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How cold spells are measured and how they are changing

As part of her PhD, Weronika researched the changes in cold spells between 1980-2025, using a new method that tracks cold spells in space and time. She analysed four cold spell characteristics – frequency, intensity, area, and persistence.

Though there can be other contributing factors to changes in cold spells – such as loss of sea ice and shifting weather patterns which can change how much temperature fluctuates about the background warming – Weronika’s research shows that the dominant driver to decreasing cold spells is the rise in Earth’s average temperatures. Global warming is making cold spells less frequent, less intense, and smaller across most of the Northern Hemisphere.

Weronika explains her method: “Local cold events in this study were identified when the temperature dropped below the 5th percent of all temperature values for three consecutive days. Events that meet this requirement are then tracked. We use the winds over the event area to estimate where the cold extreme might be present on the next day. If there is an extreme in this region on the next day, we label this as part of the same cold spell event. This way we build a catalogue of all cold spells, with the knowledge of their location and pathway.”

“This is the first study that considers and compares how cold spells have changed as a result of mean background temperature rise and also from changes in the temperature variability about this background temperature rise,” she emphasises.

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When asked about the most unexpected discovery during her research, Weronika shares: “Only in Northern North America, the reduction in temperature variability about the background mean warming was found to also significantly decrease the frequency and the severity of cold spells. More specifically, we find that the changes in these temperature variabilities in northern North America are found to contribute to one third of the total change in intensity from mean background warming effects. Based on other studies this reduction of temperature variance might be caused by sea ice loss, leading to cold extremes warming faster than hotter extremes.”

Weronika’s work contributes to a growing body of evidence. Research published by the Intergovernmental Panel on Climate Change (IPCC) confirms that winter cold spells have been decreasing since 1950 and that anthropogenic greenhouse gases are very likely the main cause for this.

Weronika shares: “In Europe, studies show there has been a decline in cold spell frequency, with a severity comparable to the European cold winter of 2009/10 being half as likely to occur as a consequence of anthropogenic climate change. IPCC reports also state that, on land, the magnitude of temperature extremes increases more strongly than global mean temperature, and the highest increase of temperature is projected in Arctic regions, at about three times the rate of global warming.”

The importance of looking at cold spells

Where did Weronika’s interest in cold spells come from? She shares:

“Cold spells and snowfall were always a rare occurrence in the winter in the UK, so I found myself wondering when I was younger how they form and why. I think this made me want to research extreme cold weather events to further understand them.”

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Further information

Read the research paper published in AGU Geophysical Research Letters to learn more about Weronika’s work on cold spells.

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What is a storm?

Wind is the movement of air in our atmosphere.

Air is forced to move by differences in atmospheric pressure, and the Earth’s rotation means that the wind circulates around areas of lower pressure, known as a cyclone. If there is a greater difference in pressure, this causes stronger winds around the cyclone.

Storms often bring heavy rainfall that may lead to flooding. Storms move moisture around the atmosphere, which forces warm and moist air to rise. Wherever the warm, moist air rises, clouds are formed. The formation of clouds also releases energy which can further intensify the storm.

Why are storms named?

In the UK, a storm is given a name when it has the potential to cause disruption or damage as a result of strong winds, heavy rainfall or snow, leading to amber or red weather warnings being issued.

In Europe there are three storm naming groups, and each September there is a new alphabetical list of names issued for the upcoming storm season. The UK storm season begins in September and ends in August the following year.

Storms can impact many countries at once, and to avoid confusion, the UK adopts a storm name if another European weather service has already named it.

What causes storms in the UK?

The UK is renowned for being stormy, and it’s because of the jet stream. The jet stream is a core of strong winds around 8-11 km above the Earth’s surface, blowing from west to east, which directs storms across the Atlantic to the UK.

As the jet stream moves storms across the Atlantic, they can draw up more and more moisture, and that’s why storms often bring heavy rainfall to the UK.

What about climate change?

Storms tend to vary naturally in intensity and frequency on an annual basis – this makes identifying trends in storms particularly challenging. However, links between human-caused global warming and storms should be expected.

“As human-caused climate change continues to warm the atmosphere, the air is able to hold more moisture. This leads to more condensation in clouds, releasing more energy and intensifying storms. The result is that storms with heavy rain are expected to become more common, and storms with strong surface winds may be more damaging.”

- Dr Ben Harvey, research scientist at the National Centre for Atmospheric Science and University of Reading

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“The most damaging UK storms tend to be those which intensify quickly, known as explosively deepening cyclones, and these are particularly sensitive to the availability of moisture to fuel their development. But other factors also contribute to the storminess of the UK. For example, the large-scale temperature contrast between the sub-tropical and polar air masses is decreasing as the Arctic rapidly warms. This is expected to contribute to fewer storms overall, even if the most extreme storms intensify.”

- Dr Ben Harvey, research scientist at the National Centre for Atmospheric Science and University of Reading

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Two recent papers written by Dr Kieran Hunt, a meteorologist at the National Centre for Atmospheric Science and University of Reading, trace this evolution, revealing how meteorological English grew from lived experience into a precise scientific language – and why it still carries echoes of its past.

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In its earliest form, meteorological English was built for survival, not science. Words were grounded in what people could feel (wind, rain, and storm) and what they needed to survive.

Early English speakers used experience-based vocabulary to describe the atmosphere – terms shaped by farming, sailing, and exposure to the elements. At this stage, meteorological language was practical and rooted in the natural world rather than influenced by scientific measurements.

For example, the Old English word weder encompassed many of the meanings associated with weather today, but could also refer to wind, air or storms.

The biggest shift in meteorological English came with the rise of modern science in the 17th and 18th centuries.

As atmospheric observation became systematic, scientists needed new terms and more precise meanings for existing terms to describe what they were measuring. The result was a surge of technical terms, and many were borrowed from Latin and Greek.

Words we now take for granted were once innovations. Temperature originally referred to temperate or moderate conditions before being redefined as a measurable quantity. Pressure originally described pain or bodily discomfort before Robert Boyle applied it to a physical quantity in 1660. Humidity entered English from Latin roots relating to moisture and wetness.

Weather was no longer just experienced; it was measured, recorded and predicted. And as meteorology developed into a formal science, its vocabulary became more standardised and widely shared. Growing observational networks and scientific understanding required consistent terminology – enabling communication between researchers, forecasters and the public.

At the same time, older meanings did not disappear entirely. Many words retained traces of their earlier uses, giving modern meteorological English its layered character.

Meteorological English is still evolving, just like the atmosphere itself. And as climate science and forecasting continue to advance, new words, and new meanings, will inevitably emerge.

For researchers at NCAS and beyond, this history is a reminder that communication is central to science. The words used to describe weather shape how it is understood, not just by scientists, but by society.

Explore cloud linguistics

Take a look at the linguistic journeys of 10 weather words

Read Part 1: How weather got its words: a history of meteorological English: Old English to the Age of Discovery

Read Part 2: How weather got its words: a history of meteorological English: The scientific age and beyond

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The expedition, led at sea by Dr Ming-Xi Yang of Plymouth Marine Laboratory, combines two complementary research programmes. COCO-VOC – led by Dr Ming-Xi Yang – focuses on ocean-emitted volatile organic compounds (VOCs). Meanwhile, CARES – led by Professor Alex Archibald of National Centre for Atmospheric Science and University of Cambridge – examines marine sulfur cycling. Together, these projects aim to quantify how gases and aerosols produced by the ocean affect atmospheric chemistry, cloud formation, and climate regulation.

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Sailing from Southampton to the Cape Verde region, the National Oceanography Centre’s research vessel RRS Discovery provided a unique platform for studying ocean–atmosphere exchange across a range of marine environments.

Over a ten-day transit, followed by an intensive two-and-a-half-week study period, the team investigated conditions in both nutrient-poor ocean and more biologically productive coastal zones.

Researchers deployed an advanced suite of instruments onboard, housed in specialised containers across the ship. These measured a broad spectrum of atmospheric gases and aerosol particles, alongside ocean properties from the surface microlayer down to depths of 1000 metres.

A key focus of the work is sulfur chemistry, which plays a pivotal role in cloud formation. Marine sulfur compounds can contribute to aerosol production, influencing cloud reflectivity and lifetime – factors that are central to the Earth’s energy balance.

In parallel, the team studied VOCs emitted from the ocean and how they affect the lifetime of methane, a potent greenhouse gas.

“This is a highly collaborative and integrative science project. By combining detailed atmospheric observations with ocean measurements, we aim to better understand how marine emissions shape atmospheric composition and climate processes.”

– Dr Ming-Xi Yang, research scientist at the Plymouth Marine Laboratory (PML)

The campaign also provides an important training opportunity for early-career researchers, with a cohort of PhD students gaining hands-on experience in field measurements and interdisciplinary science at sea.

More photo: Science in action

Dr Pete Edwards, a research scientist at NCAS and the University of York, emphasises the significance of the work: “These remote ocean processes have strong impacts on climate. Improving our understanding of how gases and particles are exchanged between the ocean and atmosphere will help us refine predictions of future climate change.”

The findings from this campaign are expected to enhance climate models and reduce uncertainties in projections of atmospheric composition and cloud dynamics. By advancing knowledge of remote marine environments – regions that are currently under-observed but globally influential – the project represents a critical step toward more accurate climate forecasting.

On board the research ship

The project brings together expertise from NCAS, PML, and UK universities – including Leeds, York, Manchester and East Anglia – alongside collaborators from the United States and Canada, in a coordinated effort to better understand marine emissions and their global impacts.

This collaborative effort underscores NCAS’s commitment to supporting cutting-edge research that addresses key challenges in understanding the Earth system and its response to environmental change.

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The oceans cover more than 70% of the Earth’s surface. They absorb the majority of solar heat and retain it longer than the land or the atmosphere.

Sea surface temperature – also known as SST – is a significant component of the Earth’s climate system as it impacts the exchanges of energy and gases between the ocean and the atmosphere. SST is an essential tool in weather forecasting and atmospheric model simulations, as well as ecosystem and marine life monitoring and management, and even tourism. In particular, SST helps to identify the El Niño and La Niña cycles, which impact global weather patterns, ocean circulation, and marine ecosystems. We are currently entering a new El Niño, which means that the sea temperatures in the Pacific near the equator are warmer than average.

SST is measured with the use of remote sensing instruments like satellites, and direct measurement instruments, like buoys and ships.

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What’s unusual about sea surface temperatures this year?

The daily global average SST reached its highest temperature on record in August this year. The Copernicus Climate Change Service, which has been monitoring SST since 1979, confirmed that the temperature reached 21.1°C on 22 August, compared to the previous record of 21.09°C in March 2024. The timing of this record is unusual too, as typically global ocean temperatures reach their highest peak in March and April.

As El Niño – set to be the hottest in at least a century – continues to develop, oceans are expected to continue to warm.

How do ocean temperatures affect the UK and the world?

From damaged fisheries to extreme weather events, the rise in ocean temperatures has consequences that spread across the whole world.

Is there a trend of seas getting warmer across recent years?

This new SST record reflects the continued long-term warming of the global ocean. Due to human-induced climate change, warm ocean events are not only becoming more frequent, but they are also more severe and last longer.

According to the National Oceanography Centre, the number of marine heatwaves has doubled since 1982. At the same time, cold marine conditions have become increasingly rare.

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Dr Congbo Song, a researcher at the University of Manchester and , led the analysis of PM2.5, the fine particles produced by smoke that are small enough to travel deep into the lungs and harm health.

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The study found that smoke pollution entered every home monitored during the wildfires, including properties up to 60km from the moorland fires outside Manchester. However, indoor pollution levels were significantly higher in homes where residents had opened windows during the hot weather – as temperatures rose above 33°C.

During the wildfires, average overnight PM2.5 levels in bedrooms increased from a normal level of 2.7 micrograms per cubic metre to 7.8 micrograms per cubic metre when windows were closed, and to 11.8 micrograms per cubic metre when windows were open.

“On average, the enhancement of daily PM2.5 during the wildfire period is 8.6 micrograms in bedrooms and 9.2 micrograms in kitchens, compared to the pre-wildfire baseline,” explains Dr Congbo Song.

He adds: “In some homes, overnight concentrations rose to more than 100 micrograms per cubic metre, many times higher than typical levels. The analysis suggests that more than 80% of the monitored households ventilated more overnight during the heatwave-wildfire events, leading to more wildfire smoke particles infiltrating people’s homes.”

While pollution levels generally rose less in homes where windows remained closed, this did not prevent smoke from entering indoors. Closing windows reduced exposure, but PM2.5 concentrations still remained two to four times higher than normal.

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The researchers say the findings support UK Health Security Agency advice to stay indoors and keep windows closed when wildfire smoke levels are high. However, they also highlight the difficult trade-off many households face during periods of extreme heat.

The findings suggest there is a need for clearer, evidence-based guidance to help households balance the risks of smoke exposure and overheating during wildfire events, especially as periods of extreme heat become more common.

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Intense rainfall can also occur during hot weather because, as the land surface heats up, it warms the air near the ground. This causes the warm air to rapidly rise, known as convection. As the air rises and cools, water vapour condenses into clouds, which can lead to heavy rainfall. A warmer atmosphere becomes ‘thirstier’ for water, driving evapotranspiration and making the ground drier and droughts worse if there is a prolonged shortage of water.

Drought conditions can actually make the impacts of heavy rainfall worse. During prolonged dry spells, soil can become hard and compacted, reducing its ability to absorb water. When heavy rain eventually falls, more of the water runs across the surface rather than soaking into the ground, increasing the risk of flooding.

Does climate change affect every region, or each season, in the same way?

No – while some areas may become hotter and drier overall, others are expected to receive more rainfall. For example, the Mediterranean is projected to get drier, while India is projected to get wetter. Even in places that experience drought, rainfall is often becoming more extreme, with wetter wet periods and drier dry periods.

Climate change impacts on atmospheric circulation can also affect how much rain different regions receive. The North Atlantic storm track, which is most active in winter, is expected to intensify with climate change, bringing more powerful storms and more rainfall to the UK in winter. In contrast, UK summers are projected to become drier overall, although rainfall is likely to be more intense when it does occur.

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What is drought?

Drought represents a chain of impacts across the water cycle. It begins with meteorological drought, when a place receives less rainfall than normal. As the lack of rain continues and soils dry out, there becomes insufficient soil moisture to support crops and vegetation – this is known as agricultural or ecosystem drought. If these conditions are persistent, less water reaches streams, rivers, lakes, reservoirs, and groundwater stores – leading to hydrological drought. Drought typically means a prolonged shortage of rainfall, which creates a shortage in soil moisture, and finally a shortage of water in rivers and other bodies of water.

When a region is declared as in drought, or water scarcity, it is based on an assessment of current water levels and long-term weather forecasts. There may be restrictions on water use in certain areas, such as hosepipe bans, but these don’t always match the local drought conditions due to different plans to manage water between regions.

How is climate change affecting drought?

NCAS research has identified emerging agricultural drought hotspots across Europe, North America, southern Africa and northern South America, where droughts are projected to become more frequent and intense with climate change. These changes pose growing risks to food production, water resources and ecosystems.

Scientists are also warning about a rise in “flash droughts” which develop rapidly over weeks, rather than months. These events can quickly reduce soil moisture, damage crops, increase wildfire risk and threaten livelihoods. Research suggests the frequency of agricultural flash droughts could more than double in parts of Europe, South America and Africa during this century with climate change.

For the UK, drought remains a recurring feature of the climate, but climate change is expected to make summers hotter and drier while increasing evaporation rates. This could raise the risk of summer droughts, placing greater pressure on water supplies, agriculture, biodiversity and public health.

As climate change increases the risk of severe drought, the risk of severe flooding also rises – so while the UK is experiencing prolonged dry conditions during the summer months, it is likely that many regions will also suffer from significant floods in the coming months and year. This is because when it rains, a warmer atmosphere leads to heavier rainfall.

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Role of research in drought preparedness and climate resilience

Recent media coverage of dry conditions across the UK has highlighted the real-world impacts of prolonged periods of low rainfall, from stressed crops and falling reservoir levels to concerns over future water security. These challenges underline the importance of atmospheric science and NCAS’s research, which can provide the evidence needed to understand how climate change is influencing drought risk, helping improve forecasts, inform water management decisions, and strengthen preparedness and climate resilience in a warming world.

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Feedback loop of wildfires and climate change

Wildfires are a natural part of many ecosystems, but human-driven climate change (primarily caused by burning fossil fuels) is making large and severe fires more likely. Higher temperatures, changes in rainfall patterns, and more frequent heatwaves can dry out vegetation and soils, creating landscapes that are more susceptible to burning.

The two-way relationship between wildfires and climate change is complex.

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Forest fires, grassland fires, and climate impacts

The climate impact of wildfires is driven largely by forest fires because forests contain such substantial carbon stocks. As global temperatures rise and precipitation patterns shift, forest fires are becoming more frequent and widespread, increasing the amount of carbon released into the atmosphere.

The total area of land burnt annually is actually dominated by grassland fires, and the area burnt each year has been decreasing because of land use change in Africa. Grassland fires release significant amounts of carbon into the atmosphere, but much of the ecosystem’s carbon remains safely stored underground in roots and soils. When a fire sweeps through, it primarily burns above-ground vegetation.

In healthy ecosystems, much of this carbon can eventually be reabsorbed as vegetation regrows following a fire or in the next growing season. This is part of the natural fire-recovery cycle. However, where fires become more frequent, more severe, or are followed by land-use change, recovery can be slow or incomplete. In these cases, carbon that was previously stored on land can remain in the atmosphere for decades or longer, contributing to climate change.

Wildfires also release large quantities of aerosol particles. One of the most important of these is black carbon. Black carbon absorbs sunlight and can cause short-term warming of the atmosphere. When deposited on snow and ice, it darkens the surface, causing it to absorb more solar radiation and melt more quickly.

Wildfire emissions can influence regions far from the original fire. For example, wildfires in eastern Siberia have contributed to elevated levels of black carbon in the Arctic, and smoke from fires in the Amazon has been linked to decreased albedo and increased melting of glaciers in South America. These impacts demonstrate how wildfire emissions can affect climate processes on regional and global scales.

The impacts of wildfires extend beyond greenhouse gas emissions alone. Smoke particles interact with sunlight and clouds, affecting atmospheric chemistry and weather patterns. Quantifying the effects of wildfires on the climate remains challenging because the amount and composition of emissions vary considerably depending on the type of vegetation burning, fuel conditions, fire behaviour, and weather conditions.

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The role of research in understanding wildfires in a changing world

As wildfires become more frequent and severe in a warming climate, understanding their long-term impacts is increasingly important. Scientists are working to improve estimates of wildfire emissions, understand how wildfire smoke interacts with the atmosphere, and assess how changing fire regimes may influence future climate.

Understanding these interconnected processes is essential for informing climate mitigation, adaptation and environmental risk management. As climate change continues to alter fire-prone regions around the world, evidence-based approaches will be critical for reducing risks and building resilience to future wildfire events.

NCAS research helps improve understanding of the links between wildfires, atmospheric chemistry, air pollution, and climate change. Through advanced atmospheric measurements, Earth observation, modelling and long-term monitoring, NCAS scientists can track wildfire emissions, assess their impacts on atmospheric composition, and improve predictions of how wildfire activity may change in the future. This evidence can help policymakers and environmental agencies better understand climate risks, evaluate mitigation strategies, and strengthen adaptation planning in a warming world.

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Heatwaves create prolonged dry conditions that make wildfires more likely. Extended periods of hot weather dry out vegetation and soil, making it easier to ignite and sustain a fire. In the UK, this is particularly relevant for moorland areas, where peat soils can begin to burn when conditions are dry enough. Once ignited, peat fires can be extremely difficult to extinguish.

People living close to a fire, as well as emergency responders, can be directly exposed to these pollutants. However, the effects can extend far beyond the immediate area, as smoke and pollutants can be transported by the wind across entire regions, impacting people many miles away.

As climate change increases the frequency and intensity of heatwaves, the conditions that drive wildfires are expected to become more common. This highlights the need for prevention, preparedness and response strategies that consider not only the direct risks posed by wildfires, but also the wider impacts on air quality, public health, and the climate. Understanding these interconnected challenges is essential for effective long-term planning in a warming world, and integrated approaches to environmental monitoring and risk management.

Although air quality in the UK has improved significantly in recent decades, air pollution remains responsible for tens of thousands of premature deaths each year and continues to place a substantial burden on health services and the economy. As temperatures rise and extreme weather events become more frequent, there is a growing need to understand how future climate conditions could influence air pollution levels and public exposure.

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NCAS research is helping to provide this understanding by examining how climate change, heatwaves, wildfires and air quality interact across different timescales and regions. Through advanced atmospheric measurements, modelling, long-term monitoring, and toxicology studies, NCAS is generating the evidence needed to support more informed decision-making, from local air quality management and public health planning to national climate adaptation and resilience strategies.

In the UK, air quality is monitored through a network of sites operated by DEFRA and local authorities, which primarily measure legally regulated pollutants such as PM2.5, ozone and nitrogen dioxide. Complementing this network is a smaller number of atmospheric ‘supersites’, operated in partnership with national research organisations and universities, which provide much more detailed observations of the atmosphere and a wider range of pollutants.

NCAS currently operates three urban supersites in Manchester, Birmingham and London in partnership with DEFRA. These facilities provide the high-quality measurements needed to improve understanding of pollutant sources, track how air quality responds to changing weather and climate conditions, and strengthen the evidence base used to assess future environmental risks and guide policy decisions.

Case study: The impacts of Dovestone and Tintwistle wildfires on air quality in Manchester during July 2026

Following prolonged heatwaves and dry weather, major wildfires at Tintwistle Moor and Dovestone Reservoir in July 2026 produced smoke plumes that were carried into Greater Manchester by easterly winds. Air quality monitoring stations across the city detected significant increases in pollution, particularly between 12 and 15 July.

The most notable impact was on fine particulate matter (PM₂.₅). While typical annual average concentrations in Manchester are below 10 µg m⁻³, some locations recorded levels exceeding 100 µg m⁻³ for several hours. At the Manchester Air Quality Supersite (MAQS), the smoke was found to consist predominantly of very small particles and organic matter, characteristics consistent with peat and biomass burning.

PM₂.₅ concentrations exceeded the World Health Organization’s 24-hour guideline value for an extended period between 11 and 18 July. This is important because evidence suggests wildfire smoke can have greater health impacts than equivalent levels of particulate pollution from typical urban sources.

The wildfire event demonstrated how prolonged moorland fires can affect air quality far beyond the fire zone and highlighted the importance of comprehensive monitoring networks in understanding and responding to wildfire smoke episodes.

The graph shows levels of fine particulate detected at the Manchester air quality monitoring stations and the Manchester Air Quality Supersite from 9 July – 21 July 2026, with concentrations at all sites rising above typical levels.

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Thanks to strict regulations, particulate matter air pollution from human activity in transportation, households, and industry are decreasing in Europe – so the developing source of desert dust is becoming more significant.

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To determine the level of desert dust pollution across Europe, over 50 researchers have collected data over the past 10 years from over 100 measuring stations and combined it with modelling and artificial intelligence (AI).

Rising desert dust pollution in southern and western Europe

Southern Europe is particularly affected – from Greece in the east through Italy to Spain and Portugal. The study also detected elevated dust levels in western France. Air masses from the Sahara often flow out into the Atlantic and then turn north again towards western Europe.

In southern Europe, the average concentration of desert dust is 5.3 micrograms per cubic metre of air – more than twice as high as in central and northern Europe, where an average of 2.1 micrograms was measured.

Overall, the amount of dust has increased by about half a microgram per cubic metre during the last decade, which corresponds to an increase of 10-25%.

To enable scientists to make longer-term comparisons, they used ice core data from Colle Gnifetti on the Swiss-Italian border. Dust particles trapped in the ice of the Alpine glacier over recent centuries reveal that the concentration of desert dust there has more than doubled over the last 150 years.

Through chemical analyses, the scientists can determine the origin of particulate matter found at ground level very accurately. Desert dust is easy to distinguish from other particulate matter, by using the concentration of aluminium in airborne particulate matter. This element is characteristic of dust particles transported from deserts. Particulate matter from urban construction sites is very high in calcium, and particles from traffic and household emissions contain mainly soot or carbon from the combustion of petroleum.

The role of drying deserts, atmospheric circulation changes, and climate change

According to the study, the rise in desert dust is driven by the continued drying of the Sahara in North Africa, alongside changes in atmospheric circulation that carry strong winds and dust into Europe.

The number of storms carrying desert dust to Europe from the Sahara has not actually increased, but they have become more intense over the 10 years studied, and as a result they are now transporting more dust to Europe than they did before.

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Forecasting desert dust to protect health and support the energy sector

Researchers used AI to improve existing physical models of particulate matter distribution. Traditional models are good at predicting major desert dust events but often miss smaller ones and have difficulty estimating ground-level dust concentrations.

Combining measurements from more than 100 locations with AI enabled the team to produce a reliable, health-focused map of dust particles across Europe. This dataset can now serve as a foundation for future studies on long-term health effects.

One option would be to develop dust warning systems, similar to urban air quality alerts, to help vulnerable groups and people with respiratory conditions take precautions during high-dust periods. The energy sector could benefit too, as airborne dust can reduce solar panel efficiency by both blocking sunlight and accumulating on panel surfaces. Better forecasting would allow energy providers to offset these losses and help maintain grid stability.

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At 190 metres tall, the BT Tower Atmospheric Observatory filters and analyses air as it moves upwards from the streets and buildings of central and Greater London. It is one of the very few sites in the world capable of directly measuring emissions from a major city centre.

NCAS researchers have used air pollution monitoring equipment mounted on the BT Tower to collect real-world insight into the quality of the air that the people of London are breathing every day, for the last decade. We asked them about the observatory, what changes there have been in air pollution, and what air quality could be like in the near future.

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What does the BT Tower atmospheric observatory measure and how?

A gas inlet mast on top of the tower pumps air into the 35th floor laboratory, collecting pollution from nearby roads, commercial residential buildings, and some urban parkland. The observatory can detect air pollution emissions within a 2-4 km radius. Depending on the weather conditions, concentrations of air pollution can be detected from much further afield – Greater London, South West England, and Europe.

“To measure air pollutant concentrations of gases like ozone, we use equipment similar to those found in usual air quality monitoring stations. But for measuring emissions we need to use instruments that can take samples much faster. For example our measurements of nitrogen oxide (NO) and nitrogen dioxide (NO₂), which combined are referred to as NO_x, are taken 5 times per second. These are coupled with fast measurements of the wind speed, direction and turbulence by the University of Reading to tell us how much is being emitted 2-4 km upwind of the tower, every hour. The UK Centre for Ecology & Hydrology also operate fast greenhouse gas analysers, that measure the emissions of carbon dioxide and methane, and the University of Manchester operates instrumentation that makes fast measurements of black carbon,” explains Dr Will Drysdale, research scientist at the National Centre for Atmospheric Science and University of York.

“Air pollutant concentration calculations and instrument calibration are completed regularly. Emissions require a more complicated data processing pipeline, bringing together the different data streams from the BT Tower’s measurements e.g pollutant concentration, air turbulence – and relying on the University of York’s supercomputer called Viking to do the data analysis. Then more data is used to add scientific context. For example, we use data collected by automatic traffic counters to explore road emissions, and compare it with other air quality monitoring stations and emissions inventories. These inventories are either national or city wide, and provide “bottom-up” estimates of emission at around 1 km scales, which we then compare with our “top-down” measurements. The data is made available via the Centre for Environmental Data Analysis or the European Fluxes Database,” describes Dr Will Drysdale.

Why is it important to have an atmospheric observatory on the BT Tower?

Most air quality stations measure the concentration of pollution that is present in the air. The BT Tower Atmospheric Observatory goes a step further – from its unique position high above London, it measures emissions produced by the city itself. This information helps scientists and policymakers understand whether actions to reduce harmful air pollution and greenhouse gases are working, and where further improvements can be made.

These measurements support cleaner air, climate action, and evidence-based decisions not just in London, but across the UK. The BT Tower Atmospheric Observatory also provides the only long-term measurement of nitrogen oxide emissions from a megacity in the world.

The site has been used by NCAS and other leading research organisations, such as Imperial College London, UK Centre for Ecology & Hydrology (UKCEH), University of Manchester, University of Reading, and University of York. It has also supported major UK Research and Innovation-funded research programmes.

How has air quality changed in London since measurements have been made on top of the BT Tower?

Research from the BT Tower Atmospheric Observatory has helped reveal how London’s air pollution sources have changed over time.

One of the most significant changes has been the decline in emissions from road traffic. Nitrogen oxides emissions from vehicles in central London are estimated to have fallen by about 73 % between 2016 and 2025. This reduction is partly due to the success of air quality policies in central London, the increasing prevalence of Euro 6 vehicles and electric cars, and changes to congestion that resulted from pandemic-reduced mobility.

Measurements from the BT Tower also showed that carbon dioxide emissions in central London fell by around 60 % during COVID-19 lockdowns, closely reflecting reductions in traffic. These unique observations demonstrated how direct emissions measurements can reveal changes that conventional monitoring may miss.

The impact of cleaner vehicle technologies has also been seen in measurements of black carbon. “We found only minimal emissions from traffic, which is consistent with emissions reductions associated with Euro 6, the standard for diesel engines specified by ULEZ. This is in contrast to previous measurements in London, collected in 2012, which showed a strong association between traffic and black carbon. At the time, diesel particle filters had only been introduced relatively recently. And while domestic wood burning is also known to be a source of black carbon in the UK, this was predictably not found to be the case in central London which is mainly commercial rather than residential,” explains Dr James Allan, senior research scientist at the National Centre for Atmospheric Science and University of Manchester.

As emissions from traffic have declined, other sources have become relatively more important. Measurements showed that the combustion of natural gas in boilers accounted for 72 % of nitrogen oxides emissions within a few kilometres radius of London’s BT Tower between 2021 and 2023. Industrial and non-domestic boilers, which are larger than those in private homes, are the main contributors in central London, which is not a highly residential area. Domestic heating also emerged as a more significant contributor in some areas of Greater London. This evidence informed the 2026 Warm Homes Plan, supporting efforts to reduce fuel poverty, improve health outcomes, and cut emissions.

The research also highlighted the growing importance of other urban pollution sources. Emissions of black carbon from non-road mobile machinery, including generators and heavy machinery used on building sites, have started to surpass the black carbon emissions from vehicles. This is particularly clear in areas with dense construction.

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Air quality predictions: What to expect in London in the near future?

As the benefits of policies targeting vehicle emissions continue to emerge, researchers suggest that future efforts to improve air quality will need to widen their geographic reach and focus beyond emissions from diesel exhausts.

However, as emissions from road traffic continue to fall, other sources of pollution are becoming more prominent. Researchers say further progress will require tackling emissions from heating as well as transport.

“Getting combustion out of cities is central to further improving air quality in the UK. We will either need to electrify the heating of homes and businesses or think much more seriously about how pollution from gas burning can be cleaned up, as we currently do for cars, trucks and buses,” says Professor Alastair Lewis, senior research scientist at the National Centre for Atmospheric Science and University of York.

Researchers also caution that improvements in one pollutant can sometimes have unintended consequences for another. A reduction in nitrogen dioxide levels by cutting diesel and petrol emissions in cities such as London can lead to an increase in ozone because of changes in atmospheric chemistry. This unwanted side-effect can however be overcome by cutting emissions in other places, like solvents from paints and aerosols.

Research also points to construction as an increasingly important source of urban air pollution. As emissions from vehicles have declined, black carbon emissions from non-road mobile machinery, including generators and heavy machinery used on building sites, have become more significant.

Dr James Allan outlines how important regulatory attention is for the construction sector: “Even if observed emissions from construction equipment comply with emission standards, black carbon output from generators, machinery and construction vehicles remains significant. The Ultra Low Emission Zone in London, and stricter vehicle emission standards, have led to marked improvements in urban air quality. Traditionally non-road mobile machinery has always lagged road vehicles in terms of regulation, but rules for the construction sector are being tightened up, so we could start to observe more positive outcomes for air quality.”

Together, these insights suggest that while London’s air quality is likely to continue improving in the coming years, achieving further gains will depend on addressing a broader range of pollution sources, including building heating systems and construction activities, while carefully monitoring pollutants such as ozone as the city’s emissions profile changes.

As plans for the BT Tower’s future evolve, with its transformation into a hotel, preserving the observatory will protect vital environmental research and ensure monitoring of future changes in air pollution emissions.

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New estimates, published by the World Health Organization, show levels of fine particulate matter (known as PM2.5) declined globally up to 2020, but have since remained largely unchanged. Low and middle income countries are more affected than high income countries, revealing disparities in exposure to harmful air pollutants.

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Dr Matthew Thomas, a research scientist at the National Centre for Atmospheric Science and University of Manchester, developed the Data Integration Model for Air Quality (DIMAQ) in collaboration with the World Health Organization as part of his PhD. Over the last decade, DIMAQ has underpinned the WHO’s global estimates of population exposure to ambient air pollution.

The latest WHO release, five years on from the last global update, incorporates new data and methodological advances to provide the most up-to-date assessment of global air pollution trends and inequalities.

Matthew’s work on DIMAQ brings together satellite observations, atmospheric models, and ground-based monitoring data to provide a consistent picture of air pollution levels around the world, enabling meaningful comparisons between countries.

“DIMAQ was designed to bring together different sources of data to give a consistent and accurate picture of global exposure to air pollution. I am delighted to see it continue to support WHO’s assessments and inform international efforts to reduce the health impacts of air pollution. It’s incredibly rewarding.”

– Dr Matthew Thomas, research scientist at NCAS and the University of Manchester

The updated figures highlight significant disparities between countries. In 2023, exposure to PM2.5 above the WHO Air Quality Guidelines was more than 13 times higher in low and middle income countries than in high income countries, affecting around 6.5 billion people worldwide.

Exposure to both ambient and household air pollution remains a major driver of non-communicable diseases, including heart disease, stroke, chronic respiratory conditions and lung cancer, with the greatest burden falling on vulnerable populations.

Regional trends highlight mixed progress. While Asia experiences the highest levels of air pollution, it also displays the greatest progress. In other regions, including Africa and Western Asia, there has been little change over the last decade.

Urban areas typically experience higher pollution levels than rural areas, but cities have also shown stronger improvements irrespective of their income level. In contrast, some rural areas, particularly in low-income countries, have seen pollution increase.

Bruce Gordon, Director of Environment, Climate Change, One Health and Migration, at WHO, said:

“WHO is committed to providing robust, evidence-based data, which is essential for bold decision-making. We cannot address the climate and air pollution crisis or protect public health without reliable information that highlights global inequalities and disparities. Placing science at the forefront to drive monitoring and foster multi-sectoral collaboration is crucial to ensuring universal access to clean air and energy, safeguarding both the health of people and the planet – now and for future generations.”

The ongoing use of DIMAQ by WHO demonstrates how atmospheric science provides an evidence base for international policy and action, and supports global efforts to cut deaths linked to human-derived air pollution by 50% by 2040.

The DIMAQ work builds on Matthew’s wider research in modelling for global public health, spanning air pollution, environmental exposure assessment and environmental epidemiology.

Read about the global air pollution estimates on the WHO’s website

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What do heatwaves mean for wildfires?

Heatwaves are periods of abnormally hot weather usually lasting several days. Persistent high temperatures cause hot, dry conditions in which wildfires can spread.

Dr James Allan, senior scientist at NCAS and the University of Manchester, explains how heatwaves make wildfires more likely:

“Wildfires are more likely during heatwaves, particularly prolonged ones, because the vegetation gets dried out and so is easier to ignite and sustain a fire. In the case of moorland fires, peat within the soil can burn if the ground is dry enough, and this can be extremely difficult to extinguish once started.”

He describes the consequences of rainfall and plant growth:

“If a warm period in the spring or summer follows a period of rainfall, this can initially cause a lot of plant growth, so if this new growth subsequently dries out during hot weather, there can be more material to burn, also making a fire more intense and likely to sustain itself.”

And he goes on to talk about how wildfires begin:

“While heatwaves make wildfires more likely, there always has to be an ignition source. While fires can be started deliberately through arson, many are often accidental through activities such as barbecues or smoking. But even without any human activity, it is also possible for them to start naturally, such as through lightning strikes.”

Are heatwaves and wildfires harmful?

Heatwaves pose a risk to everyone’s health. Heatwaves are particularly hazardous to older people, children, people with pre-existing medical conditions, and those working long hours and in extreme conditions or exertive roles, e.g. factory or construction workers.

Wildfires have the potential to injure and kill people, and also cause extensive damage to ecosystems, property and livelihoods.

How does climate change affect heatwaves and wildfires?

Human-induced climate change means that summer weather is occurring on top of a warmer background climate.

With every degree of additional warming to the Earth’s climate, the frequency and intensity of heatwaves are projected to get worse in future. Soaring temperatures also lead to conditions that allow wildfires to spread quickly and far.

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Air pollution levels are closely linked to the weather, and hot spells often arrive hand-in-hand with poor air quality.

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We spoke to James to learn more about the impacts of heatwaves on air quality.

How do heatwaves affect air quality?

Heatwaves are periods of abnormally hot weather lasting at least three days.

They are most common when long-lasting high pressure weather systems develop during the summer, leading to clear skies and generally settled, dry weather.

“Heatwaves are known to affect air quality in a number of ways. As soils dry out, the air can carry more wind-blown dust. Also, dry summer vegetation makes it more likely for wildfires to occur, particularly when people spend more time outdoors in the countryside. While many global headlines focus on forest fires, the UK is also susceptible to moorland fires – something that recently prompted the government to create two new wildfire bases in the north of England. The air quality impacts of wildfires can be severe for those downwind,” says James.

He continues: “The hot and sunny weather is also known to promote the creation of harmful ‘secondary air pollution’ through atmospheric chemical reactions. Pollutants emitted within the UK and mainland Europe, such as oxides of nitrogen (known as NOx) and non-methane volatile organic compounds (VOCs), react with sunlight to form ozone and secondary particulate matter. The increased temperature can increase VOCs that come from evaporation, or promote natural plant activity. Higher temperatures and sunlight means the atmospheric chemistry progresses faster, and the winds from the south mean that the UK experiences the processed emissions from mainland Europe and beyond.”

How is air quality monitored in the UK?

James explains:

“Air quality in the UK is monitored by a network of sites operated by DEFRA and local governments, but these are usually limited to making measurements of the legally-binding pollutants such as PM_2.5 (fine airborne particulate matter), ozone and nitrogen dioxide.

“In addition to these, a smaller network of ‘supersites’ is operated in partnership with National Research Organisations and universities to make more detailed measurements of air pollutants. These will provide insights into the sources and processes affecting air quality, and equip us with the knowledge to better manage and predict pollution in the future. Currently, three urban supersites at Manchester, Birmingham, and London are operated by NCAS and DEFRA.”

What is the latest data showing?

“When analysing the composition of PM_2.5, a striking trend can be seen when analysing data from previous heatwaves. As temperatures increase, an increase in the PM_2.5 concentration is seen, but it is also evident that the PM_2.5 consists almost entirely of organic matter. This behaviour is replicated across all three measurement supersites, in Manchester, Birmingham, and London, implying it is a country-wide phenomenon. The organic matter is likely secondary, produced through enhanced photochemistry and VOC emissions,” explains James.

He adds: “This is really interesting, because there is evidence to suggest that this type of PM_2.5 may be more toxic. However our current level of scientific understanding and ability to predict organic matter PM_2.5 is poor compared to other types of PM_2.5. It is this uncertainty that motivates some of the air pollution research going on at NCAS. In addition to detailed measurements of PM2.5, trace gases and VOCs at the supersites, we are also conducting laboratory studies and developing state-of-the-art modelling tools.

In Manchester, London, and Birmingham, the concentration of PM_2.5 in the air increases as temperature rises. Shown in green, it is clear that organic matter contributes most to the PM_2.5 levels. The PM_2.5 data presented in these graphs is from 2019 and 2026, and shows average concentration levels across a range of ambient temperatures.

“While air quality continues to improve at a national level, air pollution is still responsible for tens of thousands of deaths within the UK. Continued improvement to the air we breathe will benefit people’s health, the burden on the NHS, and the overall economy. NCAS’s ongoing work will allow us to inform better planning for air pollution in a warmer future,” highlights James.

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Climate scientists are now replaying the past to predict the future, to show how everyday weather could feel in a warmer world.

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A research team is taking an unusual approach to understanding the impacts of global warming on weather. Researchers have recreated real weather from the past in computer models, and then “warmed it up” to see how it could change.

Using historical pressure observations to reconstruct the weather of 1903, the researchers created a simulated version of the same year under higher temperatures and carbon dioxide levels. By holding weather patterns constant, the scientists were able to isolate the impacts of climate change that are directly related to changes in temperature and humidity, rather than shifts in weather patterns.

“In the warmer world experiments, almost every day becomes hotter. Cold days become significantly milder, while already warm days become even hotter.”

– Dr Rhidian Thomas, climate scientist at the National Centre for Atmospheric Science and University of Reading

The study shows that warming does not affect all days equally. While temperatures rise across the board, the most noticeable increases occur during both cold snaps and warm spells. Days that would once sit below freezing are pushed upward, while those above 20°C see the most pronounced jumps.

This could have wide implications, from reducing frost days that ecosystems rely on, to intensifying heat exposure for vulnerable people during already warm periods.

“By anchoring our analysis in real historical weather patterns, we are able to provide a more tangible sense of how a warming world translates into lived experience,” explains Dr Rhidian Thomas.

Beyond temperature, the study highlights a shift in the characteristics of rainfall. While rainfall may decrease in some regions, the way it falls changes. Lighter rain becomes less common, heavy downpours become more frequent, and dry spells are punctuated by heavier bursts of rain – which could increase the risk of flooding and complicate water management.

For countries in the Western Mediterranean, the study shows that rainfall can decline outside of the winter months, even without changes in the position of storm tracks.

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The research team includes scientists from the National Centre for Atmospheric Science, University of Reading, University of Edinburgh, University of Colorado at Boulder, and NOAA Physical Sciences Laboratory.

The work is funded by the Natural Environment Research Council, and uses JASMIN – the UK’s collaborative data analysis environment.

Read more about the research

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Southampton hosts a high volume of maritime traffic, including frequent visits from large cruise ships, making it a prime location to study shipping emissions.

“Shipping is an important but relatively under-explored source of air pollution in coastal towns and cities. In Southampton, emissions from vessels, particularly when cruise ships are docked, can be transported into residential areas under certain weather conditions, such as prevailing southwesterly winds.”

– Dr Will Drysdale, a research scientist at the University of York and NCAS

To capture these impacts, the team is deploying a “lab in a van” – a mobile sampling platform fitted with a suite of advanced air quality monitors. This flexible setup allows the research team to measure pollutant concentrations at fixed locations and while driving through the city.

By positioning the mobile lab downwind of busy shipping lanes, the team can directly observe emissions from passing vessels. In addition, mobile surveys across the port area enable comparisons between upwind and downwind locations, helping to quantify the broader contribution of shipping activity to local air pollution.

Check out the 'lab in a van'

The research aims to fill key knowledge gaps about the scale and variability of shipping-related emissions, particularly in urban coastal settings where large numbers of people live and work close to ports.

“Understanding how these emissions disperse and affect air quality is essential for informing future mitigation strategies. Our measurements will help build a more complete picture of the impact of shipping on local environments and public health.” – Dr Will Drysdale

The campaign reflects NCAS’s wider commitment to advancing atmospheric science through targeted field experiments, providing robust scientific evidence to support policy and improve air quality across the UK.

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Acknowledgements:

• Supported by the Clean Maritime Research Hub.

• In partnership with Incheon National University and Air Quality Associates Inc, who are providing modelled emissions data from a port air quality management system (known as PAQman), which aims to help ports manage their air quality impacts, and will be compared with measurements made in the mobile lab.

• In collaboration with STFC – RAL, to investigate the use of low cost sensors as a way to augment the PAQman’s models long term.

• The mobile air quality monitoring laboratory van is funded by NCAS and supported by the Wolfson Atmospheric Chemistry Laboratories at the University of York.

Clean air matters to everyone. But the sources, impacts and solutions to air pollution can vary widely depending on where you live, work and travel.

This Clean Air Day, research from (NCAS) highlights how understanding air quality across different settings – from homes and city streets to ports and airports – can help protect people’s health and support better decisions for communities across the UK and beyond.

Air pollution and everyday health

Air pollution can affect people’s health across their lifespan. NCAS research has shown that even short-term exposure can make a difference. In one study, just a single hour of exposure to everyday levels of air pollution was found to affect both lung function and brain activity, underlining how closely air quality is tied to daily wellbeing.

Scientists are also working to better explain the “invisible threat” of air pollution. Many harmful pollutants can’t be seen, but they can penetrate deep into the lungs and enter the bloodstream, increasing the risk of respiratory illness, cardiovascular disease and other health problems. Learn more about the impacts of air pollution on human health.

NCAS researchers have contributed to major national reports, including work with the Royal College of Physicians, helping to build the scientific evidence that connects air pollution directly to public health outcomes.

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People and inequality

Air pollution does not affect everyone equally. NCAS research has highlighted clear disparities in exposure across the UK, with minoritised ethnic groups often facing higher levels of pollution. This reflects patterns in housing, infrastructure and urban development.

Studies in Bradford, for example, revealed high levels of indoor air pollution in family homes, showing that air quality challenges are not limited to outdoor environments. Together, these findings emphasise the need for solutions that consider people’s lived experiences and ensure that improvements in air quality benefit all communities.

From homes to cities and transport hubs

Air pollution sources differ depending on location, and NCAS research is helping to map these differences in detail.

In cities like London, the sources of pollution are changing. As vehicle emissions have decreased, other sources have become more important. Gas boilers are now a leading contributor to urban air pollution, while construction activity has emerged as a significant source of black carbon. These shifts highlight the importance of continuously updating our understanding of urban pollution.

At the same time, cutting-edge monitoring techniques are improving how scientists track vehicle exhaust emissions in real time, offering new ways to identify hotspots and support targeted action in busy urban areas.

Transport hubs also play a crucial role. Research around UK airports has shown that air pollution linked to aviation can affect nearby communities, raising important questions about how to balance economic activity with local health impacts.

NCAS scientists are also investigating air quality in busy ports, such as Southampton, because emissions from vessels – particularly when cruise ships are docked – can be transported into residential areas.

Monitoring air quality in Southampton

Innovation and solutions

Alongside identifying problems, NCAS research is exploring solutions to reduce emissions across different sectors.

In aviation, scientists are investigating how sustainable aviation fuels influence both air quality and climate.

Measuring jet fuel emissions

In construction, low-emission hydrogen engines are being studied as a potential way to cut pollution from heavy machinery.

Meanwhile, regulations on paints and solvents have already led to significant reductions in harmful emissions, although further policy updates are needed to keep pace with scientific understanding.

NCAS scientists have also confirmed a major global reduction in ship sulfur emissions following international regulations, demonstrating how coordinated policy action can deliver measurable improvements in air quality.

These examples show how science can inform innovation, helping industries transition to cleaner technologies or products.

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A global perspective

Air pollution is not confined by national borders. NCAS research in East Asia has explored how air pollution interacts with climate change, demonstrating that the same emissions can influence both local air quality and global warming. Understanding these links is essential for developing strategies that deliver benefits for both health and climate.

Connecting the dots for Clean Air Day

Across all of this work, a common theme emerges: air quality is shaped by the connection between people, places and activities. From the air inside our homes to emissions from global shipping, every source contributes to a bigger picture.

By combining detailed measurements, innovative technologies and community-focused research, NCAS is building a clearer understanding of how air pollution affects people – and how it can be reduced. This evidence is crucial for policymakers, city planners and communities working to create cleaner, healthier environments.

On Clean Air Day, the message is simple: improving air quality starts with understanding it. And through its research, NCAS is helping turn that understanding into action that benefits people across the UK and beyond.

Busting common air pollution myths

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Severe weather events across parts of Africa have intensified in recent years, contributing to widespread flooding, damage to infrastructure, displacement and loss of life. Millions of people are affected annually, highlighting the need for more timely, accurate and actionable weather information.

The African Meteorological Satellite Application Facility (AMSAF), officially launched on 18 May 2026 and supported by the European Commission’s Global Gateway, marks a significant step forward in harnessing next-generation satellite data to improve short-term weather forecasting – known as nowcasting – across the continent.

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Advancing early warning capability across Africa

AMSAF has been designed to increase the capacity of African meteorological and hydrological services to access and use advanced satellite data in near real time.

The system will draw on satellite data, which provides high-resolution, rapid-update observations of weather systems across Africa. Using this data, AMSAF will support the production of highly localised forecasts covering a 0-6 hour timeframe – critical for anticipating severe weather events such as thunderstorms, flash floods and high winds.

A network of four regional centres will underpin the facility, with hubs located in Senegal, Kenya, Cameroon and South Africa. These centres, working with the African Centre of Meteorological Application for Development, will generate tailored weather products and distribute them to meteorological services across the African continent. The disseminated products will be a bespoke selection, aligned with regional priorities and national needs.

Translating science into impact

Researchers at the National Centre for Atmospheric Science (NCAS) and the School of Earth, Environment and Sustainability at the University of Leeds, are central partners in the AMSAF Technical Assistance Service Team (TAST). Alongside colleagues at the Finnish Meteorological Institute, Agencia Estatal de Meteorología, and Meteo Maroc, they are responsible for designing and implementing the technical systems that will enable AMSAF to operate effectively.

Dr Alex Roberts, a nowcasting research scientist at NCAS and the University of Leeds explains:

“Our role reflects a long-standing commitment to advancing meteorological science in Africa and ensuring that research translates into real-world impact. We have a strong track record in satellite-based nowcasting and capacity building, including contributions through programmes such as the Global Challenges Research Fund: African SWIFT initiative.

“Our earlier work helped to introduce nowcasting techniques in several African countries and demonstrated the value of collaborative “testbeds” in operational forecasting. These insights have directly informed the design of AMSAF, ensuring it is both scientifically robust and practically relevant.

“A related and award-winning output of the nowcasting work in Leeds is FASTA (the Forecasting African Storms Application), a digital platform developed by NCAS and partners that provides accessible, user-friendly tools for satellite-based nowcasting.”

Building sustainable capability and local ownership

Training and capacity building are at the heart of the AMSAF initiative. The TAST will work closely with regional hubs to support the installation, operation and maintenance of both local and cloud-based data processing systems. Forecasters and technical staff will receive training in using satellite data, generating forecasts and disseminating warnings effectively.

Importantly, the programme is designed to enable long-term sustainability and a transition towards full African ownership. By equipping regional and national institutions with the skills and infrastructure they need, AMSAF aims to create a self-sustaining system that continues to deliver benefits beyond the lifetime of the initial project.

The initiative is closely aligned with continental and global policy frameworks. It supports the African Union’s Multi-Hazard Early Warning and Early Action System and contributes directly to the United Nations’ “Early Warnings for All” initiative, which seeks to ensure that everyone on Earth is protected by early warning systems.

Disaster preparedness and economic resilience

The societal benefits of AMSAF are far-reaching. Improved nowcasting will enable governments, emergency responders and communities to act more quickly and effectively in the face of severe weather. This can reduce loss of life, limit damage to infrastructure and support more efficient disaster response.

Beyond emergencies, better weather information has significant implications for key economic sectors. Agriculture – which employs a large proportion of the population in many African countries – will benefit from more reliable short-term forecasts, helping farmers make informed decisions about planting, irrigation and harvesting. Similarly, sectors such as aviation, transport and energy will be better equipped to manage weather-related risks.

By strengthening resilience to climate variability and extreme events, AMSAF also contributes to long-term development goals, helping to safeguard livelihoods and support economic stability.

Aligning with UK industrial strategy and global goals

NCAS’s involvement in AMSAF highlights the UK’s role as a global leader in atmospheric science, earth observation and climate services. The project aligns strongly with the UK’s Industrial Strategy priorities, particularly in advancing science and innovation, strengthening international partnerships and supporting the growth of the space and data sectors.

Through collaboration with European and African partners, NCAS and the University of Leeds are helping to position UK expertise at the forefront of next-generation satellite applications. This enhances opportunities for knowledge exchange, innovation and future collaboration in the rapidly expanding global Earth observation market.

At the same time, AMSAF contributes to several United Nations Sustainable Development Goals – from climate action and sustainable communities, to zero hunger and international partnerships.

A step change in African weather services

The launch of AMSAF represents a major milestone in the evolution of weather services across Africa. By combining cutting-edge satellite technology with local expertise and strong international partnerships, the initiative is set to deliver a step change in forecasting capability.

With NCAS at its core, the programme exemplifies how UK science can support global development challenges – transforming data into decisions, and research into resilience for communities most exposed to extreme weather.

The African Meteorological Satellite Application Facility (AMSAF) is supported through the European Commission’s Global Gateway Africa-Europe Space Partnership Programme, under Component 2: Strengthening Early Warning Systems in Africa (SEWA).

SEWA is jointly implemented by the European Organisation for the Exploitation of Meteorological Satellites, European Centre for Medium-Range Weather Forecasts, and African Union Commission.

NCAS and the University of Leeds contribute to the AMSAF Technical Assistance Service Team.

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Professor Alastair Lewis recently produced a rapid response report for the Parliamentary Office of Science and Technology on the health impacts of airports on local residents. We spoke to him about airports, air pollution, health, regulation, and the role of atmospheric scientists.

What air pollution comes from an airport?

“Aircraft engines release a mix of pollutants into the air, including nitrogen oxides and particulate matter. Aircraft-related air pollution is not just about how many planes fly, it is also about how airports operate. Emissions occur not just during take-off and landing, but also while planes taxi, idle, and queue on the runway,” explains Professor Alastair Lewis, atmospheric chemist at the National Centre for Atmospheric Science and University of York, and Chair of the UK Government’s independent science advisory body on air pollution, the Defra Air Quality Expert Group.

Importantly, this pollution does not stay within the boundaries of the airport – it can travel tens of kilometres, especially downwind. This means that communities well outside airport grounds can still be affected. Ground delays increase the time aircraft engines run at low power, a state that can produce higher emissions close to the ground where nearby residents are most exposed.

“Over the past two decades, cleaner road vehicles have reduced traffic-related air pollution. While aircraft still emit less nitrogen oxide overall than road transport, their relative contribution is increasing as other sectors clean up faster,” adds Alastair.

Future projections suggest aviation emissions may remain broadly the same through to 2040, even as road emissions fall sharply. Sustainable aviation fuels may help cut greenhouse gas emissions and impacts on climate change, but they will not eliminate exhaust pollution and their impacts on air pollution are still uncertain.

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How does air pollution affect health?

Emissions of nitrogen oxides and particulate matter are associated with respiratory and heart disease, as well as longer-term conditions such as diabetes and cancer. Ultrafine particle matter emissions are of particular concern because they are not routinely regulated or monitored, despite emerging evidence of their health effects.

Research shows that on days with longer aircraft taxi times, people living within 10 kilometres of airports were more likely to be hospitalised for respiratory and cardiovascular problems. This makes it clear that airport efficiency is a public health issue.

Are there regulation gaps on airport air quality?

“Despite the clear health links, air pollution from airports sits in a regulatory grey area. Local authorities are responsible for local air quality, but existing frameworks mainly focus on roads and industry. Unlike power stations or factories, individual airports do not have caps on air pollutant emissions. Airports can incentivise lower emissions by charging higher polluting aircraft more to use the airport facilities, but otherwise they have little control over emissions. Organisations involved in aviation management, such as the Civil Aviation Authority and airport operators are not legally responsible for meeting national or local air quality standards,” outlines Alastair.

International limits on aircraft emissions exist, but these are not designed to protect people living near airports from everyday exposure. This gap highlights the importance of robust atmospheric science to inform smarter policy and regulation.

What is the role of atmospheric scientists?

This is where NCAS and the wider atmospheric science community make a difference. By measuring pollution from the ground and in the air, modelling how it moves through the atmosphere, and working with medical researchers to link exposure to health outcomes, atmospheric scientists provide the evidence policymakers need to protect communities.

Atmospheric research also has the potential to identify which mitigation measures work – from cleaner ground operations and smarter airport design, to using sustainable aviation fuel and fairer planning decisions.

“By improving our understanding of airport air pollution, atmospheric science supports healthier planning, better regulation and more informed public debate. It ensures that decisions about aviation consider not just where we fly, but how we live and breathe on the ground,” comments Alastair.

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