Pan American Health Organization

Climate change and health


Climate change is deemed “the biggest global health threat of the 21st century” (). Due to the complexity of the processes involved, the exact extent to which health may be influenced by the changing climate remains unknown. Nonetheless, based on current knowledge and future projections, with a high degree of certainty it is clear that the climate is changing, and that health is and will continue to be affected by this change.

Anthropogenic drivers throughout the climate system are very likely the dominant cause of global warming observed since the mid-twentieth century (). This rapid climate change poses direct and indirect human health challenges (). There is overwhelming evidence of the burden of disease and deaths from environmental risks (), which are expected to increase as the climate continues to change. The World Health Organization (WHO) has estimated—considering only a few of the associated health risks and assuming continued progress in economic growth and health protection—that climate change will cause about 250,000 additional deaths per year by the 2030s ().

Although climate change will affect everyone, population groups that are socially and economically vulnerable are at greatest risk, and their needs must be addressed in a timely manner (). The health sector must be ready to acknowledge, understand, and help societies to mitigate the impacts and to adapt to this new world while promoting better and more equitable conditions for all people.

First, the health sector should lead by example, reducing health systems’ emissions of greenhouse gases (GHG) while helping to stimulate change in the entire health system supply chain. To achieve that, health care facilities need to be made safer, more resilient, and more environmentally friendly.

Reducing emissions helps mitigate the impacts of climate change and improves air quality, with beneficial health gains. Worldwide, more than 7 million deaths annually are attributable to air pollution (), and air quality in 20% of cities in high-income countries and 90% of cities in low- and middle-income countries in the Americas do not meet WHO air quality guidelines (). Globally, health-related costs attributable to polluting fuels were US$ 5.3 trillion in 2015 (), more than the total spent on health by all the world’s governments. A coordinated effort to reduce emissions by health and other sectors would have a truly global positive impact.

Second, the health sector must focus on adapting to the changing climate. Health personnel should participate in training to identify and understand the effect of climate change; advocate and act to reduce the climate footprint produced by the health sector; and help to increase health systems’ resilience.

Third, the health sector also has a role to play in maximizing health co-benefits in intersectoral actions. Health outcomes need to be considered when planning energy, transportation, food, water, and urban systems. Further, when discussing health, it is crucial to identify related and interacting health concerns and responses of politically, economically, and socially marginalized people. In this chapter, crosscutting actions are proposed to advance integrated and effective responses to the climate change agenda in the Americas.

The world in a changing climate

Climate scientists agree that GHG emissions are the primary cause of current trends in global warming (). Carbon dioxide, methane, nitrous oxide, and ozone are the main GHGs; since 1750, atmospheric concentrations of the first three have increased significantly—by 40%, 150%, and 20%, respectively—and it is estimated that GHGs are at their highest levels in 800,000 years. This sharp increase is mainly due to burning fossil fuels and industrial manufacturing processes, which are responsible for about 78% of the increase.

Because GHGs act to trap heat, as their concentration in the atmosphere increases, so does the temperature (Figure 1). The unprecedented concentration of GHG in the atmosphere has led to an increase in the global average temperature of about 0.85°C between 1880 and 2012 (). Based on current trends, atmospheric concentrations of GHG will be almost four times preindustrial levels by the end of this century (). By the 2090s, this will cause the global mean surface temperature to rise by an additional 3.7°C from 1986–2005 temperatures; the increase would be in addition to the warming that has already occurred since the preindustrial era (Figure 2).

Figure 1. Both the atmospheric carbon dioxide concentration and the global average temperatures are rising ()

Source: Carbon dioxide data from the NOAA Earth System Research Laboratory and temperature data from the Goddard Institute for Space Studies,

Figure 2. Exposure to warming resulting from projections of climate and population changes in the 21st century. Changes in summertime temperatures between 1995 and 2090, for the RCP8.5 scenario, using the mean of the projections produced by the CMIP5 climate models

Source: Watts N, Adger WN, Agnolucci P, Blackstock J, Byass P, Cai W, et al. Health and climate change: policy responses to protect public health. The Lancet 2015;386(10006):1861–1914(). Reprinted with permission from the authors.

The extent of warming may cause severe disruptions to precipitation patterns and to the frequency and intensity of extreme weather events such as storms, hurricanes, heat waves, heavy precipitation, and storm surges in coastal areas. In addition, oceans will become warmer and more acidic, and glaciers will begin to melt, causing sea levels to rise. The global sea level has increased approximately 20 cm during the past century, far more than in the previous two millennia, and is now projected to rise another 26 cm to 98 cm by the year 2100 (). A rising sea level exacerbates storm surges, worsens coastal erosion, and increases salinization of aquifers; these, in turn, increase pressure on water and food-production systems and cause floods in low-lying areas—all of which will likely have both direct and indirect impacts on health ().

How climate change affects human health

Health is influenced by climate and weather in many ways, and for several reasons it is difficult to anticipate all the impacts. First, an individual’s health responds to climatic events that are happening in different timescales—from daily variations to seasonal to interannual fluctuations—and these interconnected, causal links may be cumulative or can partially negate themselves (e.g., the El Niño Southern Oscillation occurs in irregular cycles of 2 to 7 years and may exacerbate the effects of regular dry periods or long-term climate changes). Second, it is often difficult to assess which responses can be disentangled from other factors and attributed solely to climate. Third, the time-lag between exposure and effect makes it difficult or impossible to determine the link. Assessing the effects of a climate change on health means identifying the changes in baseline values (of climate and health responses, discounting the responses to climate-unrelated factors). In turn, calculating those baselines is also difficult due to the short time that those data are reliably collected and registered worldwide.

Despite those difficulties, many researchers have concluded that health is and will continue to be affected by the changing climate in numerous ways. In fact, although climate warming may bring benefits to some regions (e.g., milder winters may reduce deaths or increase crop productivity in colder areas), the magnitude and severity of negative impacts are projected to overwhelmingly outweigh positive ones (). The Intergovernmental Panel on Climate Change (IPCC) () divides the impacts of climate change on health into three pathways: direct impacts, indirect impacts through natural systems, and indirect impacts through socioeconomic systems. However, health outcomes are not necessarily derived directly from those drivers. The social determinants of health (both individual and collective) and the presence and quality of health systems may modulate, for better or worse, the final health outcomes of those changes (Figure 3).

Figure 3.Impacts of climate change on human health; modified from Refs.()

Source: Adapted from Watts N, Adger WN, Agnolucci P, Blackstock J, Byass P, Cai W, et al. Health and climate change: policy responses to protect public health. The Lancet 2015;386(10006):1861–1914, and Levy BS, Patz J, eds. Climate change and public health. Oxford: Oxford University Press; 2015.

Direct impacts of climate change on human health

Heat waves

Heat waves are periods unusually warmer than average; they can last from days to months. A a 2°C increase in one region may be considered normal, while in another it may be unusually warm. Heat waves are generally the result of trapped air. Although not all heat waves are caused by climate change, they are more frequent, intense, and longer lasting now than in the past () and their frequency is projected to increase in the future ().

Heat waves may lead to heat stress, potentially leading to more cases of heat-related illnesses (e.g., heat stroke and heat exhaustion), respiratory allergies and airways diseases, decreased chemical tolerance, and fatigue (Figure 4). In addition, heat wave episodes have been linked to increased rates of admissions for mental disorders in emergency departments (mood- and anxiety-related disorders, dementia) and increased mortality associated with diagnosed mental health illness ().

Figure 4. Likelihood of disorders from prolonged exposure to heat or intense activity

Note: The heat index is a measure of how hot it feels when relative humidity is factored in with the actual air temperature. For example, if the air temperature is 96°F and the relative humidity is 65%, the heat index is 121°F. The National Weather Service will initiate alert procedures when the heat index is expected to exceed 105°F to 110°F (depending on local climate) for at least 2 consecutive days ().
Source: National Oceanic and Atmospheric Administration. National Weather Service heat safety home page [Internet]. Available from:

Excessive heat also increases the risk of wildfires (). For example, in Alberta, Canada, 70,000 people were displaced in 2016 (). Over the last 30 years in the United States, heat wave–related events kill more people than tornadoes, floods, and hurricanes combined (). Heat waves also increase energy demands because of greater use of air conditioners.

Heat waves may produce health effects in everyone, but effects can be more pronounced for the poor, who have inadequate housing and lack air conditioning, and for the elderly () and children, whose age make them more susceptible to extreme temperatures. Effects can be particularly harmful for people who work outdoors, since exposure to extreme temperature can reduce cognitive function and increase the risk of injury or cause lapses in safety ().


Between 2006 and 2015, almost a quarter (22.9%) of all disasters1 () in the world occurred in the Americas, causing 254,508 deaths and US$ 436 billion in damages. The most common events were hydrological and meteorological, which were responsible for 5.6% of disaster-related deaths and more than 73% of disaster-related damages (). Although not every disaster can be attributed to climate change, the number of extreme weather events has increased in the last decades. For example, the EM-DAT2 averaged 335 climate-related disasters annually between 2005 and 2014—an increase of 14% compared to the decade between 1995 and 2004, and almost twice the number in the 10-year span 1985 and 1994. If this trend continues, the number of disasters is expected to increase still further in coming decades (). Warming ocean temperatures are expected to cause an increase in the number of hurricanes and very intense tropical cyclones along the coast of Brazil, the northern portion of South America, in the Caribbean, and along both the east and west coasts of North and Central America (Figure 5) ().

Figure 5. Simulation of tropical cyclones

Note: Simulated occurrence of very intense tropical cyclones (Saffir-Simpson category 4 or 5) for present day (top); late 21st century, RCP4.5 CMIP5 multimodel ensemble (middle); and difference between late 21st century minus present-day conditions (bottom). Occurrence is defined as number of days a tropical cyclone with surface winds >131 miles/hour was found in each grid box (50 km) during a 20-year simulation period ().
Source: Bender MA, Knutson TR, Tuleya RE, Sirutis JJ, Vecchi GA, Garner ST, et al. Modeled impact of anthropogenic warming on the frequency of intense Atlantic hurricanes. Science 2010;327(5964):454–458.

Exposure to life-threatening situations induces extreme distress, with effects that vary according to the individual (), including post-traumatic stress disorder (), acute stress reaction, and adjustment disorder (anxiety spectrum disorders, depression) (). For example, a study with the survivors of Hurricane Mitch in Honduras showed that 22.1% of survivors experienced psychiatric problems, of which 18.3% had major depression and 11.1% had post-traumatic stress disorders ().

Indirect impacts through natural systems

Foodborne and waterborne diseases

Climate influences the growth, survival, persistence, transmission, and virulence of food and water pathogens (). Climate factors have been associated with increased contamination of pathogenic bacteria (E. coli, Campylobacter, Leptospira, Salmonella, and Vibrio); parasites (Cryptosporidium, Giardia); viruses such as hepatitis A and hepatitis E, norovirus, and poliovirus (); and harmful algal blooms ().

Gastrointestinal illnesses and waterborne diseases are linked to heavy rainfall and flooding events (). For example, in Guatemala, cholera increased almost 10-fold after Hurricane Mitch in 1998 (). Some studies have also demonstrated that waterborne diseases may be caused by decreased rainfall ().

Foodborne diseases may also increase due to climate change. The incidence of Salmonella and Campylobacter, two of the most common foodborne diseases, shows seasonal trends with more cases when temperatures are warmer (). Some foodborne toxins are also likely to increase with higher temperatures. One example is aflatoxin, a potent human liver carcinogen and a common fungal pathogen in maize, peanuts, tree nuts, and cottonseed (). Warmer weather may also promote harmful algal blooms that can produce large amounts of phycotoxins, which in turn can contaminate shellfish ().

Vector-borne diseases

Climate change is likely to expand the geographical distribution of vector-borne diseases (VBDs) to higher altitudes and extend the transmission season in those higher latitudes. Such changes are likely to occur with dengue, Zika, chikungunya, yellow fever, West Nile fever, malaria, leishmaniasis, tick-borne encephalitis, Lyme borreliosis, spotted fever rickettsioses, and Rift Valley fever—all of which are found in the Americas. Projecting the prevalence of VBDs is a complex task because of the many factors involved—environmental, biological, socioeconomic—and related to the surveillance and control strategies that are in place for VBDs.

Many studies showed that the temperature can affect the biting, survival, and reproductive rates of vectors and the survival and development rates of the pathogens they carry. For mosquito species, as water temperature rises, the larvae take a shorter time to mature () and consequently can produce more offspring. In warmer climates, adult female mosquitoes feed more frequently and digest blood faster (), which increases the speed of transmission. Similarly, warmer temperatures reduce the time it takes for viruses to develop, which increases the chance that a mosquito will transmit the virus to a new host before dying (). In addition, greater rainfall can increase the number and quality of breeding sites for some aquatic vectors. Humidity is also an important factor on diseases transmitted by ticks or sandflies (). However, not all projected responses of VBDs tend toward an increase in transmission. All species have upper temperature boundaries, which may be exceeded due to warming (e.g., temperatures above 34°C may have a negative impact on the survival of vectors and parasites) (). Furthermore, although some regions are expected to have increased precipitation, others may face more intense and prolonged droughts, which may be unsuitable for some species.

Considering only environmental factors, scientists have developed maps of the projected distribution of many vectors (e.g., for Aedes aegypti and Aedes albopictus; see Figure 6). In the case of malaria, estimates project that the additional number of people at risk of infection due to year-round transmission in South America will rise from 25 million in year 2020 to 50 million by 2080 ().

Figure 6. Potential geographic distribution patterns of (a) Aedes aegypti and (b) Aedes albopictus in 2050, under a moderate emissions scenario

Note: In blue, present-day distributions (light blue = low model agreement, dark blue = high model agreement). In orange, future distributional potential (light orange = low model agreement, dark orange = high model agreement in projecting future suitability).
Source: Reprinted with permission from Martens P, et al. Climate change and future populations at risk of malaria. Global Environmental Change 1999;9(S1):S89–S107 ().

Climate conditions also have indirect effects on the natural environment and on human systems (). For example, a drought may affect water storage, land-use irrigation practices, and population movements, which in turn may affect vector ecology and human exposure to infection (dengue,(); Zika virus, ()). Those situations are more likely to affect poorer individuals due to environmental and social conditions (e.g. lower-quality housing situated closer to vector-breeding sites), and because they lack access to preventive and curative health interventions and services (). Thus, equally important to where VBDs occur is who is infected by malaria, dengue fever, Zika virus (ZIKV), and other diseases. Women are particularly susceptible to some VBDs. For example, malaria infection is a significant cause of maternal morbidity and mortality (). In contrast, the symptoms of lymphatic filariasis affect more men than women (). Effective prevention and treatment of VBDs must take into account men and women’s reproductive health and rights. ZIKV, for example, can be sexually transmitted, necessitating condom access and education as a preventative strategy. Also, because of ZIKV’s deleterious effects on fetal brain development, women require medical services and information to determine whether to become and remain pregnant: contraception to prevent pregnancy, prenatal screening, and access to pregnancy interruption ().

When projecting infection rates of VBDs, another important factor is an analysis of vector surveillance and control strategies, both nationally and locally. Many successful experiences in vector control were undertaken in the Americas recently and may help to control transmission in the future. Potential new transmission areas need to be considered for surveillance and early-warning systems, training, control-strategy plans, and preparedness of health systems.

Airways diseases and allergens

Short-lived climate pollutants (SLCPs) are relevant not only for climate change, but are also responsible for many of the health effects caused by air pollution. The term short-lived climate pollutants derives from the brief time SLCPs can last in the atmosphere, but despite their impermanence, SLCPs are responsible for 40% to 45% of global warming () (a great part of the remaining is caused by CO2, which can last in the atmosphere for hundreds of years) because their particles are generated in great abundance and can absorb more heat than the same volume of CO2. SLCPs include black carbon (i.e., soot)—very fine particles that are the result of the incomplete combustion of fuels and biomass—methane, ozone, and hydrofluorocarbons (HFC).

The particulate matter (PM) of SLCPs that have a diameter of 10 micrometers (PM10) or less (e.g., PM2.5 micrometers) are especially relevant to health because they can penetrate deep inside the lungs and bloodstream and cause cardiovascular and respiratory disease. Among the types of fine PM, black carbon has received much attention because it not only can cause direct health issues if inhaled, but black carbon particles can travel for long distances and darken the ice sheets; that increases their heat absorption which, in turn, results in the ice sheets melting more quickly. Fuel combustion in residential and commercial buildings and in transportation accounts for approximately 80% of anthropogenic black carbon emissions, and nearly two-thirds of the PM2.5 particles from household biomass stoves are black carbon ().

Worldwide, the total economic cost of lost years of healthy life due to particulate pollution (both indoor and outdoor) was estimated in 2010 at US$ 1.9 trillion (). Health problems due to exposure to fine-particle pollution include increased respiratory symptoms, aggravated asthma, the development of chronic bronchitis, irregular heartbeat, nonfatal heart attacks, and premature death in people with heart or lung disease (). Most deaths attributable to air pollution are related to noncommunicable diseases (36% of deaths from lung cancer, 35% from chronic obstructive pulmonary disease, 34% from stroke, and 27% from ischemic heart diseases). Moreover, the greatest impact is on infant mortality; among children younger than 5, more than half the deaths from acute lower respiratory infections are due to inhaling particulate matter from indoor pollution produced by burning household solid fuels ().

Climate change may also exacerbate allergies by enhancing pollen production and other environmental allergens. Climate change and the rising levels of CO2 modify the production, allergenicity (a measure of how much particular allergens affect people), distribution, and seasonal timing of aeroallergens ().

Indirect impacts through socioeconomic systems

Food and water insecurity and undernutrition

Climate change threatens food and nutritional security by reducing food availability, disrupting the stability of food supplies and prices, and hindering access to food (). In turn, these may cause negative impacts on per capita calorie availability, childhood undernutrition, child deaths, and DALYs lost in developing countries ().

The risks of food and nutrition insecurity particularly affect poor populations in both urban and rural areas, and put already vulnerable women and children at increased risk of malnutrition. The Food and Agriculture Organization of the United Nations (FAO) states that in in a future with a warmer climate, “the population living in poverty could increase by between 35 and 122 million by 2030…largely due to [the climate-induced] negative impacts on incomes in the agricultural sector” ().

Vulnerable populations

The effects of climate change impact certain groups of people more than others, depending on their ability to cope with climate hazards. Vulnerable groups include those with low income, children, pregnant women, older adults, persons with disabilities, and persons with preexisting or chronic medical conditions. Outdoor workers are another group that needs special attention because they are exposed to the increase in temperature, degraded air quality, extreme weather, vector-borne diseases, industrial pollutants, and changes in the built environment (). Also, laborers exposed to hot indoor work environments (such as steel mills, manufacturing facilities, warehouses, and other areas that lack air conditioning) are at risk for extreme heat exposure ().

Indigenous populations also need special consideration; they are among the first to face the consequences of cliamte change because of their dependence on and close relationship to the land and the environment (). For many indigenous people, climate is already altering their physical, biological, and social life, as well as their traditional culture (). For example, the Tarahumara, an indigenous community in Mexico, faced a drought that severely reduced their maize and bean harvests, which had a significant impact on their livelihoods (). Indigenous people native to the Arctic are finding that hunting sea mammals and fishing are riskier and more difficult due to the melting ice sheets (). While indigenous peoples’ diverse and resilient livelihoods have enabled them to survive in often harsh environments, the pace at which climate is changing tests their abilities to adapt ().

It is worth noting that the negative effects on indigenous peoples go beyond immediate threats to food supply; connection to one’s place of ancestry, identity, language, livelihood, and communities is a key determinant of health. Therefore, in the event of extreme weather conditions that affect their connection to the land and way of life, indigenous people are more likely to face increased psychological, physiological, economic, and spiritual stress ().

Indigenous peoples tend to live close to nature and their environment. Their practices, beliefs, and cumulative knowledge are transmitted through generations, and generational knowledge (such as the ability to predict weather and traditional strategies for fire management) can be valuable sources of information in helping to preserve biodiversity and mitigate and adapt to climate change ().

Forced displacements and mental health

Every year, millions of people are forced to leave their homes because of floods, droughts, and other sudden or persistent environmental events associated with climate. By 2050, it is expected that around 200 million people will be displaced either permanently or temporarily in response to the effects of climate change (). For example, projections show that in a severe scenario involving a 1.8-m (6-ft) rise in sea levels by 2100, a total of 13.1 million people along the U.S. coast would risk seeing their homes inundated. The first effects have already begun to be felt. In 2016, in the Isle de Jean Charles, Louisiana, an indigenous community lost 98% of its land to rising sea levels, which forced residents to be relocated at a cost of US$ 52 million ().

Migration can lead to acculturation stress, and may well play a role in the genesis of psychiatric disorders (). Individuals who are forced to migrate after disasters are more likely to suffer from psychiatric illnesses compared to people who migrate voluntarily (). The impact of forced migration can be felt at both the individual and community levels, with mental health outcomes ranging from depression, anxiety, and psychological distress to suicidal behaviors (). High rates of suicide attempts and acculturation stress have been found specifically among farmers who were forcibly displaced ().

Table 1. Summary of the linkages between climate change and healtha

How climate change can affect health Exposure routes affected by climate change Health risks and impacts Near-term future projections
Direct impacts

Injuries, disease and deaths due to extreme weather events

Increased number of warm days and nights, increased frequency and intensity of heat waves.
Increased number and intensity of disasters such as storms, hurricanes, tornadoes, and floods.
Excess heat-related mortality; increased incidence of heat exhaustion and heat stroke; aggravated circulatory, cardiovascular, respiratory and kidney diseases. May particularly affect outdoor workers and vulnerable populations such as elders, children and people living in inadequate environments. Indigenous and traditional peoples are also expected to suffer the most.
Flood-and storm- related mortality due to the disasters caused by flooding, drowning, injuries, hypothermia, and infectious diseases. Forced displacements and migration with associated mental health disorders are expected.
It is very likely that heat waves will occur more often and last longer in many regions.
It is very likely that health losses caused by disasters such as storms, hurricanes, tornadoes, and floods will increase this century.
Indirect impacts through natural systems

Food-and water-borne diseases

More frequent and intense disasters may favor the contamination of food and water. Some environmental changes may create favorable conditions for microbial spread (e.g. higher temperatures and humidity, changing and increasingly variable rainfall, higher sea surface and freshwater temperature). Accelerated microbial growth, survival, persistence and transmission of pathogens; shifting geographic and seasonal distributions of e.g. cholera, schistosomiasis, and harmful algal blooms; disasters may produce a lack of water for hygiene and damage water and sanitation infrastructure, contaminating water and food. There is high confidence of projected increased risks from foodborne and waterborne diseases. For instance, it is projected an increase of an 8–11% in the risk of diarrhea in the tropics and subtropics in 2039 due to climate change.

Vector-borne diseases

Changes in vector, hosts and pathogen distributions through higher temperature and humidity, and changing and increasingly variable rainfall. A warmer climate will increase the reproduction rate, resilience and distribution of vector-borne diseases.
Accelerated parasite replication and increased biting rates prolonged transmission seasons; re-emergence of previously prevalent diseases; changing distribution and abundance of disease vectors, hosts and pathogens; reduced effectiveness of vector control interventions.
There is medium confidence that risks from vector-borne diseases will increase. For malaria, recent estimates projected that the additional number of people at risk of infection due to year-round transmission in South America will rise from 25 million by year 2020 to 50 million by 2080.

Airways diseases and allergens

Particulate matter and allergens deriving directly from emissions and/or wildfires, heatwaves and drier air aggravated by climate change. Excessive rainfall and flooding may favor molds. Diseases such as asthma and allergic respiratory diseases are exacerbated by exposure to aeroallergens.
Increased cardiopulmonary mortality due to high particulate matter and atmosphere levels of highly toxic ozone.
There is very high confidence that climate change will increase risks from air pollution. For example, it is projected a median 7.3% increase in summer ozone-related asthma emergency visits for children in New York City by 2020.
Indirect impacts through socio-economic systems

Food and water insecurity and undernutrition

Higher temperatures and changes in precipitation reduce both the quantity and quality of food harvested; sea-level rise reduces productive areas and productivity; weather events such as floods, droughts and heatwaves threaten freshwater sources and contribute to higher food prices. Increased risk of undernutrition resulting from lower food production (especially in the tropics) and food access; combined effects of undernutrition and infectious diseases; chronic effects of stunting and wasting in children. There is high confidence that climate change will have substantial negative impacts on per capita calorie availability; childhood undernutrition, particularly stunting and wasting; and child deaths and DALYs due to undernutrition, especially in tropical and poor regions and for vulnerable populations.

Occupational health and vulnerable populations

Heat waves, higher temperature and humidity. Extreme and prolonged heat and humidity are particularly harmful for outdoor and unprotected workers. Those individuals are at a higher risk of heat exhaustion, cardiac arrest and more frequent work accidents. Loss of work capacity and reduced labor productivity are also expected. In addition, the elders, children, and people living in poor environments (inadequate housing, no air conditioning), and indigenous and traditional populations, are expected to suffer the most and need special attention. There is high confidence of climate change will reduce work capacity and labor productivity, and will pose extra risks to vulnerable populations.

Forced displacements, mental illness, and stress

High temperatures may aggravate mental disorders. Forced displacement and migration due to sea-level rise, droughts, water and food insecurity, and civil conflicts aggravated by scarcity of resources. Disasters may also force displacements and aggravate post-traumatic stress disorders. Increase of stress on all those who are already mentally ill, create sufficient stress for some who are not yet ill to become so such as severe anxiety reactions, depression, aggression, and complex psychopathology; sense of loss. There is very high confidence of climate change on having consequences for mental health and human well-being.

a Based on information from IPCC, The Lancet, WHO.

The way forward: health within the Paris Agreement and the Sustainable Development Goals

The year 2015 was marked by the launching of two global agreements that set the stage for action in the next 15 to 20 years: the Paris Agreement () and the Sustainable Development Goals (SDGs) (). Both put the health sector at the center of international and national discussions.

The 21st Conference of the Parties of the United Nations Framework on Climate Change Convention (UNFCCC, COP21), held in Paris, came to a final agreement that includes an ambitious commitment: keeping global warming much less than 2°C above preindustrial levels, with an aspirational target of no more than 1.5°C above preindustrial levels. The document sets provisions for continuous monitoring and for revising countries’ commitments and actions every 5 years, with a view to continually raising targets. At the same time, the document clearly recognizes that all aspects of human life are intrinsically connected to the environment. Regarding emissions, it acknowledges huge differences between the richest and developing nations, and recognizes their differentiated capacities to respond to the needs for mitigation and adaptation to the effects of climate change. The agreement provides a framework for action, but also acknowledges that even with actions in place the most vulnerable populations will suffer significant impacts of climate change. Moreover, the agreement explicitly cites the right to health as an overarching concept, and recognizes that mitigation provides opportunities for health co-benefits.

In the same year, world leaders also adopted the 2030 Agenda for Sustainable Development, which includes 17 goals and 169 targets. Later, in March 2016, the agenda was expanded to include more than 230 indicators (). A key feature is integration of economic, social, and environmental dimensions of sustainable development and the linkages within and across the goals and sectors. The 2030 Agenda states clearly that a sustained systemic change cannot be achieved through single-sector goals and approaches; rather, it entails breaking down traditional silos to encourage more cross-sectoral participation to foster joint decision-making and proposals for solutions.

Health is one of the many sectors that will be affected by climate change. There is plenty of evidence in the present document and elsewhere () that shows why climate change is a health issue. Nonetheless, although an estimated US$ 70–100 billion per year will be needed globally to adapt to climate change by 2050, only a small protion of that sum is currently directed to health protection. Stakeholders in the health sector have a key role in integrating health issues into national climate change plans and into low carbon national development strategies—nationally determined contributions [NDC] and national adaptation plans [NAP]—that the Paris Agreement requires by 2020 (). SDG 3 aims to: “Ensure healthy lives and promote well-being for all at all ages.” SDG 13 states: “Take urgent action to combat climate change and its impacts.” These goals are intimately related. By implementing the SDG, we will achieve climate targets and vice versa.

The present document is organized to provide an overview of key topics for a road map of climate change and health in the Americas. First, the section “Leading by example: transforming health systems to tackle climate change” presents information on how health systems can focus efforts on reducing emissions (i.e., mitigation policies) and adapting to climate change. In addition, health should join forces with other sectors to make health a key goal of sustainable development. Many documents highlight the importance and benefits of using a Health in All Policies approach (). In this document, that approach presents intersectoral actions covering some key areas: energy, transportation, and food systems. By following this road map, the health sector will make progress creating more resilient societies.

Leading by example: transforming health systems to tackle climate change

The health sector is essential to achieving sustainable development and it plays a fundamental role in protecting human health from the impacts of climate change. However, health care systems consume large quantities of energy, water, and materials, and they generate considerable emissions and waste. For example, in the United States in the last decade, the health care sector’s GHG emissions increased by more than 30%—accounting for nearly 10% of all U.S. emissions in 2013 (). As a comparison, a previous study showed that health sector emissions in 2007 were about 8% of total emissions (). In turn, these emissions are estimated to contribute to 12% of acid rains, 10% of smog formation, and 9% of respiratory diseases from particulate matter and air pollutants, including ground-level ozone, carbon monoxide, and lead.

While it is not possible to eliminate health sector emissions, reductions are possible in health facilities and through the entire product supply chain of the health care system. In addition, in all its activities and mandates, the health sector needs to incorporate actions for building more resilient systems, and to consider adaptation plans to changing climate conditions. To achieve that, health personnel at all levels needs to be trained, and financing mechanisms need to be created to support actions on health and climate change. Finally, to guarantee that health outcomes are considered and measured in all policies, it is fundamental to engage with other sectors.

Reducing emissions from health care facilities and their supply chains

In the health sector, hospitals are the largest contributor of carbon emissions, accounting for 39% of the sector’s total. Hospitals need all-day use of numerous medical devices for sterilization, medical, and laboratory services; and equipment for heating, cooling, computing, refrigeration, laundry, and food services. Hospitals also generate GHG emissions associated with waste disposal and transportation. Other contributors to the overall carbon footprint of health systems are the prescription drugs sector (14%), physician and dental services (13%), equipment (12%), and nursing homecare services (8%) ().

Retrofitting hospitals and other health care facilities is an efficient policy to reduce environmental impacts and can be achieved by using alternative energy sources, designing greener buildings, and being more efficient in the use of water, food, and transportation. PAHO is currently addressing those issues with an initiative called Smart Hospitals (see Box 1).

It is also essential for the health sector to reduce emissions throughout its supply chain. As one of the world’s largest sector-specific purchasing powers, the health care system can reduce its impact through the products it buys. Strategies to reduce emissions include recycling programs and purchasing goods and services from environmentally-friendly suppliers. Green purchasing allows hospitals to save money, expend less energy, and reduce damage from pollutants, thus improving public health. For example, the University of Chicago Medical Center ensures that 90% of the cleaning supplies used by the hospital have green seal certification; it has also implemented a plastics recycling program that has helped to reduce the cost of waste from $55,000 to $35,000 per month (). One study shows that by reducing CO2 emissions by 150 million metric tons per year (with a co-benefit of reducing PM2.5 particles), the annual savings on health expenditures in the United States would range from US$ 6 billion to US$ 14 billion ().

Box 1. A response to disasters and climate change: PAHO’s Smart Hospitals initiative

Hospitals play a critical role in providing communities with essential medical care during or immediately after a disaster. In the Americas, 77% of health facilities are in disaster-prone areas, putting them at risk of becoming casualties themselves during hurricanes, earthquakes, or flooding. The health sector needs not only to guarantee the safety of its infrastructures, but also reduce emissions of GHG that contribute to climate change.

PAHO/WHO’s Smart Hospitals program is an initiative financed by the United Kingdom’s Department for International Development and implemented by PAHO with the ministries of health. By 2020, at least 50 health facilities in Dominica, Grenada, Saint Lucia, St. Vincent and the Grenadines, Guyana, Jamaica, and Belize will be categorized as “smart.”

A health facility is “smart” when it links structural and operational safety with green interventions at a reasonable cost-benefit ratio. In “green” health facilities, air quality and people’s working conditions improve, and water and energy costs decline. Participating health facilities have reinforced roofs and windows to resist hurricanes, and have added new rainwater-collection tanks and solar panels to supplement traditional sources of water and energy. Other measures include improvements in accessibility for people with disabilities, use of energy-efficient LED lights, and replacing air conditioners with newer, more energy-efficient models. These positive changes also affect users’ decisions to visit health facilities, increasing the number by up to 40%.

Georgetown Hospital in Saint Vincent and the Grenadines after being made “smart”

A good example of the success of these interventions is the Georgetown Hospital, a 12-bed facility serving 9,800 patients in St. Vincent and the Grenadines. Interventions applied to improve its resiliency and reduce its environmental footprint resulted in: an increase in the use of renewable energy sources and a 60% reduction in energy consumption, savings on recurring costs, and better security and fire safety measures. In 2013, a severe storm cost St. Vincent and the Grenadines an estimated US$ 2.1 million and left its only referral hospital—the Milton Cato Hospital—unable to function. Many of the district health clinics were flooded, but the “smart” Georgetown Hospital remained 100% functional during and after the event and was able to provide the community access to water from the rain-harvesting system.

The Region of the Americas could benefit from expanding such initiatives. Colombia, Mexico, Ecuador, and other countries have expressed interest in adopting PAHO/WHO’s Smart Hospitals program.

Improving health system resilience and adapting to climate change

Even with mitigation actions in place, the effects of climate change will still be felt for many years. Therefore, health systems need to be strengthened and to implement measures that will help them adapt and cope with the new challenges and risks. Fostering research and collecting data will be crucial to understanding the linkages between climate change and health. Data will provide crucial information for designing vulnerability and adaptation assessments. These baseline data will help determine the capacity of health systems and health services to cope with climate risks, identify knowledge gaps, and strengthen the case for investments in health protection.

Vulnerability and adaptation assessments are essential to identify the health impacts of climate change, and since they look at both epidemiological and climate data, they provide input for further adaptation planning and activities. The assessments can help map vulnerable populations and risks, identify weaknesses in health systems, and define strategic response interventions, ideally establishing gender-sensitive benchmarks and indicators, to ensure appropriate and equitable responses to health needs of women and men. Moreover, the studies will examine current and potential health risks posed by climate change—such as heat stress, undernutrition, and vector-borne diseases—and consider how the risks interact with each other and with other environmental and social determinants. In 2016, Dominica and Grenada launched their assessments that provide a national framework for action.

Due to climate change, the distribution and incidence of extreme weather events and transmission of vector-, water-, and foodborne diseases are altered. This means developing early warning systems is essential to detect, forecast, and communicate climate risks and vulnerabilities to human health. Early warning systems in health are designed to anticipate and alert the public and health professionals to expect a rapid-onset emergency, such as an extreme weather event or disease outbreak and to provide additional lead time to deploy appropriate preparedness measures and responses. Effective monitoring and early warning systems, when coupled with the capacity for adequate response, can prevent avoidable illness, injury, and death. For example, health programming informed by early warnings about a potential outbreak or heatwave can gain time to prepare operations for increased patient loads and special needs. It is important to transmit meteorological information to programs and interventions to control diseases affected by climate change such as vector-, food-, and waterborne diseases. For example, the Caribbean Institute for Meteorology and Hydrology and PAHO from Barbados and Grenada are implementing a pilot project, releasing a bulletin every three months that provides information about the expected weather as a proxy early warning system.

An emergency preparedness and management plan is necessary to ensure that health facilities can function during extreme events and to prepare them to cope with economic and social disruption (such as forced migration and food and water shortages) from climate change. For instance, pharmacies should have protocols about storage and transport of vaccines and medical equipment in extreme heat conditions. Community-based actions are at the forefront of protecting health in emergencies; a prepared, active, and well-organized community can reduce risks, save lives, and minimize the impact of emergencies. In this process, it is important that the community and every stakeholder be involved. The health sector can support this by providing and receiving information about local risks and vulnerable groups.

Developing tools in health programming and operations that include both current climate variability and projected future climate change will ensure that health programs are climate resilient; the tools are crucial to making better decisions.

Climate financing: opportunities for the health sector

The estimated costs of damage to health systems caused by climate change can be staggering. For example, considering only six events related to climate change (ozone pollution, heat waves, hurricanes, infectious disease outbreaks, river flooding, and wildfires) that struck the United States between 2000 and 2009, the health costs exceeded US$ 14 billion (). The WHO projects that by 2030, the costs of direct damage to health caused by climate change will be an additional US$ 2 billion to US$ 4 billion per year (). Yet, despite the predicted economic impact, only a very small portion of global climate financing has been allocated to health projects. According to the Climate Funds Update, funds approved for addressing climate-related damage to health between 2003 and 2016 totaled US$ 17.4 billion, and less than 0.3% of that has been allocated to projects that specifically address health; none has been allocated for projects in LAC (). Moreover, the Joint report on Multilateral Development Banks (MDB) Climate Finance (2015) states that less than 5% of the projects funded by MDB focused on “air quality and public health.”

According to a study (), of all the Latin American and Caribbean countries that submitted their intended nationally determined contributions (INDC), 81.8% recognized health as a major topic of concern. This demonstrates that although the importance of health is acknowledged, the sector needs to engage in the development of low-carbon national plans that the Paris Agreement requires by 2020, especially by proposing programs that ensure resilient and low-carbon health systems. One possible explanation for the absence of climate financing on health is that since the health community was not always actively engaged in the development of INDCs and NAPs, the health sector has not submitted proposals.

Opportunities now exist to mobilize additional resources to address health-related climate risks, and the health sector should prepare an action agenda to access climate funds for protecting human health from climate change. For example, as part of the UNFCCC negotiation process, Member States agreed with the Green Climate Fund to mobilize US$ 100 billion annually in international climate financing by 2020 (). The Fund’s mission is to invest in initiatives that contribute to low-emission and climate-resilient systems. Funding sources may include national and multilateral climate funds managed under the UNFCCC, development banks, and bilateral development agencies including the Global Environmental Facility, the Adaptation Fund, the Least Developed Countries Fund, the Global Facility for Disaster Reduction and Recovery, and Carbon Funds.

A health perspective for intersectoral action to maximize the co-benefits of addressing climate change

Besides health system responses to climate change, coordination and planning across sectors are needed to ensure coherent policies and synergies and to address the root causes of health risks. Sectors such as energy, agriculture, and transportation have the potential to reduce GHG and produce major health co-benefits (see Box 2). For example, a projection in Europe shows that reducing GHG emissions by 20% by 2020 would improve mean life expectancy by 3.3 months and reduce health damage costs by US$ 13-31 billion ().

Figure 7. GHG emissions by other economic sectors

Note: There is an opportunity to work at an intersectoral level to promote health and to reduce emissions that contribute to climate change.
Source:Reprinted with permission from Edenhofer O, et al. Summary for policymakers. In: Climate change 2014: mitigation of climate change. Contribution of Working Group III to the Fifth Assessment Report of the IPPC. New York: Cambridge University Press; 2014 ().

Box 2. Co-benefits of tackling air pollution

Air pollution is the leading environmental risk to health in the Americas. Implementing a targeted set of measures to specifically address short-lived climate pollutants (SLCPs) is expected to save approximately 2.4 million lives a year by 2050 and reduce global warming by an additional 0.5°C (Figure). Thus, tackling air pollution is one of the most effective ways to address both issues, and has clear co-benefits. Despite the advances, in order to implement intersectoral action and mitigate the risks posed by air pollution and climate change in the Americas, much stronger engagement of the health sector is needed.

Figure. Mitigation of short-lived climate pollutants and CO2

Note: Joint approaches to mitigating SLCP and CO 2 are more effective than separate measures for halting global warming. The black line represents the measured global temperature. The green line represents the projected temperature increase without mitigation actions. The red line represents the projected increase with CO2 emissions control. The dark blue represents actions to control methane (CH4) and black carbon (BC). Basically, both CO2 and CH4+BC would yield the same temperature control. The light blue line represents an integrated initiative to control all three (CO2, CH4, and BC), which would yield an additional reduction of 0.5°C in comparison to controlling only CO2 or only CH4+BC.

Sources: Shindell D, et al. Simultaneously mitigating near-term climate change and improving human health and food security. Science 2012;335.
WHO. BreatheLife campaign [Internet]; 2016. Available from:
UNEP/WMO. Integrated assessment of black carbon and tropospheric ozone: summary for decision makers. Nairobi: UNON/Publishing Services Section. Nairobi, ISO 14001:2004; 2011. Available from: dewa/Portals/67/pdf/BlackCarbon_SDM.pdf.

Energy, climate change, and health

Current situation and trends. Energy is crucial for virtually all human activities. It is used for lighting, cooking, heating, cooling, transportation, for medical technologies, and the production of almost everything we use in modern life. However, depending on how the energy is produced, it can affect ecosystems, the climate, and human health. Energy use is, by far, the human activity that contributes the most to GHG emissions (), accounting for about 60% of total GHG emissions, and the burning of fossil fuels is responsible for more than 80% of the total primary energy supply ().

The Americas is particularly inequitable in the distribution of energy. Primary energy demand in 2013 in the United States alone was 29,906 million barrels of oil equivalent (MBOE), while all LAC countries used about one-third of that (11,969 MBOE). Moreover, while Canada and the United States use more than 13,000 kWh of electricity per capita per year, Haiti uses only 49 kWh. Emissions of CO2 due to the combustion of fossil fuels go hand in hand, with the United States producing 16.18 tons of CO2 per capita in 2013 and Haiti 0.21 tons (). As economies of the Region grow, energy production and demand quickly escalate. For example, in many countries in LAC, energy consumption has tripled in the 40 years between 1973 and 2013. Energy consumption has also increased in more developed countries, but at a slower rate; during the same period, it increased by 50% in Canada and 10% in the United States. Even with the current coverage, 6.8% of the population of the Americas still lack access to electricity and 15% lack access to clean fuels for cooking and heating (). The challenge is therefore to give everyone access to energy without raising GHG and black carbon emissions.

Implications for health systems. The combustion of fossil fuels creates short-term health risks from air pollution and long-term health risks related to climate change. Energy production is responsible for 85% of particulate matter and almost all the sulfur oxides and nitrogen oxides (). Moreover, people living in poverty bear a disproportionate health burden both because of greater exposure (e.g., from reliance on solid fuels for cooking, or living in polluted neighborhoods) and greater vulnerability to factors such as malnutrition and poor access to health care (). Hence, the strong connection between policies on health and energy is evident.

Many low-income countries have a high share of renewable energy in their energy matrices, but this is because they rely on polluting energy sources such as wood, dung, and charcoal for cooking and heating. The use of coal is particularly harmful for both climate change and human health. Coal is used to generate electricity, for industrial applications, and for household cooking and heating. The WHO guidelines on indoor air quality () recommend that households avoid using coal because of its carcinogenic effects. However, more than 90 million people in the Americas still use biomass as the main source of the household energy, and its use is particularly high in Haiti, Honduras, Guatemala, Nicaragua, and Paraguay (). Burning wood as an energy source is alarmingly high in Central America (82%) (). Biomass combustion produces harmful CO2, PM2.5 and black carbon, which have severe health implications and contribute to 25% of ambient air pollution ().

Successful cases to promote health. Internalizing the health costs of fossil fuel use would dispel the arguments that fossil fuels are “cheap” and necessary to alleviate poverty, and could level the field for clean renewable energy sources (). The costs of renewable energy technologies have declined substantially in the last years, but many financial, policy, and information barriers remain (). Renewable and clean energy technologies have demonstrated substantial performance improvements. In the Americas, the United States, Costa Rica, and Mexico have increased their production of wind energy (). However, the percentage of renewables to all the energy production is still low, less than 1%. Ecuador has significantly reduced its use of solid fuels by promoting induction cook stoves and electric water heaters. The program gives 80 KWh of electricity per household (“cooking without cost”) and 20 KWh for heating water (). A transition to climate-friendly, renewable energy can bring about immediate health co-benefits. For example, solar panels at rural health facilities in Guyana support cold-chain refrigerators and other important clinic functions. A recent study has shown that energy efficiency measures and low-carbon energy sources can save between US$ 5.7 million and US$ 210 million annually in the Region ().

Health and climate change in food systems

Current situation and trends. Food systems, from production to distribution, contribute 19%–29% of global anthropogenic GHG emissions (). Most of these emissions are attributed to agricultural production (80%–86%), which includes associated deforestation and forest degradation practices (). The remaining contributors are pre- and post-production activities such as fertilizer manufacturing, transportation, and packaging ().

Dietary patterns that include a large amount of meat have a greater impact on the climate, since livestock production accounts for 80% of the methane emitted by the sector (). Current trends trends indicate a higher demand for meat in the future (). In addition to increasing the atmospheric accumulation of GHG, industrial agricultural systems seeking a high yield and mass production of low-priced commodities also cause topsoil loss, waste, water pollution and eutrophication, reduced soil fertility, loss of natural pest controls, extinction of species, and diminished biodiversity (). One-third of the carbon released from soil to the atmosphere in the postindustrial era occurred due to soil erosion (). Thus, the restoration of soils is important for mitigating global warming by keeping carbon in the soil and sequestrating it from the atmosphere, thereby reducing its atmospheric accumulation ().

Implications for health systems. Food systems not only contribute to climate change; they also suffer from its effects. For example, in 2014, Central America was hit by a major drought that affected the production of basic grain crops, particularly maize and beans. As a result, over 500,000 families in El Salvador, Guatemala, Honduras, and Nicaragua were recorded as suffering from serious food insecurity (). In 2012, hot and dry conditions in Brazil and Argentina resulted in an 8% increase in global food prices (), impacting food availability and affordability. These effects in turn reduce capita calorie availability, causing childhood undernutrition, child deaths, and DALYs lost in developing countries ().

Although the Region’s GHG emissions are lower than those in other regions, the countries of LAC are especially vulnerable to GHG effects because of their economic dependence on agriculture. In northeast Brazil, parts of the Andean region, and Central America, climate change is expected to affect crop yields and local economies and compromise food security (). Crop failure can entail economic hardships and/or increase food expenses, which in turn have been associated with depression and demoralization (). In drought-prone areas, higher levels of distress and helplessness were registered ().

Successful cases to promote health. Agro-ecological and agro-forestry systems have been demonstrated to be more sustainable and to better promote health by reducing direct and indirect impacts of climate change (). Such systems are more efficient at removing atmospheric carbon and storing it, which helps compensate for GHG emissions (), and can also help moderate temperature extremes (). For example, in Brazil, an agro-forestry system reduced peak temperatures by 5.4°C (). In Cuba, organic farms emitted six times less GHG and produced two times more food than nonorganic ones ().

Ancestral peasantry practices also have useful lessons to impart. Terracing systems from the Andean region are efficient ways to control land degradation and maintain the soil’s fertility and nutrients. Such systems have helped to preserve a great variety of potatoes and pulses (). In Peru, those globally important agricultural heritage practices are conducted collaboratively by FAO, national and local governments, research institutions, and rural communities. Furthermore, the Caribbean Policy Development Centre, with the support of UN Women, has been training women in the Region how to adopt sustainable agricultural practices to combat soil erosion and increase soil fertility, which can reduce emissions and improve carbon sequestration ().

Sustainable transportation: tackling climate change and promoting health

Current situation and trends. The second largest source of GHG emissions is the transportation sector; since 1970, it has doubled emissions, a faster rate of increase than any other energy end-use sector. In 2010, the transport sector was responsible for approximately 23% of total energy-related CO2 emissions, or 14% of global GHG emissions ().

Cars and freight transport are responsible for 80% of the sector’s CO2 emissions. Transportation generates other GHG and air pollutants such as methane, volatile organic compounds, nitrogen oxides, sulfur dioxide, carbon monoxide, F-gases, and black carbon (). The world’s population is expected to reach 9.7 billion people by 2050 (), with 66% living in urban areas (). In the Americas, it is expected that 86.8% of the population in 2050 will reside in urban areas. Transportation is a key aspect of urban life and is the heart of a new urban agenda.

Implications for health systems. Health risks linked to transportation are usually associated to traffic injuries and road safety, but transport systems have other health-related impacts: air pollutants, noise, stress, physical inactivity, and loss of social cohesion. The world’s transportation systems cause approximately 7 million deaths per year. Of those, 3.3 million are attributable to air pollution, 1.2 million to traffic injuries, and 2.5 million are associated with sedentary lifestyles.

Air quality in Latin America has worsened due to rapid urban development and to greater use of motorized vehicles, particularly private automobiles (). In LAC, the use of leaded gasoline increases toxic exposure, which may increase the risk of neurological impairment, especially among children.

Successful cases to promote health. Transit-friendly and walkable/cyclable communities help reduce air pollution and can increase the likelihood and frequency of physical activity (), thus reducing the burden of some cancers, diabetes, heart disease, and mental illness (). Active travel and rapid bus or light rail transportation are health-enhancing strategies for reducing CO2 and SLCP emissions. Other health-promoting policies are shifting to cleaner heavy-duty diesel vehicles and low-emissions vehicles and fuels (including fuels with reduced sulfur content), and implementing stricter emissions and efficiency standards for both particulate matter and ozone precursors, including oxides of nitrogen (NOx).

Transportation systems play a very important part in people’s health. Although it may seem difficult to implement large, city-wide policies, some recent examples highlight the beneficial health results of those interventions. In the Americas, Bogotá (Colombia) and Curitiba (Brazil) introduced significant changes in public transportation systems to stimulate the use of non-motorized transportation (i.e., walking and cycling) and/or fast public modes of transportation (). However, progress is still needed in measuring the environmental and health benefits of those interventions, using a clear set of indicators. The city of London provides one successful example of how health indicators can be used to both define and measure the success of interventions. The city defined a public transportation system that encourages non-motorized travel, and the benefits include an increase in physical activity, cleaner air, less noise, more connected neighborhoods, less stress and fear, and fewer road traffic injuries ().

Road map to promote health in a changing climate

Evidence shows that the human cost of inaction on climate change is unacceptably high. Compared to a future without climate change, the following additional deaths are projected for the year 2030: 38,000 deaths among the elderly caused by heat exposure, 48,000 to diarrhea, 60,000 to malaria, and 95,000 to childhood undernutrition (). Thus, mitigation and adaptation to avert the health impacts of climate change could provide substantial human and economic benefits.

Health policymakers need information to assess the magnitude of the current and projected impacts of climate change and their implications for health, and to formulate and implement responses to ensure adaptation and strengthen health systems. Moreover, health stakeholders need to engage with other sectors such as energy, transportation, and agriculture because there are health co-benefits to reducing GHG emissions in those sectors. What follows is a proposed road map.

Reducing emissions of health care facilities

  1. Assess health systems emissions in every country. Studies like that conducted by Sherman and Eckelman () can be used as models.
  2. Heath care facilities should adhere to the following principles in order to become more climate-friendly (adapted from WHO’s Health Care Without Harm; ():
    • Reduce health care energy consumption and costs through conservation measures and use of low-emission energy sources;
    • Generate part of their own energy from sustainable clean sources;
    • Build health care facilities that are responsive to local climate conditions and that optimize air circulation and light, thereby reducing energy and resource demands;
    • Offer green spaces for patients, visitors, and medical personnel which will help reduce local temperatures and promote healthy lifestyles and engagement with nature;
    • Reduce transportation requirements for products and people and adopt sustainable, low-emission fuels;
    • Use foods grown with greener practices and locally produced foods, thus reducing emissions from transportation;
    • Reduce generation of wastes, and create and use efficient treatment and recycling systems;
    • Reduce consumption of water and implement efficient treatment and recycling systems.
  3. Create and use adequate mechanisms to measure, reduce, monitor, and audit the carbon footprint of health care facilities and systems.

Reducing emissions of health supply chain

  1. Identify environmentally friendly suppliers in the health care supply chain.
  2. Implement green purchasing policies by reviewing facility procurement practices and giving incentives to buy from environmentally friendly suppliers.

Training health personnel and informing people

  1. Provide training for health personnel at all levels. All workers must be able to identify and understand the direct impacts of health care facilities and the emissions of the medical supply chain. PAHO offers a virtual course (Climate Change and Health – in Spanish only) (), which may serve as a basis for other training.
  2. Engage communities and prepare health literacy and health promotion programs to control and communicate the causes and effects of climate change on health.
  3. Improve access to climate and health data to better inform scientists the general population on how to identify, minimize, and prevent health impacts from climate change.

Adapting to climate change: delivering better health services in a changing world

  1. Foster research to make decisions based on the best evidence. The health community should produce and/or collaborate with research on the links between health and climate change. The sector should also report best management practices to lead by example and to serve as inspiration.
  2. Develop vulnerability and adaptation assessment plans, engaging all stakeholders.
  3. Monitor climate risks and map populations in vulnerable conditions, such as migrants and displaced people. It is especially important to also consider the gender-differentiated impacts of climate change.
  4. Prepare early warning systems and improve communication between the health sector and meteorological agencies.
  5. Evaluate disaster risks in the health sector and strengthen the organizational structure of disaster risk management offices in the ministries of health.
  6. Develop and implement disaster risk management and emergency preparedness plans to address extreme weather events and their impacts on health infrastructure and personnel.

Financing health on climate action and increasing governance

  1. Develop a strategy to access climate finance, ensuring financing for the health system to avoid and to cope with climate change risks.
  2. Explicitly include the relationship between climate change and human health in the INDC, NAP, NAMA, and other UNFCCC instruments; ratify and follow the Sendai Framework for Disaster Risk Reduction 2015–2030 and any other relevant national or international strategies or treaties.
  3. Develop and update the WHO climate and health country profiles (), which include country-specific climate hazards projections and modeled projections for low-emission scenarios, and current and future health risks from climate change.
  4. Support multisectoral collaboration for climate action to maximize co-benefits, and use the SDG targets and indicators to foster intersectoral efforts.
  5. Consider all groups while designing the interventions to ensure that the needs of more vulnerable groups are properly addressed as a priority.

Energy, health, and climate change

  1. Lead by example by investing in clean energy solutions in health facilities and offices and by using the purchasing power of the health sector to decarbonize the health care supply chain.
  2. Advocate for policies that enable a rapid phase-out of coal and transition to clean and renewable energy. Carbon reduction measures bring immediate and valuable health benefits, and should not be viewed as only costing money.
  3. Advocate that health impact assessments and health economic evaluations be included in decision-making on energy projects and policies. Projects related to fossil fuels should include cost-benefit analyses for health and climate impacts. For example: according to the impact assessment accompanying the European Commission Climate and Energy Package, reducing GHG emissions by 20% by 2020 would reduce sulfur dioxide, nitrogen oxides, and PM2.5 emissions by 10%–15% compared to baseline emissions in 1990, thus reducing health damage costs by €12 to €29 billion ().

Agriculture, climate change, and health

  1. Engage with the food and agriculture sector to include health impacts in the decision-making process of policies.
  2. Develop agro-ecological and agro-forestry systems, which are more sustainable and more effective at promoting health, thus reducing direct and indirect impacts on food and nutrition security, health, and climate.
  3. Follow and promote WHO healthy diets guidelines. Transitioning to more plant-based diets that are in line with standard dietary guidelines could reduce global mortality by 6%–10% and reduce food-related GHG by 29%–70% in 2050, compared to a reference scenario in 2050 ().

Transportation, climate change, and health

  1. Engage with the transportation sector to include health impacts in the decision-making process of policies.
  2. Reduce the need for individual cars by improving and promoting public transportation, better city planning, more integrated neighborhoods, and building better infrastructures for walking and cycling. This could greatly reduce road deaths and injuries as well as GHG emissions.
  3. Identify, build monitoring systems, measure, and improve city planning through a set of environmental and health indicators. Ideally, those indicators would be aligned with ones proposed in the SDGs, and used to clearly show the cost-benefit of those interventions—e.g., using DALYs or health expenditures saved.

Figure 8. Road map for the health sector to tackle climate change


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1. Disaster: Any event or series of events causing a serious disruption in a community’s infrastructure. Disasters often result in widespread human, material, economic, or environmental loss and impact, and frequently exceed the affected community’s ability to mitigate the damage using existing resources.

2. The OFDA/CRED International Disaster Database.

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