We generated five new and compiled previously published Holocene temperature timeseries from southwestern Greenland. We found temperature maxima between 7500 and 5000 years ago, with temperatures approx. 2–5 °C higher than 1994–2024. Afterward, temperatures gradually cooled towards the present, following maximum summer insolation. Local variations in the magnitude and timing of the thermal maximum are related to topography and proximity to the ice sheet and the ocean.

During the last ice age, Northern Hemisphere ice sheets reshaped global climate. They shifted North Atlantic winds southward, increasing summer rainfall across Eurasia. They also altered tropical and Southern Hemisphere weather patterns, affecting rainfall far beyond the ice-covered regions. Our results show that the height and shape of the ice sheets had a much greater influence on global wind and rainfall patterns than changes in Earth’s orbit, greenhouse gases, or surface reflectivity.