Dust Decline Amplifies High‐Cloud Ice‐to‐Liquid Transition and Buffers the Radiative Feedback Under Warming

Abstract The response of the cloud phase to global warming is a critical yet poorly constrained component of Earth's climate sensitivity. While rising temperatures drive a thermodynamic transition from ice to liquid clouds, the role of ice‐nucleating particles in modulating this shift remains underexplored. Here, we provide evidence that the declining trend of mineral dust in the Northern Hemisphere (NH) may act as a microphysical amplifier of this transition. Satellite observations of high clouds (<440 hPa) in mid‐high latitudes show the NH undergoes more rapid ice‐to‐liquid replacement than the Southern Hemisphere, which increases cloud optical depth and creates a radiative buffer (cooling feedback) that offsets 25% of the positive net feedback by global warming. These findings highlight a hemisphere‐dependent coupling between aerosol trends and high‐cloud feedbacks, suggesting this overlooked buffering mechanism is essential for refining climate sensitivity estimates and reducing systematic biases in warming projections.