sentences:  Before the Younger Dryas temperatures were similar to present but the forest cover incomplete.During the younger Dryas 12.9-11.5 kya brought about by the last Heinrich event, there was a pronounced weakening of the summer monsoon over East Africa, and montane forest retreated and East African lake levels fell.Forests reached the same range and density as present day after the younger Dryas when the climate again became moister.