The World Health Organization (WHO) warned Wednesday that killer diseases will spread, health problems will worsen, and existing humanitarian crises will grow more severe with climate change.
The WHO, which is holding the first-ever global conference on health and climate in Geneva this week, urged nations to act quickly to reduce the emissions of greenhouse gases, which lead to climate change. The agency said green energy and transport policies could save millions of lives each year, by cutting air pollution. The WHO also called for initiatives to help communities prepare for heat, extreme weather, infectious diseases and food insecurity caused by climate change.
“The evidence is overwhelming: climate change endangers human health,” says Dr. Margaret Chan, WHO Director-General. “Solutions exist and we need to act decisively to change this trajectory.”
The WHO’s new statement also notes that climate change also has serious economic consequences. The U.N. agency says the direct damage costs to health (i.e. excluding costs in health-determining sectors such as agriculture and water and sanitation) is estimated to be between $2 billion and $4 billion a year by 2030. The current global temperature increases expected by the end of the century already greatly exceeding our adaptive capacity.
Climate change is one of the most rapidly emerging and widespread public health threats that the world has ever faced. Over the last 50 years, human activities – particularly the burning of fossil fuels – have released sufficient quantities of carbon dioxide and other greenhouse gases to trap additional heat in the lower atmosphere and affect the global climate. In the last 100 years, the world has warmed by approximately 0.75oC. Each of the last 3 decades has been successively warmer than any preceding decade since 1850.
As a result, sea levels are rising, glaciers are melting, and precipitation patterns are changing; extreme weather events are also becoming more intense and frequent.
Although some countries could see temporary localized benefits from global warming — for instance, cold countries could experience fewer winter deaths due to more temperate weather — the WHO says the overall health effects will be overwhelmingly negative. “Without effective action to mitigate and adapt to the adverse effects of climate change on health, society will face one of its most serious health challenges,” warns Dr. Flavia Bustreo, WHO assistant director general of family, women’s and children’s health.
‘A significant and emerging threat to public health’
Rising temperatures and variable precipitation are likely to decrease the production of staple foods in many of the poorest regions – by up to 50 percent by 2020 in some African countries, the WHO reports. This will increase the prevalence of malnutrition and undernutrition, which already cause at least 3.1 million deaths every year. Deadly diseases such as cholera, malaria, and dengue fever, which are all highly sensitive to weather and climate, are expected to become endemic in entirely new regions of the world — in fact, we’ve already seen this start happening.
The effects of climate change on human health include direct and indirect effects; immediate and long-term effects; and acute and chronic effects. While there are many mechanisms through which these effects can take place, here are five of the concerns highlighted by the WHO:
Rising temperatures
Rising temperatures contribute both directly and indirectly to a range of health risks. In moderate climates, even small increases in temperature can vastly expand the geographic distribution of disease-carrying insects, raising the risk of vector-borne infections. In fact, scientists have already documented several such diseases — including Lyme disease, Chikungunya, and dengue fever — that are appearing in places previously unaffected by the pathogens.
Extreme high air temperatures contribute directly to deaths from cardiovascular and respiratory disease, particularly among elderly people. In the heat wave of summer 2003 in Europe for example, more than 70,000 excess deaths were documented. High temperatures also raise the levels of ozone and other pollutants in the air that exacerbate cardiovascular and respiratory disease. Pollen and other allergen levels are also higher in extreme heat. These can trigger asthma, which affects around 300 million people. Ongoing rises in global temperatures are expected to further increase this burden, warns the WHO.
Floods
Floods are increasing in both frequency and intensity due to rising sea levels and increasingly extreme weather events, says the WHO. Floods pose several key health risks: They contaminate freshwater supplies, damage or destroy sewage pipes, wipe out crops, heighten the risk of water-borne diseases, and create breeding grounds for disease-carrying insects such as mosquitoes. They also cause drownings and physical injuries, damage homes, and disrupt the supply of medical and health services.
Floods are also associated with significant psychological distress, often leading to mental illness and even suicide, says the WHO. The agency further states that the mental health consequences of floods “have not been fully addressed by those in the field of disaster preparedness or service delivery,” although it is generally accepted that natural disasters, such as earthquakes, floods, and hurricanes, “take a heavy toll on the mental health of the people involved, most of whom live in developing countries, where [the] capacity to take care of these problems is extremely limited.”
Rainfall patterns
Increasingly variable rainfall patterns are likely to affect the supply of fresh water, warns the WHO. A lack of safe water can compromise hygiene and increase the risk of diarrheal disease, which already kills almost 600,000 children aged under 5, every year. In extreme cases, water scarcity leads to drought and famine. Other health-related implications of drought include food shortages (resulting in malnutrition and starvation), poor air quality/increased airborne particles (resulting in respiratory infections like pneumonia and valley fever – a fungal infection found in many areas of the southwestern United States, Mexico, Central and South America.
While some drought-related health effects are experienced in the short-term and can be directly observed and measured, the slow rise or chronic nature of drought can result in longer term, indirect health implications that are not always easy to anticipate or monitor. However, the effects are very real: By the 2090s, climate change is expected to widen the area affected by drought, double the frequency of extreme droughts, and increase their average duration six-fold, the WHO cautions.
Patterns of infection
Climatic conditions strongly affect water-borne diseases and diseases transmitted through insects, snails or other cold blooded animals. Changes in climate have already been shown to lengthen the transmission seasons of important vector-borne diseases and to alter their geographic range. For example, climate change is projected to widen significantly the area of China where the snail-borne disease schistosomiasis occurs (schistosomiasis is a parasitic disease that can cause severe immune reactions and damage to the intestinal organs).
Malaria is another infectious disease that is strongly influenced by climate. Transmitted by Anopheles mosquitoes, malaria kills almost 800,000 people every year – mainly African children under 5 years old. The Aedes mosquito — the vector of dengue fever — is also highly sensitive to climate conditions. Studies suggest that climate change could expose an additional 2 billion people to transmission of dengue fever within the next several decades.
Vulnerable populations
Everyone will be affected by these changes, the WHO says, but not equally. Vulnerability to climate change will be determined by a community or individual’s ability to adapt. As a result, the impacts of climate change will disproportionately affect people living in poverty in poorer, developing countries — notwithstanding their minimal per-capita contributions to greenhouse-gas emissions. It’s here where the damage will be greatest and where people have the lowest capacity to cope.
According to UN Women, some 70 percent of people in the developing world living below the poverty threshold are women, yet gender issues receive little attention in the climate change debate. People are vulnerable to the hazards of climate change to a greater or lesser degree depending on factors such as their wealth, education, skills, management capability and access to technology, infrastructure and information. Women’s access to these resources is often inferior to that of men, and this increases their vulnerability and limits their ability to cope with the advent of climate shocks and to recover when they have passed. These gender-related inequalities are particularly pervasive in the developing world, where women make up an estimated 70 percent of people living below the poverty threshold, and where the effects of climate change are already worse due to poor economic conditions.
Studies have shown that women disproportionately suffer the impacts of disasters, severe weather events, and climate change because of cultural norms and the inequitable distribution of roles, resources, and power, especially in developing countries. Other particularly vulnerable populations include children, the elderly, and the poor.
‘Reducing climate change can yield substantial and immediate health benefits’
Already, seven million people die prematurely each year because of air pollution — that’s one in eight total global deaths. And tens of thousands more die from shifting patterns of disease and extreme weather events, such as heat waves and floods. The WHO expects that climate change will cause approximately 250,000 additional deaths every year between 2030 and 2050 due to heat exposure, diarrhea, malaria, and childhood under-nutrition.
However, “the good news is that reducing climate change can yield substantial and immediate health benefits,” says Dr. Maria Neira, director of the Public Health, Environmental and Social Determinants of Health Department at WHO, “[t]here is now solid evidence that mitigating climate change can greatly reduce this toll.”
Previously unrecognized health benefits could be realized from fast action to reduce climate change and its consequences, says the WHO. For example, changes in energy and transport policies could save millions of lives annually from cancer, heart disease, stroke, and other diseases caused by high levels of air pollution. The right energy and transport policies could also reduce the burden of disease associated with physical inactivity and traffic injury. Additionally, enhanced disease surveillance and monitoring could help public health officials stay on top of emerging infectious diseases.
“We can reduce dramatically non-communicable diseases, cardiovascular diseases, heart disease, respiratory diseases, by promoting, for instance a more sustainable, low-carbon society where instead of using very pollutant and solid fuels,” Dr. Neira said, “we will move into a more sustainable energy consumption and, therefore, by doing so, we will obtain plenty of benefits for our health.”