Scientists supported by CPO’s Atmospheric Chemistry, Carbon Cycle and Climate (AC4) Program are investigating the hydroxyl radical (OH), a molecule that despite its short lifetime of a few seconds, reacts with harmful gases and acts as a cleaning agent in Earth’s atmosphere. AC4-funded scientist Loretta Mickley of Harvard University worked with a team of researchers to compile a review exploring how OH, influenced by climate and human activities, impacts air quality, climate, and public health. This study works toward an AC4 initiative to explain trends, patterns, and extremes detectable in the existing long–term observational records of atmospheric composition.
OH reacts with certain air pollutants and greenhouse gases, breaking them down to help maintain air quality. However, difficulties in directly observing OH responses to climate and uncertainties in models make it challenging to predict OH changes. Climate warming, emissions, and human choices contribute to this complexity. Moreover, in a warmer climate, OH concentration in the atmosphere will increase primarily because of its dependence on water vapor. To confidently project OH, scientists need to reduce uncertainties in reactions, measurements, and emissions. This study, published in the Annual Review of Earth and Planetary Sciences, recommends specific constraints on measured and modeled reactions to enhance confidence in regional and global OH budgets. The authors lay out future considerations based on climate projections and technological advances, and stress that future work should aim to reduce uncertainty through coordinated laboratory, field, and modeling efforts.
For more information, contact Clara Deck.
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