Act Now on Climate Change

How bad are the effects of Climate Change in Human Health?

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Global climate change comes with an increase in the earth’s temperature. it has the potential for direct and indirect impacts on the environment and public health. Some of the direct impacts that occur are heatwaves and extreme winters. The severity of these health risks will depend on the ability of public health and safety systems to prepare for these changing threats, as well as factors such as an individual’s behavior, age, gender, and economic status.

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 and change. Here are how climate change impacts human health:

Temperature – Related Impact

Warmer average temperatures will lead to hotter days and more frequent and longer heatwaves. Heatwaves can cause the heart to work hard to cool the body, if the condition of the heart is limited it can cause fatal disorders. Exposure to extreme heat can lead to heatstroke and dehydration, as well as cardiovascular, respiratory, and cerebrovascular disease. Urban areas are typically warmer than their rural surroundings. Large metropolitan areas such as St. Louis, Philadelphia, Chicago, and Cincinnati have seen notable increases in death rates during heat waves. A heatwave also occurred in France in early August 2003. Another direct impact due to hot temperatures is an increase in cases of asthma and skin cancer.

Several diseases as a cause of death associated with extremely cold temperatures are ischemic heart disease, cerebrovascular disease, and respiratory disease, especially influenza. The indirect impact of global climate change is the occurrence of diseases, which are environment-based and malnutrition. These environmental-based diseases include vector-borne disease, rodent-borne disease, and water-borne disease. Diseases due to malnutrition (malnutrition) due to crop failure and decreased agricultural production.

Air Quality Impact

Poor air quality, whether outdoors or indoors, can negatively affect the human respiratory and cardiovascular systems. Wildfires, which are expected to continue to increase in number and severity as the climate changes, create smoke and other unhealthy air pollutants. Wildfires emit fine particles and ozone precursors that in turn increase the risk of premature death and adverse chronic and acute cardiovascular and respiratory health outcomes.

Air pollution epidemiology studies describe the relationship between a population’s historical exposure to air pollutants and the risk of adverse health outcomes. Populations exposed to ozone air pollution are at greater risk of dying prematurely, being admitted to the hospital for respiratory hospital admissions, being admitted to the emergency department, and suffering from aggravated asthma, among other impacts. Current levels of ground-level ozone have been estimated to be responsible for tens of thousands of hospital and emergency room visits, millions of cases of acute respiratory symptoms and school absences, and thousands of premature deaths each year in the United States.

Impact From Extreme Weather Events

Globally, the number of reported weather-related natural disasters has more than tripled since the 1960s. Every year, these disasters result in over 60 000 deaths, mainly in developing countries. While it is intuitive that extremes can have health impacts such as death or injury during an event (for example, drowning during floods), health impacts can also occur before or after an extreme event, as individuals may be involved in activities that put their health at risks, such as disaster preparation and post-event cleanup. Extreme events can affect human health in a number of ways by:

  • Reducing the availability of safe food and drinking water.
  • Contributing to carbon monoxide poisoning from improper use of portable electric generators during and after storms.
  • Creating or worsening mental health impacts such as depression and post-traumatic stress disorder (PTSD).
  • Increasing stomach and intestinal illness, particularly following power outages.

Vector-borne Diseases

Vector-borne diseases are illnesses that are transmitted by vectors, which include mosquitoes, ticks, and fleas. These vectors can carry infective pathogens such as viruses, bacteria, and protozoa, which can be transferred from one host (carrier) to another. The seasonality, distribution, and prevalence of vector-borne diseases are influenced significantly by climate factors, primarily high and low-temperature extremes and precipitation patterns.  In recent years, several important vector-borne pathogens have been introduced or reintroduced into the United States. These include the West Nile virus, dengue virus, and chikungunya virus. In the case of the 2009 dengue outbreak in southern Florida, climate change was not responsible for the reintroduction of the virus in this area, which arrived via infected travelers from disease-endemic regions of the Caribbean. Other diseases in this case are lime disease, west Nile virus.

Water-related Illness

Projections of temperature, precipitation, extreme events such as flooding and drought, and other climate factors vary by region of the United States, Europe and thus the extent of climate health impacts will also vary by region. There are some pathogen and their selected health outcomes and symptoms:

  • Algae (Toxigenic marine species of Alexandrium, Pseudo-nitzschia, Dinophysis, Gambierdiscus; Karenia brevis) : Gastrointestinal and neurologic illness caused by shellfish poisoning. Asthma exacerbations, eye irritations caused by contact with aerosolized toxins (K. brevis).
  • Cyanobacteria : Liver and kidney damage, gastroenteritis (diarrhea and vomiting), neurological disorders, and respiratory arrest.
  • Enteric bacteria & protozoan parasites: Salmonella enterica; Campylobacter species; Toxigenic Escherichia coli; Cryptosporidium ; Giardia : Enteric pathogens generally cause gastroenteritis. Some cases may be severe and may be associated with long-term and recurring effects.
  • and etc.

Food Safety and Nutrition

Extreme weather events could also disrupt or slow the distribution of food. Climate change will have a variety of impacts that may increase the risk of exposure to chemical contaminants in food. For example, higher sea surface temperatures will lead to higher mercury concentrations in seafood, and increases in extreme weather events will introduce contaminants into the food chain through stormwater runoff. Extreme events, such as flooding and drought, create challenges for food distribution if roads and waterways are damaged or made inaccessible.

Mental Health

Any changes in a person’s physical health or surrounding environment can also have serious impacts on their mental health. In particular, experiencing an extreme weather event can cause stress and other mental health consequences, particularly when a person loses loved ones or their home. Individuals with mental illness are especially vulnerable to extreme heat; studies have found that having a pre-existing mental illness tripled the risk of death during heat waves. People taking medication for mental illness that makes it difficult to regulate their body temperature are particularly at risk. Even the perceived threat of climate change (for example from reading or watching news reports about climate change) can influence stress responses and mental health.

WHO Response

Many policies and individual choices have the potential to reduce greenhouse gas emissions and produce major health co-benefits.  2015, the WHO Executive Board endorsed a new work plan on climate change and health. This includes:

  • Partnerships: to coordinate with partner agencies within the UN system, and ensure that health is properly represented in the climate change agenda.
  • Awareness-raising: to provide and disseminate information on the threats that climate change presents to human health, and opportunities to promote health while cutting carbon emissions.
  • Science and evidence: to coordinate reviews of the scientific evidence on the links between climate change and health, and develop a global research agenda.
  • Support for implementation of the public health response to climate change: to assist countries in building capacity to reduce health vulnerability to climate change, and promote health while reducing carbon emissions.


This series of the blog is part of Act Global Project of Act Now on Climate Change. We will be portraying how climate change is affecting us and what is need to do to prevent it from worsening.  Act Now!



Written by: Kurnia Wardhani M.J.



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