The WHO (World Health Organization) estimates over 250,000 additional deaths worldwide annually due to climate change for the period 2030-2050. In defining the boundaries within which to consider the impact of the climate crisis as a contributing factor to human health problems, I excluded deaths caused by extreme weather events, as well as those affecting climate migrants, who, crossing seas, mountain passes, deserts, or confronting human traffickers, are undoubtedly exposed to greater risk. Likewise, I did not consider cases of malnutrition resulting from crop failures caused by weather anomalies and the "food insecurity" affecting the economically most vulnerable segment of the population, who not only face reduced availability of basic foods but also suffer from price increases determined by international market rules, which, in effect, further limit their accessibility.
The ones just listed are all consequences that have a significant impact on people's well-being, health, and very lives, but on this page of the notebook, we focus on aspects directly linked to specific pathologies.
In 2021, over 200 medical journals published an unprecedented joint editorial urging world leaders to act: "The science is unequivocal: a 1.5°C global warming above the pre-industrial average, coupled with continued biodiversity loss, risks catastrophic health damage from which there will be no reversal."
It's hot and you die
In the summer of 2022, between 60,000 and 70,000 premature deaths in Europe were attributed to heat; if the data from the summer of 2023 were added together, the figure would exceed 100,000. Heatwave risks for the population have already been at critical levels in southern Europe for some time. Heatwaves occur when very high temperatures are recorded for several consecutive days, often combined with high humidity, strong solar radiation, and a lack of ventilation.
Those most at risk are those whose work forces them to remain outdoors or those who cannot afford air conditioning and adequate insulation for their homes, as well as the elderly and children, whose body's thermoregulatory capacity is more limited. As evidence of the increased risk, it is worth remembering that every summer the Ministry of Health activates the National Warning Forecast System, with the technical and scientific support of the Department of Epidemiology of the Lazio Regional Health Service, a center of expertise within the Department of Civil Protection.
The system allows for the forecasting, surveillance, and prevention of the effects of heat waves on the population's health, monitoring 27 Italian cities: Ancona, Bari, Bologna, Bolzano, Brescia, Cagliari, Campobasso, Catania, Civitavecchia, Florence, Frosinone, Genoa, Latina, Messina, Milan, Naples, Palermo, Perugia, Pescara, Reggio Calabria, Rieti, Rome, Turin, Trieste, Venice, Verona, Viterbo.
For each specific urban area, weather and climate conditions that can have a significant impact on the health of vulnerable individuals are detected.
The system provides a pre-alert level for health and social services and two subsequent alert levels that are triggered based on temperatures measured at 8:00 a.m. and 2:00 p.m., as well as perceived temperatures. Perceived temperatures are a parameter of so-called bioclimatic discomfort that takes into account air temperature and relative humidity.
Heat causes health problems when it disrupts the body's temperature regulation system. Normally, the body, which shouldn't be exposed to an external temperature above 37°C, protects itself through vasodilation and sweating, but in certain physical and environmental conditions, this isn't enough. High temperatures combined with high humidity stress the heart's muscles and cells, requiring the heart to pump more blood, and sweat eliminates sodium, potassium, and other minerals essential for proper body function . Extreme heat can also worsen the health of people with pre-existing chronic conditions.
Worsening of health condition
Prolonged exposure to these conditions can cause mild ailments, such as cramps, fainting, and swelling, or more serious ones, such as congestion, heat stroke, and dehydration. In a more detailed discussion, we're referring to:
Sunstroke: caused by an increase in body temperature due to insufficient thermoregulation. It occurs with prolonged exposure to solar radiation, especially on very hot, windless summer days.
Cramps: caused by a loss of sodium, due to sweating, and a consequent alteration of the water-salt balance.
Edema: caused by fluid retention in the lower limbs as a consequence of prolonged peripheral vasodilation.
Dehydration: Caused by a loss of water from the body greater than the intake, which negatively impacts multiple body functions.
Kidney disease: Exposure to extreme heat can lead to acute kidney failure due to dehydration. In individuals with chronic heat exposure (e.g., agricultural workers), it can contribute to chronic kidney failure.
Effects on blood pressure: People with hypertension and heart disease, especially the elderly, but also many healthy people, may experience episodes of low blood pressure.
Heat stress: It is caused by a collapse of the peripheral vessels with insufficient blood supply to the brain.
Symptoms may arise in excessively hot environments, especially in unacclimated individuals, with reduced cardiac efficiency (insufficient compensation for widespread peripheral vasodilation) due to decreased blood volume resulting from dehydration. If not diagnosed and treated promptly, it can progress to heat stroke.
Heatstroke occurs when the physiological ability to regulate body temperature is compromised, such as when exposed to excessively high temperatures, combined with high humidity and poor ventilation. Loss of consciousness may occur. Body temperature rises rapidly (within 10-15 minutes) to 40-41°C, followed by possible internal organ failure, which can lead to death.
Although less severe, respiratory allergies are on the rise as a direct consequence of climate change. Warm periods of the year are becoming longer and more frequent, with a wider range of pollination periods for various plant species. This causes allergies to lose their usual seasonality, appearing at other times of the year as well. Rising temperatures are also associated with a greater proliferation of mold and fungi, which can cause symptoms such as asthma or rhinitis in allergy sufferers .
Widening spread of infectious diseases
In a changing climate, the frequency and distribution of many infectious diseases are also changing: climatic conditions are becoming increasingly suitable for the transmission of multiple pathogens, directly influencing their biological characteristics (such as growth, survival, and virulence) and their vectors, and indirectly favoring transmission through ecosystem modification and changes in human behavior. Increased temperatures and precipitation can promote a range of infections, from vector-borne to enteric infections to parasitic diseases ( The Lancet Microbe , 2021).
Italy, due to its geographic location between North Africa and Europe, is particularly affected by climate variations. The humid climate and long, hot seasons have increased the presence of mosquitoes, such as the tiger mosquito, and with them, the risk of spreading viruses that use them as vectors. Thus, diseases once confined to humid areas are appearing more frequently. Some examples: West Nile Fever (WNF), a potentially neuroinvasive bird-borne viral infection, which recorded a significant increase in incidence in 2023; Chikungunya, characterized by fever and debilitating joint pain; Dengue, of which autochthonous cases have been recorded in Lombardy; leishmaniasis; Lyme borreliosis, transmitted by the Ixodes ricinus tick, which is no longer found only in wooded areas but also in parks; and finally, malaria, whose Plasmodium is transmitted by the bites of mosquitoes of the Anopheles genus.
Among other infectious diseases that spread more easily are those transmitted by contaminated water: from typhoid fever to cholera to salmonella , a problem that particularly affects areas affected by flooding. Even seawater, with rising temperatures, can harbor threats and pose a danger to fish. In warmer waters, vibrio bacteria proliferate more, and if ingested with fish or shellfish, they can cause diarrheal symptoms.
Then there are the consequences, still little studied because they are linked to less-explored dynamics, which could open up even more problematic scenarios. Climate change contributes to changing the habits of certain animal species, from those previously sedentary, which migrate to new areas, to others accustomed to migrating to warmer zones, which, with rising temperatures, are no longer encouraged to do so. These phenomena can lead animal species that had never had contact with each other to coexist in the same territories, resulting in the sharing of pathogens and the potential development of new diseases. They can also contribute to the prolongation of a parasite's life cycle in a given animal, increasing the risk of its spread.
The climate crisis is therefore acting as a multiplier of health risks that, in the short term, can be contained through the implementation of prevention strategies, active surveillance of the spread of new pathogens, and a general adjustment in the commitment of resources to healthcare. Unfortunately, the global trend is toward increased military spending while simultaneously cutting public healthcare spending. Once again, those who will pay the highest price will be the most vulnerable, those who, in a society of inequality, find themselves relegated to the "disadvantaged" category.
MarTa
Sitography
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Source: A-infos-en@ainfos.ca
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