3.1: Climate Change, Health, and Vulnerable Populations

The health effects of climate change are already occurring globally and are predicted to become devastating by midcentury if significant greenhouse gas reductions do not occur. Illnesses and deaths from climate change will vary widely across the globe based on geographic, economic, and individual factors. The Lancet Countdown: Tracking Progress on Health and Climate Change has summarized the health effects of climate change and is tracking them over time. In order to save lives, it is critical to understand the general relationships between climate change and health and to learn to predict how these general relationships will play out in a local community. The burning of fossil fuels causes climate change and also causes other direct human health consequences, so there can be direct and immediate health benefits from taking action today to stop and reverse climate change.

The most direct effect from climate change is from heat. Average temperatures are rising globally, and dangerous extreme heat events— “heat waves”—will become increasingly common. Extremes of heat have increased significantly since 1990 in every region of the world, with 157 million more people exposed to heat wave events in 2017 than in 2000. Increased heat increases energy and turbulence in the Earth’s atmosphere. This energy can manifest as dramatic weather fluctuations, including extreme droughts and violent storms. In 2017, a total of 712 extreme weather events resulted in $326 billion in economic losses, almost triple the total losses of 2016.

Figure 3.1.1 Health effects of climate change. Reproduced from Centers for Disease Control and Prevention.

Most of the health effects from climate change are a direct or indirect result of high heat and weather extremes. For example, oscillation from extremely wet to extremely hot and dry increases the risk of fire. This is because vegetation grows rapidly in unusually wet periods and dies in subsequent drought. If hot, windy conditions follow, the dead brush ignites easily and fuels large firestorms. As another example, heat increases the risk of infectious disease outbreaks, both because certain species of mosquitoes and ticks can survive warmer winters and become established in areas where they could not previously live, and because warmer temperatures encourage bacteria and parasites to proliferate, resulting in outbreaks of food-borne and waterborne illness. Storms, floods, and droughts all contribute indirectly or directly to food and water scarcity, population displacement, conflict, and mental health issues (Table 3.1.1).

Table 3.1.1 Summary of health effects from climate change

Climate-Related Stressor	Climate-Related Causes	Secondary Effects	Health Effects
Heat	Overall warming	Extreme heat days Ozone smog pollution Reduced work capacity	Heat-related illness Respiratory illnesses Economic stress
Drought	Shifts in rainfall patterns	Reduced agricultural yield Food scarcity	Malnutrition Population displacement
Fire	Shifts in rainfall patterns	Smoke (particulate matter) Property damage	Death Respiratory illnesses Cardiovascular illnesses Population displacement Mental health effects
Increased weed pollen	Higher CO2 levels Overall warming	More weeds and invasive plant species	Worsened allergies and asthma
Sea level rise	Melting of Antarctic and Greenland ice	Coastal flooding Property damage	Population displacement Drownings Mental health effects
Extreme weather events	Increased atmospheric energy Warming of oceans	Coastal and river flooding Property damage Drinking water contamination Mold growth	Population displacement Drownings Diarrheal disease Respiratory and skin disease Chemical contamination Mental health effects
Vector-borne disease	Overall warming Shifts in rainfall patterns	Mosquito- and tickborne illnesses shifting north and to higher elevations	Malaria, dengue fever, Zika, chikungunya, Lyme disease, and emerging illnesses
Algal blooms	Overall warming Runoff from heavy rains	Marine mammal and bird die-offs Fishery contamination and loss	Diarrheal disease Neurological disease Economic stress Malnutrition

Source: Watts, N., et al. 2018. The 2018 report of the Lancet Countdown on health and climate change: shaping the health of nations for centuries to come. Lancet 392(10163), 2479–2514. https://doi.org/10.1016/S0140-6736(18)32594-7; Mora, C., et al. 2018. Broad threat to humanity from cumulative climate hazards intensified by greenhouse gas emissions. Nature Climate Change 8, 1062–1071. https://doi.org/10.1038/s41558-018-0315-6.

Ultimately, some areas will be inundated because of sea level rise; other areas will face increasing challenges from drought-associated food and water shortages; still other areas will encounter river flooding, outbreaks of vector-borne disease, and increased agricultural pest pressures, resulting in more intensive pesticide use and higher crop losses. In some countries, these events will lead to increased conflicts over remaining resources, population displacement and migration, an overstrained public health system, and general social disruption. Even politically stable countries will be stressed by internally displaced populations and an influx of refugees and migrants. Experience from such events, both in the United States and globally, has shown that the people most likely to suffer and die include the poorest segments of society, the very young, the elderly, and the disabled. The health effects in general will be more severe in poorer countries, placing the worst health burdens on those who contributed least to creating the problem.

Health effects of heat

Extreme heat, the most direct effect of global warming, causes large numbers of deaths and severe illnesses, depending on the intensity and duration of the heat event. Extreme heat events are projected to continue to increase significantly in the United States and worldwide (Figure 3.1.2). Those most likely to die or require emergency hospitalization include the elderly, infants, pregnant women, outdoor workers, and people with a range of underlying health conditions. Major increases in deaths, hospitalizations, and emergency room visits always occur during heat waves, but even during a non-heat-wave period there are clearly documented associations between increased temperatures and a range of health problems. It has been documented in many countries that hospital and emergency room visits increase with increased heat, including from respiratory disease, emphysema, heart disease, heart attack, stroke, diabetes, renal failure, intestinal infections, heat stroke, dehydration, hypertension, and asthma. Studies have also shown that for every increase of temperature by 10°F there is a nearly 9% increase in preterm births.

Figure 3.1.2 Increase in summer heat wave days over time. Reproduced from NOAA.

People exposed to heat can sometimes cool off and rehydrate at night, but if the nights remain hot, there is no opportunity for recovery. Urban areas with extensive paved surfaces are also high-risk zones. Dark pavement and roofing absorbs heat and results in temperatures that are several degrees hotter than nearby tree-shaded or grassy areas. This phenomenon, known as the urban heat island effect, can be mitigated by lighter-colored roofing material, street trees, and parks. Unfortunately many inner-city communities lack natural cooling resources such as trees and parks. A national analysis in the US found significant racial and ethnic disparities in heat-risk-related land cover of neighborhoods, even after adjusting for other factors that influence tree growth. Lack of access to air conditioning is also correlated with risks of heat-related illness and death. One study using heat wave data from Chicago, Detroit, Minneapolis, and Pittsburgh found that African Americans had a 5.3% higher risk of heat-related mortality than Caucasians and that 64% of this disparity was potentially attributable to disparities in air conditioning.

Heat reduces work productivity, especially in active outdoor jobs. The 2018 Lancet Countdown estimated that 153 billion hours of work were lost in 2017 because of excessive heat, an increase of 62 billion hours lost relative to 2000. Lack of acclimatization to heat is an important risk factor. Workers in hot environments are most likely to develop heat-related illness during their first 2 weeks on the job. Research has shown that people living in normally cooler areas tend to be more susceptible to health effects from heat waves. As one example, during the 2006 California heat wave, the greatest increase in emergency department visits occurred in the normally cooler coastal cities. This phenomenon is probably both because fewer buildings are air-conditioned in these areas, and because people there are less physiologically acclimated to heat.

Figure 3.1.3 Complex mix of air pollution from a power plant. Slide by Gina Solomon.

Health effects of air pollution

Heat increases the atmospheric conversion of air pollution from gasoline and diesel exhaust into ozone smog. Thus the health threat on hot days stems both from heat itself and from ground-level ozone pollution that can cause respiratory and cardiac damage. Ozone is created from other pollutants such as volatile organic compounds (VOCs) and nitrogen oxides that are emitted from industrial sources, power plants, cars, and trucks (Figure 3.1.3). These chemicals are transformed by sunlight in a chemical reaction that breaks down oxygen in the air and results in ozone formation. Heat dramatically speeds up this chemical reaction. As the ambient temperature rises, ground-level ozone levels also rise. Ozone in the upper atmosphere is beneficial because it protects us from the damaging ultraviolet rays of the sun. But ground-level ozone is extremely toxic to our lungs. Ozone in the lower atmosphere is also known as smog because it creates a gray-brown haze that looks like a combination of smoke and fog.

The health effects of inhaled ozone include cough, difficulty breathing, chest pain, decreased lung function, and asthmatic symptoms. These symptoms send people to the emergency department with acute illness. Over time, ozone can also cause significant long-term damage to airways, affecting the white blood cells that protect our lungs.

Warmer weather conditions with higher concentrations of carbon dioxide (CO₂) in the air also foster the growth of allergenic weeds such as ragweed. Studies in greenhouses with carefully controlled atmospheric composition have shown that air slightly enriched in CO₂, at concentrations we expect to see due to climate change within the next few decades, causes ragweed to grow more lushly; worse, the plants produce about three times more pollen. That extra airborne pollen will seriously worsen the suffering of individuals with pollen allergies. These findings suggest an increase in health challenges associated with nuisance symptoms such as hay fever, as well as more serious conditions such as asthma.

In addition to ozone pollution and allergens, particulate matter is also a threat to health. Particulate matter is discussed in more detail below, since it is produced in massive quantities from wildfire smoke and also from the combustion of petroleum and coal—the same sources that produce most of the carbon dioxide in the atmosphere.

Health effects of wildfires

Figure 3.1.4 Health effects of air pollution. Reproduced from Public Health England.

A warming climate places enormous stress on many species of trees as weather conditions become too warm and either too wet or too dry for the climate to which the trees are adapted. Stressed trees are much more susceptible to fungal infestations, and bark beetles have been decimating the conifer forests of the western United States. Dead trees create conditions that are ideal for massive wildfires. In December 2017, the US Forest Service estimated that there were 129 million dead trees in California, mostly due to drought and bark beetle infestation. Drought conditions in numerous countries around the world are similarly fueling fires in places ranging from Australia and Indonesia to Canada. Rainy conditions that may follow a drought come too late to save the trees, but rain results in fast growth (and subsequent dieback) of grasses and shrubs that provide kindling to start massive wildfires. Wildfires are a natural part of forest cycles, but the fires that occur with climate change are intense firestorms that cover vast areas, burn so hot that they destroy everything in their path, and damage ecosystems while they threaten humans. In rural areas, fast-moving wildfires can burn down homes and destroy communities. In recent fires, deaths have occurred among both emergency responders and local residents when they were unable to escape from the path of the fire or their escape route was cut off.

The health effects of wildfire smoke are similar to the health effects of other particulate matter (PM) in the air (Figure 3.1.4). The small particles (known as PM2.5 because they are less than 2.5 micrometers in diameter) are less visible but more dangerous. These particles cause lung inflammation that results in impaired function, cough, phlegm, bronchitis, worsened asthma, heart attacks, heart failure, and premature death. These effects especially occur in people with underlying health conditions, such as heart disease, lung disease, and asthma. Even healthy people can be sickened when wildfire smoke is severe, leading to decreased exercise tolerance, cough, sore throat, and eye irritation. Smoke from large fires can cover areas of hundreds of square miles and can affect entire cities or even entire states for periods of time that can range from days to months.

Health effects of flooding

Although it is difficult to pin any single weather event on climate change, climate models show that extreme weather fluctuations increase as the Earth warms. For example, rain is more likely to fall in large amounts when it does occur, leading to increased risk of flooding. Sea level rise will result in inundation of low-lying coastal areas, especially during high tides and storm surges. Hurricanes are projected to become more powerful as a result of warming waters in the Atlantic and the Gulf of Mexico. The combination of major storms and sea level rise will predictably result in both coastal and river flooding, both in the US and worldwide.

When Hurricane Florence flooded the Carolinas in 2018, not only did people lose their lives, but there were enormous health implications, both immediately and in the longer term. Hurricane Florence was considered a “1,000-year storm,” but such storm events will no longer be rare in the future, as what is now considered an unusual or extreme storm will become a relatively frequent occurrence.

Fifteen percent of all deaths related to natural disasters are due to floods. People who are disabled or elderly are often less able to evacuate before a major storm. In some floods, nursing homes and hospitals are inundated, leaving elderly and sick people in miserable conditions, without adequate care. In the flooding after Hurricanes Katrina, Sandy, and Maria, emergency generators at medical facilities failed, and oxygen supplies, respirators, heart monitors, and all other advanced medical systems stopped functioning, as did air conditioners and lighting. Conditions in these facilities were horrific, and many people suffered and died in the days and weeks following these storms.

Figure 3.1.5 Flooded homes after Hurricane Katrina, New Orleans, 2005. Photographs by Gina Solomon.

Flood waters are often contaminated with sewage and chemicals, resulting in gastrointestinal illnesses and skin diseases after contact. After people’s homes are flooded and the waters recede, it looks like the contents of the home have been picked up and swirled around in a huge blender. The walls grow a thick carpet of black and brown mold over mud and scum (Figure 3.1.5). Testing in flooded homes reveals high airborne levels of mold and endotoxin, which are extremely dangerous to people’s health. Endotoxin is produced by certain kinds of gram-negative bacteria that thrive in damp conditions; it can cause respiratory distress, low blood pressure, and shock. Mold can cause allergic reactions, asthma, and other health problems. For these reasons, returning home to sift through personal belongings can be dangerous and requires respirators, protective coveralls, and gloves.

Floods also cause massive destruction of residential and commercial structures, making neighborhoods completely uninhabitable. There can also be damage to oil and gas pipelines, water mains, roads, sewage treatment plants, and other infrastructure that creates contamination across the entire landscape. Industrial facilities, hazardous waste sites, and petroleum storage tanks may rupture in the flood and spread toxic contamination into the mud and soil, both outdoors and inside the flooded homes. Testing in New Orleans after the 2005 flood from Hurricanes Katrina and Rita revealed toxic petroleum chemicals, heavy metals such as lead and arsenic, and pesticides in the sediment that was left behind from the flooding. All of these issues need to be addressed in the cleanup, and they pose hazards to returning residents and to cleanup workers.

Floods cause massive population displacement and homelessness. Some people can evacuate the area and stay elsewhere with family or friends, at least for a while. Others have no place to go and must be housed in temporary shelters, sometimes for months. The large numbers of displaced people need food, water, and health care. Evacuees with underlying chronic diseases frequently experience exacerbations of their illness, often from lack of essential medications. For example, diabetics who don’t have their insulin, people with seizure disorders, and people with severe psychiatric illnesses are all at high risk of serious and sometimes life-threatening exacerbations. Family and community structures and daily routines are completely disrupted, leading to depression, anxiety, post-traumatic stress disorder, and confusion for many people, especially the elderly. Rates of suicide almost always spike after hurricanes and floods.

Infectious diseases

Flooding causes obvious immediate risks of injury and death but also can impair drinking water quality by increasing runoff of contaminants into surface water sources. Runoff of soil and sediment into rivers and streams can lead to growth of parasites in the water, especially Cryptosporidium and Giardia. Both of these parasites can cause severe diarrhea and especially severe illness in people with immunosuppression. The combination of extreme rainfall and a malfunction at a drinking water treatment facility is the most likely set of factors that can lead to a major outbreak of one of these parasitic diseases.

Increased heat from climate change is another factor that substantially increases the risk of infectious disease spread. The combination of warmer conditions and altered rainfall patterns can lead to ponding of warm, stagnant water—conditions ideal for the life cycle of numerous pests, including the mosquitoes that carry diseases ranging from malaria and yellow fever to dengue fever and chikungunya.

Figure 3.1.6 Habitat suitability for disease-carrying mosquitoes in the United States. Reproduced from Centers for Disease Control and Prevention.

As one example, the Aedes albopictus mosquito—known as the Asian tiger mosquito—came into Southern California in a shipment of imported ornamental “lucky money trees” (Pachira aquatica) from Asia in the early 2000s. It entered Texas at about the same time in shipments of used tires. Aedes albopictus and a similar mosquito known as Aedes aegypti are both relatively new to the United States but have been spreading northward rapidly (Figure 3.1.6). In the past, these species would not have survived the winters in temperate climates, but their range has been steadily extending northward as a result of the warming climate. In the tropics, the range of these pests is extending to higher elevations in mountainous areas, exposing new populations to threat. For example, the highlands of sub-Saharan Africa had a 27.6% rise in the potential for transmission of malaria from 1950 to 2017 due to warming. The Aedes mosquitoes are hard to avoid, because they prefer to prey on humans, they bite during the day, and they breed in little pools of water, such as in plant pots, abandoned tires, kiddie pools, bird baths, and other items that lie around collecting water in many people’s yards.

Aedes mosquitoes are capable of transmitting a variety of diseases that weren’t previously thought to occur in the United States and that are not carried by local mosquitos, including dengue fever, chikungunya, and zika virus. Zika caused a well-publicized epidemic in South America and raised public fears because it can cause microcephaly—a devastating birth defect—in infants when women are exposed during pregnancy. Zika was also detected in southern Florida in 2016 and has become endemic to the area since that time.

Dengue is nicknamed breakbone fever because people who have it feel like their bones are breaking. The illness is characterized by severe headaches, generalized aches and pains, high fevers, and total loss of appetite with nausea and vomiting. The symptoms of chikungunya are similar, with high fever and body aches; this disease entered Italy in 2007 and recurred in 2017 after a decade’s hiatus.

Lyme disease and other fevers that include rash and arthritis are spread by ticks. The populations of ticks that carry these diseases are moving northward into Canada. Agricultural pests and invasive plant and animal species are also moving around the globe as a consequence of air travel and trade. When invasive species arrive in an area, they can outcompete local plants, animals, or insects and may thrive in the warmer conditions brought by a changing climate. One reason that agricultural pests and invasive species are important is that they can be enormously destructive to native species and to local food crops; the other reason they are important is that they can result in major increases in pesticide use to fight them. Many pesticides are associated with serious human health risks, ranging from neurological toxicity, to reproductive effects, to cancer.

Food-borne diseases are also a concern with climate change. Many people are familiar with Salmonella and E. coli food poisoning outbreaks. Warming conditions are ideal for bacterial species, since bacteria proliferate far more rapidly as temperatures increase. Several species of Vibrio cause severe skin diseases after water contact, and severe gastrointestinal illness from consumption of contaminated shellfish. Vibrio shellfish poisoning has now moved into the cool waters off Alaska during summer seasons.

Harmful algal blooms and health

Figure 3.1.7 Increase in reported harmful algal bloom events over time. Reproduced from NOAA.

Harmful algal blooms (HABs)—sometimes called red tides—are another health threat associated with climate change. The combination of nitrogen- and phosphorus-rich water and heat creates conditions ideal for the explosion of small marine organisms and algae. The nutrients are often contributed by fertilizer runoff in rain events, resulting in pollution of lakes and coastal waters. Explosions of algal growth are toxic to fishes and amphibians because the oxygen levels in the water drop to dangerously low levels. HABs are doubly dangerous because they produce toxins that can directly poison creatures that are in contact with the water. In many cases, HABs are quite visible, creating greenish, blue, or red material on the surface of the water. In some cases, the problem is less visible, thereby failing to alert people to the danger.

HABs often result in major die-offs of aquatic species, including fishes, birds, and marine mammals. Dogs and livestock that drink from, or swim in, contaminated water are also at high risk of death. People can be affected in some cases from skin contact with the contaminated water, or inhalation of ocean spray. In most cases, however, people are poisoned from contaminated seafood. The symptoms of HAB poisoning vary depending on the organism. Brevetoxins, most commonly associated with “red tides” off the Florida coast, are respiratory toxins when inhaled, leading to asthmatic symptoms even in those who do not have asthma. Cyanobacteria, known as blue-green algae, are found in freshwater as well as in salt water. They produce toxins such as microcystin that affect the liver and gastrointestinal tract, causing vomiting, diarrhea, and sometimes fatal liver failure. Some of these toxins are also potential carcinogens. Other categories of HAB toxins affect the nervous system. Most of these toxins affect humans through consumption of contaminated shellfish. For this reason, the names of the diseases include “paralytic shellfish poisoning,” “neurotoxic shellfish poisoning,” and “amnestic shellfish poisoning.”

Amnestic shellfish poisoning is caused by domoic acid, which is produced by a microscopic diatom in the genus Pseudo-nitzchia. This organism grows explosively in salt water when there is nutrient pollution from runoff and when the ocean gets warm, but it does not cause a visible bloom like a red tide. Shellfish, including clams, mussels, oysters, and crabs, consume the organism and do not die. Instead, they sequester large quantities of the toxin in their bodies, poisoning anything that eats them.

Domoic acid is neurotoxic, causing seizures and death in marine mammals and birds. The first sign of an offshore bloom is marine mammals washing up on the beaches: sea otters, sea lions, seals, whales. The toxin also affects humans. Symptoms start quickly, within 24 hours after ingesting contaminated shellfish. Initially it seems like any other food-borne illness, with nausea, vomiting, diarrhea, and abdominal pain. Then the neurological symptoms begin, including headache, dizziness, weakness, seizures, and changes in mental status. And ultimately, for those people who do recover, some develop anterograde memory loss, which means that from the time of the illness onward, they are not able to retain memories. These people classically can’t remember what they had for breakfast that morning, even though they have clear memories of their lives prior to the poisoning event. The treatment is supportive care. There is no antidote.

The first reported outbreak of amnestic shellfish poisoning was in 1987 in Prince Edward Island, Canada. Three people died in that outbreak, and over 100 people suffered permanent neurological effects. Since that time, the US, Canada, the European Union, and numerous other countries have put in place programs to monitor seafood and attempt to ensure that scientists detect domoic acid and other HABs before people become ill. The California Dungeness crab fishery was shut down for the entire 2015 season because of domoic acid contamination, resulting in enormous economic losses but also saving many lives and preventing severe debilitating illness.

Health and social inequality

Climate change has a disproportionate impact on vulnerable and socially marginalized populations. Globally, those countries most threatened by the risks of global warming are generally the ones that have the fewest resources to respond and protect themselves; these are also the same countries that are least responsible for climate pollution. According to the World Health Organization (WHO), diarrhea, malaria, malnutrition, and heat stress are the top causes of death worldwide associated with climate change. WHO estimates that the direct health costs of climate change will be approximately $2.4 billion per year within the next few decades.

Within wealthy countries such as the United States, poor communities are at greatest risk of harm. Researchers have developed the term the climate gap to describe the disproportionate affect of climate change on people of color and the poor. Risk to any community or individual is a function of hazard multiplied by vulnerability. Hazard in this context could include any climate stressor such as living in an urban heat island or in a floodplain. Vulnerability describes the ability to anticipate, cope with, resist, and recover from a stressor, such as a heat wave or flood. Both hazards and vulnerabilities are often greater in poor communities of color, resulting in greater overall risks of harm.

Climate change also exacerbates social inequality by increasing costs for basic necessities such as food and water. Insurance rates in flood and fire zones also rise, resulting in a higher proportion of uninsured or underinsured individuals in poor communities. Despite the burdens on the poor and on communities of color, however, studies have shown that such communities are more inclined to support strong government action to reduce greenhouse gas emissions.

The State of California has taken an innovative approach to addressing climate change and social inequality. Over a billion dollars of funding from the state auctions of carbon credits has been allocated to disadvantaged communities for projects to improve rail and other public transit, transit-oriented development, affordable housing, bike lanes and sidewalks, agricultural land preservation, rebate programs for zero-emission vehicles, weatherization programs for low-income communities, urban forestry, and fire risk reduction. In addition to reducing greenhouse gases, these investments bring jobs into disadvantaged communities, create local conditions that promote health, and help redress environmental injustices. This program has the potential to serve as a model for a way to use a market-based greenhouse gas cap-andtrade program to generate funds that serve to also address principles of health and climate justice.

Direct health threats from fossil fuels

Fossil fuels, including coal, oil, and natural gas, continue to be the main sources of energy in our global economy. These energy sources fuel power plants, providing us with electricity; they fuel our automobiles and trucks; and they fuel our industrial sector, producing plastics, chemicals, cement, and consumer products. Fossil fuels also are used in agriculture to make fertilizer, pesticides, and all the equipment used to grow, harvest, and process food.

Fossil fuels have direct health effects at every stage of their production and use. Coal mining, oil drilling, and hydraulic fracturing (“fracking”) for oil and gas cause emissions of toxic chemicals to air and water, as well as occasional dramatic disasters, ranging from worker fatalities in mine collapses, explosions, or fires, to massive spills such as the 2010 Deepwater Horizon BP oil spill in the Gulf of Mexico. Transport of these fuels is beset with pipeline leaks, rail disasters including explosions, and spills from ocean tankers. Processing of fossil fuels at refineries affects local communities on a daily basis with air pollution that includes known human carcinogens such as benzene and formaldehyde, asthma-causing chemicals like nitrogen oxides, and reproductive toxicants. Worse still, the highly flammable mixtures under high pressures and temperatures at refineries can result in explosions and fires, sometimes killing workers or sending hundreds or even thousands of local residents to emergency departments.

Combustion of fossil fuels results in release of carbon dioxide, the greenhouse gas that has the longest atmospheric life and is the greatest contributor to climate change. Other air pollutants released when fossil fuels are burned include particulate matter, benzene, other volatile organic compounds that can be transformed into ozone, and heavy metals such as mercury. Harmful chemicals such as sulfur oxides and nitrogen oxides are also released.

Particulate matter is a special concern; black carbon particles small enough to be inhaled deep into our lungs are released from power plants, refineries, many industrial facilities, diesel engines, diesel generators, and many other sources. Particulate matter has serious effects on our hearts and lungs—it increases death rates by increasing arrhythmias (abnormal heartbeats), causing abnormal clotting in blood vessels, worsening bronchitis, triggering asthma attacks, and causing strokes and heart attacks. In 2015, particulate matter from fossil fuel combustion was responsible for 2.9 million premature deaths, with coal burning being responsible for more than 16% of these deaths. Black carbon particles from coal or diesel exhaust contain high concentrations of cancer-causing chemicals known as polycyclic aromatic hydrocarbons (PAHs), which over time can lead to lung cancer and other cancers.

Poor people of color are more greatly affected by the fossil fuel industry, from the points of production near refineries, to the points of emission near power plants, major roadways, ports, rail yards, and airports. An analysis of the demographic patterns of exposure to particulate matter and nitrogen oxides from power plants and petroleum refineries found that minorities are more likely than non-Hispanic whites to live near these facilities, even when the analysis controlled for household income.

Assessing local risk from climate change

As we live our daily lives, it’s easy to ignore the dangers around us. Many people think that the scenes they see on television or in the newspapers couldn’t happen to their own community. It is hard to imagine how our own communities would look after a devastating fire, storm, or flood. In fact, most communities are at risk from climate change in the coming years and decades. The way to protect ourselves is to open our eyes to the hazards and vulnerabilities in our communities and to prepare, so if disaster does occur, we can protect both ourselves and others around us.

The steps to assessing local risk include first identifying the hazards. For example, low-lying areas may be at risk of flooding, especially if they are in the potential path of coastal storm surge or river flooding. However, the widespread flooding in September of 2018 after Hurricane Florence in North and South Carolina included low-lying areas simply inundated by heavy rainfall. Areas along the urban-wildland interface may face a high risk of catastrophic fire. Highly urbanized neighborhoods without much tree cover may be at particular risk from extreme heat events, especially if many people lack air conditioning or in the event of a power failure. Coastal and lake areas face the potential for HAB events, and warmer, wetter zones have higher risk of mosquito-borne disease outbreaks. Identifying local hazards from climate change can help create plans to either reduce those hazards or to prepare for a potential event.

Local vulnerabilities can also be assessed at any scale, from a single family to an entire state. For example, identifying the presence and locations of elderly or disabled people who may need extra assistance in the event of an evacuation, or who may be more vulnerable to heat, can help ensure that those people receive the assistance they need. Schools, day care centers, hospitals, nursing homes, and other facilities that can be difficult to evacuate are also critical to locate. Such facilities should have extensive plans for preparing and responding to disasters.

In climate catastrophes, relatively few people will die in the immediate event. The main brunt of the illnesses and deaths occurs in the aftermath, when the effectiveness of the response and recovery is critical to determining the outcome for many people. For example, if people with underlying illnesses or acute injuries are able to access timely medical care, they may avoid serious outcomes. Mental health services, relocation services, housing, food, safe drinking water, and social support are all essential components for recovery.

Ultimately we will need to make very difficult decisions as a society. For example, rebuilding homes and communities after flooding may be seen as an increasingly unwise investment of resources. Adequately protecting against sea level rise or flooding is a very expensive effort, and it can realistically be done only in limited areas. Strategies to reduce the risk of wildfire are also evolving, as people realize that fire suppression is ultimately bound to fail, and as massive tree die-offs occur from drought and pest infestations. Yet optimal forest management is controversial and complex.

Reducing climate vulnerability

The interconnections between climate change, health, and justice suggest the importance of incorporating co-benefits into climate mitigation policy to ensure that solutions leverage improvements in community health while advancing climate justice. Linking social equity, health, and sustainability goals in environmental policy can mobilize key constituencies to address climate change.

The State of California has made significant efforts to integrate equity into policies and programs to address climate change, in order to ensure that disadvantaged populations receive an appropriate distribution of benefits as well as protection from additional harms. Disadvantaged communities in California have been identified and prioritized for funding, using the California Communities Environmental Health Screening Tool (CalEnviroScreen). CalEnviroScreen was developed through a public process that included extensive community input. It enables the identification of communities in California that are burdened by multiple sources of pollution and face a combination of factors, including contact with pollutants, adverse environmental conditions in their community, biological vulnerability due to underlying disease burden or age distribution, and social vulnerability due to poverty and other community characteristics. The concept of using cumulative impacts in communities to prioritize areas for funding allows some principles of climate justice to be integrated into climate mitigation decisions.

Other approaches to reducing greenhouse gases (GHGs) while adapting to a changing climate and protecting public health include the following:

• Promote alternative modes of transit, including walking, biking, and public transit. These strategies reduce GHGs while directly enhancing health by reducing motor vehicle pollution and increasing physical activity.
• Make communities greener by planting trees and developing green/ cool roof projects, parks, and buffer zones in flood-prone areas. These strategies reduce air pollution and noise, directly improve mental and physical health, and reduce the urban heat island effect.
• Construct green, efficient buildings that reduce GHGs while also improving indoor air quality, thereby directly benefiting the health of occupants. Such buildings may also be more resilient to heat while using less energy for cooling.
• Reduce fossil fuel use, and gain a series of direct benefits to public health in communities affected by air pollution. Reduced fossil fuel combustion will reduce toxic chemical emissions and particulate matter pollution. It will also reduce the emissions of ozone precursor chemicals, thus reducing smog despite a warming climate.
• Reduce consumption of meat and high-fat dairy products to substantially reduce emissions of methane, which is sometimes referred to as a super pollutant because of its potency as a GHG. Reduced meat and dairy fat consumption would also reduce risks of cardiovascular disease and cancer, both of which are associated with diet.

There are numerous actions we can all take in the near term to reduce our climate footprint while also benefiting our health and the health of our communities. At the same time, we must evaluate the risks in our local areas and develop strategies to reduce those risks or increase our resilience so that we will escape the worst effects of climate change and protect our families, our neighbors, our environment, and people around the globe.