It poses “the greatest risk of the 21st century for public health, but also the greatest opportunity.” This is how the World Health Organization (WHO) characterized climate change and its ramifications, in its 2014 report. If opportunities remain, the risks in the past five years have become even starker.
Some 250,000 additional deaths per year are expected on average between 2030 and 2050, due to heat exposure, malaria, malnutrition and diarrhea.
How exactly will climate change affect our health, and what kinds of problems is it already causing? Who will be the most affected? What can we do to limit its impact?
Below, we’ll explore these questions, and more.
Human-induced global warming has already reached 1 °C above pre-industrial levels, according to the Intergovernmental Panel on Climate Change (IPCC). The last four years have been the warmest ever recorded since 1880, when the Earth's surface air temperature was first recorded. There has also been a rise in the number of heatwaves.
Illness and Mortality
The number of people vulnerable to heatwaves – likely to fall ill or suffer from worsening heart failure, for example – rose from 125 million in 2000 to 175 million in 2015, according to the scientific journal The Lancet. Analysts fear a repeat of 2003, when 70,000 people died across Europe during the heatwave that summer.
The amounts of allergens and pollutants in the air – such as pollen and ozone – also tend to increase with the temperature, causing asthma attacks and aggravating cardiovascular and respiratory diseases.
The number of deaths attributed to air pollution is expected to increase with the rise in temperatures, particularly in Africa, as a result of rapid urbanization.
Depression, Hunger and Violence
Violence and rates of depression have been found to rise with the mercury. A Stanford University study last year in Mexico and the United States revealed that as temperatures rose, acts of suicide and violence increased.
Prolonged, unseasonable heat also affects agricultural production. The productivity of laborers has fallen by 5.3% in rural areas since 2000, according to The Lancet. This poses a threat to the livelihoods of farming communities all over the world, while chronic malnutrition is already affecting over 800 million people.
In 2050, almost half of farmland in Africa is expected to be subject to previously unknown climatic conditions, with major consequences on agricultural production. Latin America and South Asia are also expected to face food security problems. According to The Lancet, each additional degree of warming would lead to a 6% drop in wheat yields and 10% for rice.
With the rise in global temperatures, heatwaves are expected to be both more frequent and more intense. Combined with high humidity, as in tropical regions, they are likely to become more deadly by the end of the century, and millions of people will be forced into exile. The surge in the health effects from climate change will put pressure on healthcare systems.
It has been proven that human activities contribute to disrupting rainfall patterns around the world. The number of weather-related natural disasters recorded each year has more than tripled since the 1960s.
The frequency and intensity of flooding are increasing, causing drownings and fostering the transmission of certain diseases like cholera. In recent years, there has also been an increase in droughts caused by the lack of rainfall.
A 2018 WHO report forecasts that increasingly variable rainfall patterns are likely to affect the supply of fresh water.
Also, “a lack of safe water can compromise hygiene and increase the risk of diarrheal disease, which kills over 500,000 children aged under 5 years, every year,” says the report. More regions are expected to fall prey to drought by 2090. And “climate change is expected to double the frequency of extreme droughts and increase their average duration by a factor of six.”
“It is natural disasters caused by extreme climate events that have the most serious consequences”, says Christophe Paquet, Head of the Health & Social Protection Division at Agence Française de Développement (AFD). “They expose vulnerable groups to exogenous shocks which not only have an impact on their health, but more generally on their capacity for economic survival.”
Global warming is currently disrupting the distribution areas of a number of animal and plant species. Some flee from waters that have become too warm or land that has become too arid. Others, on the contrary, colonize new territories due to the milder temperatures.
For example, certain species of mosquitoes, such as the tiger mosquito, are spreading over wider areas, and can carry diseases like dengue fever or chikungunya in areas where populations are unprepared to cope with them.
In Australia, thousands of rats are leaving regions where food is scarce and going to large cities, carrying diseases and infecting other animals on their way.
Global warming has been linked to the increase in the incidence of malaria in Kenya and Madagascar, as well as to the reemergence of chikungunya in the Indian Ocean in 2005. The ability of the mosquito carrying dengue fever to transmit the infection has increased by over 9% since 1950, according to a report published by the scientific journal The Lancet.
The epidemic periods of certain diseases are also becoming longer: this is the case with meningitis, which persists in the Sahel due to a longer dry season and spreading deserts.
“Over half of the Member States of the World Organisation for Animal Health also report the emergence or reemergence of infectious diseases directly linked to the climate,” says Christophe Paquet, “the first being Rift Valley fever, West Nile fever and bluetongue disease”.
With the gradual extension of the areas affected by mosquitos carrying dengue fever or chikungunya, the prevalence of these diseases could be much higher in the coming years. An estimated 2 billion more people could be exposed to the risk of dengue transmission by 2080.
Heavy rainfall combined with higher temperatures could also foster the proliferation of cholera and diarrheal illnesses where there is a lack of hygiene and sanitation. We can also expect meningitis epidemics to spread well beyond their traditional areas in Africa, due to longer and more intense dry seasons.
And beyond what we can expect, are new and unknown diseases that could yet emerge.
We will all feel the effects of climate change. But some are more exposed than others, particularly people in small island States, on coasts, on mountains, in tropical regions, in polar regions and large cities.
Some are also more vulnerable because they live in countries where working outside is common, air conditioners are rare and where healthcare systems are deficient. “In the Least Developed Countries, health systems that are underfunded, structurally fragile and already faced with demographic and epidemiological transitions will not be able to cope with these situations without energetic action to build their capacities”, Christophe Paquet warns.
It is currently estimated that every year, 100 million people are faced with health expenses that plunge them into poverty due to a lack of sufficient social protection. In Africa and Southeast Asia, one family in three has to sell possessions or get into debt to finance vital care.
Children, pregnant women, the elderly, disabled or sick are more fragile than the rest of the population and will be even more exposed to the health consequences of global warming.
A great injustice is slowly appearing: populations in developing countries have contributed very little to global warming, but they are the ones who will pay a heavy price.
This is the most obvious solution: to limit the impact of climate change on human health, we need to start by curbing climate change and to do so, reduce our greenhouse gas emissions. Major changes are required in several sectors: transport, food, housing, industry, forestry.
The timing is right, as a number of solutions can already be implemented.
Agence Française de Développement is fully mobilized on this front: it is today assisting a number of countries with the revision of their climate commitments and the definition of long-term low-carbon and resilient strategies. It has also set two main objectives: make its activity 100% compatible with the Paris Climate Agreement, and earmark at least €5 billion in financing per year for the climate starting in 2020.
More cities and countries are starting to implement measures to adapt to the consequences of global warming. The objective: increased resilience.
Today, AFD is helping a number of vulnerable countries with the preparation of structural programs in the field of adaptation to climate change, support for the construction of dykes, and the restoration of natural areas. In 2018, AFD earmarked €1.6 billion for this purpose.
The resilience to climate change of the poorest countries will also depend on the quality of their health systems. “In the Least Developed Countries, we need to support adaptation efforts in the six building blocks of a health system defined by WHO: infrastructure, equipment, drugs, human resources, governance and information systems”, says the AFD’s Christophe Paquet.
“To achieve this, it is vital to direct the means provided by development assistance towards adaptation programs integrating a holistic vision of health and go beyond the fight against a given disease.”
For example, Agence Française de Développement is supporting a program in the Comoros, which has refurbished hospitals and healthcare centers, provided equipment and drugs, trained nurses and midwives, and set up a third-party payment system allowing women to access obstetrical care almost free of charge.
In 2018, AFD committed €497 million to health around the world. This has improved access to healthcare for 14 million people.
Serious health crises can be avoided, or at least mitigated, by strengthening epidemic detection, monitoring and alert mechanisms at the regional level.
This firstly involves facilitating the communication of health information on ongoing epidemics between countries and across regions, but also strengthening the resources available to these countries to treat diseases and prevent them from spreading.
For further reading: Southeast Asia Faces the Rise of Emerging Diseases
“For example, thanks to AFD’s support, the Indian Ocean Commission has built a capacity for disease surveillance and alerts, which today cover its five Member States, including la Réunion,” says Christophe Paquet.
“We recently contributed to the addition of an animal health component. Indeed, if humans want to be in good health, their environment has to be so too.”