Changing Earth-Sun Distance Drifts Global Circulation Patterns

Modern observations reveal that large-scale ocean-atmosphere circulation (OAC) is drifting toward higher latitudes under global warming. Paleoclimate proxies indicate that similar OAC drifts occurred on orbital timescale as well. However, the characteristics and underlying mechanisms remain unclear. Here, by conducting simulations with different Earth's orbits, we investigate how changes in Earth-Sun distance affect the OAC. We find that a closer Earth-Sun distance (perihelion) causes a poleward drift of OAC. This drift in circulation is dynamically consistent with displacement of meridional temperature gradient. Precession alters the perihelion season on orbital timescales, leading to a seasonal poleward drift in OAC. This drift is amplified during the hemispheric summer, reaching magnitudes of $\sim$10° under high eccentricity. The identified OAC drifts reshape the seasonality of precipitation and temperature over land, as well as ocean upwelling and downwelling, ultimately affecting the distribution of Earth's terrestrial and marine ecosystems.