Freshwater discharges in a simulation of the Last Glacial Maximum climate using improved river routing

Abstract

[1] The large ice-sheets over North America and Europe at the Last Glacial Maximum (LGM) strongly disturbed river pathways. This has never been taken into account in simulations of the LGM climate, even if it could have an impact on the freshwater input to the ocean. Here, we have introduced a more realistic river routing in LGM atmospheric general circulation model simulations. A comparison with classical LGM simulations shows that the discharge into the Arctic Ocean is not drastically different. Even if the Ob and Yenisei rivers could not reach the Arctic Ocean because of the Fennoscandian ice sheet (which results in a lake South of this ice sheet), the discharge of other rivers nearby is increased due to the influence of this lake. The maximum monthly discharge into the North Atlantic Ocean decreases by 34000 m3/s between 54 and 66°N, while it is stronger by 35000 m3/s between 28 and 54°N.