The rise in average global temperatures, the rise in sea levels resulting from the melting of Arctic ice and the increase in extreme weather events will force humanity to adapt to a world that is markedly different from the one we know today. From an environmental and social standpoint, but also from a health one.

How human health could deteriorate, between heatwaves and disease

Climate change will affect the balances governing air quality, the supply of drinking water and food production. The World Health Organization (WHO) has indicated that already "between 2030 and 2050, there will be hundreds of thousands of additional deaths every year compared to today, caused by malnutrition and diseases such as malaria and diarrhoea. Although the rise in average global temperatures may offer some local benefits in certain parts of the world, particularly the colder ones, the overall effects will be overwhelmingly negative."

The WHO emphasises in particular that "mortality from cardiovascular or respiratory diseases caused by increasingly frequent and prolonged heatwaves will increase sharply, affecting older people above all." A study by the European Commission's Joint Research Centre published in the journal Lancet Planetary Health indicates that over the next 30 years, heatwaves could become the leading environmental cause of premature death in the southern EU countries.

"In particular," Ansa specifies, "the increase in frequency and intensity of heatwaves such as those recorded this year could cause an exponential rise in deaths: from 2,700 in the period 1981–2010 to around 151,000 between 2071 and 2100." "The air," the WHO adds, "will also contain ever higher concentrations of pollutants, starting with ozone. Reactions linked to pollen and other allergens will become increasingly frequent: a particular problem for the approximately 300 million people around the world who suffer from asthma."

Catastrophic weather events have tripled compared to the 1960s

But it is not only diseases that will affect human health — natural disasters will too: the number of catastrophic events has already tripled worldwide compared to levels recorded in the 1960s. Every year, such phenomena claim the lives of more than 60,000 people, mainly in developing countries. This is also due to the fact that, today, more than half of the world's population lives less than 60 kilometres from the sea.

"In the future there will be more and more catastrophic events, affecting homes, healthcare facilities and other types of essential services. This will increase health risks, particularly with regard to communicable diseases," the WHO continues. "Above all, the most dangerous infections appear to be sensitive to climate variations. Their spatial distribution, seasonality, incidence and even severity could be altered," confirms a study published in the journal Nature and conducted by a group of researchers at the University of Liverpool. The analysis considered, in particular, the hundred diseases deemed most threatening to humans and domestic animals. Taking into account humidity levels, rainfall, extreme weather events and temperatures, the researchers concluded that 63 per cent of the diseases studied can vary depending on the climate — beginning with cholera, which is extremely sensitive to certain weather factors, and continuing with parasitic liver infections, Lyme disease and anthrax.

The melting of ice and anthrax cases in Russia

The latter was the focus of an analysis carried out in 2016 by Russian scientists, after 24 cases were recorded on the Yamal Peninsula, 2,500 kilometres northeast of Moscow. The disease had in fact disappeared from the region 75 years earlier. It is likely that the infection was triggered by the carcass of a reindeer: the animal had died of anthrax and its remains had been trapped in the ice for decades — until rising temperatures caused it to thaw.

Numerous experts, moreover, have highlighted how the melting of the ice cap — and permafrost in particular — could in the coming decades reach layers that have remained frozen for hundreds of years, if not millennia, releasing bacteria and viruses that have been in a dormant state over time. A further threat comes from rainfall, which will become increasingly difficult to manage. Periods of severe drought (the frequency of which is forecast to double and the duration to increase sixfold by 2090 compared to current levels) will alternate with exceptional accumulations of precipitation. Flooding will increase, compounded by episodes of heavy rainfall on arid soils that are unable to absorb excess water.

Insects could multiply the transmission of certain diseases

In a particularly worrying domino effect, freshwater sources could easily become contaminated. And stagnant pools could form, creating a perfect habitat for the breeding of disease-carrying insects, starting with Anopheles mosquitoes and ticks. Malaria, which is currently responsible for the deaths of 429,000 people per year, could spread widely, as could other diseases: "Two billion more people than today could be exposed to the risk of dengue transmission by 2080," the World Health Organization adds.

The amount of drinking water available to humans will decrease, exacerbating the conditions of those who already struggle to find safe sources today: diarrhoeal diseases currently kill almost 600,000 children every year. Without forgetting that in many regions — especially the most disadvantaged ones — rising temperatures will make food production even more difficult, as confirmed by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (Ipcc), published in 2014. This will result in an increase in cases of malnutrition, which currently causes the deaths of 3.1 million people every year. "Overall, climate change could cause approximately 250,000 additional deaths per year compared to today, between 2030 and 2050: 38,000 attributable to heat exposure among elderly people, 48,000 caused by diarrhoea, 60,000 by malaria and 95,000 by child malnutrition," the WHO concludes.

Risks in the United States and Europe too

The most exposed are the most vulnerable nations, but the effects of climate change on health will concern the entire world. This is confirmed by the American Medical Society Consortium on Climate and Health (Mscch), in a report that highlights how cases of respiratory (starting with asthma) and cardiac conditions are set to rise worldwide.

"Even today, specialists in the United States are recording an increase in diseases linked to climate change," explained Mona Sarfaty, physician and director of the consortium. And Europeans will not be spared the consequences: Marie McIntyre, of the University of Liverpool, has stressed that "a large number of climate-sensitive pathogens are found precisely in the Old Continent." Without forgetting that largely coastal countries, such as Italy, may have to contend with epochal changes to their territory.