Is Arctic Amplification dominated by regional radiative forcing

Is Arctic Amplification dominated by regional radiative forcing and feedbacks: Perspectives from the * World-Avoided scenario John G. Virgin 1 & Karen L. Smith 2, 3 1 Department of Geography & Environmental Management University of Waterloo, Ontario, Canada 2 Department of Physical and Environmental Sciences University of Toronto Scarborough, Toronto, Ontario, Canada 3 Lamont-Doherty Earth Observatory Palisades, New York, NY 27 th IUGG General *Recently accepted to Geophysical Research Letters

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Arctic Amplification • Typically associated with meridionally varying radiative feedbacks • The Planck and lapse rate feedbacks dominate in the winter • The surface albedo feedback dominates in the summer Virgin & Smith (2019): Is AA dominated by regional radiative forcing and Pithan & Mauritsen (2014) 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Poleward Energy Transport The role of poleward energy flux into in contributing to AA is not as well understood… Zelinka & Hartmann (2012) Hwang, Frierson, and Kay (2011) Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Radiative Forcing AA is typically evaluated in response to a radiative forcing that is either spatially homogenous or highly idealistic Stuecker et al. (2018) Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Model Integrations Representative Concentration Pathway 4. 5 (RCP 45) • Greenhouse gas concentrations rise to 538 ppm and stabilize after 2100 The World Avoided (WAVD) • ODS emissions set to grow at 3. 5% per year from 1985 onwards Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments The Whole Atmosphere Community Climate Model (WACCM 4) • “High-top” Chemistry-Climate Model • Similar physical parametrizations to the “low-top” CAM 4 • Chemistry component that couples chemical, radiative, and dynamical processes in the stratosphere • 66 vertical levels resolving up into the lower thermosphere WACCM 4 CLM Virgin & Smith (2019): Is AA dominated by regional radiative forcing and CPL POP CICE 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments The Arctic Energy Budget • Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments The Arctic Energy Budget • Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments The Arctic Energy Budget • Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments The Arctic Energy Budget • Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments The Arctic Energy Budget • Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments The Arctic Energy Budget • Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments The Arctic Energy Budget • Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Radiative Forcing • The global mean net RF in the WAVD is 3. 76 Wm-2 • Combined result of both GHG’s and ODS’s • Stratospheric ozone loss results in a negative (-0. 19 Wm-2) net Arctic RF in the WAVD • Long-wave = -0. 48 Wm-2 • Short-wave = 0. 29 Wm-2 Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Arctic Energy Budget Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Arctic Energy Budget Statistically Significant differences between scenarios for: • LW Cloud feedback • PET by the atmosphere Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Contributions of Uncertainty • The stratosphere-adjusted radiative forcing, as opposed to the effective radiative forcing • Cloud feedback quantification using the adjusted cloud radiative effect Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Concluding Remarks • Despite a negative net RF in the Arctic in the WAVD from ozone loss, AA still occurred at a similar magnitude to RCP 45 Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Concluding Remarks • Despite a negative net RF in the Arctic in the WAVD from ozone loss, AA still occurred at a similar magnitude to RCP 45 • In the WAVD, AA is maintained by greater energy flux convergence into the Arctic by the atmosphere, and a stronger long-wave cloud feedback Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments Concluding Remarks • Despite a negative net RF in the Arctic in the WAVD from ozone loss, AA still occurred at a similar magnitude to RCP 45 • In the WAVD, AA is maintained by greater energy flux convergence into the Arctic by the atmosphere, and a stronger long-wave cloud feedback • Arctic Amplification under the presence of a negative radiative forcing highlights that its key drivers (forcing, feedbacks, or poleward energy transport) may depend on the context of the evolving climate state & experiment design Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments FIN Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General

Introduction – Methods – Results – Limitations – Conclusions - Acknowledgments This work has been supported by: Article Full Citation: • • Department of Physical & Environmental Sciences, University of Toronto Scarborough Virgin, J. G. , & Smith, K. L. (2019). Is Arctic Amplification dominated by regional radiative forcing and feedbacks: Perspectives from the World-Avoided scenario. Geophysical Research Letters, 46(11). https: //doi. org/10. 1029/2019 GL 082320 References: • NSF Division of Polar Programs award: PLR-1603350 • Hwang, Y. -T. , Frierson, D. M. , & Kay, J. E. (2011). Coupling between arctic feedbacks and changes in poleward energy transport. Geophysical Research Letters, 38(17). • Pithan, F. , & Mauritsen, T. (2014). Arctic amplification dominated by temperature feedbacks in contemporary climate models. Nature Geoscience, 7 (3), 181. • Stuecker, M. F. , Bitz, C. M. , Armour, K. C. , Proistosescu, C. , Kang, S. M. , Xie, S. -P. , . . . others (2018). Polar amplification dominated by local forcing and feedbacks. Nature Climate Change, 8(12), 1076 • Zelinka, M. D. , & Hartmann, D. L. (2012). Climate feedbacks and their implications for poleward energy flux changes in a warming climate. Journal of Climate, 25 (2), 608 -624. Data Access: • Post-Processed Data files: • https: //arcticdata. io/catalog/view/doi: 10. 1873 9/A 2416 SZ 8 Z • Plotting Scripts: • https: //github. com/John. Virgin/Perspectives. From-World-Avoided. Virgin & Smith (2019): Is AA dominated by regional radiative forcing and 27 th IUGG General