Poster's note : there's also a useful paper examining the same thing from a
paleo point of view

Energy transport, polar amplification, and ITCZ shifts in the GeoMIP G1
Rick D. Russotto1 and Thomas P. Ackerman1,21Department of Atmospheric
Sciences, University of Washington, Seattle, WA, USA
2Joint Institute for the Study of the Atmosphere and Ocean, University of
Washington, Seattle, WA, USA
Received: 03 Sep 2017 – Discussion started: 12 Sep 2017
Revised: 21 Dec 2017 – Accepted: 04 Jan 2018 – Published: 15 Feb 2018
Abstract. The polar amplification of warming and the ability of the
Intertropical Convergence Zone (ITCZ) to shift to the north or south are
two very important problems in climate science. Examining these behaviors
in global climate models (GCMs) running solar geoengineering experiments is
helpful not only for predicting the effects of solar geoengineering but
also for understanding how these processes work under increased carbon
dioxide (CO2). Both polar amplification and ITCZ shifts are closely related
to the meridional transport of moist static energy (MSE) by the atmosphere.
This study examines changes in MSE transport in 10 fully coupled GCMs in
experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP),
in which the solar constant is reduced to compensate for the radiative
forcing from abruptly quadrupled CO2 concentrations. In G1, poleward MSE
transport decreases relative to preindustrial conditions in all models, in
contrast to the Coupled Model Intercomparison Project phase 5 (CMIP5)
abrupt4xCO2 experiment, in which poleward MSE transport increases. We show
that since poleward energy transport decreases rather than increases, and
local feedbacks cannot change the sign of an initial temperature change,
the residual polar amplification in the G1 experiment must be due to the
net positive forcing in the polar regions and net negative forcing in the
tropics, which arise from the different spatial patterns of the
simultaneously imposed solar and CO2 forcings. However, the reduction in
poleward energy transport likely plays a role in limiting the polar warming
in G1. An attribution study with a moist energy balance model shows that
cloud feedbacks are the largest source of uncertainty regarding changes in
poleward energy transport in midlatitudes in G1, as well as for changes in
cross-equatorial energy transport, which are anticorrelated with ITCZ

*Citation:* Russotto, R. D. and Ackerman, T. P.: Energy transport, polar
amplification, and ITCZ shifts in the GeoMIP G1 ensemble, Atmos. Chem.
Phys., 18, 2287-2305,, 2018

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