2024-06-05 ノースカロライナ州立大学(NCState)
＜関連情報＞
- https://news.ncsu.edu/2024/06/climate-change-and-ozone/
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023EF003941
不確実な気候感受性の下でのオゾン汚染現象の頻度と大きさの変化の予測 Projecting Changes in the Frequency and Magnitude of Ozone Pollution Events Under Uncertain Climate Sensitivity
James D. East, Erwan Monier, Rebecca K. Saari, Fernando Garcia-Menendez
Earth’s Future Published: 02 June 2024
DOI:https://doi.org/10.1029/2023EF003941
Abstract
Climate change is projected to worsen ozone pollution over many populated regions, with larger impacts at higher concentrations. More intense and frequent ozone episodes risk setbacks to human health and environmental policy achievements. However, assessing these changes is complicated by uncertain climate sensitivity, closely related to climate model response, and internal variability in simulations projecting climate’s influence on air quality. Here, leveraging a global modeling framework that one-way couples a human activity model, an Earth system model of intermediate complexity, and an atmospheric chemistry model, we investigate the role of climate sensitivity in climate-induced changes to high ozone pollution episodes in the United States using multiple greenhouse gas emissions scenarios, representations of climate sensitivity, and initial condition members. We bias correct and evaluate historical model simulations, identifying modeled and observed O3 episodes using extreme value theory, and extend the approach to projections of mid- and end-century climate impacts. Results show that the influence of climate sensitivity can be as significant as that of greenhouse gas emissions scenario absent precursor emissions changes. Climate change is projected to increase the magnitude of the highest annually occurring O3 concentrations by over 2.3 ppb on average across the U.S. at mid-century under a high climate sensitivity and moderate emissions scenario, but the increase is limited to less than 0.3 ppb under lower climate sensitivity. Further, we show that areas in the U.S. currently meeting air quality standards risk being pushed into non-compliance due to a climate-induced increase in frequency of high ozone days.
Key Points
- We project climate impacts on US ozone episodes with spatially varying bias correction and a climate and air quality simulation ensemble
- Climate sensitivity can be as influential as GHG scenario without air pollutant emissions changes in mid-century ozone episodes
- Climate-induced increases in ozone pollution may increase risk of not meeting air quality standards in several areas of the U.S.
Plain Language Summary
Climate change can worsen O3 air pollution across much of the U.S., threatening environmental policy goals and posing health risks. Projections of this impact rely on models that have uncertainties associated with simulating future climate. We investigated the influence of uncertainty from climate sensitivity, or the simulated change in Earth’s average surface temperature in response to an increase in atmospheric CO2, on projections of air quality using a collection of simulations. To improve O3 estimates based on model simulations, we applied a new bias correction method to the model concentrations that accounts for spatial differences in atmospheric pollution. Then, we applied extreme value statistics to describe the behavior of the highest O3 concentrations. We found that, under climate change, the most polluted days worsen and occur more frequently, making it more difficult to meet air quality standards in highly populated regions and suggesting that continued efforts to mitigate pollutant emissions are necessary to counteract climate change’s effects on O3. Further, our results indicate that the model’s climate sensitivity is as influential as greenhouse gas emissions scenario for mid-century projections, showing that the strength of the earth system’s response to greenhouse gas levels is a critical consideration when simulating climate impacts.
