ENVIRSC 3CC3 Midterm: Chapter 7 Midterm Notes

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Chapter 7: from greenhouse to icehouse - the last 50 million years. From greenhouse to icehouse: the last 50 million years. The past 50 million years has seen a transition from greenhouse climate to icehouse - so. There is evidence showing that this occurred where ice is present. There are two possible explanations for why this occurred. As the climate cools two types of glacial ice form on land. There was an asteroid impact about 65 myr, and no evidence of any substantial amount. 35 myr we see first local ice on antarctica. The first continental ice sheets of significant size - 2. 75 myr. Fossil remains of vegetation in both hemispheres indicate progressive cooling. Appearance of conifer forests of spruce and larch by 20 myr. Smooth-edged leaves = warmer, jagged-edged leave colder climates. Estimated temperature trend shows erratic but progressive cooling in northern middle latitudes. Parts of the deep ocean have accumulated a continuous climate record for the whole 50.