The ozone-climate penalty over South America and Africa by 2100
The ozone-climate penalty over South America and Africa by 2100
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DOI：
10.5194/acp-22-12331-2022
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发表时间：
2022-09-21
影响因子：
6.3
通讯作者：
Verbeeck, Hans
中科院分区：
文献类型：
--
作者：
Brown, Flossie;Folberth, Gerd A.;Verbeeck, Hans
气候变化有可能通过改变大气化学、输送和干沉降，增加地表臭氧（O-3）浓度，即所谓的“臭氧-气候惩罚”。在热带地区，地表O-3对气候变化的响应研究相对较少，但对空气污染、人类和生态系统健康具有重要影响。在这项研究中，我们使用三个最先进的地球系统模型，遵循CMIP6的共享社会经济路径3-7.0排放情景，评估了南美洲和非洲由于气候变化而导致的地表O-3变化。为了量化仅由气候变化引起的变化，我们评估了包含气候变化的模拟与具有固定当前气候的模拟之间的差异。我们发现，到2100年，模型预测在由于前体排放的影响，即城市和生物质燃烧地区，臭氧-气候惩罚已经被预测为高的地区，即城市和生物质燃烧地区，尽管平均而言，模型预测由于气候变化，地表O-3会减少。我们发现污染地区的年平均地表O-3有一个小而强劲的正趋势。此外，在生物质燃烧季节，在大量燃烧生物质的地区，如亚马逊森林砍伐弧线，季节平均O-3浓度增加了15 ppb（模式范围12至18 ppb）。研究表明，污染地区的臭氧-气候惩罚是由O-3化学品生产速率的增加所驱动的，而O-3化学品生产速率受氮氧化物浓度的强烈影响，因此是特定于所选择的排放途径的。多元线性回归发现，NOx浓度的变化是O-3产量变化的一个强有力的预测因子，而异戊二烯排放率的增加与O-3破坏的增加正相关，这表明在热带非洲和南美洲的大部分地区都存在NOx限制条件。然而，对于气候变化在偏远、低氮氧化物地区的作用，各模式存在分歧，部分原因是各模式产生的氮氧化物浓度存在显著差异。我们还发现，刚果盆地臭氧-气候惩罚的大小和位置在模式间的差异大于亚马逊流域，因此需要进一步的模式开发和验证来约束中非的响应。我们得出的结论是，如果气候根据本文使用的排放情景发生变化，模型预测生物质燃烧地点的森林地区和城市人口将面临高O-3暴露的风险增加，而不考虑通过规定的排放情景对O-3的直接影响。
Climate change has the potential to increase surface ozone (O-3) concentrations, known as the "ozone-climate penalty", through changes to atmospheric chemistry, transport and dry deposition. In the tropics, the response of surface O-3 to changing climate is relatively understudied but has important consequences for air pollution and human and ecosystem health. In this study, we evaluate the change in surface O-3 due to climate change over South America and Africa using three state-of-the-art Earth system models that follow the Shared Socioeconomic Pathway 3-7.0 emission scenario from CMIP6. In order to quantify changes due to climate change alone, we evaluate the difference between simulations including climate change and simulations with a fixed present-day climate. We find that by 2100, models predict an ozone-climate penalty in areas where O-3 is already predicted to be high due to the impacts of precursor emissions, namely urban and biomass burning areas, although on average, models predict a decrease in surface O-3 due to climate change. We identify a small but robust positive trend in annual mean surface O-3 over polluted areas. Additionally, during biomass burning seasons, seasonal mean O-3 concentrations increase by 15 ppb (model range 12 to 18 ppb) in areas with substantial biomass burning such as the arc of deforestation in the Amazon. The ozone-climate penalty in polluted areas is shown to be driven by an increased rate of O-3 chemical production, which is strongly influenced by NOx concentrations and is therefore specific to the emission pathway chosen. Multiple linear regression finds the change in NOx concentration to be a strong predictor of the change in O-3 production, whereas increased isoprene emission rate is positively correlated with increased O-3 destruction, suggesting NOx-limited conditions over the majority of tropical Africa and South America. However, models disagree on the role of climate change in remote, low-NOx regions, partly because of significant differences in NOx concentrations produced by each model. We also find that the magnitude and location of the ozone-climate penalty in the Congo Basin has greater inter-model variation than that in the Amazon, so further model development and validation are needed to constrain the response in central Africa. We conclude that if the climate were to change according to the emission scenario used here, models predict that forested areas in biomass burning locations and urban populations will be at increasing risk of high O-3 exposure, irrespective of any direct impacts on O-3 via the prescribed emission scenario.