Here is a NASA-generated graph of the dO 18 values of shells of marine animals t
ID: 119306 • Letter: H
Question
Here is a NASA-generated graph of the dO18 values of shells of marine animals termed foraminifera found in deep sea cores. The graph below shows the results of averaging thousands of deep sea core data to produce an “average ocean” value for fluctuation of dO18 in the ocean water over the past 600,000 years. Demonstrate that you understand how to interpret dO18 data by interpreting the trends shown on the graph. Examine the data on the Y axis: do the trends where the red line drops towards the X axis represent global cooling of the oceans and the formation of ice sheets at the poles (and the red line rising to peaks represents global warm periods) OR does the red line falling trend represent global warm periods and the rising limbs of the curve represent global cooling? Answer the question by labeling which of the peaks are “cold” and “warm” periods.
Averaged 180 in deep sea sediment carbonate 1.2 1.0 0 -4 -6 0 50 100 150 200 250 300 350 400 450 500 550 600 Thous ands of Years Before PresentExplanation / Answer
Oxygen isotopic ratio cycles are cyclical variations in the ratio of abundance of oxygen with an atomic mass of 18 to the abundance of oxygen with an atmoic mass of 16.
Delta O-18 changes directly as a result of temperature fluctuations, Delta O 18 values that are high represent cold climate and that are low represent warm climate.
So in the graph given in the question the peaks of the graph represent colder climate and the depths represent warm climate , The highest peak is the most coldest one and the lowest value is warmest and it keeps on decreasing as the peak deteriorates.
Also the thing to notice is that the height of the peaks have been decreasing which tell us that the earth as a whole is warming as compared to the previous years.
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