Direct greenhouse gas emissions
Contenido
Entre 1970 y 2004, las emisiones de gases de efecto invernadero (medidas en equivalente de CO) aumentaron a un ritmo medio del 1,6 % anual, mientras que las emisiones de CO procedentes del uso de combustibles fósiles aumentaron a un ritmo del 1,9 % anual.[27][28] Las emisiones antropogénicas totales a finales de 2009 se estimaron en 49,5 gigatoneladas equivalentes de CO2.[29]Estas emisiones incluyen el CO procedente del uso de combustibles fósiles y del uso de la tierra, así como las emisiones de metano, óxido nitroso y otros gases de efecto invernadero cubiertos por el Protocolo de Kioto.
En la actualidad, la principal fuente de emisiones de CO es la quema de carbón, gas natural y petróleo para producir electricidad y calor son las mayor fuente de emisiones de gases de efecto invernadero a nivel mundial.[30].
Otra medida es la de las emisiones per cápita. Esto divide las emisiones anuales totales de un país entre su población de mediados de año. Las emisiones per cápita pueden basarse en emisiones históricas o anuales (Banuri et al., 1996, pp. 106-07).
Aunque a veces se considera que las ciudades contribuyen de manera desproporcionada a las emisiones, las emisiones per cápita tienden a ser más bajas para las ciudades que los promedios de sus países.[31].
Regional and national attribution of emissions
According to the Environmental Protection Agency (United States) (EPA), greenhouse gas emissions in the United States can be traced from different sectors.[32] Some of the variables that have been reported[33] include:.
These different measures are sometimes used by different countries to assert various political/ethical positions on climate change (Banuri et al., 1996, p. 94).[34] The use of different measures leads to a lack of comparability, which is problematic when monitoring progress towards goals. There are arguments for the adoption of a common measurement tool, or at least for the development of communication between the different tools.[33].
Emissions can be measured over long periods of time. This type of measurement is called historical or cumulative emissions. Cumulative emissions give some indication of who is responsible for the accumulation of atmospheric greenhouse gas concentration (IEA, 2007, p. 199).[35].
The balance of national accounts would be positively related to carbon emissions. The balance of the national accounts shows the difference between exports and imports. For many richer nations, such as the United States, the balance of accounts is negative because more goods are imported than exported. This is mainly due to the fact that it is cheaper to produce goods outside of developed countries, leading the economies of developed countries to become increasingly dependent on services rather than goods. We believed that a positive balance of accounts would mean that more production was taking place in a country, so more factories working would increase carbon emission levels.[36].
Emissions can also be measured over shorter time periods. Changes in emissions can, for example, be measured against a base year of 1990. 1990 was used in the United Nations Framework Convention on Climate Change (UNFCCC) as a reference year for emissions, and is also used in the Kyoto Protocol (some gases are also measured from 1995 onwards). A country's emissions can also be reported as a proportion of global emissions for a particular year.
Due to change in land use
Change in land use, for example clearing forests for agricultural use, can affect the concentration of greenhouse gases in the atmosphere by altering the amount of carbon that flows out of the atmosphere into carbon sinks.[37].
Consideration of land use change can be understood as an attempt to measure "net" emissions, that is, gross emissions from all sources minus the removal of emissions from the atmosphere by carbon sinks (Banuri et al., 1996, pp. 92-93).
There are large uncertainties in measuring net carbon emissions.[38] In addition, there is controversy over how carbon sinks should be distributed between different regions and over time (Banuri et al., 1996, p. 93). For example, focusing on more recent changes in carbon sinks is likely to favor regions that have deforested earlier, for example, Europe.
Greenhouse gas intensity
Greenhouse gas intensity is a relationship between greenhouse gas emissions and another measure, for example, gross domestic product (GDP) or energy use.[39] The terms "carbon intensity" and "emissions intensity" are also sometimes used. Emission intensities can be calculated using market exchange rates (MCR) or purchasing power parity (PPP) (Banuri et al., 1996, p. 96). Calculations based on the TCM show large differences in intensities between developed and developing countries, while calculations based on PPP show smaller differences.
Cumulative and historical emissions
Cumulative anthropogenic (i.e., man-made) emissions of CO from the use of fossil fuels are a major cause of global warming,[40] and give some indication of which countries have contributed the most to human-induced climate change.[41].
Overall, developed countries accounted for 83.8% of industrial CO emissions during this period and 67.8% of total CO emissions. Developing countries accounted for 16.2% of industrial CO emissions during this period and 32.2% of total CO emissions. The estimate of total CO emissions includes biotic carbon emissions, mainly from deforestation. Banuri et al. (1996, p. 94) calculated cumulative per capita emissions based on the then population. The ratio between per capita emissions of industrialized countries and developing countries was estimated at more than 10 to 1.
The inclusion of biotic emissions raises the same controversy mentioned above in relation to carbon sinks and land use change (Banuri et al., 1996, pp. 93-94). The actual calculation of net emissions is very complex and is affected by the way carbon sinks are distributed between regions and the dynamics of the climate system.
Non-member countries of the Organization for Economic Cooperation and Development accounted for 42% of cumulative energy-related CO emissions between 1890 and 2007.[42] During this period, the US accounted for 28% of emissions; the EU, 23%; Russia, 11%; China, 9%; other OECD countries, 5%; Japan, 4%; India, 3%; and the rest of the world, 18%.
Annual emissions
Due to China's rapid economic development, its annual per capita emissions are rapidly approaching the levels of the Annex I group of the Kyoto Protocol (i.e., developed countries excluding the US).[43] Other countries with rapidly growing emissions are South Korea, Iran and Australia (which apart from the oil-rich states of the Persian Gulf, now has the highest per capita emissions rate in the world). On the other hand, the annual per capita emissions of the EU-15 and the US gradually decrease over time. Emissions in Russia and Ukraine have decreased most rapidly since 1990 due to the economic restructuring of these countries.[44].
Energy statistics for fast-growing economies are less accurate than those for industrialized countries. For China's annual emissions in 2008, the Netherlands Environmental Assessment Agency estimated an uncertainty range of around 10%.[43].
The "greenhouse gas footprint" refers to emissions resulting from the creation of products or services. It is more comprehensive than the commonly used carbon footprint, which measures only carbon dioxide, one of many greenhouse gases.
2015 was the first year in which both total global economic growth and a reduction in carbon emissions were observed.[45].
Main issuing countries
In 2009, the top ten annual emitting countries accounted for around two-thirds of annual energy-related CO emissions.[46].
Relative CO2 emission of various fuels
One liter of gasoline, when used as fuel, produces 2.32 kg (about 1,300 liters or 1.3 cubic meters) of carbon dioxide, a greenhouse gas. One US gallon produces 19.4 lb (1,291.5 gallons or 172.65 cubic feet).[48][49][50].