The emission of large quantities of gases, caused by human activity, which have a greenhouse effect in the atmosphere, are at the origin of climate changes which are already being felt on both a global and regional scale.More infos
Significant thinning of the ozone layer exposes living beings to an elevated level of ultraviolet (UV) rays. An international agreement limiting emissions of substances that destroy the ozone has allowed the thickness of this protective layer over the Poles to stabilise. However, for unknown reasons, the layer is becoming thinner in other latitudes.
By modifying the global flux of rivers and evaporation, man is the major culprit in the alteration of the water cycle. On a planetary scale, shortages of freshwater are becoming increasingly frequent.
200liters / day / capita
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The living world is made up of a complex system within which species interact with each other and are interdependent. As an integral part of this system humans are tributary to biodiversity for their survival because biodiversity guarantees, amongst other things, the regulation of the quality of the air, climatic stability, soil fertility, etc. Species that die out take with them other living organisms that depend on them.
The collapse of biodiversity is caused, first and foremost, by the destruction of natural habitats, but also by pollution, excessive hunting and fishing, or is also a result of climate change. Even though extinction and the appearance of new species are natural processes it is estimated that the current rate of erosion of biodiversity is 100 times greater than the natural rhythm and is comparable to the last great extinction, that which saw the disappearance of the dinosaurs. If this trajectory is maintained, 75% of species will have disappeared in four centuries and the planet will thus experience a sixth massive extinction.
The major function of the hormonal or endocrine system is to regulate the development, growth and reproduction of living beings. Endocrine disrupters are substances that are foreign to the organism which enter the blood via food, the skin or respiration. Once ingested, the organism mistakes them for hormones which alter numerous essential biological functions.
Endocrine disrupters are omnipresent in our daily life! They are used in the manufacture of food, medication, cosmetics and plastics. Subsequently disseminated in water, the air and the soil by the combustion of materials or the elimination of refuse, they contaminate the totality of the food chain on their way. The risks associated with endocrine disrupters form the object of numerous scientific research projects.
The worrying increase in cases of infertility, malformations and behavioural problems in both animals and humans has alarmed the World Health Organisation (WHO). Even in very weak doses, that is to say often below legal levels, the combined substances between them represent a dangerous cocktail for living beings.
A wide range of goods (fertilisers, mobile phones, cigarettes …) and services (production of energy) which we benefit from daily, are produced from primary materials such as lead, phosphorous, mercury or uranium. These are extracted from the ground then artificially concentrated. However, some of these heavy metals and radio-active materials are dangerous for living organisms. Left in the open air or released into water courses, the waste produced by mining activity pollutes the environment. Production sites, as well as large tips where objects containing dangerous substances end up, are also at the origin of significant contamination.
These elements penetrate our organism through food, breathing, skin contact or irradiation. Occasional exposure to high doses or frequent exposure to low doses provokes a multitude of harmful effects to human health (nervous troubles, lung disease, cancers) and to living organisms in general. In certain countries progress has been made in the decontamination of polluted sites and the protection of workers. This necessitates a considerable financial investment which is rarely to be found in poor or developing countries.
Certain atmospheric gases, known by the name of greenhouse gases, are playing a major role in global warming. Coming essentially from the burning of fossil fuels (coal, petrol and natural gas) the concentration of greenhouse gases in the atmosphere has increased enormously with the intensification of human activities. It is one of the principal processes at the origin of global warming.
Since 1880 an increase of 0.85°C in the average global temperature has been recorded with an acceleration of this trend over the last 60 years. If nothing is done, the Earth could heat up by 4.8°C between now and 2100 causing an acceleration in the melting of ice and a rise in sea level of approximately 1m.
Millions of people living in coastal regions are threatened by rising sea levels. However, the increase in the concentration of greenhouse gases in the atmosphere does not only manifest through more frequent heatwaves or melting glaciers; it is the totality of the climate that becomes unstable, creating an intensification of extreme meteorological events, such as extremes of heat and cold, cyclones or extreme rainfall.
In the same way as the forests and the soil, the oceans are regarded as wells of carbon because they absorb large quantities of atmospheric CO2, the result of burning fossil fuels. In water, carbon dioxide dissolves to form carbonic acid. This latter modifies the chemical balance of seawater, making it more acidic. Over the past two hundred years the oceans have absorbed a quarter of the CO2 emitted through human activity and their acidity has increased by 30%.
Due to its corrosive effect, this acidification has a detrimental effect on marine organisms consisting of a skeleton or of a shell of calcium carbonate. For this reason, coral reefs, oysters, sea urchins or calcareous planktons are strongly affected. If these creatures are in danger, it is the entire food chain that is threatened. Today, over a thousand million people in the world depend on marine resources for their protein. If CO2 emissions are not reduced by the end of this century the oceans could become 150 times more acidic; conditions the Earth has not known for at least 20 million years.
The consequences of intensive agriculture
Phosphates and nitrates are the major components of chemical fertilisers used in agriculture and gardens to improve plant growth. These substances, of mineral origin derive respectively from phosphorus and nitrogen which are naturally present on Earth. The increased utilisation of chemical fertilisers, notably in intensive agriculture, deteriorates the quality of the soil and compromises production capacities. It leads to the asphyxiation of marine zones.
Phosphates and nitrates reach water courses by infiltrating the ground water thus polluting drinking water and damaging freshwater and seawater to the point of asphyxiation. Over-nourished algae flourish, greatly reducing the availability of oxygen for other living beings. This process, called eutrophication, brings with it the erosion of biodiversity and the multiplication of harmful species. This infringement alarms scientists who fear a massive extinction of marine species caused by a lack of oxygen in the oceans which will affect the entirety of the food chain. Today, it is estimated that the planetary limit of the nitrogen and phosphorus cycle has already been breached.
Over the past 50 years the rhythm of conversion of forests and other ecosystems into agricultural land has accelerated considerably. Today, the disappearance and fragmentation of natural territories has become the primary cause of attack on biodiversity. Territories that are too small and disconnected make it difficult for fauna to move around for food and to reproduce. The mass destruction of tropical forests is particularly preoccupying.
These latter are home to the essential of earthly biodiversity and also play a key role in the climatic system and water cycle. This is because forests draw in large quantities of carbon from the atmosphere and release water and oxygen by evapo-transpiration; they represent the lungs of the planet. Even though the rate of deforestation has slowed down globally in the world, over 129 million hectares of forests have been lost over the last quarter of a century, almost 30 times the surface area of Switzerland.
Solid or liquid, mineral or organic, the particles in suspension are of natural or human origin and of various sizes. Aerosols are naturally emitted into the atmosphere through volcanic eruptions, the mixing of ocean waters, forest fires or the dispersion of pollen. Human activities also diffuse aerosols via the combustion of fossil fuels (coal, petrol), the incineration of refuse and certain industrial processes (metallurgy, manufacture of cement).
Through their action on sunlight and the water cycle, the growing concentration of anthropic aerosols in the air has a direct influence on climate. In Asia, the particles in suspension form a gigantic brown cloud which affects the monsoon system. This has caused a reduction in precipitations over India. Aerosols also threaten human and animal health. Particles of diameters smaller than 10 micrometres are the most toxic because they can penetrate deeply into the respiratory system. These “fine particles” cause the deaths of around 7.2 million people per year.