Climate change is already affecting our environment, manifesting itself in particular through rising temperatures, an increase in the frequency of certain extreme weather events such as heat waves, and changes in the phenology and distribution of flora and fauna.
Combined with other environmental changes, it is identified as one of the greatest risks to public health worldwide. Indeed, the health impacts are wide-ranging: the emergence or re-emergence of infectious diseases, an increase in the frequency and intensity of extreme weather events (such as heat waves, floods, severe windstorms, or wildfires), interactions with air pollution, changes in natural resources, and more. Some of these impacts are already observable in France, such as the increase in the number of heat waves.

Preventing these health impacts relies on adaptation and mitigation. Adaptation involves implementing measures to reduce impacts that are already observable. Mitigation involves reducing greenhouse gas emissions to limit future warming and protect future generations. Mitigation also allows us to take action now on key health determinants, such as air pollution or physical activity.

What impact can climate change have on health?

The influence of climatic factors on health has been known since ancient times. Seasonal variations in the incidence of many diseases illustrate this. This influence can be direct, as in the case of extreme weather events such as heat waves, floods, severe windstorms, or wildfires.
It can also be indirect, as the climate affects ecosystems, environmental pollutants, the economy, infrastructure, and more. It can thus contribute to certain infectious diseases and allergies, affect mental health, and increase social inequalities. Climate
change is rapidly and profoundly altering several climate and environmental factors that are critical to health.

For example, in France, by 2030, we can expect:

• an increase in the frequency and intensity of extreme weather events, such as heat waves, floods, and wildfires...

• the emergence or re-emergence of infectious risks due to environmental changes, such as the geographic spread of vectors for dengue, malaria, and chikungunya

  • changes in the environment and lifestyles leading to new exposures, such as sun exposure and UV-related risks, swimming and leptospirosis, and the interaction between air pollution and temperatures…

Is climate change a source of social or regional inequalities?

The consequences of climate change vary depending on the regions and ecosystems affected.

Thus, climate change hinders health improvements in developing countries. It is a driver of poverty and exacerbates gender inequalities. For example, food insecurity or reduced access to water primarily affects girls and women in developing countries.

It also exacerbates social health inequalities in developed countries. The ability to adapt to changing risks depends on socioeconomic factors. For example, in developed countries, limited access to green spaces or poverty increases the risk of heat- and cold-related deaths. Air conditioning systems that release heat into the air cause a significant increase in outdoor temperatures, thereby increasing the exposure of people in the neighborhood who cannot afford such systems.

What mitigation and adaptation measures can reduce risks associated with global warming?

Developing preventive measures is necessary to limit health risks sensitive to climate change. Prevention has two aspects: mitigation and adaptation.

Mitigation

This can be likened to primary prevention, as it aims to reduce the magnitude of climate change and thus future health risks by reducing greenhouse gas (GHG) emissions. It requires major changes in several sectors of society, such as energy production and consumption, housing, agriculture, and transportation. Taking into account the potential health impacts of these changes is important to avoid choices that endanger human health and to maximize the associated health co-benefits. Knowledge from epidemiology can thus help guide mitigation efforts by quantifying the potential health co-benefits of proposed policies. Mitigation measures taken today will not stop the warming that is already underway—and therefore do not eliminate the need for adaptation—but should help limit it. Recent IPCC findings show that the expected health impacts under global warming of +1.5°C would be much less severe than those expected under warming of +2°C. Every half-degree counts.

Adaptation

It can be viewed as a form of secondary prevention aimed at interrupting an ongoing harmful process to limit its impact. It can take various forms. Direct adaptation is a specific action in response to a specific problem (for example, in France, the national heatwave plan). Adaptation of management processes, on the other hand, advocates for changes within organizations to address new risks through an interdisciplinary approach.

Finally, the adaptation of societies will depend on their ability to develop new approaches to education, training, and research, promoting interdisciplinarity and the capacity to innovate in order to address complex problems.