Water – Cabot Institute for the Environment blog

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

Posted on March 11, 2024 by amanda.woodman-hardy

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.

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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

Posted on February 8, 2024 by amanda.woodman-hardy

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

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

Posted on January 8, 2024January 8, 2024 by amanda.woodman-hardy

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.

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

Posted on October 30, 2023November 28, 2023 by amanda.woodman-hardy

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 policy, regulation 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 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. afforestation, bioenergy), 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 farming, livestock 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 plastics, bioplastics 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℃

Posted on June 29, 2023 by amanda.woodman-hardy

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

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

Posted on April 19, 2023 by amanda.woodman-hardy

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.

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.

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

Posted on March 8, 2023March 8, 2023 by amanda.woodman-hardy

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.

Towards urban climate resilience: learning from Lusaka

Posted on November 29, 2022March 29, 2023 by janet.crompton

“This is a long shot!”

These were the words used by Richard Jones (Science Fellow, Met Office) in August 2021 when he asked if I would consider leading a NERC proposal for a rapid six-month collaborative international research and scoping project, aligned to the COP26 Adaptation and Resilience theme. The deadline was incredibly tight but the opportunity was too good to pass up – we set to work!

Background to Lusaka and FRACTAL

Zambia’s capital city, Lusaka, is one of Africa’s fastest growing cities, with around 100,000 people in the early 1960s to more than 3 million people today. 70% of residents live in informal settlements and some areas are highly prone to flooding due to the low topography and highly permeable limestone sitting on impermeable bedrock, which gets easily saturated. When coupled with poor drainage and ineffective waste management, heavy rainfall events during the wet season (November to March) can lead to severe localised flooding impacting communities and creating serious health risks, such as cholera outbreaks. Evidence from climate change studies shows that heavy rainfall events are, in general, projected to increase in intensity over the coming decades (IPCC AR6, Libanda and Ngonga 2018). Addressing flood resilience in Lusaka is therefore a priority for communities and city authorities, and it became the focus of our proposal.

Lusaka was a focal city in the Future Resilience for African CiTies and Lands (FRACTAL) project funded jointly by NERC and DFID from 2015 to 2021. Led by the Climate System Analysis Group (CSAG) at the University of Cape Town, FRACTAL helped to improve scientific knowledge about regional climate in southern Africa and advance innovative engagement processes amongst researchers, practitioners, decision-makers and communities, to enhance the resilience of southern African cities in a changing climate. I was lucky enough to contribute to FRACTAL, exploring new approaches to climate data analysis (Daron et al., 2019) and climate risk communication (Jack et al., 2020), as well as taking part in engagements in Maputo, Mozambique – another focal city. At the end of FRACTAL there was a strong desire amongst partners to sustain relationships and continue collaborative research.

I joined the University of Bristol in April 2021 with a joint position through the Met Office Academic Partnership (MOAP). Motivated by the potential to grow my network, work across disciplines, and engage with experts at Bristol in climate impacts and risk research, I was excited about the opportunities ahead. So when Richard alerted me to the NERC call, it felt like an amazing opportunity to continue the work of FRACTAL and bring colleagues at the University of Bristol into the “FRACTAL family” – an affectionate term we use for the research team, which really has become a family from many years of working together.

Advancing understanding of flood risk through participatory processes

Working closely with colleagues at Bristol, University of Zambia, University of Cape Town, Stockholm Environment Institute (SEI – Oxford), Red Cross Climate Centre, and the Met Office, we honed a concept building on an idea from Chris Jack at CSAG to take a “deep dive” into the issues of flooding in Lusaka – an issue only partly explored in FRACTAL. Having already established effective relationships amongst those involved, and with high levels of trust and buy-in from key institutions in Lusaka (e.g., Lusaka City Council, Lusaka Water Security Initiative – LuWSI), it was far easier to work together and co-design the project; indeed the project conceived wouldn’t have been possible if starting from scratch. Our aim was to advance understanding of flood risk and solutions from different perspectives, and co-explore climate resilient development pathways that address the complex issue of flood risk in Lusaka, particularly in George and Kanyama compounds (informal settlements). The proposal centred on the use of participatory processes that enable different communities (researchers, local residents, city decision makers) to share and interrogate different types of knowledge, from scientific model datasets to lived experiences of flooding in vulnerable communities.

The proposal was well received and the FRACTAL-PLUS project started in October 2021, shortly before COP26; PLUS conveys how the project built upon FRACTAL but also stands for “Participatory climate information distillation for urban flood resilience in LUSaka”. The central concept of climate information distillation refers to the process of extracting meaning from multiple sources of information, through careful and open consideration of the assumptions, strengths and limitations in constructing the information.

The “Learning Lab” approach

Following an initial evidence gathering and dialogue phase at the end of 2021, we conducted two collaborative “Learning Labs” held in Lusaka in January and March 2022. Due to Covid-19, the first Learning Lab was held as a hybrid event on 26-27 January 2022. It was facilitated by the University of Zambia team with 20 in-person attendees including city stakeholders, the local project team and Richard Jones who was able to travel at short notice. The remainder of the project team joined via Zoom. Using interactive exercises, games (a great way to promote trust and exchange of ideas), presentations, and discussions on key challenges, the Lab helped unite participants to work together. I was amazed at the way participants threw themselves into the activities with such enthusiasm – in my experience, this kind of thing never happens when first engaging with people from different institutions and backgrounds. Yet because trust and relationships were already established, there was no apparent barrier to the engagement and dialogue. The Lab helped to further articulate the complexities of addressing flood risks in the city, and showed that past efforts – including expensive infrastructure investments – had done little to reduce the risks faced by many residents.

One of the highlights of the Labs, and the project overall, was the involvement of cartoon artist Bethuel Mangena, who developed a number of cartoons to support the process and extract meaning (in effect, distilling) the complicated and sensitive issues being discussed. The cartoon below was used to illustrate the purpose of the Lab, as a meeting place for ideas and conversations drawing on different sources of information (e.g., climate data, city plans and policies) and experiences of people from flood-affected communities. All of the cartoons generated in the project, including the feature image for this blog, are available in a Flickr cartoon gallery – well worth a look!

Image: Cartoon highlighting role of Learning Labs in FRACTAL-PLUS by Bethuel Mangena

Integrating scientific and experiential knowledge of flood risk

In addition to the Labs, desk-based work was completed to support the aims of the project. This included work by colleagues in Geographical Sciences at Bristol, Tom O’Shea and Jeff Neal, to generate high-resolution flood maps for Lusaka based on historic rainfall information and for future climate scenarios. In addition, Mary Zhang, now at the University of Oxford but in the School of Policy Studies at Bristol during the project, collaborated with colleagues at SEI-Oxford and the University of Zambia to design and conduct online and in-person surveys and interviews to elicit the lived experiences of flooding from residents in George and Kanyama, as well as experiences of those managing flood risks in the city authorities. This work resulted in new information and knowledge, such as the relative perceived roles of climate change and flood management approaches in the levels of risk faced, that was further interrogated in the second Learning Lab.

Thanks to a reduction in covid risk, the second lab was able to take place entirely in person. Sadly I was unable to travel to Lusaka for the Lab, but the decision to remove the virtual element and focus on in-person interactions helped further promote active engagement amongst city decision-makers, researchers and other participants, and ultimately better achieve the goals of the Lab. Indeed the project helped us learn the limits of hybrid events. Whilst I remain a big advocate for remote technology, the project showed it can be far more productive to have solely in-person events where everyone is truly present.

The second Lab took place at the end of March 2022. In addition to Lusaka participants and members of the project team, we were also joined by the Mayor of Lusaka, Ms. Chilando Chitangala. As well as demonstrating how trusted and respected our partners in Lusaka are, the attendance of the mayor showed the commitment of the city government to addressing climate risks in Lusaka. We were extremely grateful for her time engaging in the discussions and sharing her perspectives.

During the lab the team focused on interrogating all of the evidence available, including the new understanding gained through the project from surveys, interviews, climate and flood data analysis, towards collaboratively mapping climate resilient development pathways for the city. The richness and openness in the discussions allowed progress to be made, though it remains clear that addressing flood risk in informal settlements in Lusaka is an incredibly challenging endeavour.

Photo: Participants at March 2022 Learning Lab in Lusaka

What did we achieve?

The main outcomes from the project include:

Enabling co-exploration of knowledge and information to guide city officials (including the mayor – see quote below) in developing Lusaka’s new integrated development plan.
Demonstrating that flooding will be an ongoing issue even if current drainage plans are implemented, with projections of more intense rainfall over the 21st century pointing to the need for more holistic, long-term and potentially radical solutions.
A plan to integrate flood modelling outputs into the Lusaka Water Security Initiative (LuWSI) digital flood atlas for Lusaka.
Sustaining relationships between FRACTAL partners and building new links with researchers at Bristol to enable future collaborations, including input to a new proposal in development for a multi-year follow-on to FRACTAL.
A range of outputs, including contributing to a FRACTAL “principles” paper (McClure et al., 2022) supporting future participatory projects.

It has been such a privilege to lead the FRACTAL-PLUS project. I’m extremely grateful to the FRACTAL family for trusting me to lead the project, and for the input from colleagues at Bristol – Jeff Neal, Tom O’Shea, Rachel James, Mary Zhang, and especially Lauren Brown who expertly managed the project and guided me throughout.

I really hope I can visit Lusaka in the future. The city has a special place in my heart, even if I have only been there via Zoom!

“FRACTAL-PLUS has done well to zero in on the issue of urban floods and how climate change pressures are making it worse. The people of Lusaka have continually experienced floods in various parts of the city. While the problem is widespread, the most affected people remain to be those in informal settlements such as George and Kanyama where climate change challenges interact with poor infrastructure, poor quality housing and poorly managed solid waste.” Mayor Ms. Chilando Chitangala, 29 March 2022

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This blog is written by Dr Joe Daron, Senior Research Fellow, Faculty of Science, University of Bristol;

Science Manager, International Climate Services, Met Office; and Cabot Institute for the Environment member.

Find out more about Joe’s research at https://research-information.bris.ac.uk/en/persons/joe-daron.

The Horn of Africa has had years of drought, yet groundwater supplies are increasing – why?

Posted on November 7, 2022March 29, 2023 by janet.crompton

The Horn of Africa – which includes Somalia, Ethiopia, Kenya and some surrounding countries – has been hit by increasingly frequent and devastating droughts. Despite this, it seems the region has an increasing amount of groundwater. And this water could help support drought-stricken rural communities.

That’s the key finding from our new research, in which we discovered that while overall rainfall is decreasing, an increase in “high-intensity” rainfall has led to more water being stored deep underground. It’s a paradoxical finding, yet one that may help one of the world’s most vulnerable regions adapt to climate change.

In the Horn of Africa, rural communities live in a constant state of water scarcity punctuated by frequent periods of food insecurity. People there rely on the “long rains” between March and May and the “short rains” between October and December to support their lives and livelihoods.

As we write this, the region’s drylands are experiencing a fifth consecutive season of below-average rainfall. This has left 50 million people in acute food insecurity. The droughts have caused water shortages, livestock deaths, crop failures, conflict and even mental health challenges.

The drought is so severe that it is even affecting zebras, giraffes and other wildlife, as all surface waters are drying up and edible vegetation is becoming scarce. Worryingly, a sixth failed rainy season has already been predicted for March to May 2023.

Long rains down, short rains up

In a new paper we investigated changes in seasonal rainfall in the Horn of Africa over the past 30 years. We found the total rainfall within the “long rains” season is declining, perhaps related to the warming of a particular part of the Pacific Ocean. However, rainfall is increasing in the “short rains”. That’s largely due to a climate phenomenon known as the Indian Ocean Dipole, when a warmer-than-usual Indian Ocean produces higher rainfall in east Africa, similar to El Niño in the Pacific.

We then investigated what these rainfall trends mean for water stored below ground. Has it decreased in line with declining “long rains”, or risen due to the increasing “short rains”?

Map of East Africa — The Horn of Africa borders the Red Sea, the Gulf of Aden and the Indian Ocean.
Peter Hermes Furian / shutterstock

To do this we made use of a pair of satellites which orbit repeatedly and detect small changes in the Earth’s gravitational field that can be interpreted as changes in the mass of water storage. If there’s a significant increase in water storage underground, then the satellite will record a stronger gravity field at that location compared to the previous measurement, and vice versa. From this, the mass of water added or lost in that location can be determined.

Using these satellite-derived estimates, we found that water storage has been increasing in recent decades. The increase correlates with the increasing “short rains”, and has happened despite the “long rains” getting drier.

Given that the long rains deliver more seasonal rain than the short rains, we wanted to understand the paradoxical finding that underground water is increasing. A clue is given by examining how rainfall is converted into groundwater in drylands.

When rain is light and drizzly, much of the water that reaches the ground dampens the soil surface and soon evaporates back into the warm, dry atmosphere. To become groundwater, rainfall instead needs to be intense enough so that water will quickly infiltrate deep into the soil. This mostly happens when lots of rain falls at once and causes dry riverbeds to fill with water which can then leak into underground aquifers.

People stand in river, rainy sky. — Heavy rains fill a dry river bed in the Somali region of Ethiopia.
Stanley Dullea / shutterstock

These most intense rainfall events are increasing in the “short rains”, in line with the overall increase in total rain in that season. And despite a decrease in overall rainfall in the “long rains”, intense rainfall has remained consistently high over time. This means that both rainy seasons have enough intense rainfall to increase the amount of water stored underground.

Finally, we demonstrated that the increasing water storage in this region is not connected to any rise in soil moisture near the surface. It therefore represents “banked” water that resides deep below ground and likely contributes to a growing regional groundwater aquifer in this region.

Groundwater can help people adapt to climate change

While early warning networks and humanitarian organisations focus on the urgent impacts of drought, our new research points to a silver lining that may support long-term climate adaptation. Those rising groundwater supplies we have identified may potentially be exploited to support people in rural areas whose food and water are increasingly insecure.

But there are some caveats. First, we have not assessed the depth of the available groundwater across the region, but we suggest that the water table is shallow enough to be affected by seasonal rainfall. This means it may also be shallow enough to support new bore holes to extract it. Second, we do not know anything about the quality of the stored groundwater and whether it can be deemed suitable for drinking. Finally, we do not know exactly what will happen if the most extreme droughts of the past few seasons continue and both long and short rains fail, causing intense rainfall to decrease too.

Nevertheless, our findings point to the need for extensive groundwater surveys across the Horn of Africa drylands to ascertain whether this increasing water resource may be viable enough to offset the devastating droughts. Groundwater could potentially irrigate fields and provide drinking water for humans and livestock, as part of a strategy to help this vulnerable region adapt to the effects of climate change.

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This blog was written by Cabot Institute for the Environment member Katerina Michaelides, Associate Professor, School of Geographical Sciences, University of Bristol; Michael Singer, Professor in Physical Geography (Hydrology and Geomorphology), Cardiff University; and Markus Adloff, PostDoctoral Researcher, Earth System Modelling, Université de Berne. This article is republished from The Conversation under a Creative Commons license. Read the original article.

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

Posted on October 25, 2022April 16, 2023 by janet.crompton

We’ve got lots of media trained climate change experts. If you need an expert for an interview, here is a list of Caboteers 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

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 Vikki Thompson – expert on climate extremes, particularly heat extremes. Follow on Twitter @ClimateVikki

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 @jlbamber

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

Professor Tony Payne – expert in the effects of climate change on earth systems and glaciers.

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

Net Zero / Energy / Renewables

Professor Valeska Ting – Engineer and expert in net zero, low carbon technologies, low carbon energy and flying. Also an accomplished STEM communicator, is an BAME Expert Voice for the BBC Academy. Follow on Twitter @ProfValeskaTing.

Dr Colin Nolden – expert in sustainable energy policy, regulation and business models and interactions with secondary markets such as carbon markets and other sectors such as mobility. Colin will be at COP27. Colin will be in attendance in the Blue Zone at COP27.

Climate finance

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 at COP27. Follow on Twitter @alixdietzel. Alix will be in attendance in the Blue Zone at COP27.

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.

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.

Land, nature and food

Viola Heinrich – expert in emissions and climate mitiagion potential within the land use sector in the tropics, especially the Brazilian Amazon. IPCC author. Follow on Twitter @vh_trees.

Dr Taro Takahashi – expert on farming, livestock production systems as well as progamme 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.

Climate change and infrastructure

Dr Maria Pregnolato – expert on effects of climate change and flooding on infrastructure. Follow on Twitter @MariaPregnolat1.

Plastic and the environment

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

Climate change and health

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

Cabot Institute for the Environment at COP27

We will have three academics in attendance at the Blue Zone at COP27. These are:

Dr Alix Dietzel, Dr Rachel James and Dr Colin Nolden. All are media-trained and feature in the list above.

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.