How much will future mid-latitude extremes respond to a changing meridional surface temperature gradient?

Arctic amplification (AA) has the potential to modify the atmospheric general circulation, which could affect temperature and precipitation extremes throughout the Northern Hemisphere. However, detecting this influence is a significant challenge due to a small observational record and large internal variability. This challenge also extends to model-based studies seeking to attribute extremes to AA; different studies reach different conclusions depending on the initial state of the climate system, the processes and couplings represented in the model, and the way in which AA is prescribed in the model. The implementation of AA in models almost exclusively focuses on some sort of imposed sea-ice loss or manipulation of sea-ice albedo. While current research is beginning to suggest that sea-ice loss can generate vertically propagating planetary waves which may affect the timing of the breakdown of the stratospheric polar vortex, focusing on sea-ice loss neglects the importance of the weakening surface meridional temperature gradient as the defining signal of AA and does not falsify the hypothesis that changes in the strength of the meridional temperature gradient could affect the strength of the baroclinic jets and thereby Rossby wave propagation and any related extremes. For this work, we simulate two global warming scenarios under 1% CO2 increases per year using a fully-coupled Earth system model. The first simulation is allowed to develop AA as expected; the second masks AA by "locking" the surface meridional temperature gradient through direct modification of solar radiation while still allowing the mean global surface temperature to increase in response to CO2 forcing. By comparing changes in local wave activity between the two simulations, we are able to determine the role that the changing meridional surface temperature gradient plays in the development of midlatitude extremes and to link changes in those extremes to changes in jet dynamics.