Global environmental problems. Global environmental problems The causes of global environmental problems briefly

The essence of the problem:

An environmental problem arose in the sphere of relationships between human society and the environment (nature). IN Lately The conflict between society and nature has intensified, creating a real threat of irreversible changes in natural systems, undermining natural conditions and the existence of current and future generations of inhabitants of planet Earth.

Causes of environmental problems:

Many years of uncontrolled and not always justified spending natural resources(mining, industrial deforestation, etc.);

Industrialization of the economy (the emergence of a large number of industries that emit harmful substances into the environment);

Increase in the number of people and their needs, etc.

In industrial developed countries ecological problems are predominantly “industrial in nature”, and in developing countries they are primarily due to the “reuse of natural resources” (forests, soil cover and other natural resources).

Currently, the epicenter of environmental problems is moving from developed countries to developing ones due to the fact that a number of hazardous industries are being transferred there.

In some areas of the Earth, the conflict between man and nature has become so acute that it has reached the level of an ecological crisis.

Environmental problems can be divided into three groups:

1. Environmental degradation as a result of irrational environmental management (deforestation, soil erosion, arid desertification, etc.).

2. Pollution of the lithosphere, hydrosphere and atmosphere with solid, liquid and gaseous waste from anthropogenic activities (“photochemical fog” (“smog”) over large industrial agglomerations, “acid rain”, garbage dumps, oil pollution of the world’s oceans, radioactive pollution of the world’s oceans as a result disposal of radioactive waste, etc.).

3. Poisoning of the environment by chemicals created during the production process (chemicals, pesticides, freons - ozone layer destroyers)

In addition, many environmental problems arise as a result of environmental disasters at industrial enterprises (disaster at Chernobyl nuclear power plant in 1986) and in certain areas (forest fires).

Ways to solve environmental problems:

application of energy-saving and resource-saving technologies;

studying permissible limits of impact on nature and taking protective measures, including prohibitive ones;

the use of environmentally less harmful technologies and production;

carrying out activities aimed at eliminating the consequences of environmental crises and disasters, restoring damaged ecosystems;

educational activities aimed at developing a caring attitude towards nature, etc.

In the 70s of the 20th century, the UN put forward the slogan “There is only one Earth” and determined the main way to solve the environmental problem - such an organization of production and non-production activities of people that would ensure normal “eco-development”, conservation and transformation of the environment in the interests of all humanity and every person.

Ecological problem- one of global problems modernity. It is closely related to issues of resource scarcity. environmental safety and environmental crisis. One of the ways to resolve the environmental problem is the path of “sustainable development”, proposed as the main alternative for the development of human civilization.

Global environmental problems

Scientific and technological progress has confronted humanity with a number of new, very complex problems that it had not encountered before at all, or the problems were not so large-scale. Among them, a special place is occupied by the relationship between man and the environment. In the 20th century, nature was under pressure from a 4-fold increase in population and an 18-fold increase in global production. Scientists claim that since about the 1960-70s. environmental changes under human influence have become worldwide, i.e. affecting all countries of the world without exception, which is why they began to be called global. The most relevant among them are:

• Earth's climate change;
• air pollution;
• ozone layer destruction;
• depletion of reserves fresh water and pollution of the oceans;
• land pollution, destruction of soil cover;
• depletion of biological diversity, etc.

Environmental changes in the 1970s-90s. and forecast for

2030 are reflected in table. 1. UN Secretary-General Kofi Annan presented the report “We the Peoples: The Role of the United Nations in the 21st Century” at the meeting of heads of state and government of UN member countries (September 2000). The report examines the priority strategic areas facing humanity in the new millennium and emphasizes that “the challenge of ensuring a sustainable future for future generations will be one of the most challenging.”

Table 1. Environmental changes and expected trends until 2030

Characteristic	Trend 1970-1990	Scenario 2030
Reduction of area of ​​natural ecosystems	Reduction at a rate of 0.5-1.0% per year on land; by the beginning of the 1990s. about 40% of them have survived	Continued trend, approaching almost complete elimination on land
Consumption of primary biological products	Consumption growth: 40% onshore, 25% global (1985 est.)	Consumption growth: 80-85% on land, 50-60% global
Changes in the concentration of greenhouse gases in the atmosphere	Increase in greenhouse gas concentrations from tenths of a percent to a few percent annually	Increased concentration, accelerated growth of CO and CH 4 concentrations due to accelerated destruction of biota
Depletion of the ozone layer, growing ozone hole over Antarctica	Depletion of the ozone layer by 1-2% per year, increase in the area of ​​ozone holes	The trend will continue even if CFC emissions cease by 2000.
Declining forest area, especially tropical forests	Reduction at a rate from 117 (1980) to 180 ± 20 thousand km 2 (1989) per year; reforestation refers to the clearing of forests as 1:10	Continuation of the trend, reduction in forest area in the tropics from 18 (1990) to 9-11 million km 2, reduction in the area of ​​temperate forests
Desertification	Expansion of desert area (60 thousand km 2 per year), increase in technogenic desertification. toxic deserts	The trend will continue, the rate may increase due to a decrease in moisture turnover on land and the accumulation of pollutants in soils
Land degradation	Increased erosion (24 billion tons annually), decreased fertility, accumulation of pollutants, acidification, salinization	Continuation of the trend, growth of erosion and pollution, reduction of agricultural land per capita
Rising sea levels	Sea level rise by 1-2 mm per year	The trend will continue, the level rise may accelerate to 7 mm per year
Natural disasters, man-made accidents	Increase in numbers by 5-7%, increase in damage by 5-10%, increase in the number of victims by 6-12% per year	Maintaining and strengthening trends
Species extinction	Rapid extinction of species	Increasing trend towards destruction of the biosphere
Qualitative depletion of land waters	Volume growth Wastewater, point and area sources of pollution, number of pollutants and their concentrations	Preservation and growth of trends
Accumulation of pollutants in environments and organisms, migration in trophic chains	An increase in the mass and number of pollutants accumulated in environments and organisms, an increase in the radioactivity of the environment, “chemical bombs”	Continuation of trends and their possible strengthening
Deterioration in quality of life, increase in diseases associated with environmental pollution (including genetic), emergence of new diseases	Rising poverty, food shortages, high infant mortality, high level morbidity, lack of clean drinking water in developing countries; an increase in genetic diseases, a high accident rate, an increase in drug consumption, an increase in allergic diseases in developed countries; AIDS pandemic in the world, decreased immune status	Continuing trends, growing food shortages, growing diseases associated with environmental disturbances (including genetic ones), expanding the territory of infectious diseases, emergence of new diseases

Environmental problem

Environment (natural environment, natural environment) is called that part of nature with which human society directly interacts in its life and economic activities.

Although the second half of the 20th century. - this is a time of unprecedented rates of economic growth, but it is increasingly being carried out without proper consideration of the capabilities of the natural environment and the permissible economic loads on it. As a result, degradation of the natural environment occurs.

Irrational environmental management

An example of environmental degradation as a result of unsustainable environmental management is deforestation and depletion of land resources. The process of deforestation is expressed in a reduction in the area under natural vegetation, and primarily forest. According to some estimates, during the emergence of agriculture and cattle breeding, forests covered 62 million km2 of land, and taking into account shrubs and copses - 75 million km2, or 56% of its entire surface. As a result of deforestation, which has been going on for 10 thousand years, their area has decreased to 40 million km 2, and the average forest cover has decreased to 30%. Nowadays, deforestation continues at an increasingly rapid pace: about 100 thousand are destroyed annually. km 2. Forest areas are disappearing as the cultivation of land and pastures expands, and timber harvesting increases. A particularly dangerous situation has developed in the tropical forest zone, primarily in countries such as Brazil and the Philippines. Indonesia, Thailand.

As a result of soil degradation processes, about 7 million hectares of fertile land are lost annually from global agricultural production. The main reasons for this process are growing urbanization, water and wind erosion, as well as chemical (contamination with heavy metals, chemical compounds) and physical (destruction of soil cover during mining, construction and other work) degradation. The process of soil degradation is particularly intense in drylands, which occupy about 6 million km2 and are most characteristic of Asia and Africa. The main desertification areas are also located within the drylands, where due to high growth rates rural population Overgrazing of livestock, deforestation and unsustainable irrigated agriculture lead to anthropogenic desertification (60 thousand km 2 annually).

Pollution of the natural environment with waste

Another reason for the degradation of the natural environment is its pollution with waste from industrial and non-industrial human activities. These wastes are divided into solid, liquid and gaseous.

The following calculations are indicative. Currently, on average, about 20 tons of raw materials are mined and grown annually per inhabitant of the Earth. At the same time, 50 km 3 of fossil rocks (more than 1000 billion tons) are extracted from the subsoil alone, which, using an energy power of 2500 W and 800 tons of water, are converted into 2 tons of the final product, of which 50% is thrown away immediately, the rest goes into delayed waste.

The structure of solid waste is dominated by industrial and mining waste. In general and per capita, they are especially large in Russia and the USA. Japan. In terms of per capita indicator of solid household waste, the lead belongs to the United States, where each resident produces 800 kg of garbage per year (400 kg per resident of Moscow).

Liquid waste primarily pollutes the hydrosphere, with the main pollutants here being wastewater and oil. Total volume of wastewater in beginning of XXI V. amounted to about 1860 km 3. To dilute a unit volume of contaminated wastewater to a level acceptable for use, an average of 10 to 100 and even 200 units of clean water is required. Asia, North America and Europe account for about 90% of the world's wastewater discharges.

As a result, the degradation of the aquatic environment today has become global. Approximately 1.3 billion people use only contaminated water at home, and 2.5 billion experience a chronic lack of fresh water, which causes many epidemic diseases. Due to the pollution of rivers and seas, fishing opportunities are reduced.

Of great concern is air pollution with dust and gaseous waste, emissions of which are directly related to the combustion of mineral fuels and biomass, as well as mining, construction and other earthworks (2/3 of all emissions occur in developed Western countries, including the USA - 120 million tons). Examples of major pollutants are typically particulate matter, sulfur dioxide, nitrogen oxides and carbon monoxide. Every year, about 60 million tons of particulate matter are emitted into the Earth's atmosphere, which contribute to the formation of smog and reduce the transparency of the atmosphere. Sulfur dioxide (100 million tons) and nitrogen oxides (about 70 million tons) are the main sources of acid rain. A large-scale and dangerous aspect of the environmental crisis is the impact of greenhouse gases, primarily carbon dioxide and methane, on the lower layers of the atmosphere. Carbon dioxide enters the atmosphere mainly as a result of the combustion of mineral fuels (2/3 of all receipts). Sources of methane entering the atmosphere include biomass combustion, some types of agricultural production, and gas leaks from oil and gas wells. The international community has decided to reduce emissions carbon dioxide by 20% by 2005 and by 50% by the middle of the 21st century. In developed countries of the world, appropriate laws and regulations have been adopted for this purpose (for example, a special tax on carbon dioxide emissions).

Depletion of the gene pool

One aspect of the environmental problem is the decrease in biological diversity. The biological diversity of the Earth is estimated at 10-20 million species, including in the territory former USSR-10-12% of the total. The damage in this area is already quite noticeable. This occurs due to the destruction of plant and animal habitats, overexploitation of agricultural resources, and environmental pollution. According to American scientists, over the past 200 years, about 900 thousand species of plants and animals have disappeared on Earth. In the second half of the 20th century. the process of reduction of the gene pool has sharply accelerated, and if current trends continue over the last quarter of a century, the disappearance of 1/5 of all species currently inhabiting our planet is possible.

Ecological situation in Russia at the beginning of the 21st century.

The environmental situation in our country is determined by two factors: a decrease in environmental protection costs, on the one hand, and a smaller scale of economic activity than before, on the other.

For example, in 2000, there were almost 21 thousand enterprises operating in Russia that emitted emissions into the atmosphere. These emissions amounted (including cars) to more than 85 million tons, of which almost 16 million were without any treatment. For comparison, in the USSR, emissions from stationary sources and road transport were in the mid-80s. 95 million tons, in Russia in the early 90s - about 60 million tons. The largest air polluters in modern conditions are Siberian and Ural federal districts. They accounted for about 54% of total emissions from stationary sources.

According to the State Water Cadastre, in 2000 the total water intake from natural objects will be 86 km 3 (of which more than 67 km 3 was used for domestic drinking, industrial needs, irrigation and agricultural water supply). The total volume of discharge of contaminated wastewater into surface water exceeded 20 km\ of which 25% occurs in the Central Federal District. In the USSR this figure was 160 km 3, in Russia in the 90s. - 70 km 3 (40% of them are unrefined or insufficiently purified).

In 2000, more than 130 million tons of toxic waste were generated throughout Russia. Only 38% of the waste was fully used and neutralized. The largest number of them was formed in the Siberian Federal District (31% of the entire Russian Federation). If we talk about solid waste in general, then in the USSR about 15 billion tons of it were generated annually, in Russia in the early 90s. — 7 billion tons.

Thus, although in Russia in the 90s. Due to the economic crisis, there was a sharp decrease in emissions of all types of waste; subsequent economic growth leads to an increase in the volume of polluting waste environment.

Activity modern man has significantly changed the natural environment throughout our planet.

The essence of the modern environmental crisis is the contradiction between the almost limitless possibilities human activity, transforming nature, and disabilities biosphere in the resource support of this activity.

The global nature of the modern environmental crisis distinguishes it from previous crises. In this regard traditional methods exiting the crisis by moving to new territories is practically impossible. Changes in production methods, consumption rates and volumes of natural resource use remain real.

Over the past two or three centuries, man's technical ability to change the natural environment has rapidly increased, reaching its highest point in the era of scientific and technological progress. However, it turned out that the growth of human power most often led to an increase in the consequences of his activities that were negative for nature and ultimately dangerous for the existence of man himself.

Among the most acute for humanity and still unresolved environmental problems The following can be included:

· demographic crisis (a sharp increase in the world's population);

· urbanization;

· reduction of forest area;

· erosion and decrease in soil fertility;

· shortage of fresh water;

· negative consequences of energy production;

· pollution of the natural environment;

· destruction of the ozone layer of the stratosphere;

· anthropogenic climate change;

· decrease in biological diversity (decrease in the number of species of organisms);

· reducing the resistance of natural ecosystems to anthropogenic impact;

· the impact of negative changes in the natural environment on public health.

Increasing the Earth's population. The human population is characterized by a “demographic explosion” of unprecedented scale, i.e., a sharp increase in population growth rates that has continued since the mid-20th century. It is especially pronounced in developing countries in Asia, Africa and Latin America. The highest population growth has occurred in recent decades. At the end of the 1990s, the world's population was already 6 billion people, while in the 30s of the 20th century. The world's population was 2 billion people. It is believed that the population density of the Earth is approaching a critical level. However, according to many scientists, its population will eventually stabilize at 10-12 billion people.

Population growth, along with industrial development, is the second main factor of negative impact on the biosphere, since the increase in human population is accompanied by an increase in the need for agricultural and industrial products and the volume of natural resources involved. These processes lead to increased environmental pollution and negative impacts on the biosphere.

The increase in food production, the creation of new jobs, and the expansion of industrial production are accompanied by the consumption of non-renewable natural resources, but the main reason for the contradictions between man and nature is the rapid increase in the total anthropogenic load on it.

Specifics of demographic processes in different countries associated with a whole range of factors, including highest value have socio-economic and environmental. If in industrialized countries the impact on nature is associated mainly with technogenic pollution, then in developing countries the main impact is associated with the direct destruction of nature as a result of prohibitively high loads on ecosystems: deforestation, depletion available resources etc.

Although total number The world's population is increasing, while in some countries there is no population growth or even a decline. Thus, birth rates in Russia throughout the 20th century. decreased and in the mid-60s for the first time dropped below the level of simple renewal. At the end of the 90s of the last century, these negative trends intensified significantly, and in 1991-1992. In Russia, a unique demographic situation has developed, the graphic display of which is called the “Russian cross” (Fig. 16.1).

The essence of this phenomenon, observed in peacetime and in the absence of any global catastrophes, is that mortality rates in various regions and in Russia as a whole began to consistently exceed birth rates, which leads to population extinction (Fig. 16.1).

Urbanization(from Latin urbanus - urban) - the process of concentrating population and economic life in major cities. If before 1900 While only about 14% of the Earth's population lived in cities, today approximately half of the Earth's population lives in cities. Cities require the highest concentration of food, water, fuel and other life support resources. Natural ecosystems are also unable to process the amount of waste that is generated during the life of people in cities. The main consequences of urbanization: depletion of energy resources, environmental pollution, degradation of water, forest and soil resources, loss of agricultural land. In addition, there is evidence that in cities the incidence of disease in people is on average two times higher than in rural areas.

Global biosphere pollution. Pollution is one of the oldest problems. It arose with the advent of the first settlements with their streams of sewage and various household wastes. But before the development of industrial civilization, pollution was greatly limited in its nature and distribution. All waste decomposed under the influence of microorganisms and was included in the cycles of substances. Since the second half of the 20th century. In the process of production activities, people create synthetic substances, which, in the form of waste, enter the environment (the atmosphere, hydrosphere, soil) and are almost not involved in the biosphere cycle of substances. It is also important that synthetic materials are often toxic to living organisms.

In most cases, pollutants, widely distributed in the atmosphere, hydrosphere and soil, are gradually dispersed throughout the biosphere. Atmospheric transport plays a major role. Rising air currents and winds transport pollutants over different distances and ensure their circulation in the atmosphere. Anthropogenic emissions of carbon dioxide, nitrogen oxides, sulfur dioxide or mercury increase the background concentrations of these pollutants in the atmosphere. Diluting pollutants in the environment (in water or air), reducing the concentration in a given area of ​​the biosphere, does not reduce their danger to nature and humans, but only delays the negative consequences.

Air pollution. The main cause of air pollution is the burning of fossil fuels. Other causes include emissions from chemical industry by-products, dust emissions, radioactive gases from nuclear power plants, and automobile exhaust. The main substances that pollute the atmosphere are gases (90%) and solid particles (dust). Due to human activities, dust, carbon dioxide (CO 2), carbon monoxide(CO), sulfur dioxide (SO 2), methane (CH 4), nitrogen oxides (NO 2, NO, N 2 O).

Soil pollution. Increasing soil fertility is often achieved by applying large amounts of fertilizers, using chemical protection from pests, which allows intensifying agricultural production. Widespread use of artificial chemical substances leads to contamination of soils and living organisms. In addition, precipitation carrying pollutants falls on the soil surface and is also a source of soil pollution. Surface and groundwater wash pollutants into the aquatic environment (rivers, lakes, seas).

Fertilizers are, of course, necessary to replenish the soil's reserves of nutrients removed from the harvest. The desire to increase the productivity of agricultural plants leads to oversaturation of soils with fertilizers. However, according to the law on marginal yield, plant productivity does not increase in direct proportion to the amount of fertilizer applied. Excess fertilizer in the soil leads to excess nitrogen and phosphorus in products and deteriorates the structure of soils.

Pollution of continental and oceanic waters. Numerous pollutants can be dissolved in water or transported in suspension over vast distances from discharge sites. Most toxicants, no matter what phase they are in - gaseous, liquid or solid - are capable of polluting the hydrosphere.

Biological pollution in the form of wastewater leads to severe bacteriological contamination and leads to the spread of infectious diseases, which creates additional problems in the field of epidemiology.

Chemical pollution water pollution occurs as a result of the release of various chemical compounds used in agriculture (pesticides and mineral fertilizers), as well as waste from industrial enterprises. Very often, industrial wastewater carries substances harmful to aquatic organisms, such as lead, mercury, copper, etc. Pollution with hydrocarbons (oil and petroleum products) has become one of the main types of hydrosphere pollution in recent decades.

The environmental consequences of natural water pollution are manifested in the disruption of biogeochemical cycles of substances, a decrease in biological productivity, and the degradation of individual aquatic ecosystems.

Water pollution with organic substances affects abiotic and biotic factors operating both in flowing waters (rivers) and in large stagnant bodies of water (lakes, closed seas). In running waters, the discharge of waste saturated with organic substances causes a complete disruption of the functioning of the ecosystem. In this case, four zones are formed, which follow one after another downstream: 1) a degradation zone, where the river waters mix with the pollutant; 2) a zone of active decomposition, where fungi and bacteria, aerobic and then anaerobic, multiply and destroy organic matter; 3) recovery zone, where the water is gradually purified and restored initial characteristics; 4) clean water zone.

As a result of the active development of microorganisms in the decomposition zone, the concentration of dissolved oxygen drops sharply and the number of algae decreases. An outbreak of autotrophs (microscopic algae - phytoplankton) occurs in the third zone as a result of the appearance of nitrates and phosphates extracted by destructive microorganisms from polluting organic substances. When the removal of dissolved and suspended pollutants is completed and the initial conditions, organisms living in clean water reappear. Disturbances in the composition of animal communities living in rivers are much more pronounced, since no animals living in clean water can survive in the contaminated area.

Water pollution with toxic compounds leads to suppression of vital activity and death of organisms sensitive to this toxicant. For example, chlorine-containing insecticides, in particular DDT, inhibit photosynthesis in phytoplankton and have a strong negative impact on biocenoses due to their ability to concentrate in food chains - bioaccumulation.

One of the main factors of negative changes in the biosphere is the ultra-intensive exploitation of natural resources, which leads to consequences such as destruction of vegetation cover and deterioration of soil properties.

Destruction of vegetation cover. First of all, it is associated with deforestation. Deforestation is one of the most pressing global environmental problems. The role of forest communities in the functioning of natural ecosystems is enormous. The forest absorbs atmospheric pollution, protects the soil from erosion, and regulates runoff surface waters, prevents the decline in groundwater levels, etc. In addition, forests play big role in the process of binding free carbon dioxide from the air during photosynthesis (reducing the greenhouse effect).

A decrease in forest area causes disruption of oxygen and carbon cycles in the biosphere. Although the catastrophic consequences of deforestation are widely known, deforestation continues. The forest area on the planet decreases by almost 2% every year.

As a result of intensive livestock farming, meadow ecosystems are degenerating into wastelands.

Deterioration in physical chemical properties soil. Excessive exploitation of land for agricultural crops is a powerful factor in the destruction of natural resources. Usually there are four main reasons for the damage and destruction of land: wind and water erosion; salinization due to improper irrigation; decreased fertility; soil pollution.

Erosion is the destruction of soil as a result of the action of water or wind. Erosion processes in nature have sharply intensified under human influence. Erosion begins, first of all, where the natural vegetation cover, which holds the soil together with roots and reduces the intensity of air and water flows, is destroyed. Over its history, humanity has lost about 2 billion hectares of fertile land.

Irrigated agriculture causes irrigation erosion and secondary salinization. Excess moisture in the fields causes the groundwater level to rise to the soil surface and their intense evaporation. Salts dissolved in water accumulate in the upper soil horizon, reducing its fertility. Some scientists believe that civilization Ancient Babylon died from secondary soil salinization.

Land depletion is also caused by: the alienation of nutrients from the harvest and their incomplete subsequent return; loss of humus - deterioration of the water regime. As a result of depletion, the soil loses fertility and becomes desertified.

Depletion of the Earth's ozone layer. Anthropogenic changes in the atmosphere are also associated with the destruction of the ozone layer, which serves as a protective screen from ultraviolet radiation, which is harmful to living organisms. The process of destruction of the ozone layer occurs especially quickly above the poles of the planet, where so-called ozone holes have appeared. In 1987 registered expanding year by year (expansion rate - 4% per year) the ozone hole over Antarctica (extending the contours of the continent) and a less significant similar formation in the Arctic.

The danger of depleting the ozone layer is that the intensity of ultraviolet radiation harmful to living organisms may increase. Scientists believe that the main reason for the depletion of the ozone layer (screen) is the use by people of chlorofluorocarbons (freons), which are widely used in everyday life and in production (aerosols, foaming agents, solvents, etc.). In 1990 global production of ozone-depleting substances amounted to more than 1,300 thousand tons. Chlorofluorocarbons, entering the atmosphere, decompose in the stratosphere with the release of chlorine atoms, which catalyze the conversion of ozone into oxygen. In the lower layers of the atmosphere, freons can persist for decades. From here they enter the stratosphere, where their content is estimated to increase annually by about 5%. It is assumed that one of the reasons for the depletion of the ozone layer may be the destruction of forests as producers of oxygen on Earth.

Global climate change. Currently, the main causes of changes in the Earth's climate system are considered to be anthropogenic emissions (emissions) of gases (carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride), which increase the natural greenhouse effect. These gases allow sunlight to pass through, but partially block infrared thermal radiation emitted by the Earth's surface. In recent decades, the greenhouse effect has intensified, which leads to heating of the lower parts of the atmosphere, which, in turn, causes changes in climatic and meteorological parameters.

Greenhouse effect. The greenhouse effect is understood as an increase in the average temperature of the surface part of the Earth's atmosphere as a result of changes in the heat balance caused by greenhouse gases. The main greenhouse gases are carbon dioxide and water vapor. The contribution of carbon dioxide to the greenhouse effect, according to various sources, ranges from 50 to 65%. Other greenhouse gases include methane (20%), nitrogen oxides (5%), etc. An increase in the concentration of greenhouse gases leads to the fact that solar radiation continues to penetrate unhindered earth's surface, and long-wave (infrared) radiation coming from the Earth is absorbed by greenhouse gases. As a result, the lower troposphere heats up above normal levels and the overall heat balance of the Earth changes. According to available data, due to greenhouse gases, the average annual air temperature on Earth over the past century has increased by 0.3...0.6 °C.

It is believed that before the advent of the industrial era (late 19th century), carbon flows between the atmosphere, continents and oceans were balanced. But over the past 100 years, the content of carbon dioxide in the atmosphere has increased significantly as a result of anthropogenic inputs (Fig. 16.2). One of their main sources is the combustion of fossil fuels, but this process is also accelerated as a result of the development of agriculture and deforestation.

Intensive farming causes soil carbon loss. The fixation of carbon dioxide by agricultural plants during photosynthesis does not compensate for the amount released from the soil as a result of plowing. Deforestation leads to additional release of carbon dioxide into the atmosphere when wood is burned. Forests are important carbon sinks, since forest biomass contains 1.5 times more carbon, and forest humus contains 4 times more carbon than the entire atmosphere.

The Earth's photosynthetic green belt and ocean carbonate system maintain constant levels of carbon dioxide in the atmosphere. But the rapidly increasing rates of burning fossil fuels and the formation of large amounts of carbon dioxide during the development of civilization on Earth are beginning to exceed the ability of plants to completely assimilate carbon dioxide during photosynthesis.

Most of the atmospheric carbon stores end up in the ocean, which contains 50 times more carbon dioxide than the atmosphere, or in plants and soil. The rate at which carbon stocks are built up in these terrestrial or oceanic reservoirs depends on many factors. The ocean and atmosphere form the global climate system, and changes in one of these blocks can affect the other. In order to be able to predict the direction of climate change, you need to thoroughly know the transformation processes various forms carbon in the ocean, the transfer of carbon into the deep layers of the water column and its accumulation in bottom sediments.

Most of the carbon in the ocean for a long time persists in deep waters and in seabed sediments. One of the possible ways for carbon to enter from the surface productive layers of the ocean into the depths of the ocean is through biological pump. This path begins with phytoplankton - single-celled organisms, which create the basis of the oceanic the food chain, absorbing carbon dioxide and nutrients and creating organic matter through the process of photosynthesis. Phytoplankton and the zooplankton that feed on them produce particles of organic matter in the form of dead organisms and waste products.

In the process of respiration of aquatic organisms, part of the associated organic matter carbon is oxidized to mineral forms (carbon dioxide) in the upper ocean, which in turn can escape into the atmosphere. Fixed organic carbon in the form of organic particles (the bodies of aquatic organisms, the products of their excretions in the form of sticky lumps) under the influence of gravity settles into the depths of the ocean, where it either oxidizes or becomes part of sedimentary organic material. How quickly and in what volume carbon dioxide from the atmosphere enters the depths of the ocean, where it lingers for a long time and where it is switched off from the biogeochemical carbon cycle, depends on the intensity of the functioning of marine ecosystems. The transition of carbon from inorganic form (carbon dioxide) to organic form (biomass and detritus), transformation and transfer of carbon into the depths is called a “biological pump”, i.e. a process as a result of which carbon is pumped out of the atmosphere and accumulates in the ocean (in water and bottom sediments).

Studies have shown that over the past 100 years, the concentration of carbon dioxide in the atmosphere has increased by 25%, and methane by 100%. The rapid growth of carbon dioxide and methane in the atmosphere was accompanied by a global increase in temperature. Thus, in the 1980s, the average air temperature in the Northern Hemisphere increased compared to late XIX V. by 0.5...0.6°C (Fig. 16.3). According to available forecasts, the average temperature on Earth by 2020-2050. may increase by 1.2...2.5°C compared to the pre-industrial era. Warming can lead to intensive melting of glaciers and an increase in the level of the World Ocean by 0.5... 1.5 m over the specified period. As a result, many densely populated coastal areas will be flooded. However, with a general increase in precipitation in the central regions of the continents, the climate may become drier. For example, in the 80-90s of the XX century. In Africa and North America, catastrophic droughts have become more frequent, which are associated with global warming.

In recent decades, climate warming and increased precipitation in Russia have had a significant impact on the hydrological characteristics of water resources. Thus, in the basins of the Volga, Don and Dnieper rivers there was an increase in flows by 20...40%. The increase in Volga flow was the main factor in the increase in 1978-1995. level of the Caspian Sea by almost 2.5 m. In the Caspian regions, more than 320 thousand hectares of land were flooded and taken out of land use.

With climate warming, the risk of dangerous floods is expected to increase in many regions of Russia, where river flows are predicted to increase. Projected changes in water levels will lead to changes in erosion processes in watersheds and river beds, increased turbidity and deterioration in water quality.

The climate on Earth has always changed, and there have not been any long periods during which it remained stable. But never before has the climate changed at such a rate as it is now.

In addition to the content of greenhouse gases, there are also such important parameters that actively influence the Earth’s climate, such as the content of water vapor in the atmosphere and moisture circulation over land. As a result of an increase in the average surface air temperature, the content of water vapor in the Earth's atmosphere increases, which leads to an increase in the greenhouse effect. The moisture cycle over land, which is 99% determined by vegetation, is being disrupted due to the accelerating loss of forests on the planet.

At the same time, global warming can also lead to the opposite trend - to regional cooling as a result of changes in the directions of sea currents. Already in the first decades of the 21st century. the warm waters of the Gulf Stream may no longer be a barrier to cold currents coming from the Arctic Ocean (from the Labrador Peninsula). Thus, against the background of general planetary warming, local cooling in northern Europe is very likely. The effect of the disappearance of ocean heating can manifest itself very quickly, and, most importantly, it will be sudden and sharp. The consequences of a possible local cooling against the backdrop of general warming may affect Iceland, Ireland, Great Britain, the Scandinavian countries, Murmansk and Arkhangelsk region, Republics of Karelia and Komi, other adjacent regions of Russia.

Results of human influence on the biosphere. IN modern era human activities have a huge impact on natural conditions the entire planet. The flora and fauna of land have been especially changed. Many species of animals and plants have been completely destroyed by humans, and even more species are under threat of extinction. It is estimated that over 120 species and subspecies of mammals and about 150 species of birds have recently disappeared.

Enormous changes have occurred in the vegetation cover of most of the surface of the continents. Over vast areas, wild vegetation has been destroyed and replaced by agricultural fields. The forests that have survived to this day are largely secondary, i.e., highly modified as a result of human impact in comparison with the natural vegetation cover. Great changes have also occurred in the vegetation cover of many areas of the steppes and savannas due to intensive grazing by livestock.

Human impact on natural vegetation has had a noticeable impact on the process of soil formation in the relevant areas and has led to changes in the physical and chemical properties of soils. The soils in agricultural fields have changed even more due to the systematic use of artificial chemical fertilizers and the removal of a significant part of the biomass of growing plants. In many areas, environmentally unsound soil cultivation has led to increased erosion, as a result of which the soil cover has been destroyed over large areas.

The influence of human activities on the hydrological regime of land is rapidly increasing. The flow of not only small, but also many large rivers has changed significantly as a result of the creation of hydraulic structures, the withdrawal of water to meet the needs of industry and the urban population, and the irrigation of agricultural fields. The creation of large reservoirs, the area of ​​which in many cases is comparable to the area of ​​large natural lakes, has dramatically changed the regime of evaporation and runoff over vast areas.

The period in the history of the relationship between man and nature from the beginning of the 20th century. and to this day is characterized by the expansion of its expansion: the settlement of all territories available for habitation, the intensive development of industrial and agricultural production, the discovery and start of operation of new methods of releasing and converting energy (including the energy of the atomic nucleus), the beginning of the exploration of near-Earth space and solar system in general, as well as unprecedented population growth.

The history of human influence on the biosphere shows that technological progress is constantly increasing the possibilities of impact on the environment, creating the preconditions for the emergence of major environmental crises. On the other hand, the same technological progress expands the possibilities of eliminating created by man deterioration of the natural environment. These two opposing trends manifested themselves most clearly in the second half of the 20th century. and are currently ongoing.

Control questions and tasks

1. Describe the main directions of human influence on the biosphere.

2. What is the essence of the modern environmental crisis?

3. List the most important environmental problems of our time.

4. What factors influence global climate change?

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This topic belongs to the section:

Ecology

Nature develops according to its own laws as a single whole. Large-scale impact.. Goal environmental education and education, the formation of environmental .. in every person at all stages of his life.

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