Guide #11 (F04)
|GEOL 125: Earth History|
What evidence exists that past climate differed from today's climate? Where can we look to find relatively continuous records of climate change, and how are changes recorded?
How do foraminifera (foram) shells record variations in ice volume and temperature? What mechanisms cause fractionation of oxygen isotopes as climate changes?
Draw a graph showing the changes in foram 180/160 ratios during the Cenozoic. What does this indicate about climate? Why might climate have changed during the Cenozoic?
Draw a graph showing the 180/160 ratio in foram shells (CaCO3) in deep sea sediments vs. time during the past 150,000 years. What does this indicate about the past climate of the earth? When did the last major glaciation end? How does this graph compare to the records of CO2 in ice cores and to the Milankovitch curve?
What factors favor the growth of large ice sheets? Why? How long does it take to accumulate an ice sheet 2 km thick, if the average accumulation rate (precipitation minus evaporation) is 10 cm/y?
What aspects of the Earth's orbit around the sun may vary, and what effect does this have on seasonality? How might tectonics influence global climate? What correlations exist between continental configuration and climate?
How has the CO2 content of the atmosphere changed with time? Draw one graph showing CO2 concentration since 1800 and another to show the changes over the past 200 kyr. How has this information been obtained? Why is the CO2 content of the atmosphere increasing at present? What effect might this have on climate? Why? Would this be beneficial or harmful? Explain.
Is there evidence that climate is warming at present? What effect might this have on rainfall? How might climate change and the concentration of atmospheric CO2 be linked? (Hint - there are two different linkages that have been proposed.)
What is meant by the term 'Snowball Earth'? What is the evidence that this was ever the condition? When did this occur? What might permit the earth to escape from the snowball Earth condition?
Terms to know
|albedo||latent heat||sensible heat|
|planktonic foram||glacial moraine||U-shaped valley|
|marine terrace||wave-cut bench||ice cores|
|stratosphere||troposphere||drowned river valley|
|Younger-Dryas||pollen||continental ice sheet|
|snowball earth||multiple stable states||ice-rafted debris|