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For more details on this graph, see the Radiative Forcing fact sheet. | For more details on this graph, see the Radiative Forcing fact sheet. | ||
The secondary graph represents the radiative forcing over two and a half centuries (history and projections). In the 5th IPCC report, the radiative forcing is 2.3 W/m<sup>2</sup>. The values of the forcing in 2100 gave their name to the IPCC scenarios ( | The secondary graph represents the radiative forcing over two and a half centuries (history and projections). In the 5th IPCC report, the radiative forcing is 2.3 W/m<sup>2</sup>. The values of the forcing in 2100 gave their name to the IPCC scenarios (SSP 2.6, SSP 4.5 etc.). The colours of these scenarios can be found in the graphs of maps n°5, 11, 15, 21, 22 and 24. | ||
For more details on this graph, see the fact sheet on | For more details on this graph, see the fact sheet on SSP scenarios. | ||
==To go further == | ==To go further == | ||
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*Strat H<sub>2</sub>O [stratospheric water vapor]: Aircraft burn kerosene to propel themselves. This combustion, like all combustions, releases CO<sub>2</sub> and water vapour. Water vapour is usually not counted in the carbon footprint of hydrocarbons because these water molecules are intended to remain in the atmosphere for only one to three weeks before being washed away by rain. As far as aeroplanes are concerned, it's a bit different because they fly at an altitude, close to the stratosphere, where, as the name suggests, the air is stratified. There are no vertical convective movements, almost no clouds and no rain. When water vapour is emitted by aeroplanes, it can stay there for several years and at that point we can start to take into account its greenhouse effect. | *Strat H<sub>2</sub>O [stratospheric water vapor]: Aircraft burn kerosene to propel themselves. This combustion, like all combustions, releases CO<sub>2</sub> and water vapour. Water vapour is usually not counted in the carbon footprint of hydrocarbons because these water molecules are intended to remain in the atmosphere for only one to three weeks before being washed away by rain. As far as aeroplanes are concerned, it's a bit different because they fly at an altitude, close to the stratosphere, where, as the name suggests, the air is stratified. There are no vertical convective movements, almost no clouds and no rain. When water vapour is emitted by aeroplanes, it can stay there for several years and at that point we can start to take into account its greenhouse effect. | ||
*Trop. O<sub>3</sub> [Tropospheric Ozone]: Tropospheric ozone. Ozone is like cholesterol, it can be good and bad. The "good ozone" is stratospheric ozone, i.e. the ozone layer, which is very high in the atmosphere. It protects us from the sun's ultraviolet rays. The "bad ozone" is ground-level ozone, the ozone that is at ground level in "ozone pollution", especially in cities in hot weather. Ozone is a greenhouse gas, so as our activities produce it, its presence causes a positive radiative forcing. However, ozone is not included in carbon budgets. This is because we do not produce it directly. On the other hand, we do produce ozone precursors such as nitrogen oxides (NO<sub>x</sub>), volatile organic compounds (VOCs), methane (CH<sub>4</sub>) and carbon monoxide (CO). | *Trop. O<sub>3</sub> [Tropospheric Ozone]: Tropospheric ozone. Ozone is like cholesterol, it can be good and bad. The "good ozone" is stratospheric ozone, i.e. the ozone layer, which is very high in the atmosphere. It protects us from the sun's ultraviolet rays. The "bad ozone" is ground-level ozone, the ozone that is at ground level in "ozone pollution", especially in cities in hot weather. Ozone is a greenhouse gas, so as our activities produce it, its presence causes a positive radiative forcing. However, ozone is not included in carbon budgets. This is because we do not produce it directly. On the other hand, we do produce ozone precursors such as nitrogen oxides (NO<sub>x</sub>), volatile organic compounds (VOCs), methane (CH<sub>4</sub>) and carbon monoxide (CO). | ||
*Other WMGHG [Well Mixed | *Other WMGHG [Well Mixed Greenhouse Gases]: Other well mixed GHGs, or long-lived GHGs (synonymous because if they are long-lived, then they have time to mix well) are mainly methane, nitrous oxide and some other gases such as HFCs. | ||
*CO<sub>2</sub>: We can see here that this is quantitatively the main element. | *CO<sub>2</sub>: We can see here that this is quantitatively the main element. | ||
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*Land Use] : Land use. For example, when deforestation, a dark green surface is replaced by a light beige surface. The albedo effect cools the earth. | *Land Use] : Land use. For example, when deforestation, a dark green surface is replaced by a light beige surface. The albedo effect cools the earth. | ||
*Stat. O<sub>3</sub> [stratospheric Ozone]: Stratospheric ozone. The ozone in the stratosphere, the "good ozone", which protects us from ultraviolet radiation. As the amount of ozone has decreased because of CFCs (the hole in the ozone layer), the greenhouse effect of this ozone has logically decreased. This is what you can see on this part of the graph. | *Stat. O<sub>3</sub> [stratospheric Ozone]: Stratospheric ozone. The ozone in the stratosphere, the "good ozone", which protects us from ultraviolet radiation. As the amount of ozone has decreased because of CFCs (the hole in the ozone layer), the greenhouse effect of this ozone has logically decreased. This is what you can see on this part of the graph. | ||
*Volcanic: Large volcanic eruptions send ash into the stratosphere. The ash in the troposphere is washed away by rain in one to three weeks, but the ash that reaches the stratosphere stays much longer. This is because, as the name suggests, the air in the stratosphere is stratified, i.e. vertically stable. There are no vertical convective movements, but there are very powerful horizontal currents, the | *Volcanic: Large volcanic eruptions send ash into the stratosphere. The ash in the troposphere is washed away by rain in one to three weeks, but the ash that reaches the stratosphere stays much longer. This is because, as the name suggests, the air in the stratosphere is stratified, i.e. vertically stable. There are no vertical convective movements, but there are very powerful horizontal currents, the jet-streams, which mix these ashes over the entire surface of the earth. The result is a cooling of the earth for a few months to a few years. The phenomenon is similar to that of aerosols, it's just that the origin of aerosols is not the same. | ||
===SSP === | ===SSP === | ||
SSP is an acronym for [[wikipedia:Shared_Socioeconomic_Pathways|'''S'''hared '''S'''ocioeconomic '''P'''athways]] as introduced in the 6th Assessment Report by Working Group 1 of the IPCC<ref name=":0">Definition of Shared Socio-economic Pathways, full report 6, working group 1, [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report_smaller.pdf p1-100]</ref>. These are the different scenarios proposed by the IPCC. SSPs are “pathways” that examine how global society, demographics and economics might change over the next century. The new SSPs offer five pathways that the world could take. The SSPs’ quantitative projections of 15 socio-economic drivers include population, gross domestic product (GDP) and urbanization<ref name=":0" />. Compared to previous scenarios, these offer a broader view of a “business as usual” world without future climate policy, with global warming in 2100 ranging from a low of 3.1°C to a high of 5.1°C above pre-industrial levels. | |||
Overview of the five different Shared Socioeconomic Pathways<ref>[https://www.sciencedirect.com/science/article/pii/S0959378016300681]</ref>: | Overview of the five different Shared Socioeconomic Pathways<ref>The Shared Socioeconomic Pathways and their energy, land use, and greenhouse gas emissions implications: An overview[https://www.sciencedirect.com/science/article/pii/S0959378016300681]</ref>: | ||
{| class="wikitable" | {| class="wikitable" | ||
|SSP1 | |SSP1 | ||
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