The emission trends for air pollutants are determined by three factors: the change in driving forces (fossil-fuel use, fertilizer use), the assumed air pollution control policy, and the assumed climate policy (as the last induces changes in energy consumption leading to changes (generally reductions) in air polluting emissions). We have illustrated the trends in air pollutants by looking at SOdos and NOx (Fig. 7). In general, similar trends can be seen for other air pollutants.
RCP6 and you may RCPcuatro
Emissions of SO2 and NOx across the RCPs. Grey area indicates the 90th percentile of the literature (only scenarios included in Van Vuuren et al. 2008b, i.e. 22 scenarios; the scenarios were also harmonized for their starting year-but using a different inventory). Dotted lines indicate SRES scenarios. The different studies use slightly different data for the start year
All RCPs include the assumption that air pollution control becomes more stringent, over time, as a result of rising income levels. Globally, this would cause emissions to decrease, over time-although trends can be different for specific regions or at particular moments in time. A second factor that influences the results across the RCPs is climate policy. In general, the lowest emissions are found for the scenario with the most stringent climate policy (RCP2.6) and the highest for the scenario without climate policy (RCP8.5), although this does not apply to all regions, at all times. The overall correlation is a result of the fact that climate policy induces systemic changes in the energy system, away from technologies with high greenhouse gas emission levels, which also have high emissions of air pollutants (e.g. coal use without CCS has high emission levels of COdos, but also of SO2). In contrast, the application of energy efficiency or use of renewables reduces both greenhouse gas emissions and air pollutants. The range of air pollution projections, generally, is smaller than that found in the literature. This is mostly due to the RCPs’ shared assumption of stringent air pollution policies increasing proportionally with income (van Ruijven et al. 2008). As such, one may conclude that the RCPs show a range of plausible development pathways for air pollutants and policy interventions, but they are not fully representative of the literature on air polluting emissions, as the set does not include scenarios which assume that very little or no reduction of emissions will be achieved. This may limit the use of the RCPs for specific air pollution applications.
The newest pollutants on the RCPs were downscaled to help you 0.5° ? 0.5° grids per industry (Masui ainsi que al. 2011; Riahi ainsi que al. 2011; Thomson et al. 2011; Van Vuuren ainsi que al. 2011a)-making it possible for their use in atmospheric climate and you can biochemistry designs (Fig. 8). The results show that for some gases, emissions is actually centered inside particular elements (e.g. Eastern You, Western Europe, East Asia and India). Additionally, a broad trend will likely be detailed all over the RCPs and you may fumes, indicating you to definitely emissions tend to getting relatively a lot more concentrated inside the currently low-money places.
Concentrations from greenhouse gases
The greenhouse gas concentrations in the RCPs closely correspond to the emissions trends discussed earlier (Fig. 9). For CO2, RCP8.5 follows the upper range in the literature (rapidly increasing concentrations). 5 show a stabilizing CO2 concentration (close to the median range in the literature). Finally, RCP2.6 has a peak in CO2 concentrations around 2050, followed by a modest CO2, by the end of the century. For CH4 and N2O, the order in which the RCPs can be placed are also a direct result of the assumed level of climate policy. The trends in CH4 concentrations are more pronounced, as a result of the relatively short lifetime of CH4. Emission reductions, as in the RCP2.6 and RCP4.5, therefore, may lead to an emission peak much earlier in the century. For N2O, in contrast, a relatively long lifetime and a modest reduction potential imply an increase in concentrations, in all RCPs. For both CH4 and N2O, the concentration levels correspond well with the range in the literature. Further information on the calculations of concentration can be found in Meinshausen et al. (2011b)