What Do Heatwaves Tell Us About Climate Change?

How extreme heat reveals the pace of climate change

Heatwaves are becoming longer, more intense, and more frequent. This is not a matter of natural variation. Research shows these changes are directly linked to rising greenhouse gas concentrations in the atmosphere. As carbon dioxide and methane trap more heat, the planet warms, and temperature extremes become more severe.

Attribution studies have gone further. Scientists can now measure how much worse a specific heatwave was because of climate change. This makes extreme heat one of the clearest indicators of a warming planet. For businesses, these events are no longer rare disruptions. They are recurring risks that affect operations, supply chains, energy costs, and workforce health.

Understanding this link matters for planning. The more the planet warms, the more often extreme heat will occur. Consequently, businesses need to factor these risks into their strategies now, not in five years.

What the research shows about heatwaves and warming

The Intergovernmental Panel on Climate Change has documented the trend clearly. According to the World Meteorological Organization’s summary of IPCC findings, human-caused climate change has increased both the frequency and intensity of heatwaves since the 1950s. Moreover, every additional 0.5°C of warming brings measurable increases in the intensity, frequency, and duration of temperature extremes.

This is not abstract science. The World Health Organization estimates that approximately 489,000 heat-related deaths occurred globally each year between 2000 and 2019. During the same period, the number of people exposed to heatwaves increased by around 125 million between 2000 and 2016 alone.

Chatham House analysed 152 extreme-weather attribution studies conducted over the past 20 years. In 93% of those studies, researchers found that human-induced climate change made extreme heat more likely or more severe. This level of consistency across independent research is significant. It shows that the link between emissions and heatwaves is well-established, not speculative.

Dr Vikki Thompson of the University of Bristol put it simply: climate change is making heatwaves hotter and last longer around the world. Therefore, what might once have been a one-in-50-year event can now happen every few years.

Recent heatwaves show the scale of the shift

Attribution science has made it possible to assess individual heatwaves. For example, the June 2024 heatwave across the US, Mexico, and Central America was found to be 35 times more likely because of climate change. In addition, temperatures during that event were 1.4°C warmer than they would have been without human influence.

Similarly, research into a recent heatwave in Australia found it was approximately 1.6°C hotter due to climate change. A Nordic heatwave was made at least 10 times more likely by human-caused warming. These figures are not projections. They describe events that have already happened.

This matters because it moves the conversation from future risk to present reality. Businesses that operate across regions, manage outdoor workforces, or rely on temperature-sensitive supply chains are already experiencing these impacts. Furthermore, the frequency of such events is increasing.

Why extreme heat creates wider business risks

Heatwaves do not occur in isolation. They interact with other systems in ways that multiply their impact. Prolonged heat can worsen drought, which in turn affects water availability for agriculture, manufacturing, and energy generation. Wildfires become more intense when vegetation is dry and temperatures are high.

Urban areas face additional pressure. The urban heat island effect means that cities are often several degrees warmer than surrounding rural areas. This increases cooling demand, strains energy infrastructure, and raises health risks for workers and residents. Consequently, businesses in dense urban centres may face higher energy costs and operational disruptions during heatwaves.

Labour productivity also declines in extreme heat. Outdoor work becomes hazardous, and indoor environments without adequate cooling become unsafe. In sectors such as construction, logistics, and agriculture, this can lead to delays, reduced output, and increased health and safety costs.

Power networks are particularly vulnerable. High temperatures increase electricity demand for cooling just as they reduce the efficiency of generation and transmission infrastructure. This can lead to supply shortages or outages, which disrupt operations and increase costs for businesses reliant on stable power supplies.

Food supply chains are affected too. Heat stress reduces crop yields and livestock productivity. It also increases spoilage rates during transport and storage. For businesses that depend on agricultural inputs or food distribution, these disruptions can lead to cost increases and supply uncertainty.

Air quality often deteriorates during heatwaves. High temperatures accelerate the formation of ground-level ozone and exacerbate pollution from wildfires. This affects workforce health and can lead to absenteeism or reduced productivity, particularly in urban areas.

What UK businesses should consider

The UK has experienced several notable heatwaves in recent years. July 2022 saw temperatures exceed 40°C for the first time on record. Transport infrastructure buckled, schools closed, and businesses faced significant disruption. These events are becoming more frequent as the climate continues to warm.

For small and medium-sized enterprises, the implications are practical and immediate. Overheating in offices and warehouses affects productivity and health. Supply chain delays caused by extreme weather in the UK or overseas can disrupt operations. Energy costs rise during periods of high demand, and insurance premiums may increase as climate risks become more apparent.

Businesses that operate or source from regions more vulnerable to extreme heat face additional risks. This includes parts of Southern Europe, North Africa, and Asia, where heatwaves are becoming more intense. Consequently, understanding where your supply chain is exposed to heat risk is an important part of climate adaptation planning.

Some sectors face more direct impacts. Construction firms must manage worker safety in extreme heat and adjust schedules accordingly. Food producers and retailers need to account for spoilage risks and changing growing conditions. Manufacturers that rely on stable energy supply or water availability should assess how heatwaves might affect production.

There are also opportunities. Businesses that proactively adapt to heat risk can reduce costs, protect their workforce, and maintain service continuity when competitors struggle. For example, improving building insulation and ventilation can lower cooling costs and improve comfort. Flexible working arrangements during extreme heat can protect employee health and maintain productivity.

Companies that report carbon emissions or participate in public sector procurement already face scrutiny on climate performance. Understanding how heatwaves relate to emissions and warming strengthens the business case for reducing your carbon footprint. It also helps you communicate climate risks and actions to customers, investors, and supply chain partners.

Our net-zero program supports businesses with carbon reporting and emissions reduction planning, helping you meet compliance requirements and manage climate-related risks.

Five key points about heatwaves and climate change

• Heatwaves are becoming longer, more intense, and more frequent because of human-caused climate change, primarily from burning fossil fuels.
• Research shows that 93% of extreme-weather attribution studies found climate change made extreme heat more likely or more severe.
• The World Health Organization estimates approximately 489,000 heat-related deaths occurred globally each year between 2000 and 2019.
• Every additional 0.5°C of warming brings measurable increases in the intensity, frequency, and duration of temperature extremes.
• Heatwaves interact with other systems, worsening drought, wildfires, energy demand, air quality, and labour productivity.

How to plan for increasing heat risk

Climate adaptation is no longer optional. Heatwaves will continue to become more frequent and severe as long as greenhouse gas concentrations keep rising. Businesses that treat extreme heat as a one-off event rather than a recurring risk will face repeated disruption and rising costs.

Start by understanding your exposure. Where are your operations, workforce, and supply chain most vulnerable to heat? What happened during the last major heatwave in your region? Which parts of your business were most affected? These questions help you identify priorities.

Next, consider your energy resilience. Can your operations continue if power supply becomes unstable during a heatwave? Are your cooling systems adequate for higher temperatures? How might energy costs change during periods of peak demand?

Workforce planning is equally important. How will you protect employee health during extreme heat? Do you have policies for flexible working or adjusted schedules? Are outdoor workers adequately protected? These are health and safety issues, but they also affect productivity and business continuity.

Supply chain risks require attention too. If you rely on suppliers in regions vulnerable to extreme heat, consider how their operations might be disrupted. Can you diversify sourcing or build in more flexibility? Are your logistics partners prepared for heat-related delays?

For businesses with physical premises, building design matters. Poor ventilation and inadequate insulation increase cooling costs and reduce comfort. Retrofitting existing buildings can be expensive, but the costs of inaction are rising. Green roofs, reflective surfaces, and natural ventilation can all reduce heat stress and energy use.

Finally, consider the role of emissions reduction. While adaptation helps you manage the impacts of climate change, reducing your carbon footprint addresses the underlying cause. Every tonne of CO2 avoided contributes to limiting future warming. For many businesses, this is also a commercial advantage as customers, investors, and procurers increasingly favour low-carbon suppliers.

Our compliance support helps businesses meet ESG reporting requirements and manage climate-related risks within their operations and supply chains.

Where to find further information

The UK government provides guidance on climate adaptation and heat risk through the Department for Energy Security and Net Zero. Their publications include assessments of climate risks facing the UK and advice for businesses on adaptation planning.

The Met Office issues heat-health alerts and provides climate projections for the UK. These resources help businesses understand current risks and plan for future conditions.

For information on workplace health and safety during extreme heat, the Health and Safety Executive offers guidance on managing temperature risks for employees. This includes advice on risk assessment, workplace adjustments, and legal responsibilities.

The Climate Change Committee publishes detailed analysis of climate risks and adaptation progress in the UK. Their reports provide evidence-based assessments relevant to business planning and policy.