Climate change may pose a growing risk to global blood supplies, affecting both availability and demand, according to a new study.

These factors may reduce the number of eligible donors while simultaneously increasing the need for transfusions.

The study highlights that blood-borne infections could become more widespread as warmer climates and increased rainfall encourage the spread of mosquito-borne illnesses such as dengue fever, West Nile virus, and malaria. This could prevent more people from donating blood, further tightening supply. In Europe, where around 25 million units of blood are used annually for surgeries, chronic illnesses, trauma care, and neonatal treatment, such disruptions could have serious consequences.

Extreme weather events are also expected to complicate blood collection and distribution. Natural disasters and climate-related disruptions can limit people’s ability to travel, while also affecting the storage, safety, and transportation of blood, which has a limited shelf life.

In addition, climate-related health effects may reduce donor eligibility. Changes in temperature and environmental conditions can influence haemoglobin levels, blood pressure, and hydration, while heat stress and psychological factors such as climate anxiety could further impact potential donors.

At the same time, demand for blood may rise. The researchers note that increases in certain health conditions, including pregnancy complications, cardiovascular diseases, and sickle cell disease, along with injuries linked to disasters, could drive higher transfusion needs.

To address these challenges, the study suggests several strategies, including the use of mobile and adaptable blood collection centres, techniques like cell salvage that allow patients to reuse their own blood, and stronger international cooperation. It also emphasizes the importance of expanding and diversifying the donor base, particularly as climate change may drive migration and shift population demographics.