sentences:  Palaeobotany relies on the fact that each ecosystem is characterised by certain plants, which in turn act as a proxy for climate by knowing which modern habitats they occur in.A lake core taken from "Sacred lake" at on the mountain, traces the warming of the climate by studying pollen found in the core.The depth of the core can be calibrated with an age by using carbon-14 dating techniques assuming a constant sedimentation rate.