Recent Northern Hemisphere tropical expansion primarily driven by black carbon and tropospheric ozone

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Abstract

Observational analyses have shown the width of the tropical belt increasing in recent decades as the world has warmed1. This expansion is important because it is associated with shifts in large-scale atmospheric circulation2,3,4 and major climate zones5,6. Although recent studies have attributed tropical expansion in the Southern Hemisphere to ozone depletion7,8,9,10, the drivers of Northern Hemisphere expansion are not well known and the expansion has not so far been reproduced by climate models11. Here we use a climate model with detailed aerosol physics to show that increases in heterogeneous warming agents—including black carbon aerosols and tropospheric ozone—are noticeably better than greenhouse gases at driving expansion, and can account for the observed summertime maximum in tropical expansion. Mechanistically, atmospheric heating from black carbon and tropospheric ozone has occurred at the mid-latitudes, generating a poleward shift of the tropospheric jet12, thereby relocating the main division between tropical and temperate air masses. Although we still underestimate tropical expansion, the true aerosol forcing is poorly known and could also be underestimated. Thus, although the insensitivity of models needs further investigation, black carbon and tropospheric ozone, both of which are strongly influenced by human activities, are the most likely causes of observed Northern Hemisphere tropical expansion.

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Figure 1: 1970–2009 annual mean tropospheric trends.
Figure 2: Observed and modelled 1979–1999 Northern Hemisphere tropical expansion based on five metrics.
Figure 3: Northern Hemisphere seasonal tropical expansion based on the combined ALL metric.
Figure 4: Northern Hemisphere 1970–2009 annual mean tropical expansion for each metric versus the expansion index for CAM simulations.

References

  1. 1

    Seidel, D. J., Fu, Q., Randel, W. J. & Reichler, T. J. Widening of the tropical belt in a changing climate. Nature Geosci. 1, 21–24 (2008)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Hu, Y. & Fu, Q. Observed poleward expansion of the Hadley circulation since 1979. Atmos. Chem. Phys. 7, 5229–5236 (2007)

    ADS  CAS  Article  Google Scholar 

  3. 3

    Fu, Q., Johanson, C. M., Wallace, J. M. & Reichler, T. Enhanced mid-latitude tropospheric warming in satellite measurements. Science 312, 1179 (2006)

    CAS  Article  Google Scholar 

  4. 4

    Fu, Q. & Lin, P. Poleward shift of subtropical jets inferred from satellite-observed lower stratospheric temperatures. J. Clim. 24, 5597–5603 (2011)

    ADS  Article  Google Scholar 

  5. 5

    Zhou, Y. P., Xu, K.-M., Sud, Y. C. & Betts, A. K. Recent trends of the tropical hydrological cycle inferred from Global Precipitation Climatology Project and International Satellite Cloud Climatology Project data. J. Geophys. Res. 116, D09101 (2011)

    ADS  Google Scholar 

  6. 6

    Bender, F., Ramanathan, V. & Tselioudis, G. Changes in extratropical storm track cloudiness 1983–2008: observational support for a poleward shift. Clim. Dyn. http://dx.doi.org/10.1007/s00382-011-1065-6 (2011)

  7. 7

    Son, S.-W., Tandon, L. M., Polvani, L. M. & Waugh, D. W. Ozone hole and Southern Hemisphere climate change. Geophys. Res. Lett. 36, L15705 (2009)

    ADS  Article  Google Scholar 

  8. 8

    Polvani, L. M., Waugh, D. W., Correa, G. J. P. & Son, S.-W. Stratospheric ozone depletion: the main driver of twentieth-century atmospheric circulation changes in the Southern Hemisphere. J. Clim. 24, 795–812 (2011)

    ADS  Article  Google Scholar 

  9. 9

    Son, S.-W. et al. Impact of stratospheric ozone on Southern Hemisphere circulation change: a multimodel assessment. J. Geophys. Res. 115, D00M07 (2010)

    Article  Google Scholar 

  10. 10

    Kang, S. M., Polvani, L. M., Fyfe, J. C. & Sigmond, M. Impact of polar ozone depletion on subtropical precipitation. Science 332, 951–954 (2011)

    ADS  CAS  Article  Google Scholar 

  11. 11

    Johanson, C. M. & Fu, Q. Hadley cell widening: model simulations versus observations. J. Clim. 22, 2713–2725 (2009)

    ADS  Article  Google Scholar 

  12. 12

    Allen, R. J., Sherwood, S. C., Norris, J. R. & Zender, C. S. The equilibrium response to idealized thermal forcings in a comprehensive GCM: implications for recent tropical expansion. Atmos. Chem. Phys. Discuss. 11, 31643–31688 (2011)

    ADS  Article  Google Scholar 

  13. 13

    Lu, J., Vecchi, G. A. & Reichler, T. Expansion of the Hadley cell under global warming. Geophys. Res. Lett. 34, L06805 (2007)

    ADS  Google Scholar 

  14. 14

    Lu, J., Deser, C. & Reichler, T. Cause of the widening of the tropical belt since 1958. Geophys. Res. Lett. 36, L03803 (2009)

    ADS  Article  Google Scholar 

  15. 15

    Allen, R. J. & Sherwood, S. C. The impact of natural versus anthropogenic aerosols on atmospheric circulation in the Community Atmosphere Model. Clim. Dyn. 36, 1959–1978 (2011)

    Article  Google Scholar 

  16. 16

    Ming, Y., Ramaswamy, V. & Chen, G. A model investigation of aerosol-induced changes in boreal winter extratropical circulation. J. Clim. 24, 6077–6091 (2011)

    ADS  Article  Google Scholar 

  17. 17

    Quaas, J., Boucher, O., Bellouin, N. & Kinne, S. Satellite-based estimate of the direct and indirect aerosol climate forcing. J. Geophys. Res. 113, D05204 (2008)

    ADS  Article  Google Scholar 

  18. 18

    Collins, W. D. et al. Description of the NCAR Community Atmosphere Model (CAM3). Technical Report NCAR/TN-464+STR (National Center for Atmospheric Research, 2004)

    Google Scholar 

  19. 19

    The GFDL Global Atmospheric Model Development Team The new GFDL global atmosphere and land model AM2–LM2: evaluation with prescribed SST simulations. J. Clim. 17, 4641–4673 (2004)

    ADS  Article  Google Scholar 

  20. 20

    Forster, P. et al. In Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (eds Solomon, S. et al.) Ch. 2 130–234 (Cambridge University Press, 2007)

    Google Scholar 

  21. 21

    Schulz, M. et al. Radiative forcing by aerosols as derived from the AeroCom present-day and pre-industrial simulations. Atmos. Chem. Phys. 6, 5225–5246 (2006)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Ramanathan, V. & Carmichael, G. Global and regional climate changes due to black carbon. Nature Geosci. 1, 221–227 (2008)

    ADS  CAS  Article  Google Scholar 

  23. 23

    Sato, M. et al. Global atmospheric black carbon inferred from AERONET. Proc. Natl Acad. Sci. USA 100, 6319–6324 (2003)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Chung, S. H. & Seinfeld, J. H. Global distribution and climate forcing of carbonaceous aerosols. J. Geophys. Res. 107, D19 (2002)

    Google Scholar 

  25. 25

    Dwyer, J. G., Norris, J. R. & Ruckstuhl, C. Do climate models reproduce the observed solar dimming and brightening over China and Japan? J. Geophys. Res. 115, D00K08 (2010)

    ADS  Article  Google Scholar 

  26. 26

    Shindell, D. et al. Simultaneously mitigating near-term climate change and improving human health and food security. Science 335, 183–189 (2012)

    ADS  CAS  Article  Google Scholar 

  27. 27

    Flanner, M. G., Zender, C. S., Randerson, J. T. & Rasch, P. J. Present-day climate forcing and response from black carbon in snow. J. Geophys. Res. 112, D11202 (2007)

    ADS  Article  Google Scholar 

  28. 28

    Flanner, M. G. et al. Springtime warming and reduced snow cover from carbonaceous particles. Atmos. Chem. Phys. 9, 2481–2497 (2009)

    ADS  CAS  Article  Google Scholar 

  29. 29

    Bond, T. C. & Bergstrom, R. W. Light absorption by carbonaceous aerosols: an investigative review. Aerosol Sci. Technol. 40, 27–67 (2006)

    ADS  CAS  Article  Google Scholar 

  30. 30

    Wilks, D. S. Statistical Methods in the Atmospheric Sciences (Academic Press, 2006)

    Google Scholar 

  31. 31

    Adler, R. et al. The version-2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979–present) . J. Hydrometeorol. 4, 1147–1167 (2003)

    ADS  Article  Google Scholar 

  32. 32

    Durre, I., Vose, R. S. & Wuertz, D. M. Overview of the Integrated Global Radiosonde Archive. J. Clim. 19, 53–68 (2006)

    ADS  Article  Google Scholar 

  33. 33

    Kalnay, E. et al. The NCEP/NCAR 40-year reanalysis project. Bull. Am. Meteorol. Soc. 77, 437–471 (1996)

    ADS  Article  Google Scholar 

  34. 34

    Kanamitsu, M. et al. NCEP-DOE AMIP-II Reanalysis (R-2). Bull. Am. Meteorol. Soc. 83, 1631–1643 (2002)

    ADS  Article  Google Scholar 

  35. 35

    Uppala, S. et al. The ERA-40 re-analysis. Q. J. R. Meteorol. Soc. 131, 2961–3012 (2005)

    ADS  Article  Google Scholar 

  36. 36

    Rienecker, M. M. et al. MERRA: NASA’s Modern-Era Retrospective Analysis for Research and Applications. J. Clim. 24, 3624–3648 (2011)

    ADS  Article  Google Scholar 

  37. 37

    Saha, S. et al. The NCEP Climate Forecast System Reanalysis. Bull. Am. Meteorol. Soc. 91, 1015–1057 (2010)

    ADS  Article  Google Scholar 

  38. 38

    Clement, A., Burgman, R. & Norris, J. R. Observational and model evidence for positive low-level cloud feedback. Science 325, 460–464 (2009)

    ADS  CAS  Article  Google Scholar 

  39. 39

    Rossow, W. B. & Schiffer, R. A. ISCCP cloud data products. Bull. Am. Meteorol. Soc. 72, 2–20 (1991)

    ADS  Article  Google Scholar 

  40. 40

    Rossow, W. B. & Schiffer, R. A. Advances in understanding clouds from ISCCP. Bull. Am. Meteorol. Soc. 80, 2261–2287 (1999)

    ADS  Article  Google Scholar 

  41. 41

    Jacobowitz, H. et al. The Advanced Very High Resolution Radiometer Pathfinder Atmosphere (PATMOS) climate data set: a resource for climate research. Bull. Am. Meteorol. Soc. 84, 785–793 (2003)

    ADS  Article  Google Scholar 

  42. 42

    Pavolonis, M., Heidinger, A. & Uttal, T. Daytime global cloud typing from AVHRR and VIRS: algorithm description, validation, and comparisons. J. Appl. Meteorol. 44, 804–826 (2005)

    ADS  Article  Google Scholar 

  43. 43

    Yu, L. & Weller, R. A. Objectively analyzed air-sea heat fluxes for the global ice-free oceans (1981–2005). Bull. Am. Meteorol. Soc. 88, 527–539 (2007)

    ADS  Article  Google Scholar 

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Acknowledgements

This study was funded by R.J.A.’s University of California at Riverside initial complement. We acknowledge the individual modelling groups, the Program for Climate Model Diagnosis and Intercomparison and the Working Group on Coupled Modeling of the World Climate Research Programme (WCRP) for their part in making available the WCRP CMIP3 multimodel data set. Support of this data set is provided by the Office of Science, US Department of Energy.

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R.J.A. conceived the project, designed the study, carried out all data analysis and wrote the manuscript. S.C.S. advised on methods and interpretation, and assisted in the writing of the manuscript. J.N. provided homogenized cloud data and assisted in experimental design. C.S.Z. assisted with CAM experiments, including the SNICAR model.

Corresponding author

Correspondence to Robert J. Allen.

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The authors declare no competing financial interests.

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Allen, R., Sherwood, S., Norris, J. et al. Recent Northern Hemisphere tropical expansion primarily driven by black carbon and tropospheric ozone. Nature 485, 350–354 (2012). https://doi.org/10.1038/nature11097

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