UK heat stress impact on food, farming, crops and farmed animals: experts comment

Jez Fredenburgh, senior analyst – food and climate, the Energy and Climate Intelligence Unit (ECIU):   

“The UK’s food system, including nature and farmed animals, is increasingly coming under strain from periods of high heat, and we’ve had two record breaking heat waves in both May and June. These can have disastrous consequences. For example, during summer 2022, when temperatures reached more than 40C in the UK, around 18,500 chickens died in transport due to heat stress [1] and wildfire incidents increased by more than 300% compared to the year before. [2]   
 
“Heat stress is already causing economic losses of £205 million annually across wheat, barley, oats, dairy cattle, free range hens, and lambs, according to research included in the Climate Change Committees latest adaptation report. In an ‘extreme year’ (from a high climate and business-as-usual agriculture scenario) this could rocket to as much as £2.3 billion in the 2030s. [3] Farmers and consumers cannot afford this pressure.   
 
“There’s lots we can do to adapt, like planting trees to shade livestock and reduce the number of animals in a single indoor system, but ultimately reducing emissions and hitting net zero is the only way to stop heat stress getting worse.” 


Ben Andrews, salad and brassica grower, Herefordshire (supplies Abel & Cole with lettuces) [4]: 

“This week’s heat wave is likely to affect both our lettuces and brassicas – but all food crops that farmers grow will be impacted negatively. Lettuce really doesn’t like heat – its maximum optimum growing temperature is 20C and over 24C heat stress starts kicking in. If it goes over 35C, like it’s projected to this week, the plant will likely ‘bolt’, which means it starts to flower and we can no longer sell it.  

“We usually grow lettuce well in the UK during a ‘normal’ summer when it is too hot for the growers in southern Europe who supply us during winter. But our summers are now regularly seeing temperatures that match those in the warmer growing regions, so it’s getting increasingly difficult to plan our crops. We still generally have cold, wet springs and occasional wet summers, so we can’t simply shift our growing schedule to any sort of ‘new normal’ earlier in the year.  

“The financial impact of the lettuces will hit us hard, but it could be even bigger with our kale crop. We pick it throughout autumn and winter and heat stress now will massively stunt its growth – even with perfect conditions it won’t recover.  

“But it’s not just lettuces and brassicas that will be impacted – all crops will be. Shoppers might see a shortage of one product on the shelves and not think things are too bad, but climate change is wreaking havoc on our ability to grow all food consistently, with big financial impacts on farming families.”  
 

Sophie Gregory, dairy farmer, Dorset [5]:

“We’ve got 600 dairy cows on our farm and keeping them – and us – cool in this heat is a challenge. Their milk yields drop in hot weather because they tend to eat less, so this is both a matter of animal welfare and food production that we take very seriously.  

“Climate change is making it harder and harder to farm, but we’ve been planning ahead for several years now and doing all we can to keep our cows cool; We make the most of shade from trees, get jobs done early in the morning and later in the evening, don’t rush the cows, and have a misting system and fans on full blast in the milking parlour. We also make sure lots of drinking water is available as the cows will drink several litres more on hot days.  

“Farmers like us are on the front line of climate change though, and the only way to stop heat waves like this getting worse is reducing global and national emissions’." 
 

Tom Southall, Deputy Chief Executive at the Cold Chain Federation: 

"Increasingly frequent spells of extreme heat are a stark reminder of the growing threat climate change is placing on the cold chain - the critical frozen and chilled storage and transport system that underpins 50% of the UK's food supply. Cold chain resilience is national resilience, and the implications of a major disruption are shortages of food and pharmaceuticals, including supplies to the most vulnerable. 

“When temperatures rise sharply, as we have seen this week, every stage of that system including infrastructure and the workers who operate it come under increased strain. 

“The UK’s cold chain sector is highly resilient and robust, but it is rapidly being challenged by an increasing range of threats. These extreme conditions underline the fact that much of the country’s infrastructure, particularly refrigeration systems were not designed for the current climate, with around 50% of cold storage facilities over 20 years old. Just last month the Climate Change Committee warned that climate conditions will expose vulnerabilities in the UK’s cold chains and that existing reactive measures for resilience in times of high heat will not be sufficient 

“Businesses are committed to investing in adaptations, but the Government must urgently do more to recognise the specific threat to cold chain businesses and support investment in infrastructure to ensure the nation’s food and pharmaceutical supplies remain secure." 

 
Martin Lines, farmer and CEO of the Nature Friendly Farming Network:  

"The current heat across the UK is another reminder that farmers are on the frontline of climate change. Prolonged high temperatures place huge stress on livestock, dry out soils and reduce crop resilience, all while putting more pressure on nature.   
 
“We know there are practical ways to help farming cope with these extremes, like planting more trees, restoring hedgerows and improving soil health. These measures can cool landscapes, retain water and support wildlife at the same time. Nature-friendly farming shows what is achievable on our farms.   
 
“But adaptation can only go so far unless we urgently cut the emissions driving climate change and reduce our dependence on fossil fuels worldwide.”  

 
Dr Jonathan Amory, Associate Professor in Animal Behaviour and Welfare, School of Agriculture, Animal and Environmental Sciences, Anglia Ruskin University:  

“Heat stress is a significant welfare concern for farm animals and its occurrence is increasing with more hot days per year as the climate changes. Heat stress reduces food intake, production levels, fertility measures and impairs immune function in all livestock species and is associated with hunger, thirst, dehydration and frustration that are all important indicators of poor well-being. Dairy cows are particularly vulnerable due to milk production increasing metabolism. Humidity is an important factor and for typical UK levels dairy cows can show signs of heat stress above 20°C with each additional degree further increasing the risk.  
 
“The relatively high humidity of the UK makes efficient heat loss difficult for farm animals. That makes good building design essential for efficient ventilation, good temperature control and reliable monitoring systems giving real time data to allow early intervention by farmers. Grazing animals need opportunities for shade and access to clean water. Heat stress is more than a production issue - it is a serious challenge to animal welfare.”  
 

Chris Manley, founder, Traction Consulting, a sustainable supply chain consultant:  

“High temperatures are putting growing pressure on the food supply chain, especially the cold chain that keeps fresh food safe from field to shelf. Heatwaves increase refrigeration demand, shorten harvest windows and reduce the time available to cool and transport produce before quality drops. Recent industry insight shows fresh produce and top fruit markets can flip from shortage to surplus within days during extreme heat, overwhelming chill capacity and increasing waste.   
 
“The impact reaches far beyond refrigeration. Extreme heat reduces livestock productivity, raises animal welfare risks and slows labour and transport operations across the supply chain. Combined with rising energy costs, water stress and wider geopolitical pressures, these events highlight how vulnerable food systems have become. Climate disruption is no longer a future threat. Without faster action on mitigation and adaptation, supply chain disruption will become more frequent and more costly.”