and current and future climatic data.

We did this under two different conditions: a mitigation scenario, assuming human reliance on greenhouse gas reduces according to climate commitments already made; and an unmitigated scenario, assuming greenhouse gas emissions continue to increase at their current rate.

Our results suggest that unmitigated climate change will result in declines of Madagascar’s forests. The area of land covered by humid forest, the most extensive of the four forest types, is predicted to decrease by about 5.66%. Dry forest and spiny bush are also predicted to decline in response to unmitigated climate change. Transitional forest may actually increase by as much as 5.24%, but this gain will almost certainly come at the expense of other forest types.

We expected our model to show that mitigating climate change would result in net forest gain. Surprisingly, our results suggest entirely the opposite. Forest occurrence will decrease by up to 5.84%, even with efforts to mitigate climate change. This is because global temperatures are forecast to increase under both mitigated and unmitigated scenarios.

These predicted declines are in addition to the huge losses of forest already caused by ongoing deforestation throughout the island.

It looks as if the damage has already been done.

Climate change, a major threat

The results of our research highlight that climate change is indeed a major threat to Madagascar’s forests and likely other ecosystems worldwide. These findings are deeply concerning for the survival of Madagascar’s animals and plants, many of which depend entirely on forest habitat.

Not only will climate change decrease the size of existing forests, changes in temperature and rainfall will also affect the amount of fruit that trees produce.

A Lemur on tree in the forest.
Madagascar lemurs and other animal and plant species may become extinct if the forests disappear.
Rijasolo/AFP

Many of Madagascar’s animals, such as its lemurs, rely heavily on fruit for food. Changes in fruit availability will have serious impact on the health, reproductive success and population growth of these animals. Some animals may be able to adapt to changes in climate and habitat, but others are very sensitive to such changes. They are unlikely to survive in a hot, arid environment.

This will also have serious knock-on effects for human populations that depend on forests and animals for eco-tourism income. Approximately 75% of Madagascar’s population depends on the forest and subsistence farming for survival, and the tourism sector contributes over US$600 million towards the island’s economy annually.

To ensure that Madagascar’s forests survive, immediate action is needed to end deforestation, protect the remaining patches of forest, replant and restore forests, and mitigate global carbon emissions. Otherwise these remarkable forests will eventually disappear, along with all the animals and plants that depend on them.The Conversation

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This blog is written by Daniel Hending, Postdoctoral Research Assistant Animal Vibration Lab, University of Oxford and Cabot Institute for the Environment member Marc Holderied, Professor in Sensory Biology, University of BristolThis article is republished from The Conversation under a Creative Commons license. Read the original article.

Marc Holderied

 

 

Insects will struggle to keep pace with global temperature rise – which could be bad news for humans

Animals can only endure temperatures within a given range. The upper and lower temperatures of this range are called its critical thermal limits. As these limits are exceeded, an animal must either adjust or migrate to a cooler climate.

However, temperatures are rising across the world at a rapid pace. The record-breaking heatwaves experienced across Europe this summer are indicative of this. Heatwaves such as these can cause temperatures to regularly surpass critical thermal limits, endangering many species.

In a new study, my colleagues and I assessed how well 102 species of insect can adjust their critical thermal limits to survive temperature extremes. We found that insects have a weak capacity to do so, making them particularly vulnerable to climate change.

The impact of climate change on insects could have profound consequences for human life. Many insect species serve important ecological functions while the movement of others can disrupt the balance of ecosystems.

How do animals adjust to temperature extremes?

An animal can extend its critical thermal limits through either acclimation or adaptation.

Acclimation occurs within an animal’s lifetime (often within hours). It’s the process by which previous exposure helps give an animal or insect protection against later environmental stress. Humans acclimate to intense UV exposure through gradual tanning which later protects skin against harmful UV rays.

One way insects acclimate is by producing heat shock proteins in response to heat exposure. This prevents cells dying under temperature extremes.

A ladybird drinking a speck of water on a narrow leaf.
Insects in warmer environments develop fewer spots to reduce heat retention.
mehmetkrc/Shutterstock

Some insects can also use colour to acclimate. Ladybirds that develop in warm environments emerge from the pupal stage with less spots than insects that develop in the cold. As darker spots absorb heat, having fewer spots keeps the insect cooler.

Adaptation occurs when useful genes are passed through generations via evolution. There are multiple examples of animals evolving in response to climate change.

Over the past 150 years, some Australian parrot species such as gang-gang cockatoos and red-rumped parrots have evolved larger beaks. As a greater quantity of blood can be diverted to a larger beak, more heat can be lost into the surrounding environment.

A colourful red-rumped parrot perched on a branch.
The red-rumped parrot has evolved a larger beak to cope with higher temperatures.
Alamin-Khan/Shutterstock

But evolution occurs over a longer period than acclimation and may not allow critical thermal limits to adjust in line with the current pace of global temperature rise. Upper thermal limits are particularly slow to evolve, which may be due to the large genetic changes required for greater heat tolerance.

Research into how acclimation might help animals survive exceptional temperature rise has therefore become an area of growing scientific interest.

A weak ability to adjust to temperature extremes

When exposed to a 1℃ change in temperature, we found that insects could only modify their upper thermal limit by around 10% and their lower limit by around 15% on average. In comparison, a separate study found that fish and crustaceans could modify their limits by around 30%.

But we found that there are windows during development where an insect has a greater tolerance towards heat. As juvenile insects are less mobile than adults, they are less able to use their behaviour to modify their temperature. A caterpillar in its cocoon stage, for example, cannot move into the shade to escape the heat.

Exposed to greater temperature variations, this immobile life stage has faced strong evolutionary pressure to develop mechanisms to withstand temperature stress. Juvenile insects generally had a greater capacity for acclimating to rising temperatures than adult insects. Juveniles were able to modify their upper thermal limit by 11% on average, compared to 7% for adults.

But given that their capacity to acclimate is still relatively weak and may fall as an insect leaves this life stage, the impact is likely to be limited for adjusting to future climate change.

What does this mean for the future?

A weak ability to adjust to higher temperatures will mean many insects will need to migrate to cooler climates in order to survive. The movement of insects into new environments could upset the delicate balance of ecosystems.

Insect pests account for the loss of 40% of global crop production. As their geographical distribution changes, pests could further threaten food security. A UN report from 2021 concluded that fall armyworm populations, which feed on crops such as maize, have already expanded their range due to climate change.

A damaged corn crop following an attack by fall armyworms.
The fall armyworm is a damaging crop pest which is spreading due to climate change.
Alchemist from India/Shutterstock

Insect migration may also carry profound impacts on human health. Many of the major diseases affecting humans, including malaria, are transmitted by insects. The movement of insects over time increases the possibility of introducing infectious diseases to higher latitudes.

There have been over 770 cases of West Nile virus recorded in Europe this year. Italy’s Veneto region, where the majority of the cases originate, has emerged as an ideal habitat for Culex mosquitoes, which can host and transmit the virus. Earlier this year, scientists found that the number of mosquitoes in the region had increased by 27%.

Insect species incapable of migrating may also become extinct. This is of concern because many insects perform important ecological functions. Three quarters of the crops produced globally are fertilised by pollinators. Their loss could cause a sharp reduction in global food production.

The vulnerability of insects to temperature extremes means that we face an uncertain and worrying future if we cannot curb the pace of climate change. A clear way of protecting these species is to slow the pace of climate change by reducing fossil fuel consumption. On a smaller scale, the creation of shady habitats, which contain cooler microclimates, could provide essential respite for insects facing rising temperatures.The Conversation

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This blog is written by Hester Weaving, PhD Candidate in Entomology, University of BristolThis article is republished from The Conversation under a Creative Commons license. Read the original article.

Hester Weaving