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The lapse rate feedback is the dominant driver of stronger warming in the Arctic than the Antarctic in simulations with increased CO2. While Antarctic surface elevation has been implicated in promoting a weaker Antarctic lapse rate feedback, the mechanisms in which elevation impacts the lapse rate feedback are still unclear. Here we suggest that weaker Antarctic warming under CO2 forcing stems from shallower, less intense climatological inversions due to limited atmospheric heat transport above the ice sheet elevation and elevation‐induced katabatic winds. In slab ocean model experiments with flattened Antarctic topography, stronger climatological inversions support a stronger lapse rate feedback and annual mean Antarctic warming comparable to the Arctic under CO2 doubling. Unlike the Arctic, seasonality in warming over flat Antarctica is mainly driven by a negative shortwave cloud feedback, which exclusively dampens summer warming, with a smaller contribution from the winter‐enhanced lapse rate feedback. Plain Language Summary: Models project stronger surface warming in the Arctic than the Antarctic under climate change. A climate feedback in which more warming occurs near the surface than at higher altitudes in the atmosphere promotes this stronger Arctic warming. Antarctica's surface elevation is thought to weaken this feedback in comparison to the Arctic, but how this occurs is unclear. Here we show that Antarctic elevation weakens surface warming by changing the base state vertical temperature structure. When Antarctic topography is flattened in model experiments, Antarctica experiences more warming under climate change, resembling Arctic warming. Similarly to the Arctic, flat Antarctica warms most during the winter, but this seasonality is driven by different climate feedbacks in the Arctic versus Antarctic. These results indicate the importance of base state temperatures for warming under climate change and suggest that strong polar amplification is possible without local sea ice loss. Key Points: Antarctic elevation causes asymmetry in climatological inversions, lapse rate feedbacks, and warming between the polesIn model experiments with flattened Antarctica, strengthened inversions lead to stronger lapse rate feedback and Antarctic amplificationShortwave cloud feedback promotes seasonality in flat Antarctic warming; lapse rate feedback more strongly promotes seasonality in Arctic [ABSTRACT FROM AUTHOR]

An atmospheric GCM coupled to a slab ocean model is used lo investigate how temperature and precipitation over South America and Africa affect the annual cycle of the Atlantic ITCZ. The main conclusion of this study is that variations in precipitation and temperature forced by the annual cycle of insolation over the continents are as important as variations in insolation over the ocean and in ocean heal transport convergence in forcing the annual march of the Atlantic ITCZ observed in the control simulation. The processes involved are as follows. The intensity of precipitation over land affects the stability of the atmosphere over the tropical Atlantic Ocean, and thus modulates the intensity of deep convection and convergence in the ITCZ. Both the imposed changes in land precipitation and the subsequent changes in the strength of the ITCZ drive surface wind anomalies, thereby changing the meridional gradient of SST in proximity of the basic-stale ITCZ. Finally, atmosphere-ocean feedbacks cause the ITCZ to be displaced meridionally. Seasonal changes in surface temperature in the Sahara also have a strong influence on the position of the Atlantic ITCZ. Cold wintertime temperatures produce high surface pressure anomalies over Africa and into the tropical North Atlantic and drive stronger trade winds, which cool the North Atlantic by evaporation. The coupled interactions between the SST. the wind, and the ITCZ intensify the anomalies in the equatorial region, causing the southward displacement of the ITCZ in boreal spring. [ABSTRACT FROM AUTHOR]