Tuesday, 15 March - ICTP/UniTN/UniAQ Joint International Seminar Series on Weather and Climate

[Earth System Physics]

*ICTP/UniTN/UniAQ Joint International Seminar Series
on Weather and Climate: From Fundamentals to Applications*

Tuesday, 15 March at 15:30

**Speaker: Nicole Feldl, University of California at Santa Cruz, USA

Title: *Icy, Moist, and Seasonal: Polar Amplification in Simple and 
Complex Climates*

Register in advance for this meeting:
https://zoom.us/meeting/register/tJAuce-orjIuGdY-H52Uoj03paRhzpIoIwBl

*Abstract*
Since the 1970s, simulations of climate change forced by increased CO2 
concentrations have predicted warming that is greatest in polar regions. 
This polar-amplified warming has been variously attributed to the 
ice-albedo feedback, associated with the retreat of reflective sea ice 
in summer; the lapse rate feedback, associated with vertically 
nonuniform atmospheric warming in winter; and changes in energy 
transport by atmospheric circulations. Uncertainty in projections of 
Arctic climate change arise in part from incomplete understanding of the 
interconnected nature of these processes. Here, I present a new 
implementation of an idealized model to systematically investigate the 
roles of moist energy transport and sea ice in driving polar 
amplification. I additionally introduce a diagnostic decomposition of 
the lapse rate feedback, applied to an ensemble of comprehensive models, 
that isolates influences from dynamically distinct atmospheric regions. 
These analyses reveal the importance of ice thermodynamics and how the 
lapse-rate and sea-ice albedo feedback together dominate Arctic 
amplification as a coupled ocean-atmosphere mechanism operating across 
the seasonal cycle.