Between April 2023 and March 2024, the 10 hottest months on record since 1880 were recorded. In fact, we are witnessing an average increase in global temperatures, with the resulting climate upheavals. But even if in recent years the problem has become known, thanks to the awareness of some scientists, politicians and environmental movements (such as Fridays for Future and Extinction Rebellion ), the implications of climate change on health are still little known to the public.
According to research on the subject, approximately 3.6 billion people live in areas highly susceptible to climate change. Therefore, approximately half of the world’s population can more easily suffer from possible heat stroke, malnutrition, infections and other disorders favored by this problem, which is becoming increasingly urgent to address.
The causes of climate change
Why is there global warming?
The main cause of the increase in temperatures on Earth is the accumulation of so-called greenhouse gases, gases that, just like the glass of a greenhouse, retain heat within the atmosphere. Without these gases, life on Earth would be impossible or very different from what we know today, since they play a fundamental role in balancing the temperature. Greenhouse gases absorb, retain and (thanks to the winds) transport the heat of the sun: without them, we would be subjected to lethal extreme temperatures. However, if these gases are in excessive quantities they retain too much heat and these mechanisms are out of sync, resulting in extreme climate events.
How much does climate change depend on humans?
Humans are responsible for most of the accumulation of greenhouse gases in the atmosphere: since the Industrial Revolution, they have produced more and more carbon dioxide, methane, nitrogen monoxide and other greenhouse gases that join those naturally present. We are certain that humans are responsible for global warming because natural factors alone do not explain the numbers of the climate crisis in the slightest .
In particular, we fuel the phenomenon:
- Burning fossil fuels (coal, oil and natural gas) for transportation, industry, heating and other uses;
- By deforesting , so that the planet cannot absorb the carbon dioxide in the atmosphere;
- With livestock farming (cattle produce large quantities of methane gas) and agriculture (fertilizers containing hydrogen produce nitrogen monoxide emissions);
- With industries (mainly electronics, cosmetics and pharmaceuticals) releasing fluorinated gases (which retain the Sun’s heat about 23 thousand times more than carbon dioxide).
- Energy use, heating and transport in cities play particularly important roles. It is estimated that cities are responsible for around 75% of global emissions. Their impact is likely to increase with urbanisation unless we act now to reduce their impact.
Climate change: the consequences
Since 1880, the average temperature of the Earth has increased by 1.1 °C.
Although this may seem like a small increase, it has serious consequences that make it one of the 5 greatest risks to the planet.
In fact, global warming causes:
- Extreme weather phenomena , such as cyclones, hurricanes and tropical storms;
- More widespread aridity, which leads to more forest fires. For example, in Italy precipitation has decreased by 14% in the last 50 years;
- Rising ocean levels , resulting in floods that make some areas uninhabitable and transport toxic substances (which can end up in our food);
- Poor air quality;
- Record heat waves , particularly in Australia and Europe, which also favor forest fires;
- Increased proliferation of some pathogens and organisms that produce toxins in foods (such as molds that contaminate cereals with aflatoxins);
- Ecosystem alterations and loss of biodiversity. Some crops are disadvantaged, others grow out of control; some animal species have difficulty surviving, others move, others expand (and are often carriers of diseases);
- Ocean acidification , which leads to the death of many marine species.
- All these phenomena directly and indirectly affect the quality of life of human beings in all regions of the world, especially those in areas more vulnerable to climate change, with less access to health systems and more socially isolated.
The consequences of climate change on human health
In general, global warming has been found to increase all-cause mortality , both in the short and long term.
It is estimated that climate change has caused approximately 2 million deaths in the last 50 years.
In fact, the health consequences of the climate crisis are many:
- Adverse climate events due to global warming cause approximately 60,000 deaths each year;
- Infections spread from contaminated animals, food and water;
- Cases of food poisoning on the rise ;
- Some chronic diseases, such as cardiovascular disease , diabetes and kidney problems, worsen;
- Allergies and respiratory diseases spread and worsen ;
- Skin conditions, including irritation, hives and eczema , increase and worsen ;
- There is an increase in mental health disorders and the worsening of pre-existing ones;
- Sleep problems increase ;
- Malnutrition is spreading, mainly because the climate crisis is decreasing the yield of the land. For this reason and because of other environmental risks (such as the presence of toxins in food), climate change seems to be associated with stunting in children;
- Cases of birth defects and pregnancy complications are increasing ;
- It promotes cases of occupational diseases (from accidents at work to kidney disorders), especially in the primary sector and in transport;
- Where climate change brings floods, prolonged droughts and exposure to pollutants, as in many regions of Asia and Africa, access to clean air or water sources is impossible;
- In some countries, due to the difficulties it brings, the climate crisis increases socio-political tensions and conflicts, decreasing the possibility of access to care.
Studies show that these health impacts will continue to worsen unless we have a global response soon. What we can do is embrace policies that guide the transition to a truly green economy, which also means protecting the less wealthy so that they can be more environmentally sustainable.
People most vulnerable to the consequences of climate change
The impact of the increase in average global temperatures on chronic diseases is called the amplifier effect . In fact, heat and other environmental problems due to global warming can cause a worsening of general conditions and a worsening of the quality and life expectancy of the most vulnerable people :
- Elderly, children, pregnant women;
- Those suffering from cardiovascular diseases;
- People with diabetes, metabolic syndrome, obesity;
- People with chronic respiratory diseases (particularly asthma and COPD);
- Those who have primary and secondary lymphedema;
- People with disabilities that make it more difficult to react in emergency situations;
- People with mood disorders such as depressive syndromes and psychiatric illnesses;
- Those who reside in urban areas with high population density;
- People who work outdoors;
- Those who live on subsistence;
- According to recent studies conducted in various countries, climate change could increase the risk of premature births, respiratory problems in newborns and even cases of spontaneous abortion;
- Low-income individuals in precarious psychophysical conditions who live in densely populated and trafficked urban areas are the most vulnerable of all. The geographical areas that are particularly penalized are Europe and the Mediterranean area, where part of the world’s oldest population is concentrated.
Climate change and infections
One of the most studied and probably most impactful consequences of the climate crisis is the increase in cases of infections . High temperatures, humidity and extreme weather events, in fact, facilitate the spread of some pathogens. For example, in food and water, as in the case of:
- Schistosomiasis (from flatworms of the genus Schistosoma );
- Cholera (caused by the bacterium Vibrio cholerae );
- Salmonellosis (caused by bacteria of the genus Salmonella );
- Gastronteritis due to Escherichia coli .
Due to the humidity and heat, other infections, such as meningitis , influenza and pediatric diseases such as hand, foot and mouth disease , as well as those transmitted by insects and other animals, are also more widespread.
Zoonoses favored by climate change
With different climates, some more adaptable species (including many that carry pathogens) are favored. In addition, changing climates cause organisms to move, spreading diseases where they were not previously present. Zoonoses
( infections transmitted by non-human animals) that are spreading globally (or are “resurgent”) are generally transmitted by certain arthropods (insects and arachnids), which generally live longer and multiply more in warmer environments. In addition, heat and humidity reduce the incubation times of infections transmitted by these animals. Therefore, due to global warming, some infectious diseases widespread in tropical climates could spread elsewhere. Here, for example, are some infections that could also spread to Europe in the coming decades due to the climate crisis:
- West Nile Virus : Carried by a species of mosquito, this virus is native to Africa, but is already widespread in Italy and other areas of southern Europe. In our country, the virus has multiplied dramatically in recent years, so much so that in 2018 alone, 606 cases were recorded in humans.
- Malaria : Recent studies suggest that the disease could spread back to Europe and perhaps spread to the USA and South-East Asia, with a potential pool of infected people equal to 40% of the world’s population.
- Lyme disease : transmitted by some species of ticks and caused by a bacterium, in Italy it was considered a rare condition, but it is spreading.
- Human leishmaniasis : it is a parasitic disease, already widespread in over 80 countries, transmitted by various sandflies and phlebotomine midges.
- Ebola : This virus, which can be transmitted both by vectors and by contact with bodily fluids of infected people, causes an often fatal hemorrhagic fever.
- Nipah virus infection: widespread in Southeast Asia, in the coming years, due to deforestation and climate change, this infection could reach areas previously never considered at risk.
Climate change and respiratory, cardiovascular and neurological diseases
Climate change is associated with an increase in pollen allergies in Europe. Because it leads to increased exposure to air pollution, it also increases the incidence of coughing, sneezing, COPD (chronic obstructive pulmonary disease) and problems with lung function. In addition, exposure to high temperatures is associated with an increase in:
- Myocardial infarctions ;
- Stroke ;
- Long-term neurological problems. It may, for example, worsen conditions such as dementia and epilepsy;
- Childhood asthma, especially in conjunction with high humidity;
- Other respiratory diseases, especially those typical of children.
Climate Change and Mental Health
Rising temperatures, drought, and heat waves are associated with increased mental health hospitalizations and suicides. They also appear to exacerbate previous mental health conditions and sleep disturbances. Extreme weather events can also severely impact people, their homes, and families, leading to:
- Stress;
- Anxiety;
- Post-traumatic stress disorder;
- Depression ;
- Increased abuse of alcohol and psychotropic substances and medications.
Climate change and pregnancy
In pregnant women exposed to high temperatures, humidity, intense sun or cold, problems such as:
- Gestational hypertension ;
- Preeclampsia and eclampsia;
- Low birth weight of the baby;
- Premature birth.
Extreme weather events may negatively affect pregnancy indirectly by causing stress, worry and other psychological disturbances in the pregnant woman.
What are the health impacts of climate change in Italy?
Due to the climate crisis, precipitation in Italy has decreased by 14% in the last 50 years, which means there are more cases of forest fires and problems with crops. Global warming causes various disorders, increases mortality from pre-existing diseases and cases of heat stress, especially in the most fragile people, including the elderly, who make up a large part of the Italian population.
Infections are also increasing, especially those carried by animals (vectors), as they spread more easily, even in areas to which they previously had no access. In addition, some areas of Italy are at risk of flooding, with economic and health consequences for the people who live there.
Climate change: how to protect health?
There are more and more meetings and initiatives, at all levels, that aim to accelerate the fight against the climate crisis. For example, this was the theme of the World Health Assembly held among global experts on May 29, 2024. In
fact, it is essential to distinguish isolated and “normal” extreme events from those that could be prevented through actions that reduce the phenomenon of the climate crisis. Even more important is to identify the actions to be implemented and act, thanks to the collaboration of scientists, governments, institutions, industries, communicators and individual citizens.
Some key actions to be undertaken, at all levels, are:
- Reduce the use of coal and other fossil fuels by investing in renewable sources;
- Reduce deforestation and land use;
- Plant trees that respect the original ecosystem of the place;
- Promote energy efficiency in buildings and thermally insulate them, avoiding where possible the use of radiators and especially fireplaces and wood stoves. Prefer the use of fans to that of air conditioners;
- Prefer more sustainable modes of transport, such as bicycles and public transport, to private or more polluting ones (such as airplanes);
- Reduce your meat consumption (also a great move to make your diet healthier);
- Prefer zero-mile products, seasonal fruit and vegetables, foods certified as more eco-sustainable;
- Improve waste management (so compost and recycle appropriately)
- Reduce waste (for example, by buying less and preferring long-lasting, non-disposable objects, reusing as much as possible).
- Increase defenses against the consequences of global warming.
This measure includes:
- Improving and expanding healthcare services. Implementing telemedicine, in particular, can be useful both to support healthcare systems and to reduce emissions from the healthcare sector;
- Making air and water cleaner;
- Raise awareness about the relationship between health and climate change.