Climate change impacts health and biodiversity directly as well as indirectly, and the connections are complex. Heat waves and other climate-related disasters have direct impacts on human health, while several indirect impacts on human health are mediated by climate impacts on ecosystems and biodiversity. These range from less resilient food systems to the spread of water-related, food-related, and vector-borne disease. There are many feedback loops: for instance, climate change can reduce water and air quality, damaging human health as well as ecosystems and biodiversity, which in turn affects water and air quality. Climate change accelerates biodiversity loss, which in turn reduces the resilience of ecosystems and agriculture against climate change, as well as their capacity to adapt to it. Climate change also affects agricultural production, food and water security, the nutritional content of food, and the distribution and abundance of fish stocks, all of which impact human health. It is also likely to amplify the impact of other drivers such as land use change, pollution, and invasive species on both human health and biodiversity. Industrial farming and livestock production as well as deforestation accelerate both climate change and biodiversity loss, with significant health impacts.

Ecosystem degradation and the collapse of ecosystem services can precipitate disasters including disease epidemics, floods, storms and wildfires, with adverse consequences for human health and for ecosystems. Climate-related disasters are on the rise, and ecosystem degradation increases the vulnerability of human populations to such events. The creation of disaster-resilient societies will be essential, and is dependent on resilient ecosystems and their sustainable and secure delivery of goods and services: not only those associated with disaster resilience, but also those that normally support communities. Long-term health is an important indicator of community resilience against disasters.

The 2021 EU climate adaptation strategy notes that climate-related health threats are increasing in Europe. These include death and injury from heat, floods or wildfires; threats to food and water safety and security, and the emergence and spread of infectious diseases and allergens from geographical shifts in vectors and pathogens. EU public health systems will be affected. The European Climate and Health Observatory was launched in 2021 to address knowledge gaps on climate change impacts on human health. Recognising that human health is inextricably linked to animal and environmental health, the Commission has adopted the 'One Health' approach in analysing and preventing climate change impacts, including via the One Health European Joint Programme. The EC proposal for the 8th Environment Action Programme calls for strengthening the links between climate and health policies, and specifically mentions the need to address the impacts and risks of climate change to human health and wellbeing. The EC proposal on a European Health Union addresses serious cross-border threats including those from environmental and climatic conditions.

The EU climate adaptation strategy also emphasises nature-based solutions for building climate resilience and sustaining healthy water, oceans and soils in a cost-effective way: by protecting and restoring wetlands, peatlands, coastal and marine ecosystems; developing urban green spaces; promoting and sustainably managing forests and farmland. Nature-based solutions are particularly effective for boosting climate resilience against water impacts.  Climate change is aggravating situations of either too much or not enough water in Europe, as well as threats to water quality: it increases the risk of contaminated freshwater due to low river flows, high water temperatures, flooding and forest loss. In order to ensure sustainable freshwater supply and quality, the Commission is prioritising the Common Implementation Strategy of the Water Framework Directive and the Floods Directive (2007). The latter aims at reducing flood-related impacts on human health, the environment, cultural heritage and economic activity.