|Anthropogenic emissions by sources and removals by sinks of greenhouse gases|
|<< GLOBAL CONTEXT >>|
|Human activities have become intense to an
extent that they adversely impact the global environment and climatic system.
Continuing population growth and daily human wants lead to an increase of industrial production, energy consumption, and deforestation, thus increasing greenhouse gas emissions and causing the global warming.
According to authoritative estimates, in the 20-th century, due to anthropogenic pollution, global mean temperature increased by 0,6±0,2°C, which lead to an increase of disastrous hydro-meteorological events, such as floods, typhoons, hurricanes, etc. There are indications of rapid melting of eternal snows and glaciers in polar and highland regions worldwide. The ocean level is rising.
Scientists have proved that concentrations of greenhouse gases in the atmosphere and their radioactive forcing keep rising due to anthropogenic activities, aggravating the global warming and causing dangerous climatic changes.
The atmospheric concentration of the main anthropogenic greenhouse gas - carbon dioxide (CO2) since 1750 has increased by 31% and reached 365 ppm. Neither in the last 420 thousand years, nor, obviously, in the last 20 million years, the concentration of CO2 was as high as it is now. Nowadays, the growth rate of CO2 concentrations is the most unprecedented in the last 20 million years. Some three-quarter of global anthropogenic CO2 emissions for the past 20 years take place due to fossil fuel combustion and cement production. Global deforestation makes additional contribution to CO2 emissions.
For the period of 1990-1998, the global emissions of carbon dioxide according to IPCC estimates, amounted in 6,3±0,4 billion tons of carbon a year.
The atmospheric concentration of methane (CH4) since 1750 has increased by 151% and reached 1745 ppb. There has not been such a high concentration of CH4 during the last 420 thousand years. More than half of all global methane emissions are of an anthropogenic character, including the emissions related to mining and utilization of fossil fuels, animal husbandry, rice cultivation and waste disposal.
The atmospheric concentration of nitrous oxide (N2O) since 1750 has increased by 17% and reached 314 ppb. During the last one thousand years, as minimum, there has not been such a high concentration of N2O, as it is today. Approximately one third of the contemporary N2O emissions are of an anthropogenic character. Their sources are agricultural soils, chemical industries, etc.
Due to industrial development, concentrations of other greenhouse gases keep growing. Some of these gases have very big global warming potential (GWP), and consequently essential impact on the climatic system. Perfluorcarbons (PFCs) and hydrofluorcarbons (HFCs) belong to the group of such gases.
Some chemically active gases, such as nitrogen oxides (NOx), carbon oxide (CO) and non-methane volatile organic compounds (NMVOC) cause the indirect greenhouse effect and adversely affect the global climate system.
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