![]() ![]() Those 2007 estimates are still used for international comparisons through 2020, although the latest research on warming effects has found other values, as shown in the table above. They published these values in Annex III, and they took them from the 4th Assessment Report of the Intergovernmental Panel on Climate Change, which had been published in 2007. Īfter some intermediate updates, in 2013 this standard was updated by the Warsaw meeting of the UN Framework Convention on Climate Change (UNFCCC, decision 24/CP.19) to require using a new set of 100-year GWP values. Under the Kyoto Protocol, in 1997 the Conference of the Parties standardized international reporting, by deciding (decision 2/CP.3) that the values of GWP calculated for the IPCC Second Assessment Report were to be used for converting the various greenhouse gas emissions into comparable CO 2 equivalents. This is a net reduction of 22.26 tonnes of GWP, reducing the global warming effect by a ratio of 25:2.74 (approximately 9 times). For a starting amount of 1 tonne of methane, which has a GWP of 25, after combustion there would be 2.74 tonnes of CO 2, each tonne of which has a GWP of 1. For instance, burning methane to carbon dioxide would reduce the global warming impact, but by a smaller factor than 25:1 because the mass of methane burned is less than the mass of carbon dioxide released (ratio 1:2.74). The values given in the table assume the same mass of compound is analyzed different ratios will result from the conversion of one substance to another. The total impact of all fluorinated gases is estimated at 3% of all greenhouse gas emissions. Some have high GWP but only a low concentration in the atmosphere. The IPCC lists many other substances not shown here. AR5 has skipped 500 year values but introduced GWP estimations including the climate-carbon feedback (f) with a large amount of uncertainty. Though recent reports reflect more scientific accuracy, countries and companies continue to use SAR and AR4 values for reasons of comparison in their emission reports. Earlier reports were the Second Assessment Report (1995), Third Assessment Report (2001), Fourth Assessment Report (2007) and Fifth Assessment Report (2013). The most recent report is the IPCC Sixth Assessment Report (Working Group I) from 2023. Įstimates of GWP values over 20, 100 and 500 years are periodically compiled and revised in reports from the Intergovernmental Panel on Climate Change. CO 2 emissions cause increases in atmospheric concentrations of CO 2 that will last thousands of years. It has a GWP of 1 regardless of the time period used. ![]() : 7SM-24 Values Ĭarbon dioxide is the reference. Similarly a tonne of nitrous oxide, from manure or paddy fields for example, is equivalent to 273 tonnes of carbon dioxide. Methane has GWP (over 20 years) of 81.2 meaning that, for example, a leak of a tonne of methane is equivalent to emitting 81.2 tonnes of carbon dioxide. It is calculated as GWP times mass of the other gas. Thus it provides a common scale for measuring the climate effects of different gases. For any gas, it is the mass of CO 2 that would warm the earth as much as the mass of that gas. The carbon dioxide equivalent (CO 2e or CO 2eq or CO 2-e) is calculated from GWP. For other gases it depends on how strongly the gas absorbs infrared thermal radiation, how quickly the gas leaves the atmosphere, and the time frame being considered. Global warming potential ( GWP) is a measure of how much infrared thermal radiation a greenhouse gas added to the atmosphere would absorb over a given time frame, as a multiple of the radiation that would be absorbed by the same mass of added carbon dioxide (CO 2). Potential heat absorbed by a greenhouse gas The radiative forcing (warming influence) of long-lived atmospheric greenhouse gases has accelerated, almost doubling in 40 years. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |