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Anderson JG, Clapp CE. Coupling free radical catalysis, climate change, and human health. Phys Chem Chem Phys 2018; 20:10569-10587. [PMID: 29638230 DOI: 10.1039/c7cp08331a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present the chain of mechanisms linking free radical catalytic loss of stratospheric ozone, specifically over the central United States in summer, to increased climate forcing by CO2 and CH4 from fossil fuel use. This case directly engages detailed knowledge, emerging from in situ aircraft observations over the polar regions in winter, defining the temperature and water vapor dependence of the kinetics of heterogeneous catalytic conversion of inorganic chlorine (HCl and ClONO2) to free radical form (ClO). Analysis is placed in the context of irreversible changes to specific subsystems of the climate, most notably coupled feedbacks that link rapid changes in the Arctic with the discovery that convective storms over the central US in summer both suppress temperatures and inject water vapor deep into the stratosphere. This places the lower stratosphere over the US in summer within the same photochemical catalytic domain as the lower stratosphere of the Arctic in winter engaging the risk of amplifying the rate limiting step in the ClO dimer catalytic mechanism by some six orders of magnitude. This transitions the catalytic loss rate of ozone in lower stratosphere over the United States in summer from HOx radical control to ClOx radical control, increasing the overall ozone loss rate by some two orders of magnitude over that of the unperturbed state. Thus we address, through a combination of observations and modeling, the mechanistic foundation defining why stratospheric ozone, vulnerable to increased climate forcing, is one of the most delicate aspects of habitability on the planet.
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Affiliation(s)
- J G Anderson
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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Anderson JG, Weisenstein DK, Bowman KP, Homeyer CR, Smith JB, Wilmouth DM, Sayres DS, Klobas JE, Leroy SS, Dykema JA, Wofsy SC. Stratospheric ozone over the United States in summer linked to observations of convection and temperature via chlorine and bromine catalysis. Proc Natl Acad Sci U S A 2017; 114:E4905-E4913. [PMID: 28584119 PMCID: PMC5488921 DOI: 10.1073/pnas.1619318114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present observations defining (i) the frequency and depth of convective penetration of water into the stratosphere over the United States in summer using the Next-Generation Radar system; (ii) the altitude-dependent distribution of inorganic chlorine established in the same coordinate system as the radar observations; (iii) the high resolution temperature structure in the stratosphere over the United States in summer that resolves spatial and structural variability, including the impact of gravity waves; and (iv) the resulting amplification in the catalytic loss rates of ozone for the dominant halogen, hydrogen, and nitrogen catalytic cycles. The weather radar observations of ∼2,000 storms, on average, each summer that reach the altitude of rapidly increasing available inorganic chlorine, coupled with observed temperatures, portend a risk of initiating rapid heterogeneous catalytic conversion of inorganic chlorine to free radical form on ubiquitous sulfate-water aerosols; this, in turn, engages the element of risk associated with ozone loss in the stratosphere over the central United States in summer based upon the same reaction network that reduces stratospheric ozone over the Arctic. The summertime development of the upper-level anticyclonic flow over the United States, driven by the North American Monsoon, provides a means of retaining convectively injected water, thereby extending the time for catalytic ozone loss over the Great Plains. Trusted decadal forecasts of UV dosage over the United States in summer require understanding the response of this dynamical and photochemical system to increased forcing of the climate by increasing levels of CO2 and CH4.
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Affiliation(s)
- James G Anderson
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138;
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - Debra K Weisenstein
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - Kenneth P Bowman
- Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843
| | | | - Jessica B Smith
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - David M Wilmouth
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - David S Sayres
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - J Eric Klobas
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Stephen S Leroy
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - John A Dykema
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - Steven C Wofsy
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
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Terao Y, Sugita T, Sasano Y. Ozone loss rates in the Arctic winter stratosphere during 1994-2000 derived from POAM II/III and ILAS observations: Implications for relationships among ozone loss, PSC occurrence, and temperature. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd016789] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wilmouth DM, Stimpfle RM, Anderson JG, Elkins JW, Hurst DF, Salawitch RJ, Lait LR. Evolution of inorganic chlorine partitioning in the Arctic polar vortex. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jd006951] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Thornton BF, Toohey DW, Avallone LM, Hallar AG, Harder H, Martinez M, Simpas JB, Brune WH, Koike M, Kondo Y, Takegawa N, Anderson BE, Avery MA. Variability of active chlorine in the lowermost Arctic stratosphere. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004jd005580] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Hanisco TF. In situ observations of HO2and OH obtained on the NASA ER-2 in the high-ClO conditions of the 1999/2000 Arctic polar vortex. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001jd001024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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