How fly fishing strengthens our connection with wildlife and fosters conservation efforts

Whether it’s to reset our mental health or simply to take time out from the hurly-burly of work and urban life, many of us head for oceans and rivers to enjoy their restorative capacities.

Encountering wild animals in these blue spaces contributes to the beneficial effects of being in nature and forms the basis of tourist economies the world over.

Yet, how does our presence affect the creatures that call blue spaces home, and how do encounters with wild species change our relationships with natural environments?

River and stones with green trees and shade
The River Lyd, Devon. Avi Shankar

For nearly a decade, we have been researching human interactions with wild trout and salmon in the context of fly fishing. We spent months immersed in river environments both in the UK (the Lyd and Tamar in Devon, and the Usk and Wye in Wales) and North America (the rivers of the Gaspe region, Quebec and Lewisburg, Pennsylvania). We went fishing, observed and interviewed fly fishers, and learned as much as we could about fish behaviour.

In our recent paper, we explain how human interactions with fish can result in three kinds of interspecies encounters that strengthen people’s connections with wildlife and natural environments.

Separated encounters

Most often, wild animals remain indifferent to humans, driven as they are by natural motivations to feed and breed, within environmental habitats that humans do not fully understand.

For instance, Duane, a novice fly fisher we interviewed in Pennsylvania, didn’t know that trout eat aquatic insects: “I didn’t know squat … flies actually come out of the water?”

This lack of understanding of other species often ensures that wild animals remain undisturbed by human presence. Yet the elusiveness of creatures such as trout and salmon can also motivate people to find out more about them.

Slippery encounters

To improve their chances of catching fish, fly fishers learn about fish behaviour, river environments and the life cycles of the insects that fish feed on.

Equipped with this knowledge, fly fishers become better able to locate trout and salmon, and to select and cast a near weightless imitation “fly” designed to mimic a fish’s insect food.

Learning and honing these skills is a lifelong project during which fly fishers become savvy hunters with heightened abilities to sense what is going on in the water. Equally, fish learn too, becoming shy and ready to slip away from human contact.

Sticky encounters

On the rare occasions that fish are hooked, humans and fish enter what we call a “sticky encounter”. The mixed emotions of catching a wild salmon are captured in Annetta’s field notes:

I look down at this beautiful, majestic being. The fish is a fresh, healthy, silver, bright female … I look at her, she looks back at me … She wrangles free. She’s on a mission to spawn in her home river. I stand up but I’m weak in the knees. Full of pride, humility, and guilt.

Over time, these intense experiences of eye-to-eye contact can inspire fly fishers to consider the welfare of fish.

A wild Usk brown trout in a net
Netted: a wild Usk brown trout – most fly fishers now carefully return their catch back into the river. Avi Shankar

Fly fishers now release the majority of the fish they catch. Moreover, one fly fisher we interviewed explained that he has entirely removed the hooks from his flies, declaring: “I don’t want to catch that fish. I caught so many in my life. I know what the feeling is like.”

Stewarding blue spaces

It may seem ironic that fly fishers become passionate about conserving fish and river environments by practising what many people consider to be a cruel sport. Yet, fly fishers have first-hand experience of declining fish numbers.

Some of our interviewees spoke of trout and salmon as “canaries in the coal mine” – a warning sign of how river ecosystems are threatened by pollution, overdevelopment and climate change. In response, organisations such as the Wild Trout Trust and the Atlantic Salmon Trust highlight the necessity for conservation.

With wild populations of animals declining globally, the presence of humans in blue spaces deserves scrutiny. Nevertheless, interspecies encounters can change the relationship between people, fish and rivers from one of human gratification to one of reciprocity, stewardship and care.

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This blog is written by Professor Avi Shankar, Professor of Consumer Research at the University of Bristol. It is republished from The Conversation under a Creative Commons license. Read the original article.

Avi Shankar standin in the street
Professor Avi Shankar

To address the growing issue of microplastics in the Great Lakes, we need to curb our consumption

Microplastics in the environment is a growing global problem.
(Shutterstock)

You would be hard-pressed to find a corner of the world free from microplastics, plastic particles measuring less than five millimetres. They contaminate our drinking water, accumulate in the food we eat and have been found in the human body, including in blood, organs, placenta, semen and breast milk.

In April, delegates from across the world came together in Ottawa for the fourth session of the Intergovernmental Negotiating Committee to develop a legally binding international treaty on plastic pollution. The meeting offered a unique opportunity to identify strategies for addressing the human and environmental health impacts of plastics, including microplastics.

But do we really know what it would take to mitigate the rising amounts of microplastics in the environment?

In the Great Lakes, plastic pollution along the shorelines poses a major challenge: 86 per cent of litter collected on Great Lakes beaches is either partially or completely composed of plastic. This is worrisome, given the lakes supply 40 million people with drinking water and represent a combined GDP of US$6 trillion. Yet, recent studies show levels of microplastics reaching up to thousands of particles per cubic metre in some areas of the lakes.

CBC News takes a look at the amount of microplastics in the Great Lakes.

Mismanaged plastic waste

Improving waste management alone is unlikely to address microplastic pollution in the Great Lakes. Consider one of the most common pieces of litter on a beach: a 500 ml plastic bottle. If that bottle is not picked up and placed in a landfill or recycled, over the years it will break down into microplastics; the complete disintegration of the bottle into 100 micrometre size particles would produce 25 million microplastics.

Based on reported concentrations of microplastics and water flow rates of the Great Lakes, we can estimate the yearly amounts of plastic that need to be entering the lakes to match the concentrations of microplastics currently observed.

For Lake Superior, this adds up to the same mass of plastic contained in 1,000 bottles. But Lake Superior is the cleanest of the Great Lakes. For Lakes Huron, Michigan, Erie and Ontario, the corresponding estimates are 3,000, two million, 18,000, and nine million bottles, respectively.

According to the Canadian government’s own estimation, Canadians living in the Great Lakes Basin throw away more than 1.5 million tons of plastic waste each year, equivalent to 64 billion 500 ml bottles. If we include the United States, the total amount of plastic waste in the Great Lakes Basin rises to 21 million tons per year (or 821 billion 500 ml bottles).

For Canada and the U.S., the fraction of mismanaged plastic waste that leaks into the environment because it is not recycled, incinerated or landfilled is estimated to be between four and seven per cent.

According to our calculations, this means that it would take less than 0.001 per cent of the total mass of plastics consumed annually within the Great Lakes Basin to generate the number of microplastics present in the lakes. In other words, just 0.02 per cent of the mismanaged plastic waste already explains the microplastic concentrations in the Great Lakes — the other 99.8 per cent ending up as macro- to micro-sized litter in soils, waterways, ponds, beaches and biota.

plastic rubbish on the ground with driftwood
Plastic garbage on the shore of Lake Erie.
(Shutterstock)

What these calculations imply is that the shedding of even very minor, and arguably unavoidable, microplastic particles over the lifetime of a product can lead to significant accumulations of environmental microplastics, including in areas far removed from their source.

While better plastic waste management can help alleviate microplastics pollution, we should not count on it to bring down the microplastics concentrations in all five Great Lakes.

Curbing pollution

Microplastic pollution comes not only from plastic litter in the environment, but also from plastic that is thrown in the trash bin. Even long-lived plastics, such as those that are used in the construction industry, shed microplastics through natural wear and tear.

Once they enter an ecosystem, microplastics become extremely difficult and expensive to clean up. Recycling is the best option currently available, but even this process has been shown to produce microplastics.

At present, less than 10 per cent of plastic is recycled worldwide. With plastic production predicted to triple by 2060, achieving a fully circular plastic economy — where all plastic produced is recycled without shedding microplastic particles — faces huge economic, social, environmental and technological challenges.

And it would take many years to establish such a system, all while microplastic pollution continues to worsen. If we are serious about reducing microplastics concentrations in the environment, the reasonable course of action would be to start reducing plastic production and consumption now.The Conversation————————————

This blog is co-written by Cabot Institute for the Environment member Dr Lewis Alcott, Lecturer in Geochemistry, University of Bristol; Fereidoun Rezanezhad, Research Associate Professor, Department of Earth & Environmental Sciences, University of Waterloo; Nancy Goucher, Knowledge Mobilization Specialist, University of Waterloo; Philippe Van Cappellen, Professor of Biogeochemistry and Canada Excellence Research Chair Laureate in Ecohydrology, University of Waterloo, and Stephanie Slowinski, Research Biogeochemist, University of Waterloo

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

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

East Africa must prepare for more extreme rainfall during the short rainy season – new study

Rainy season in Kenya

East Africa has recently had an unprecedented series of failed rains. But some rainy seasons are bringing the opposite: huge amounts of rainfall.

In the last few months of 2023, the rainy season known as the “short rains” was much wetter than normal. It brought severe flooding to Kenya, Somalia and Tanzania. In Somalia, more than 2 million people were affected, with over 100 killed and 750,000 displaced from their homes. Tens of thousands of people in northern Kenya lost livestock, farmland and homes.

The very wet short rainy seasons are linked to a climate event known as a positive Indian Ocean Dipole (known as the “IOD”). And climate model projections show an increasing trend of extreme Indian Ocean dipoles.

In a new research paper, we set out to investigate what effect more frequent extreme Indian Ocean Dipole events would have on rainfall in east Africa. We did this using a large number of climate simulations and models.

Our results show that they increase the likelihood of very wet days – therefore making very wet seasons.

This could lead to extreme weather events, even more extreme than the floods of 1997, which led to 10 million people requiring emergency assistance, or those of 2019, when hundreds of thousands were displaced.

We recommend that decision-makers plan for this kind of extreme rainfall, and the resulting devastating floods.

How the Indian Ocean Dipole works

Indian Ocean Dipole events tend to occur in the second half of the year, and can last for months. They have two phases: positive and negative.

Positive events occur when the temperature of the sea surface in the western Indian Ocean is warmer than normal and the temperature in the eastern Indian Ocean is cooler than normal. Put simply, this temperature difference happens when winds move warmer water away from the ocean surface in the eastern region, allowing cooler water to rise.

In the warmer western Indian Ocean, more heated air will rise, along with water vapour. This forms clouds, bringing rain. Meanwhile, the eastern part of the Indian Ocean will be cooler and drier. This is why flooding in east Africa can happen at the same time as bushfires in Australia.

The opposite is true for negative dipole events: drier in the western Indian Ocean and wetter in the east.

Under climate change we’re expecting to see more frequent and more extreme positive dipole events – bigger differences between east and west. This is shown by climate model projections. They are believed to be driven by different paces of warming across the tropical Indian Ocean – with western and northern regions projected to warm faster than eastern parts.

Often heavy rain seasons in east Africa are attributed to El Niño, but recent research has shown that the direct impact of El Niño on east African rainfall is actually relatively modest. El Niño’s principal influence lies in its capacity to bring about positive dipole events. This occurs since El Niño events tend to cool the water in the western Pacific Ocean – around Indonesia – which also helps to cool down the water in the eastern Indian Ocean. These cooler temperatures then help kick-start a positive Indian Ocean Dipole.

Examining unprecedented events

Extreme positive Indian Ocean Dipole events are rare in the recent climate record. So to examine their potential impacts on rainfall extremes, we used a large set of climate simulations. The data allowed us to diagnose the sensitivity of rainfall to larger Indian Ocean Dipole events in a statistically robust way.

Our results show that as positive dipole events become more extreme, more wet days during the short rains season can be expected. This effect was found to be largest for the frequency of extremely wet days. Additionally, we found that as the dipole strength increases, the influence on the most extreme days becomes even larger. This means that dipole events which are even slightly “record-breaking” could lead to unprecedented levels of seasonal rainfall.

Ultimately, if positive Indian Ocean Dipole seasons increase in frequency, as predicted, regular seasons of flooding impacts will become a new normal.

One aspect not included in our analysis is the influence of a warmer atmosphere on rainfall extremes. A warmer atmosphere holds more moisture, allowing for the development of more intense rain storms. This effect could combine with the influence of extreme positive dipoles to bring unprecedented levels of rainfall to the Horn of Africa.

2023 was a year of record-breaking temperatures driven both by El Niño and global warming. We might expect that this warmer air could have intensified rain storms during the season. Indeed, evidence from a recent assessment suggests that climate change-driven warming is highly likely responsible for increased rainfall totals.

Responding to an unprecedented future

Policymakers need to plan for this.

In the long term it is crucial to ensure that any new infrastructure is robust to withstand more frequent and heavier rains, and that government, development and humanitarian actors have the capacity to respond to the challenges.

Better use of technology, such as innovations in disseminating satellite rainfall monitoring via mobile phones, can communicate immediate risk. New frontiers in AI-based weather prediction could improve the ability to anticipate localised rain storms, including initiatives focusing on eastern Africa specifically.

Linking rainfall information with hydrological models designed for dryland environments is also essential. These will help to translate weather forecasts into impact forecasts, such as identifying risks of flash flooding down normally dry channels or bank overflow of key rivers in drylands.

These technological improvements are crucial. But better use of the forecast information we already have can also make a big difference. For instance, initiatives like “forecast-based financing”, pioneered by the Red Cross Red Crescent movement, link forecast triggers to pre-approved financing and predefined action plans, helping communities protect themselves before hazards have even started.

For these endeavours to succeed, there must be dialogue between the science and practitioner communities. The scientific community can work with practitioners to integrate key insights into decisions, while practitioners can help to ensure research efforts target critical needs. With this, we can effectively build resilience to natural hazards and resist the increasing risks of our changing climate.The Conversation

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This blog is written by David MacLeod, Lecturer in Climate Risk, Cardiff University; Erik W. Kolstad, Research professor, Uni Research; Cabot Institute for the Environment member Katerina Michaelides, Professor of Dryland Hydrology, School of Geographical Sciences, University of Bristol, and Michael Singer, Professor of Hydrology and Geomorphology, Cardiff University. 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

How do you manage a dam when there’s a tropical cyclone in Mozambique?

Mozambique dam

I’d never given a huge amount of thought of what a dam manager did until I visited Pequenos Libombos dam in Mozambique in October 2023. Standing at the dam, in hot conditions, listening to the lived experience of people who work on the ground and explain what they do during a tropical cyclone leaves you with more understanding than any peer reviewed journal article. Context is everything. It’s why visiting the countries I’m researching is something I do given the chance.

That’s what members of Bristol projects REPRESA (co-led by Prof Elizabeth Kendon at University of Bristol & UK Met Office, Dr Luis Artur from Eduardo Mondlane University and Prof Francois Engelbrecht from University of the Witwatersrand) and SALIENT (led by Dr Rachel James, University of Bristol) did in October. The REPRESA project aims to understand compound tropical cyclone risks, impacts of tropical cyclones and improve early warning systems in Mozambique, Malawi and Madagascar. Seeing the research alignment in projects, the SALIENT team also joined. The SALIENT project aims to improve the characterisation and communication of future climate information for national adaptation planning in southern Africa.

On the field trip day, we travelled to Pequenos Libombos dam and heard from a government official from the Vila De Boane Municipality. It was this day where I had my epiphany that if I ever left academia, dam management is not my calling. Providing water to the local population is the dams primary role and it provides 2 million people within Maputo Province with access to water. That is more than 4 times the population of Bristol.

The management of Pequenos Libombos dam is difficult as there are many other people and industries to consider and keep safe and happy when making decisions. From the businesses who want to use the dam’s water for industrial purposes to the farming communities that are reliant on the water for irrigation, and hydroelectricity companies that want to use the dam to create energy to the communities downstream that may be flooded if the dam releases water too quickly. The dam catchment is also shared with 2 of Mozambique’s neighbouring countries; eSwatini and South Africa, adding another element of complexity to the dams management.

Management must carefully balance both periods of water surplus and deficit and Maputo has experienced numerous extreme weather events in recent years.  The 2015-2016 southern African drought impacted Central and Southern Mozambique and more recently the remnants of tropical cyclones in 2019, 2011, 2022 and 2023. During February 2023, Tropical Cyclone (TC) Freddy passed over Madagascar and southern Mozambique before returning a couple of weeks later to central Mozambique. It is thought to be the longest lived and have the highest accumulated cyclone energy of any cyclone on record, awaiting formal investigation from the World Meteorological Organization. Although TC Freddy didn’t directly pass over Pequenos Limbombos, its associated rainfall resulted in 250 mm of rainfall at the dam in one day. For context, the Bristol experiences 265mm rainfall, on average, in October, November and December combined. To avoid a breach of the dam, discharge was released at the maximum rate, which is more than 500 time more than normal.

Globally there is evidence that TCs and their impacts are being impacted by climate change. The frequency, intensity and storm tracks of TCs may be changing meanwhile, rising sea levels may lead to higher storm surges. Yet we know a limited amount about how tropical cyclones may act in a future with increased global sea surface and air temperatures.  TCs in the Indian Ocean are particularly under researched, but recent and frequent events have highlighted the importance of understanding TCs in a changing climate.

After hearing about the vast amount of rain that fell in February 2023, we walk past the disused hydroelectric generator that was forced to cease operation during the drought as it was no longer economically viable. It really hammered home the complexities faced when trying to manage such a huge piece of infrastructure during extreme events. Similarly, it is clear why research projects like REPRESA and SALIENT are needed to understand how tropical cyclones may behave in the future and explore how early warning systems and climate change adaptation can be strengthened.

Mozambique dam

The human side of extreme weather

After the talk at Pequenos Libombos Dam, we visited the Municipality of Vila de Boane. Vila de Boane is located roughly 15 km downstream from the dam and the River Umbuluzi passes through the municipality. The municipality experienced large scale flooding after the dam was forced to increase to maximum discharge during the February 2023 rainfall.

Despite already hearing about TC’s Freddy’s impacts at the dam, they were not as focused on the human impact. The leader of the municipality compellingly described how 16,000 people were impacted overnight, 6000 people were displaced and 6 people sadly died. The community water pump was destroyed, leaving people without water for 3 months. The municipality leader said he had never seen that amount of water passing through the municipality at such high speed before. Meanwhile, money that had been budgeted for development initiatives, had to be redirected to repair and response. It was not clear if extra money had been sourced for the development initiatives.

It was also highlighted that the increased release of water from the dam occurred over night with little warning. The municipality had been told to expect “above normal” rainfall and to avoid being close to rivers and move farming machinery further inland. But as the municipality leader questioned, what does “above normal” actually mean? People will perceive this message differently, which will influence how they act upon it. As part of the SALIENT research project, I am researching how we best communicate future climate information to decision makers and this anecdote will stay with me. It’s clear that improved communications are needed in both weather and climate services, something REPRESA is also aiming to research further.

Reflections and collaboration

After hearing about the vast amount of impacts the flooding had on Villa de Boane, we waited for our transport back to Maputo under the shade as it was too hot to stand in the sun. It was clear everyone from the REPRESA and SALIENT teams, both physical scientists and social scientists, had taken a lot from the field day. There was discussion about what the research should consider as well as the different angles that could be taken. It also fostered collaboration, SALIENT team member, Alan-Kennedy Asser, is providing the REPRESA team with analysis of precipitation trends from a multiple ensembles of climate models to characterise the range in future projections over the region. Meanwhile I spoke with some REPRESA team members in more depth about future climate information and will be providing risk communication training session in the future.

My personal key take away is that understanding the context and hearing the lived experiences of people working and living with extreme weather events enriches me as a researcher. Similarly, collaborating with researchers and practitioners on different projects enhances your work by providing questions and inputs from different standpoints. And finally, I’m too indecisive a person to ever be a good dam manager.

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This blog is written by Cabot Institute for the Environment member, Dr Ailish Craig, School of Geographical Sciences, University of Bristol with contributions from Dr Alan Kennedy-Asser, School of Geographical Sciences, University of Bristol and Dr Rachel James, School of Geographical Sciences, University of Bristol.

Ailish Craig
Dr Ailish Craig

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.

Limiting global warming to 2℃ is not enough – why the world must keep temperature rise below 1℃

Warming of more than 1℃ risks unsafe and harmful outcomes for humanity.
Ink Drop/Shutterstock

The Paris Climate agreement represented a historic step towards a safer future for humanity on Earth when it was adopted in 2015. The agreement strove to keep global heating below 2℃ above pre-industrial levels with the aim of limiting the increase to 1.5℃ if possible. It was signed by 196 parties around the world, representing the overwhelming majority of humanity.

But in the intervening eight years, the Arctic region has experienced record-breaking temperatures, heatwaves have gripped many parts of Asia and Australia has faced unprecedented floods and wildfires. These events remind us of the dangers associated with climate breakdown. Our newly published research argues instead that humanity is only safe at 1℃ of global warming or below.

While one extreme event cannot be solely attributed to global heating, scientific studies have shown that such events are much more likely in a warmer world. Since the Paris agreement, our understanding of the impacts of global heating have also improved.

A fishing boat surrounded by icebergs that have come off a glacier.
Fishing boat dwarfed by icebergs that came off Greenland’s largest glacier, Jakobshavn Isbrae.
Jonathan Bamber, Author provided

Rising sea levels are an inevitable consequence of global warming. This is due to the combination of increased land ice melting and warmer oceans, which cause the volume of ocean water to increase. Recent research shows that in order to eliminate the human-induced component of sea-level rise, we need to return to temperatures last seen in the pre-industrial era (usually taken to be around 1850).

Perhaps more worrying are tipping points in the climate system that are effectively irreversible on human timescales if passed. Two of these tipping points relate to the melting of the Greenland and West Antarctic ice sheets. Together, these sheets contain enough ice to raise the global sea level by more than ten metres.

The temperature threshold for these ice sheets is uncertain, but we know that it lies close to 1.5℃ of global heating above pre-industrial era levels. There’s even evidence that suggests the threshold may already have been passed in one part of west Antarctica.

Critical boundaries

A temperature change of 1.5℃ might sound quite small. But it’s worth noting that the rise of modern civilisation and the agricultural revolution some 12,000 years ago took place during a period of exceptionally stable temperatures.

Our food production, global infrastructure and ecosystem services (the goods and services provided by ecosystems to humans) are all intimately tied to that stable climate. For example, historical evidence shows that a period called the little ice age (1400-1850), when glaciers grew extensively in the northern hemisphere and frost fairs were held annually on the River Thames, was caused by a much smaller temperature change of only about 0.3℃.

A sign marking the retreat of a glacier since 1908.
Jasper National Park, Canada. Glaciers used to grow extensively in the Northern Hemisphere.
Matty Symons/Shutterstock

A recent review of the current research in this area introduces a concept called “Earth system boundaries”, which defines various thresholds beyond which life on our planet would suffer substantial harm. To avoid passing multiple critical boundaries, the authors stress the need to limit temperature rise to 1℃ or less.

In our new research, we also argue that warming of more than 1℃ risks unsafe and harmful outcomes. This potentially includes sea level rise of multiple metres, more intense hurricanes and more frequent weather extremes.

More affordable renewable energy

Although we are already at 1.2℃ above pre-industrial temperatures, reducing global temperatures is not an impossible task. Our research presents a roadmap based on current technologies that can help us work towards achieving the 1℃ warming goal. We do not need to pull a technological “rabbit out of the hat”, but instead we need to invest and implement existing approaches, such as renewable energy, at scale.

Renewable energy sources have become increasingly affordable over time. Between 2010 and 2021, the cost of producing electricity from solar energy reduced by 88%, while wind power saw a reduction of 67% over the same period. The cost of power storage in batteries (for when the availability of wind and sunlight is low) has also decreased, by 70% between 2014 and 2020.

An aerial photograph of a photovoltaic power plant on a lush hillside.
A photovoltaic power plant in Yunnan, China.
Captain Wang/Shutterstock

The cost disparity between renewable energy and alternative sources like nuclear and fossil fuels is now huge – there is a three to four-fold difference.

In addition to being affordable, renewable energy sources are abundantly available and could swiftly meet society’s energy demands. Massive capacity expansions are also currently underway across the globe, which will only further bolster the renewable energy sector. Global solar energy manufacturing capacity, for example, is expected to double in 2023 and 2024.

Removing carbon dioxide from the atmosphere

Low-cost renewable energy will enable our energy systems to transition away from fossil fuels. But it also provides the means of directly removing CO₂ from the atmosphere at a large scale.

CO₂ removal is crucial for keeping warming to 1℃ or less, even though it requires a significant amount of energy. According to research, achieving a safe climate would require dedicating between 5% and 10% of total power generation demand to effective CO₂ removal. This represents a realistic and attainable policy option.

Various measures are used to remove CO₂ from the atmosphere. These include nature-based solutions like reforestation, as well as direct air carbon capture and storage. Trees absorb CO₂ from the atmosphere through photosynthesis and then lock it up for centuries.

A group of people planting a mangrove forest next to the sea.
A mangrove forest being planted in Klong Khone Samut Songkhram Province, Thailand.
vinai chunkhajorn/Shutterstock

Direct air capture technology was originally developed in the 1960s for air purification on submarines and spacecrafts. But it has since been further adapted for use on land. When combined with underground storage methods, such as the process of converting CO₂ into stone, this technology provides a safe and permanent method of removing CO₂ from the atmosphere.

Our paper demonstrates that the tools and technology exist to achieve a safer, healthier and more prosperous future – and that it’s economically viable to do so. What appears to be lacking is the societal will and, as a consequence, the political conviction and commitment to achieve it.

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This blog is written Cabot Institute for the Environment member Jonathan Bamber, Professor of Glaciology and Earth Observation, University of Bristol and Christian Breyer, Professor of Solar Economy, Lappeenranta University of TechnologyThis article is republished from The Conversation under a Creative Commons license. Read the original article.

Jonathan Bamber
Jonathan Bamber

Nearly a quarter of people in the UK flush wet wipes down the toilet – here’s why they shouldn’t

Shutterstock/BigLike Images

Charlotte Lloyd, University of Bristol

Whether you’re cleaning your house, your car or your child, there are a variety of wet wipes manufactured for the job. Wet wipes are small, lightweight and extremely convenient. They have become a staple in most of our lives, particularly so during and since the COVID-19 pandemic.

But according to Water UK, an organisation representing the water industry, flushing wet wipes down the toilet is responsible for 93% of sewer blockages and costs around £100 million each year to sort out. And the majority of these wipes, about 90%, contain plastic.

Water UK also found that 22% of people admit to flushing wipes down the toilet, even though most of them knew they posed a hazard. And it’s estimated that 300,000 sewer blockages occur every year because of “fatbergs”, with wet wipes one of the main causes.

But it seems wet wipes could soon be banned in England – well, at least the ones that contain plastic – as the government has said it will launch a public consultation on wet wipes in response to mounting concerns about water pollution and blockages. This follows pledges made by major retailers, including Boots and Tesco, to discontinue the sale of such products.

Market projections show that 1.63 million tons of material will be produced in 2023 for wet wipes globally – an industry worth approximately $2.84 billion (£2.04 billion). Though these figures are likely to be on the conservative side as manufacturers increased the production of disinfecting wipes in 2020 during the pandemic – and have remained at the same level since.

Despite the popularity and wide use of wet wipes, not a lot is known about their environmental footprint. This is because manufacturers are not obliged to state what the wipes are made from on the packaging, only the intentionally added ingredients. This creates a challenge for both scientists and consumers alike.

What we know

Wet wipes are made from non-woven fibres that are fused together either mechanically or with the aid of chemicals or heat. The individual fibres can be made from either natural (regenerated cellulose or wood pulp) or petroleum-based (plastic) materials, including polyester and polypropylene.

Most wet wipes are a mixture of natural and synthetic fibres – and the majority contain plastic. As well as the fibres, wet wipes also contain chemicals, including cleaning or disinfecting agents which are impregnated into the material.

Wet wipes, disinfecting wipes.
Wet wipes can cause a lot of issues for our sewerage system.
JoyImage/Shutterstock

Some wipes are designed to be “flushable” and contain chemical binding agents that are designed to release the fibres of the wipe when they are exposed to water. This means that if wipes are not disposed of correctly, they can create both a plastic and a chemical hazard to the environment.

It’s well known that plastic breaks down extremely slowly and persists for centuries in landfill. And if plastic-containing wipes are released into the environment – either through littering or via the sewerage system – they can pose a number of hazards.

The plastic problem

When wet wipes reach the environment – including soil, rivers and the ocean – they generate microplastic pollution in the form of microfibers. Microfibers are one of the most prevalent types of plastic pollution in the aquatic environment and affect ecosystems as well as potentially human health through their introduction into the food chain.

The problem has been exacerbated by these “flushable” wipes. One study identified seven different types of plastics as potential components of flushable wipes – meaning that they still risk being a source of microplastic pollution. Recent work has confirmed that wet wipes (along with sanitary products) are an underestimated source of white microfibers found in the marine environment.

Data on the environmental impact of the associated chemicals is lacking, but this is something my research group is currently working on. What is known though is that plastics have the ability to absorb other contaminants such as metals and pesticides as well as pathogens. And this provides a way for pollution to be transported large distances through the environment.

Flushable wipe going down the toilet.
Are flushable wipes really flushable?
Shutterstock/nito

Driven by environmental concerns as well as impending legislation, many plastic-free wipe products are now available or being developed. But even products made from natural fibres can still pose a problem to sewerage systems and so safe disposal – in a bin – is key.

The scientific evidence surrounding the environmental effects of bio-based plastics (plastics made from non-petroleum sources such as corn or potato starch) is also lacking, so caution is needed when thinking about simply switching from petroleum-based to bio-based plastics.

With this in mind, reusable washable products are a great alternative to disposables and have a much smaller environmental footprint. They are particularly handy around the home when washing is convenient.

That said, there will remain a market for disposables, but manufacturers should have to clearly label what the wipes are made from so that consumers can make a more informed choice.The Conversation


This blog is written by Cabot Institute for the Environment member Dr Charlotte Lloyd, Royal Society Dorothy Hodgkin Research Fellow and Lecturer in Environmental Chemistry, University of Bristol.

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

Charlotte Lloyd
Dr Charlotte Lloyd

Intense downpours in the UK will increase due to climate change – new study

A flash flood in London in October 2019.
D MacDonald/Shutterstock

Elizabeth Kendon, University of Bristol

In July 2021, Kew in London experienced a month’s rain in just three hours. Across the city, tube lines were suspended and stations closed as London experienced its wettest day in decades and flash floods broke out. Just under two weeks later, it happened again: intense downpours led to widespread disruption, including the flooding of two London hospitals.

Colleagues and I have created a new set of 100-year climate projections to more accurately assess the likelihood of heavy rain downpours like these over the coming years and decades. The short answer is climate change means these extreme downpours will happen more often in the UK – and be even more intense.

To generate these projections, we used the Met Office operational weather forecast model, but run on long climate timescales. This provided very detailed climate projections – for every 2.2km grid box over the UK, for every hour, for 100 years from 1981 to 2080. These are much more detailed than traditional climate projections and needed to be run as a series of 20-year simulations that were then stitched together. Even on the Met Office supercomputer, these still took about six months to run.

We ran 12 such 100-year projections. We are not interested in the weather on a given day but rather how the occurrence of local weather extremes varies year by year. By starting the model runs in the past, it is also possible to verify the output against observations to assess the model’s performance.

At this level of detail – the “k-scale” – it is possible to more accurately assess how the most extreme downpours will change. This is because k-scale simulations better represent the small-scale atmospheric processes, such as convection, that can lead to destructive flash flooding.

The fire service attending to a vehicle stuck in floodwater.
Flash flooding can be destructive.
Ceri Breeze/Shutterstock

More emissions, more rain

Our results are now published in Nature Communications. We found that under a high emissions scenario downpours in the UK exceeding 20mm per hour could be four times as frequent by the year 2080 compared with the 1980s. This level of rainfall can potentially produce serious damage through flash flooding, with thresholds like 20mm/hr used by planners to estimate the risk of flooding when water overwhelms the usual drainage channels. Previous less detailed climate models project a much lower increase of around two and a half times over the same period.

We note that these changes are assuming that greenhouse gas emissions continue to rise at current rates. This is therefore a plausible but upper estimate. If global carbon emissions follow a lower emissions scenario, extreme rain will still increase in the UK – though at a slower rate. However, the changes are not inevitable, and if we emit less carbon in the coming decades, extreme downpours will be less frequent.

The increases are significantly greater in certain regions. For example, extreme rainfall in north-west Scotland could be almost ten times more common, while it’s closer to three times more frequent in the south of the UK. The greater future increases in the number of extreme rainfall events in the higher resolution model compared with more traditional lower resolution climate models shows the importance of having k-scale projections to enable society to adapt to climate change.

As the atmosphere warms, it can hold more moisture, at a rate of 7% more moisture for every degree of warming. On a simple level, this explains why in many regions of the world projections show an increase in precipitation as a consequence of human-induced climate change. This new study has shown that, in the UK, the intensity of downpours could increase by about 5% in the south and up to about 15% in the north for every degree of regional warming.

Group of girls with an umbrella walking through a city.
The projected increase in the intensity of rainfall is significantly greater in certain regions.
NotarYES/Shutterstock

However, it is far from a simple picture of more extreme events, decade by decade, as a steadily increasing trend. Instead, we expect periods of rapid change – with records being broken, some by a considerable margin – and periods when there is a pause, with no new records set.

This is simply a reflection of the complex interplay between natural variability and the underlying climate change signal. An analogy for this is waves coming up a beach on an incoming tide. The tide is the long-term rising trend, but there are periods when there are larger waves, followed by lulls.

Despite the underlying trend, the time between record-breaking events at the local scale can be surprisingly long – even several decades.

Our research marks the first time that such a high-resolution data set has spanned over a century. As well as being a valuable asset for planners and policymakers to prepare for the future, it can also be used by climate attribution scientists to examine current extreme rainfall events to see how much more likely they will have been because of human greenhouse gas emissions. The research highlights the importance of meeting carbon emissions targets and also planning for increasingly prevalent extreme rainfall events, which to varying degrees of intensity, look highly likely in all greenhouse gas emissions scenarios.

The tendency for extreme years to cluster poses challenges for communities trying to adapt to intense downpours and risks infrastructure being unprepared, since climate information based on several decades of past observations may not be representative of the following decades.


This blog is written by Cabot Institute for the Environment member Elizabeth Kendon, Professor of Climate Science, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Lizzie Kendon
Professor Lizzie Kendon