Climate change, biodiversity and human health

The planet is experiencing increasingly intense climate changes: heatwaves, droughts, floods and extreme events that disrupt ecosystems and the distribution of species. This transformation not only threatens flora and fauna but also has direct repercussions on human health, as it worsens air and water quality and reduces food resources.  

The accelerated loss of biodiversity reduces nature’s ability to regulate the climate and control diseases, creating a cycle in which environmental degradation and health risks reinforce one another. In this context, international organisations stress the need to implement integrated strategies that connect environmental protection with health promotion, ensuring a sustainable balance between people and nature. 

Climate change, a risk multiplier

In 2018, the World Health Organization (WHO) identified climate change as the biggest health challenge of the 21st century. On the one hand, it considers that it threatens all aspects of the society in which we live, while also acting as a multiplier of other major global risks. One of the most significant is the loss of biodiversity, which underpins life on Earth, food security, livelihoods, health and even resilience to climate change. “Biodiversity is the foundation of life and the cornerstone of sustainable development,” said António Guterres, Secretary-General of the UN, in 2025 in relation to the International Day for Biological Diversity. 

However, its preservation is at risk. The UN estimates that one million species are at risk of extinction, while 75% of terrestrial ecosystems and two-thirds of marine ecosystems have been significantly altered by human activity. “Humanity is destroying biodiversity at breakneck speed, as a result of pollution, the climate crisis, ecosystem destruction and, ultimately, short-term interests that drive the unsustainable use of our natural world,” Guterres also noted. 

Its impact on health is clear and is expected to increase alongside global warming, both directly – through exposure to high temperatures and extreme weather events — and indirectly – through impacts on the natural and social ecosystems on which our health ultimately depends, such as access to water and food. Various organisations support this view. 

The Food and Agriculture Organization (FAO), a specialized agency of the United Nations that leads international efforts to defeat hunger, estimates in its report The State of Food and Agriculture 2025Enlace externo, se abre en ventana nueva.  that around 1.7 billion people live in areas where crop productivity is declining due to human-induced land degradation. What’s more, the UN estimates that “around three billion people rely on fish for 20% of their animal protein intake and that 80% of rural populations in developing countries depend on plant-based medicine”. 

 SEE INFOGRAPHIC: The impacts of climate change and how they affect health [PDF] External link, opens in new window.

Therefore, acting to mitigate climate change and to promote the transition to a decarbonised economy that is responsible towards nature, is also to act in favour of healthy ecosystems, a less vulnerable population and a more resilient economy.