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Surviving the 2022 flood at Ahoada in Rivers state, Nigeria. Source https://meta.m.wikimedia.org/wiki/File:Flood_apocalypse2.jpg. Credit Hansel Ohioma   https://creativecommons.org/licenses/by-sa/4.0/

The fallout from climate change threatens our health by affecting the food we eat, the water we drink, the air we breathe, the safety of our homes and the weather we experience.

The severity of health risks from a changing climate depends on the effectiveness and preparedness of public health, safety and emergency response systems. Individual’s behavior, age, gender, and economic status are also important factors. Some groups of people such as the very young, the very old, the disabled and pregnant women are especially vulnerable to health impacts.

These impacts will vary based on where a person lives, how sensitive they are to health threats, how much they are exposed to climate change impacts, and how well they and their community are able to adapt to change.

Although the categories direct and direct are used interchangeably to describe climate change’s impact on health there is a lot of overlap between the two. For the purposes of this online course, direct refers to the more devastating immediate effects while indirect refers to the punishing ripple down effects of climate change.

Climate change impacts health directly due to extreme weather events. Extreme heat, rising sea levels, floods, extreme precipitation, droughts, and storms can lead to tens of thousands of deaths every year, mainly in low- and middle-income countries.

In the next lesson we will find out more about the indirect impacts of climate change. the disruption of the health care systems, gender-based violence, and more.

Direct Health Impacts

Direct impacts include injuries and fatalities from extreme weather events, heat-related illnesses, respiratory problems from air pollution, waterborne diseases from contaminated water sources and increasing transmission of vector and infectious diseases.

Addressing the direct impacts on human health requires interventions aimed at reducing exposure to climate-related hazards, stepping up the ability of people to adapt to the reality of a changing climate, and improving public health preparedness and response measures. Journalists will need to track governmental departments’ readiness to cope with climate-related events.

Injuries and fatalities 🤕

Climate-related disasters such as storms, floods, wildfires, and heatwaves can cause injuries and fatalities directly. They can also cause damage to health facilities and other essential infrastructure, cutting people off from immediate access to healthcare, treatment, food supplies and electricity.

⚠️ When an extreme weather event has occurred there may be many injuries and fatalities. While numbers are important to reflect the extensiveness of the event, don’t forget to include the voices of ordinary people. 

Extreme heat impacts 🥵

As global temperatures rise, heatwaves become more frequent and intense, leading to an increased risk of heat exhaustion, heatstroke, and dehydration especially in vulnerable populations. Extreme heaty can also worsen chronic conditions, such as cardiovascular, cerebrovascular disease and diabetes-related conditions.

  • Heatstroke is life-threatening characterized by a body temperature above 40°C (104°F). Symptoms include a lack of sweating, confusion, disorientation, rapid pulse, hot and dry skin, and loss of consciousness. Heatstroke requires immediate medical attention as it can lead to organ damage, coma, and death if left untreated.
  • High temperatures can put added stress on the cardiovascular system, particularly in individuals with pre-existing heart conditions such as coronary artery disease, congestive heart failure, and hypertension.
  • Heat can cause blood vessels to dilate and blood to collect in the extremities, increasing the risk of blood clots, particularly in individuals who are sedentary or have existing risk factors such as obesity, smoking, or a history of blood clots.

⚠️ Remember to give the public – your audience – information that can save their lives. Speak to health authorities, for example, about what people can do in times of heatwaves. This could include strategies such as staying hydrated, avoiding prolonged exposure to extreme heat, seeking shade or air-conditioned environments and other measures. For more useful information click fact sheet on the impact of heatwaves on health.

Respiratory problems 🫁

Climate change adds to existing air pollution, which makes respiratory conditions such as asthma and bronchitis worse. Air pollution drives lung cancer, asthma and chronic obstructive pulmonary disease. Higher temperatures also degrade air quality by increasing the production of ground-level ozone and particulate matter. Greenhouse gas emissions are major contributors to both climate change and air pollution (See Module 1).

Here is an article on a recent study conducted in the United States which shows a correlation or a link between toxic air from the burning of fossil fuels to preterm and low birth weights in babies.

⚠️Remember to explain the difference between air pollution and greenhouse gases which add to existing pollution. This will help you to make the connection between Climate change and health.

Wildfire impact 🔥

Wildfires cause a range of health problems from direct burn injuries to acute and chronic lung disease from smoke and pollution. It can include the loss of essential and health-supporting physical infrastructure and emergency services.

⚠️ With the likely destruction of infrastructure, reporting ideally would include information on where people can access temporary treatment and healthcare centres.


Clinic information on Zika virus Credit: WHO

Climate change can influence the distribution and behavior of disease-carrying vectors such as mosquitoes and ticks. Warmer temperatures and altered rainfall patterns can expand the geographical range of these vectors, leading to a higher incidence of diseases like malaria, dengue fever, Lyme disease, and Zika virus.

As the Earth warms up the malaria vector will develop faster, allowing them to breed faster, bite more frequently and expand into formerly unsuitable habitats. This means that mosquito larvae will develop into adults faster.

In too hot and dry a climate, though, mosquitos cannot survive. Other diseases such as Rift Valley Fever – caused by a virus that mosquitoes transmit to people – is projected to increase in prevalence. It’s an acute viral disease that affects domestic animals (such as cattle, buffalo, sheep, goats, and camels) and effectively people’s food and income supply.

⚠️ Here are examples of how journalists have investigated and written about research on the link between climate change, health and vector-borne diseases.

Water-borne diseases 🚰

These are transmitted via viruses or bacteria through water. Waterborne diseases, such as cholera, typhoid and E. coli infections, are a major public health issue causing 3.5 million deaths annually. And climate change is increasing the risk. The climate drivers that most influence waterborne illness include:

  • extreme weather events (like storms, droughts, precipitation, floods and wildfires)
  • increase in air temperature
  • increase in water temperature

Changes in temperature and precipitation patterns affect water quality and availability, increasing the risk of waterborne diseases such as cholera and dysentery. Cholera thrives during periods of increased rainfall. If these conditions intensify with climate change as projected, scientists expect to see more outbreaks, particularly in areas with poor sanitation or where flooding has occurred.

Flood events can also lead to the contamination of drinking water sources. And drought and water scarcity affect food production, making healthy diets less affordable. WHO data shows that 2 billion people lack safe drinking water.

⚠️Here is a toolkit that gives great tips on how to cover cholera and further resources linking cholera to climate change

Food-borne illnesses 🌽

WHO says 600 million people suffer from foodborne illnesses annually, with 30% of children under 5 dying as a result. Climate stressors such as heat waves and heavy rainfall affect pathogens and introduce toxins to crops. Pathogens that cause many foodborne infections such as salmonella are sensitive to temperature. This is because warm, wet weather conditions stimulate bacterial growth.

Heat waves, wildfires and severe storms are increasingly triggering power outages, which in turn affects food storage and food handling practices. If food – meat, dairy, vegetables – are not kept at optimal temperatures they spoil and become contaminated.

⚠️ When you click on this website scroll down to the sound clip where it says listen to this article. It gives a good summary of climate change and food-borne diseases.

Mental health 🤯

Extreme weather events, displacement due to climate-related disasters, and uncertainty about the future can contribute to stress, anxiety, depression, and other mental health disorders. We will explore this topic in more detail in the next lesson.


Here are more articles and resources