Geophysical Research Letters

Simulation of intense monsoons under glacial conditions



Paleoenvironmental and paleoclimatological proxy data indicate that strong continental monsoons took place under glacial conditions during marine isotopic stage 6.5 (175 ka BP). So far, no climate model has explored the possible coexistence of glacial conditions at mid and high latitudes and of interglacial monsoons in the tropics. Here we use an atmospheric general circulation model and clearly demonstrate that high insolation can generate increased monsoon activity even with surface glacial conditions. Our experiments show that Indian and African monsoons at 175 ka were stronger than nowadays and induced an increase in outflow of the Nile river to the Mediterranean sea. This freshwater supply combined with the local low glacial evaporation may explain the stagnation of the Eastern Mediterranean sea leading to the deposit of sapropel S6. Our simulations show also increased surface winds in the northern Atlantic and Pacific oceans which may have affected the bioproductivity in these areas.