This year's World Health Day, celebrated last Monday, drew international attention to the impacts of climate change on human health. Health experts predict that climate change will exacerbate global health problems that are already huge, such as malnutrition and infectious disease. Strengthening public health services, especially among vulnerable populations in the developing world, therefore needs to be a central component of climate adaptation strategies.

The World Health Organization (WHO) identifies five major health consequences of climate change:

Malnutrition

The agricultural sector is extremely sensitive to climate variability, including rising temperatures and more frequent droughts and floods. Countries with large populations depending on rain-fed subsistence farming—most notably in Africa—face the greatest risk. Malnutrition is already responsible for an estimated 3.5 million deaths each year.

Death and disease from extreme weather events

Extreme weather events can cause immediate death and injury, such as Hurricane Katrina in 2005, which killed over 1,800 people. Flooding following such events can cause outbreaks of diseases such as cholera, which can be particularly lethal when vital health infrastructure has been destroyed.

Diarrhoel disease from both scarcities of water and excess water

Each year, 1.8 million people die from diarrhea. Scarcity of water, which is essential for hygiene, or excess water due to more frequent and torrential rainfall, will aid the spread of diarrhoeal disease through contaminated food and water.

Heatwaves

In 2003, over 70,000 people died from summer heatwaves in Europe. This problem is particularly acute in urban "heat islands", and disproportionately affects elderly people with cardiovascular or respiratory disease.

Infectious Disease

Infectious diseases such as Malaria and Dengue Fever are typically constrained to regions with climates suitable to their insect vectors. With rising temperatures and altered rainfall patterns, the geographical distribution of these diseases will change, spreading them to new countries while also worsening the situation in existing countries.

Strategies for Vulnerability and Adaptation

WHO is increasing efforts to respond to the health challenges of climate change. Identifying vulnerable populations and conceiving strategies and tools for adaptation are among top priorities. Better health surveillance systems and stronger basic health services can offer significant protection, but concerted international action and cooperation across many sectors will be necessary to realize these goals.

More Data and Analysis from EarthTrends:

Public health data (over 30 indicators with data for more than 200 countries)

Map: Projected Annual Renewable Water Supply Per Person by River Basin, 2025

Feature Article: "Health, Environment and Poverty"

Additional Resources from WHO

10 Facts on Climate Change and Health

Protecting Health from Climate Change: Summary of Issues Paper