Major greenhouse gas. What is a greenhouse gas? How to reduce greenhouse gas emissions

Greenhouse gases, which are found in the atmospheres of different planets, lead to the formation of quite dangerous phenomenon. It's about the greenhouse effect. In fact, the situation can be called paradoxical. After all, it was greenhouse gases that warmed our planet, as a result of which the first living organisms appeared on it. But on the other hand, today these gases cause many environmental problems.

For many millions of years, the Sun has been heating the planet Earth, slowly turning it into an energy source itself. Part of this heat went into outer space, and part was reflected by gases in the atmosphere and heated the air around the planet. A similar process, similar to the preservation of heat under a transparent film in a greenhouse, scientists called the "greenhouse effect". And the gases leading to the occurrence of such a phenomenon are called greenhouse gases.
In the era of the formation of the earth's climate, the greenhouse effect arose as a result of active volcanic activity. Enormous volumes of water vapor emissions and carbon dioxide stuck in the atmosphere. Thus, a hyper-greenhouse effect was observed, which heated the waters of the oceans almost to the boiling point. And only green vegetation, feeding on atmospheric carbon dioxide, helped to stabilize temperature regime our planet.
But global industrialization, as well as the increase production capacity changed not only chemical composition greenhouse gases but also the meaning of this process.

Major greenhouse gases

Greenhouse gases are gaseous constituents of the atmosphere of natural or anthropogenic origin. Scientists have long been interested in the question: what kind of radiation do greenhouse gases absorb? As a result of painstaking research, they found that these gases absorb and re-emit infrared radiation. They absorb and emit radiation in the same infrared range as the Earth's surface, atmosphere and clouds.
The main greenhouse gases of the Earth are:

• water vapor
• carbon dioxide
• methane
• halogenated hydrocarbons
• nitrogen oxides.

Carbon dioxide (CO2) has the strongest impact on our planet's climate. At the very beginning of industrialization, and this is 1750, its average global concentration in the atmosphere reached 280 ± 10 ppm. In general, for 10,000 years, the concentration was at a constant level. However, research results show that already in 2005, the concentration of CO2 increased by 35% and reached 379 ppm, and this is for some 250 years.
Methane (CH4) is in second place. Its concentration increased from 715 ppb in the pre-industrial period to 1774 ppb in 2005. The volume of methane in the atmosphere gradually increased from 580 ppb to 730 ppb over 10,000 years. And over the past 250 years, it has increased by 1000 ppb.
Nitrous oxide (N2O). The volume of atmospheric nitrous oxide in 2005 reached 319 ppb and increased by 18% compared to the pre-industrial period (270 ppb). Glacial core studies suggest that N2O from natural sources has changed by less than 3% over 10,000 years. In the 21st century, almost 40% of the N2O released into the atmosphere is due to economic activity, because this compound is the basis of fertilizers. However, it is worth noting that N2O plays an important role in atmospheric chemistry because it acts as a source of NO2, which destroys stratospheric ozone. In the troposphere, NO2 is responsible for the formation of ozone and significantly affects the chemical balance.
A greenhouse gas, tropospheric ozone directly affects the climate by absorbing long-wave radiation from the Earth and short-wave radiation from the Sun, and through chemical reactions that change the volumes of other greenhouse gases, such as methane. Tropospheric ozone is responsible for the formation of an important greenhouse gas oxidant, the radical OH.
The main reason for the growth of tropospheric O3 volumes lies in the increase in the anthropogenic emission of ozone precursors - chemical substances, which are needed for its formation - primarily hydrocarbons and nitrogen oxides. The lifetime of tropospheric ozone is several months, which is significantly lower than that of other greenhouse gases (CO2, CH4, N2O).
Water vapor is also a very important natural greenhouse gas that has a significant impact on the greenhouse effect. An increase in air temperature leads to an increase in the moisture content in the atmosphere, while maintaining an approximate relative humidity, as a result of which the greenhouse effect increases, and the air temperature continues to rise. Water vapor contributes to the growth of cloudiness and changes in precipitation. Economic activity a person has an impact on the emission of water vapor, no more than 1%. Water vapor, together with the ability to absorb radiation in almost the entire infrared range, also contributes to the formation of OH - radicals.
It is worth mentioning freons, the greenhouse activity of which is 1300-8500 times higher than that of carbon dioxide. Freon sources are various refrigerators and all kinds of aerosols from antiperspirants to mosquito sprays.

Sources of greenhouse gases

Greenhouse gas emissions come from two categories of sources:

• natural sources. In the era of the absence of industry, the main sources of greenhouse gases in the atmosphere were the phenomena of evaporation of water from the oceans, volcanoes and Forest fires. However, to date, volcanoes emit only about 0.15-0.26 billion tons of carbon dioxide into the atmosphere per year. The volume of water vapor, for the same period, can be expressed in the evaporation of 355 thousand cubic kilometers of water
• anthropogenic sources. Due to intense industrial activity, greenhouse gases enter the atmosphere during the combustion of fossil fuels (carbon dioxide), during the development of oil fields (methane), due to the leakage of refrigerants and the use of aerosols (freons), rocket launches (nitrogen oxides), as well as the operation of automobile engines (ozone). In addition, the industrial activity of people contributes to the reduction of forest plantations, which are the main sinks of carbon dioxide on the continents.

Greenhouse gas reduction

Over the past hundred years, humanity has been actively developing a unified program of actions aimed at reducing greenhouse gas emissions. The most significant component of environmental policy can be called the introduction of standards for emissions of fuel products of combustion and the reduction of fuel use through the transition of the automotive industry to the creation of electric vehicles.
Activity nuclear power plants, which do not need coal or oil products, indirectly reduces the amount of carbon dioxide in the atmosphere. The calculation of greenhouse gases is carried out according to a special formula or in special programs that analyze the activities of enterprises.
Significantly reduce or completely ban deforestation is also very effective method in the fight against greenhouse gases. During their life, trees absorb huge amounts of carbon dioxide. In the process of cutting down trees, this gas is released. The decrease in areas of deforestation for arable land in tropical countries has already given tangible results to optimize global indicators of greenhouse gas emissions.
Environmentalists are very pleased with the current trend to invest in the development of various types of renewable energy. The volumes of its use on a global scale are slowly but constantly growing. It is called "green energy" because it is formed in natural regular processes that occur in nature.
Man today cannot see or feel Negative influence greenhouse gases. But our children may well face this problem. If you think not only about yourself, then you can join the solution of this problem today. You just need to plant a tree near your house, put out a fire in the forest in a timely manner, or at the first opportunity change your car to a “filled” with electricity.

Back in 1962, the Soviet climatologist and meteorologist Mikhail Ivanovich Budyko was the first to publish considerations that the burning of a huge amount of various fuels by mankind, especially increased in the second half of the 20th century, will inevitably lead to an increase in the carbon dioxide content in the atmosphere. And, as you know, it delays the return of solar and deep heat from the Earth's surface into space, which leads to the effect that we observe in glazed greenhouses. As a result of this greenhouse effect average temperature surface layer of the atmosphere should gradually increase. The conclusions of M. I. Budyko interested American meteorologists. They checked his calculations, made numerous observations themselves, and by the end of the sixties came to the firm conviction that the greenhouse effect in the Earth's atmosphere exists and is growing.

The main greenhouse gases, in order of their estimated impact on the Earth's heat balance, are water vapor, carbon dioxide, methane and ozone, and nitrogen oxide.

Rice. 3. Structure of greenhouse gas emissions by countries

Water vapor is the most important natural greenhouse gas and is a significant contributor to the greenhouse effect with a strong positive feedback. An increase in air temperature causes an increase in the moisture content of the atmosphere while maintaining approximately the same relative humidity, which causes an increase in the greenhouse effect and thereby contributes to a further increase in air temperature. The influence of water vapor can also manifest itself through an increase in cloudiness and a change in the amount of precipitation. Human economic activity contributes to the emission of water vapor, which is less than 1%.

Carbon dioxide (CO2) . In addition to water vapor, carbon dioxide plays the most important role in creating the greenhouse effect. The planetary carbon cycle is a complex system, its functioning at different characteristic times is determined by different processes, which correspond to different rates of CO2 cycle. Carbon dioxide, like nitrogen and water vapor, has been and is being released into the atmosphere from the deep layers of the planet during the degassing of the upper mantle and the earth's crust. These components of atmospheric air are among the gases emitted into the atmosphere during volcanic eruptions, released from deep cracks in the earth's crust and from hot springs.

Rice. 4. Structure of carbon dioxide emissions by regions of the planet in the 1990s

Methane (CH4). Methane is greenhouse gas. If the degree of carbon dioxide impact on the climate is conditionally taken as one, then the greenhouse activity of methane will be 23 units. The content of methane in the atmosphere has grown very rapidly over the past two centuries. Now the average content of methane CH 4 in the modern atmosphere is estimated at 1.8 ppm ( parts per million, parts per million). Its contribution to the dissipation and retention of heat radiated by the Earth heated by the sun is significantly higher than from CO 2 . In addition, methane absorbs the Earth's radiation in those "windows" of the spectrum that are transparent to other greenhouse gases. Without greenhouse gases - CO 2 , water vapor, methane and some other impurities, the average temperature on the Earth's surface would be only -23°C, and now it is about +15°C. Methane seeps out at the bottom of the ocean through cracks in the earth's crust, and is released in considerable quantities during mining and when forests are burned. Recently, a new, completely unexpected source of methane has been discovered - higher plants, but the mechanisms of formation and the significance of this process for the plants themselves have not yet been elucidated.

Nitric oxide (N2O) is the third most important greenhouse gas of the Kyoto Protocol. It is emitted during the production and use of mineral fertilizers, in chemical industry, in agriculture, etc. It accounts for about 6% of global warming.

Tropospheric ozone, I Being a greenhouse gas, tropospheric ozone (trop. O 3) has both a direct impact on the climate through the absorption of long-wave radiation from the Earth and short-wave radiation from the Sun, and through chemical reactions, which change the concentrations of other greenhouse gases, such as methane (trop. O 3 is necessary for the formation of an important greenhouse gas oxidizing agent - the radical - OH). Increasing the concentration of trails. Since the middle of the 18th century, O 3 has been the third largest positive radiative effect on the Earth's atmosphere after CO 2 and CH 4 . In general, the content of the trails. O 3 in the troposphere is determined by the processes of its formation and destruction during chemical reactions involving ozone precursors, both natural and anthropogenic, as well as by the processes of ozone transfer from the stratosphere (where its content is much higher) and the absorption of ozone by the earth's surface. Lifetime of trails. O 3 - up to several months, which is much less than other greenhouse gases (CO 2 , CH 4 , N 2 O). Path concentration. O 3 varies significantly in time, space and height, and its monitoring is a much more difficult task than monitoring well-mixed greenhouse gases in the atmosphere.

Scientists have made an unequivocal conclusion that emissions into the atmosphere caused by human activity lead to a significant increase in the concentration of greenhouse gases in the atmosphere. Based on calculations using computer models, it was shown that if the current rate of greenhouse gas emissions into the atmosphere continues, then in just 30 years the average temperature will globe rises by about 1°. This is an unusually large increase in temperature, based on paleoclimate data. It should be noted that the estimates of experts, apparently, are somewhat underestimated. Warming is likely to increase as a result of a number of natural processes. More than predicted warming may be due to the inability of the warming ocean to absorb the estimated amount of carbon dioxide from the atmosphere.

From the results of numerical simulations it also follows that the average global temperature in the next century will increase at a rate of 0.3°C per 10 years. As a result, by 2050 it may increase (compared to pre-industrial times) by 2°C, and by 2100 by 4°C. Global warming should be accompanied by an increase in precipitation (by several percent by 2030), as well as an increase in the level of the World Ocean (by 20 cm by 2030, and by 65 cm by the end of the century).

Climate impact of greenhouse gases

The group of greenhouse gases includes all types of gaseous compounds that affect the permeability of the atmosphere for sunlight and thermal energy. The presence of these gases in atmospheric air is the reason that part of the thermal energy radiated by the Earth's surface does not go into space, but remains in the surface air layers. The higher the content of greenhouse gases in the atmospheric air, the more intensively the surface of the planet overheats.

Remark 1

During geological history The ground their content is constantly changing. At the same time, there were changes in climatic indicators, as well as in a number of other parameters of the atmosphere, for example, its density, gas composition, transparency, etc., which largely determine the features of the vital activity of organisms. It is believed that since the Carboniferous period Paleozoic era(i.e., about 370 million years ago), the content of gases contributing to the greenhouse effect has stabilized at a level that allows maintaining the temperature equilibrium of the planet.

The group of greenhouse gases includes:

• water vapor,
• carbon dioxide,
• methane,
• freons,
• as well as nitrogen oxides and ozone.

Natural sources of greenhouse gases

Before the beginning of the industrial era, the main sources of greenhouse gases in the atmosphere were: the evaporation of water from the surface of the oceans, volcanic activity and forest fires. Currently, volcanoes emit about 0.15–0.26 billion tons of carbon dioxide into the atmosphere per year. The specificity of volcanic activity lies in the extremely uneven flow of carbon monoxide into the atmosphere.

A lot of it is released during large eruptions, which occur relatively rarely - less than one per decade. At the same time, along with greenhouse gases, volcanoes emit and great amount dust, which helps to reduce the intake solar radiation and some chill. As modern studies show, the effect of the largest eruptions can cause a temperature change on Earth of the order of several tenths of a degree, and last for several years. The amount of water vapor entering the atmosphere during the same period is equivalent to the evaporation of 355,000 cubic kilometers of water.

Anthropogenic sources of greenhouse gases

With the intensification of industry, greenhouse gases began to enter the atmosphere during the combustion of fossil fuels (carbon dioxide), during the development of oil fields (methane), due to the loss of refrigerants and the use of aerosols (freons), rocket launches (nitrogen oxides), the operation of automobile engines ( ozone). In addition, human industrial activity has contributed to the reduction of forest areas - the main natural sinks of carbon dioxide on the continents.

Theoretically, with the complete combustion of fossil fuels (provided that all its deposits are exhausted), approximately the same amount of carbon dioxide will enter the atmosphere, which was removed from it during the course of geological history in the process of photosynthesis and preserved in the form of fossil carbon.

Since the oldest (and thin) deposits of caustobioliths date back to the Devonian period, it can be assumed that the content of carbon dioxide in the atmosphere will be slightly less than by the end of this period or by the beginning of the next, Carboniferous period (since the full production of all useful components in modern deposits does not not only economically unprofitable, but also technically extremely difficult). At that time already existed advanced life, including terrestrial, but the climate was significantly different from the modern one. It was much warmer, more humid, the atmosphere was more dense. The content of oxygen in the atmosphere was close to modern, and carbon dioxide content was much higher - about 0.2%, i.e. about 5.6 times higher than now.

Greenhouse gases absorb reflected energy from the Sun, making the Earth's atmosphere warmer. Most of solar energy reaches the surface of the planet, and some is reflected back into space. Some gases present in the atmosphere absorb reflected energy and redirect it back to Earth as heat. The gases responsible for this are called greenhouse gases because they play the same role as the transparent plastic or glass covering the greenhouse.

Greenhouse gases and human activities

Some greenhouse gases are released naturally as a result of volcanic activity and biological processes. However, since the advent of the Industrial Revolution, turn of XIX century, humans have been releasing increasing amounts of greenhouse gases into the atmosphere. This increase accelerated with the development of the petrochemical industry.

Greenhouse effect

The heat reflected from greenhouse gases produces a measurable warming of the Earth's surface and oceans. This has a wide-ranging impact on ice, oceans, and.

The main greenhouse gases of the Earth:

water vapor

Water vapor is the most powerful and important of the Earth's greenhouse gases. The amount of water vapor in can not be directly changed by human activity - it is determined by air temperature. The warmer, the higher the rate of evaporation of water from the surface. As a result, increased evaporation leads to a greater concentration of water vapor in the lower atmosphere, which is able to absorb infrared radiation and reflect it downward.

Carbon Dioxide (CO2)

Carbon dioxide is the most important greenhouse gas. It is released into the atmosphere through the burning of fossil fuels, volcanic eruptions, decomposition organic matter and movement Vehicle. The cement production process releases large amounts of carbon dioxide. Plowing the land also releases large amounts of carbon dioxide normally stored in the soil.

Plant life, which absorbs CO2, is an important natural store of carbon dioxide. can also absorb CO2 dissolved in water.

Methane

Methane (CH4) is the second most important greenhouse gas after carbon dioxide. It is stronger than CO2 but is present in the atmosphere in much lower concentrations. CH4 can stay in the atmosphere for a shorter time than CO2 (CH4 has a residence time of about 10 years, compared to hundreds of years for CO2). natural springs methane include: wetlands; burning biomass; life processes of a large cattle; rice cultivation; extraction, combustion and processing of oil or natural gas, etc. The main natural absorber of methane is the atmosphere itself; to others, soil, where methane is oxidized by bacteria.

As with CO2, human activity is increasing CH4 concentrations faster than methane is taken up naturally.

Tropospheric ozone

The next most significant greenhouse gas is tropospheric ozone (O3). It is formed as a result of air pollution and should be distinguished from natural stratospheric O3, which protects us from many of the damaging rays of the sun. In the lower parts of the atmosphere, ozone is produced by the breakdown of other chemicals (such as nitrogen oxides). This ozone is considered a greenhouse gas, but it is short-lived and although it can contribute significantly to warming, its effects are usually local, not global.

Minor greenhouse gases

Secondary greenhouse gases are nitrogen oxides and freons. They are potentially dangerous for . However, due to the fact that their concentrations are not as significant as the above-mentioned gases, the assessment of their impact on climate has not been fully studied.

nitrogen oxides

Nitrogen oxides are found in the atmosphere through natural biological reactions in soil and water. Nonetheless a large number of released nitric oxide makes a significant contribution to global warming. The main source is the production and use of synthetic fertilizers in agricultural activities. Motor vehicles emit nitrogen oxides when running on fossil fuels such as gasoline or diesel.

Freons

Freons are a group of hydrocarbons with various types use and characteristics. CFCs are widely used as refrigerants (in air conditioners and refrigerators), foaming agents, solvents, etc. Their production is already banned in most countries, but they are still present in the atmosphere and damage the ozone layer. Hydrofluorocarbons serve as an alternative to more harmful ozone-depleting substances, and contribute much less to global change climate on the planet.

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Greenhouse gases

Greenhouse gases- gases with high transparency in the visible range and high absorption in the far infrared range. The presence of such gases in planetary atmospheres results in the greenhouse effect.

The main greenhouse gas in the atmospheres of Venus and Mars is carbon dioxide, in the atmosphere of the Earth - water vapor.

The main greenhouse gases, in order of their estimated impact on the Earth's heat balance, are water vapor, carbon dioxide, methane, and ozone

Potentially, anthropogenic halogenated hydrocarbons and nitrogen oxides can also contribute to the greenhouse effect, however, due to low concentrations in the atmosphere, the assessment of their contribution is problematic.

water vapor

Analysis of air bubbles in the ice suggests that there is more methane in the Earth's atmosphere now than at any time in the last 400,000 years. Since 1750, the average global atmospheric concentration of methane has increased by 150 percent from about 700 to 1745 parts per billion by volume (ppbv) in 1998. Per last decade, although the concentration of methane continued to rise, the growth rate slowed down. In the late 1970s, the growth rate was about 20 ppbv per year. In the 1980s, growth slowed to 9-13 ppbv per year. Between 1990 and 1998 there was an increase between 0 and 13 ppbv per year. Recent studies (Dlugokencky et al.) show a steady concentration of 1751 ppbv between 1999 and 2002.

Methane is removed from the atmosphere through several processes. The balance between methane emissions and removal processes ultimately determines the atmospheric concentrations and residence time of methane in the atmosphere. Dominant is oxidation by chemical reaction with hydroxyl radicals (OH). Methane reacts with OH in the troposphere to produce CH3 and water. Stratospheric oxidation also plays a (minor) role in removing methane from the atmosphere. These two reactions with OH account for about 90% of the removal of methane from the atmosphere. In addition to the reaction with OH, two more processes are known: the microbiological absorption of methane in soils and the reaction of methane with chlorine (Cl) atoms on the sea surface. The contribution of these processes is 7% and less than 2%, respectively.

Ozone

Ozone is a greenhouse gas. At the same time, ozone is necessary for life, as it protects the Earth from harsh ultraviolet radiation Sun.

However, scientists distinguish between stratospheric and tropospheric ozone. The first (so-called ozone layer) is a permanent and basic protection against harmful radiation. The second is considered harmful, since it can be transferred to the surface of the Earth, where it harms living beings, and besides, it is unstable and cannot be a reliable protection. In addition, the increase in the content of tropospheric ozone has contributed to the growth of the greenhouse effect of the atmosphere, which (according to the most widely accepted scientific estimates) is about 25% of the contribution of CO 2

Most tropospheric ozone is produced when nitrogen oxides (NOx), carbon monoxide (CO) and volatiles organic compounds enter into chemical reactions in the presence of sunlight. Transport, industrial emissions, and some chemical solvents are the main sources of these substances in the atmosphere. Methane, which has increased significantly in atmospheric concentrations over the past century, also contributes to the formation of ozone. The lifetime of tropospheric ozone is approximately 22 days, the main mechanisms for its removal are binding in the soil, decomposition under the action of ultraviolet rays and reactions with OH and HO 2 radicals.

Tropospheric ozone concentrations are characterized by a high level of variability and unevenness in geographical distribution. There is a monitoring system for tropospheric ozone in the United States and Europe, based on satellites and ground observation. Because ozone requires sunlight, high levels ozone are usually observed during periods of hot and sunny weather. The current average concentration of tropospheric ozone in Europe is three times higher than in the pre-industrial era.

An increase in the ozone concentration near the surface has a strong negative impact on vegetation, damaging the leaves and inhibiting their photosynthetic potential. As a result of the historical increase in ground-level ozone concentrations, the ability of the land surface to absorb CO 2 has probably been suppressed and therefore the growth rate of CO 2 has increased in the 20th century. Scientists (Sitch et al. 2007) believe that this indirect climate forcing has nearly doubled the contribution that ground-level ozone concentrations have made to climate change. A decrease in ozone pollution in the lower troposphere can compensate for 1-2 decades of CO 2 emissions, while economic costs will be relatively small (Wallack and Ramanathan, 2009).

Nitrogen oxide

The greenhouse activity of nitrous oxide is 298 times higher than that of carbon dioxide.

Freons

The greenhouse activity of freons is 1300-8500 times higher than that of carbon dioxide. The main source of freon are refrigeration units and aerosols.

see also

• Kyoto Protocol (CO 2 , CH 4 , HFCs, PFCs, N 2 O, SF 6)

Notes

Links

• Point Carbon is an analytical company specializing in providing independent estimates, forecasts, and information on greenhouse gas emissions trading.
• “G&S – atmosphere” automatic air quality monitoring system