Amplified Late Pliocene terrestrial warmth in northern high latitudes from greater radiative forcing and closed Arctic Ocean gateways

By comparing CCSM4 simulations with proxy records, we demonstrate that both model and proxy records show similar patterns of mPWP NHL terrestrial warmth, but the model underestimates the magnitude. High insolation, greater CO2 forcing, and Arctic gateways closure each contributes to reduce the underestimate by enhancing the Arctic warmth of 1-2 °C. These results highlight the importance of considering proxy NHL warmth in the context of Pliocene Arctic gateway changes, and variations in insolation and CO2 forcing.