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Abstract Tropical precipitation extremes are expected to strengthen with warming, but quantitative estimates remain uncertain because of a poor understanding of changes in convective dynamics. This uncertainty is addressed here by analyzing idealized convection-permitting simulations of radiative–convective equilibrium in long-channel geometry. Across a wide range of climates, the thermodynamic contribution to changes in instantaneous precipitation extremes follows near-surface moisture, and the dynamic contribution is positive and small but is sensitive to domain size. The shapes of mass flux profiles associated with precipitation extremes are determined by conditional sampling that favors strong vertical motion at levels where the vertical saturation specific humidity gradient is large, and mass flux profiles collapse to a common shape across climates when plotted in a moisture-based vertical coordinate. The collapse, robust to changes in microphysics and turbulence schemes, implies a thermodynamic contribution that scales with near-surface moisture despite substantial convergence aloft and allows the dynamic contribution to be defined by the pressure velocity at a single level. Linking the simplified dynamic mode to vertical velocities from entraining plume models reveals that the small dynamic mode in channel simulations (≲2% K−1) is caused by opposing height dependences of vertical velocity and density, together with the buffering influence of cloud-base buoyancies that vary little with surface temperature. These results reinforce an emerging picture of the response of extreme tropical precipitation rates to warming: a thermodynamic mode of about 7% K−1 dominates, with a minor contribution from changes in dynamics. 

Abstract. Over the past 0.8 million years, 100kyr ice ages have dominatedEarth's climate with geological evidence suggesting the last glacialinception began in the mountains of Baffin Island. Currently,state-of-the-art global climate models (GCMs) have difficulty simulatingglacial inception, possibly due in part to their coarse horizontal resolutionand the neglect of ice flow dynamics in some models. We attempt to addressthe role of regional feedbacks in the initial inception problem on BaffinIsland by asynchronously coupling the Weather Research and Forecast (WRF) model,configured as a high-resolution inner domain over Baffin and an outerdomain incorporating much of North America, to an ice flow model using theshallow ice approximation. The mass balance is calculated from WRFsimulations and used to drive the ice model, which updates the ice extentand elevation, that then serve as inputs to the next WRF run. We drive theregional WRF configuration using atmospheric boundary conditions from 1986that correspond to a relatively cold summer, and with 115kya insolation.Initially, ice accumulates on mountain glaciers, driving downslope ice flowwhich expands the size of the ice caps. However, continued iterations of theatmosphere and ice models reveal a stagnation of the ice sheet on BaffinIsland, driven by melting due to warmer temperatures at the margins of theice caps. This warming is caused by changes in the regional circulation thatare forced by elevation changes due to the ice growth. A stabilizing feedbackbetween ice elevation and atmospheric circulation thus prevents fullinception from occurring.