Climate change currently contributes to the global burden of disease and premature deaths (very high confidence).
Human beings are exposed to climate change through changing weather patterns (for example, more intense and frequent extreme events) and indirectly through changes in water, air, food quality and quantity, ecosystems, agriculture and economy. At this early stage the effects are small, but are projected to progressively increase in all countries and regions [8.4.1].
Projected trends in climate-change related exposures of importance to human health will have important consequences (high confidence).
Projected climate-change related exposures are likely to affect the health status of millions of people, particularly those with low adaptive capacity, through:
- increases in malnutrition and consequent disorders, with implications for child growth and development;
- increased deaths, disease and injury due to heatwaves, floods, storms, fires and droughts;
- the increased burden of diarrhoeal disease;
- mixed effects on the range (increases and decreases) and transmission potential of malaria in Africa;
- the increased frequency of cardio-respiratory diseases due to higher concentrations of ground-level ozone related to climate change;
- the altered spatial distribution of some infectious-disease vectors.
This is illustrated in Figure TS.9 [8.2.1, 8.4.1].
Figure TS.9. Direction and magnitude of change of selected health impacts of climate change.
Adaptive capacity needs to be improved everywhere (high confidence).
Impacts of recent hurricanes and heatwaves show that even high-income countries are not well prepared to cope with extreme weather events [8.2.1, 8.2.2].
Adverse health impacts will be greatest in low-income countries (high confidence).
Studies in temperate areas (mainly in industrialised countries) have shown that climate change is projected to bring some benefits, such as fewer deaths from cold exposure. Overall it is expected that these benefits will be outweighed by the negative health effects of rising temperatures worldwide, especially in developing countries. The balance of positive and negative health impacts will vary from one location to another, and will alter over time as temperatures continue to rise. Those at greater risk include, in all countries, the urban poor, the elderly and children, traditional societies, subsistence farmers, and coastal populations [8.1.1, 8.4.2, 8.6.1, 8.7].
Current national and international programmes and measures that aim to reduce the burdens of climate-sensitive health determinants and outcomes may need to be revised, reoriented and, in some regions, expanded to address the additional pressures of climate change (medium confidence).
This includes the consideration of climate-change related risks in disease monitoring and surveillance systems, health system planning, and preparedness. Many of the health outcomes are mediated through changes in the environment. Measures implemented in the water, agriculture, food and construction sectors can be designed to benefit human health [8.6, 8.7].
Economic development is an important component of adaptation, but on its own will not insulate the world’s population from disease and injury due to climate change (very high confidence).
Critically important will be the manner in which economic growth occurs, the distribution of the benefits of growth, and factors that directly shape the health of populations, such as education, health care, and public health infrastructure [8.3.2].