From Heatwaves To Extreme Storms, The World's Blood Stocks Are Under Threat From Climate Change

The record-breaking heat of that July had impacted more than 100 blood drives across nearly every state where the charity collected this valuable resource. By the end of the summer, the Red Cross’s supply had dropped by more than 25 percent, while the hospital demand remained the same, further straining the availability of a lifesaving product. 

What’s worse, the hurricane season that followed, especially Hurricane Helene, caused additional disruption to the supply chain.

This was not an isolated problem. The heatwaves of 2024 also caused blood shortages across India, such as in the city of Hyderabad, and the states of Karnataka and Odisha, as donors avoided venturing out in the extreme heat. During this time, blood banks reported a 60 to 65 percent drop in their collections, leading to delayed transfusions and surgeries. 

Similarly, tropical storms such as Cyclone Alfred, which hit Australia in March 2025, also led to the cancellation of over 3,500 blood donation appointments.

The story of the blood crises of 2024 to 2025 forces us to shift our perspectives on blood. It’s not just an essential medical resource; it’s also a climate-vulnerable commodity. But changes in temperatures are not just affecting blood donations – they're also reshaping blood safety.

As global temperatures continue to rise, ticks and mosquitoes – carriers of diseases such as malaria, dengue, Zika, chikungunya, and West Nile – are appearing in new locations. Some people bitten by these creatures can contract the infections without knowing it, appearing asymptomatic. 

In a study published in 2024, researchers in Colombia detected viral RNA for dengue, Zika, and chikungunya in blood donated by asymptomatic individuals during outbreak and endemic periods. Over 57 percent of infected donors showed no symptoms, undermining symptom-based screening systems that rely on donor self-reporting.

The authors explicitly warned of the growing risk warming poses in endemic regions for transfusion-transmitted infections. In response to these growing risks, the UK launched a new surveillance program in the same year to monitor donated blood for viruses expected to spread because of climate change. 

This occurred at the same time that the country was experiencing a strain on its own blood stockpile. This pressure was exacerbated by a malicious cyberattack on Synnovis, a pathology service that supports part of the National Health Service. This led to a disruption in blood testing and matching, especially in southeast England, and contributed to a shortage of type O-negative blood, the universal donor.

Although these pressures were not caused by climate change, they nevertheless demonstrate just how precarious the blood system in a developed country like UK is under “normal” conditions.

Health and climate change

It barely needs stating that blood transfusions save lives. Over 100 million blood donations are collected across the world each year, 40 percent of which, according to the World Health Organization (WHO), come from high-income countries. But despite this massive amount of donations, it’s still not enough. Many patients who require transfusions do not have timely access to safe blood.

This fact reveals the main issue at hand: as climate change becomes more disruptive, it is not introducing a new problem but exacerbating existing ones. Or to put it another way, the challenges posed by climate change on our health are not temporary crises tied up with fleeting, albeit extreme events, but rather enduring strains on an already fragile system.

Climate change is forcing us to rethink our approach to many parts of our lives that we have generally taken for granted. As global temperatures continue to rise, it is affecting different locations and regions in various unequal ways, especially our ability to grow food, secure water, build houses, or prepare for emerging diseases. 

Over the coming years, this will fundamentally alter the global environment as increasingly severe weather events impact natural ecosystems while forcing millions of humans to become climate refugees.

This much we know; there are likely few of us who are not aware of these problems. But what about their impact on healthcare? This is less frequently discussed.

Climate change has already presented severe challenges for global healthcare. Research has shown that the heatwaves of recent years have led to more deaths, especially among older populations. It is estimated that the global proportion of people over 65 years of age will rise from 10 percent in 2024 to 16 percent by 2050. The majority of these people will live in cities in countries where extreme heat and pollution put many more lives at risk.

At the same time, as global temperatures rise, we are seeing a surge in infectious diseases and cardiovascular illnesses. Shifting rainfall and melting permafrost is increasing the habitats of disease-carrying insects (as discussed above), as well as escalating waterborne bacterial risks.

The situation is so severe that in May this year, the independent Pan-European Commission on Climate and Health (PECCH) – which was convened by the WHO – concluded that climate change was a global threat to health, one that should be declared a Public Health Emergency of International Concern (PHEIC). 

This designation has traditionally been used for declarations such as those related to COVID-19 and mpox outbreaks. But while climate change may not appear like a global infection, taking the steps to regard it as a PHEIC means countries can start to coordinate international responses to address the challenges.

PECCH’s report was presented at the WHO’s 2026 World Health Assembly, where the suggestion was largely marginalized by becoming a topic at side events. Rather than declaring an emergency, the WHO has chosen to advance climate action through long-term structural changes that will be achieved through a Global Action Plan on Climate Change and Health, as well as other strategic objectives.

Relevant to our point is the WHO’s Action Framework to advance universal access to safe, effective, and quality-assured blood products that was launched during the time that the World Health Assembly met. This framework treats blood and plasma products as an essential component of universal health coverage. 

However, it did not go so far as to identify blood as something explicitly vulnerable to climate change, despite it playing a critical role in any efforts to establish climate-resilient health systems. Heatwaves, floods, trauma, cardiovascular events, and disease outbreaks all increase the need for blood, and as discussed above, the supply and safety of blood is at greater risk.

Building resilient systems

In April 2025, Dr Elvina Viennet, Research Fellow at the Australian Red Cross Lifeblood and Adjunct Senior Lecturer at Queensland University of Technology, and colleagues published the first global assessment of how climate change affects blood supplies. 

The team reviewed the existing literature on how extreme weather events are influencing the spread of infectious diseases, physical and mental health, and the safety of blood transfusions. They then assessed these results against the various stages involved in the blood supply line.

The team found that, as extreme weather events become more common and intense, they will impact all stages of the blood system. 

As we’ve already seen, extreme whether events can disrupt donation efforts, but bad weather can also make transporting blood more difficult. In the aftermath of hurricanes or wildfires, roads may not be accessible, preventing blood from being delivered where it’s needed. Damage to national and local infrastructure in such events can also delay blood testing, while the gradual shift in habitats for disease-carrying insects continues to demand more time-consuming tests of blood from potentially asymptomatic donors.

At the same time, wide scale disasters can knock out power to hospitals and other facilities, endangering blood and plasma stocks. Heatwaves will also increase the strain on existing cooling systems, increasing energy demands and putting facilities at risk of failure that add to these risks.

“Any major disruptions to the availability and safety of the blood supply puts lives at risk,” Viennet has previously told The New York Times.

However, the team believe there are important steps that can be taken to mitigate these risks. Building a climate-resilient blood supply requires flexible, context-specific strategies that account for increased disruptions and the rise of diseases. Importantly, as the global demand for blood increases, blood services will need to reassess donor exclusion rules and screening protocols as infections that have previously been linked to foreign travel become endemic in new contexts.

“Adaptable strategies are already being implemented to bolster climate resilience in blood systems. Walking blood banks, which collect donations at the site of crises, are used in both high-income and low-income countries, offering flexibility during emergencies,” the team wrote in their paper.

“Similarly, cell salvage techniques and the use of drones for blood transportation, as seen in Rwanda, improve efficiency, especially in areas with disrupted transport. These innovations reduce reliance on traditional blood supply chains and offer rapid responses to climate-related challenges.”

Nations and medical authorities also need to prepare for these risks through adaptive emergency plans. This could involve planning for supplementary blood centers during emergencies and ensuring reliable cooling systems in relevant transports, or even just adjusting routes to accommodate any weather-related disruptions. 

Facilities should also be equipped with backup power storage and protocols for prioritizing testing during any climate-related disaster. They add that the WHO’s existing report on maintaining blood supplies and their components during emergencies can be adapted for climate management plans.

As with many aspects of the climate crisis, the situation is not so bleak that we cannot take meaningful action now. But despite us being increasingly aware that climate change will impact many aspects of global health in the years to come, there is still much we do not know. Thankfully, researchers are trying to address these gaps. It’s just a question of whether or not others will listen to their results.