Implications of RCP emissions on future PM2.5 air quality and direct radiative forcing over China
Implications of RCP emissions on future PM2.5 air quality and direct radiative forcing over China
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DOI：
10.1002/2016jd025623
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发表时间：
2016-11
期刊：
影响因子：
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通讯作者：
Ke Li;H. Liao;Jia Zhu;J. Moch
中科院分区：
文献类型：
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作者：
Ke Li;H. Liao;Jia Zhu;J. Moch
中国严重的PM2.5空气污染以及2016年实施的第一个国家标准（FGNS）（年度PM2.5浓度目标低于35 µg m-3），需要采取紧急减排策略。本研究应用嵌套网格版本的戈达德地球观测系统（GEOS）化学传输模式（GEOS-Chem），基于RCP2.6、RCP4.5、RCP6.0和RCP8.5代表性浓度路径（RCP）情景下未来排放变化，定量分析了2000-2050年中国PM2.5空气质量变化和相关的直接辐射强迫（DRF）。在近期（2000-2030年），在RCP6.0和RCP8.5下，中国东部地区PM2.5浓度预计最大增幅为10-15 µg m−3，在RCP2.6和RCP4.5下，增幅小于5 µg m −3。从长期来看（2000-2050年），PM2.5污染明显改善，在除RCP6.0外的所有RCPs下，PM2.5浓度在15-30 µg m−3之间的最大降幅在中国东部。特别关注高污染区域，我们发现，在RCP2.6，RCP4.5和RCP8.5下，北京-天津-河北（BTH）冬季PM2.5浓度达到FGNS的时间是2040年之后，而夏季PM2.5浓度在RCP2.6和RCP4.5下到2030年达到这一目标。在四川盆地（SCB），冬季PM2.5浓度低于FGNS仅出现在2050年RCP2.6和RCP4.5下，尽管未来夏季PM2.5将得到很好的控制。控制未来PM2.5浓度的困难与未缓解的高硝酸盐水平有关，尽管NOx和SO2排放量在2020-2040年期间大幅减少。在RCP2.6、RCP4.5和RCP8.5下，中国东部地区（20°-45 ° N，100°-125 ° E）气溶胶浓度的变化导致2050年的正DRF分别比2000年增加1.22、1.88和0.66 W m−2。例如，当考虑PM2.5对中国的健康和气候影响时，在RCP4.5（RCP2.6）下，2050年中国东部平均PM2.5浓度相对于2000年下降了54%（43%），但以变暖为代价，DRF为1.88（1.22）W m−2。我们的研究结果表明，这将是可能的，以减轻未来的PM2.5污染在中国，但它可能需要20年的污染地区，如BTH和SCB，以满足FGNS，基于所有RCP情景。与此同时，气溶胶减少所产生的变暖效应也是显著和不可避免的。
Severe PM2.5 air pollution in China and the First Grand National Standard (FGNS), implemented in 2016 (annual PM2.5 concentration target of less than 35 µg m−3), necessitate urgent reduction strategies. This study applied the nested‐grid version of the Goddard Earth Observing System (GEOS) chemical transport model (GEOS‐Chem) to quantify 2000–2050 changes in PM2.5 air quality and related direct radiative forcing (DRF) in China, based on future emission changes under the representative concentration pathway (RCP) scenarios of RCP2.6, RCP4.5, RCP6.0, and RCP8.5. In the near term (2000–2030), a projected maximum increase in PM2.5 concentrations of 10–15 µg m−3 is found over east China under RCP6.0 and RCP8.5 and less than 5 µg m−3 under RCP2.6 and RCP4.5. In the long term (2000–2050), PM2.5 pollution clearly improves, and the largest decrease in PM2.5 concentrations of 15–30 µg m−3 is over east China under all RCPs except RCP6.0. Focusing particularly on highly polluted regions, we find that Beijing‐Tianjin‐Hebei (BTH) wintertime PM2.5 concentrations meeting the FGNS occur after 2040 under RCP2.6, RCP4.5, and RCP8.5, and summertime PM2.5 concentrations reach this goal by 2030 under RCP2.6 and RCP4.5. In Sichuan Basin (SCB), wintertime PM2.5 concentrations below the FGNS occur only in 2050 under RCP2.6 and RCP4.5, although future summertime PM2.5 will be well controlled. The difficulty in controlling future PM2.5 concentrations relates to unmitigated high levels of nitrate, although NOx and SO2 emissions show substantial reductions during 2020–2040. The changes in aerosol concentrations lead to positive aerosol DRF over east China (20°–45°N, 100°–125°E) by 1.22, 1.88, and 0.66 W m−2 in 2050 relative to 2000 under RCP2.6, RCP4.5, and RCP8.5, respectively. When considering both health and climate effects of PM2.5 over China, for example, PM2.5 concentrations averaged over east China under RCP4.5 (RCP2.6) decrease by 54% (43%) in 2050 relative to 2000, but at the cost of warming with DRF of 1.88 (1.22) W m−2. Our results indicate that it will be possible to mitigate future PM2.5 pollution in China, but it will likely take two decades for polluted regions such as BTH and SCB to meet the FGNS, based on all RCP scenarios. At the same time, the consequent warming effects from reduced aerosols are also significant and inevitable.