Chapter Nineteen Notes - Chapter 19 Climate Change I II...

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Chapter 19: Climate Change I) Both heats and colds are becoming more moderate II) Evidence only gives us a little understanding of what climate was like in the past.  Types of evidence: A) Samples taken from the ocean floor sediments and ice from Greenland 1) Sediment contains the remains of calcium carbonate shells of organisms that once lived near the  surface, since certain organisms live within narrow range of temperature, the distribution and type  of organisms within the sediment indicate the surface water temperature 2) Oxygen-isotope ratio of shells provides information about the sequence of glacier advances.   a) When ocean water evaporates Oxygen-18 remains left behind b) During periods of glacier advance, the ocean contains less water and has a higher  concentration of oxygen-18 c) Provides information about how the climate may have varied in the past d) Higher ration of O-18 to O-16 suggest a colder climate B) Vertical ice cores extracted from ice sheets 1) Glaciers form over land where temperatures are sufficiently low so that during the course of year  more snow falls than will melt and the compact snow recrystallizes into ice 2) Colder the air when snow fell, the richer the concentration of O-16 in the core 3) Record the causes of climate change a) Deduced from layers of sulfuric acid in ice that originally came from large volcanic eruption  and the sulfuric aerosols fell to earth in polar regions as acid snow b) Beryllium isotope that indicates solar activity c) Types of dust collected in the cores indicate whether climate was arid or wet C) Calcium carbonate material that forms otoliths (tiny stones) in inner ears of fish 1) As the otoliths grow they extract oxygen from the lake water 2) Oxygen-isotope ratio provides scientists with information on changes in water temperature over  the life of the fish D) Dendrochronology: study of annual growth rings of trees 1) Changes in thickness of the rings indicate climatic changes that may have taken place from year  to year 2) Presence of frost rings during particularly cold periods and chemistry of the wood itself provide  additional information about the changing climate 3) Only useful in regions that experience an annual cycle and in trees that are stressed by  temperature or moisture during their growing season 4) Growth of tree rings has been correlated with precip. And temp. Patterns for hundreds of years  into the past.
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