© 2014 Pearson Education, Inc. The Oceans and Climate Change Chapter 1 Clickers Essentials of Oceanography Eleventh Edition Alan P. Trujillo Harold V. Thurman Chapter 16 Lecture

© 2014 Pearson Education, Inc. Chapter Overview Humans are adding greenhouse gases to Earth’s atmosphere. Climate change will cause many severe problems in the ocean environment. It is necessary to reduce and mitigate the effects of these changes.

© 2014 Pearson Education, Inc. Earth’s Climate System Climate – long-term atmospheric conditions in a region Earth’s climate includes interactions of: –Atmosphere –Hydrosphere –Geosphere –Biosphere –Cryosphere

© 2014 Pearson Education, Inc. Earth’s Climate System Climate system – exchanges of energy and moisture between these spheres

© 2014 Pearson Education, Inc. Earth’s Climate System Feedback loops – modify atmospheric processes –Positive feedback loops – enhance initial change –Negative feedback loops – counteract initial change

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Determining Causes of Earth’s Climate Change Paleoclimatology Proxy data – indirect evidence using natural recorders of climate variability –Sea floor sediments –Coral deposits –Glacial ice rings –Tree rings –Pollen –Historical documents

© 2014 Pearson Education, Inc. Proxy Data – Ice Cores

© 2014 Pearson Education, Inc. Natural Causes of Climate Change Solar energy changes –Variable energy from the Sun over time –Luminosity –Sunspots – cooler, episodic dark areas on Sun –Faculae – bright spots on Sun

© 2014 Pearson Education, Inc. Natural Causes of Climate Change Lack of correlation between solar activity and average Earth temperature.

© 2014 Pearson Education, Inc. Natural Causes of Climate Change Variations in Earth’s Orbit Milankovitch Theories –Eccentricity of Earth’s orbit –Obliquity of Earth’s axis –Precession of Earth’s axis

© 2014 Pearson Education, Inc. Variations in Earth’s Orbit

© 2014 Pearson Education, Inc. Changes shape over a period of about 100,000 years, from more circular to more elliptical

© 2014 Pearson Education, Inc. Declination, or tilt, of Earth’s axis changes every 41,000 years. The declination right now is 23.5°. True north (top of Earth) is 23.5°from magnetic north.

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Precession, or wobble, of Earth’s axis changes every 26,000 years.

© 2014 Pearson Education, Inc. Other Changes to Precession Can be caused by major earthquakes that MOVE the Earth! –How an individual earthquake affects Earth's rotation depends on its size (magnitude), location and the details of how the fault slipped. Earth's rotation changes all the time as a result of not only earthquakes, but also the much larger effects of changes in atmospheric winds and oceanic currents.

© 2014 Pearson Education, Inc. According to NASA: NASA applied a complex model to perform a preliminary theoretical calculation of how the Japan earthquake (2011) —the fifth largest since 1900—affected Earth's rotation. –It caused Earth to rotate a bit faster shortening the length of the day by about 1.8 microseconds (a microsecond is one millionth of a second). –shifted the position of Earth's figure axis by about 17 centimeters –This shift in Earth's figure axis will cause Earth to wobble a bit differently as it rotates.

© 2014 Pearson Education, Inc. Natural Causes of Climate Change Volcanic eruptions Volcanic ejecta may block sunlight Need many eruptions in short time period Not observed in recent history

© 2014 Pearson Education, Inc. Natural Causes of Climate Change Movement of Earth’s Plates –Change ocean circulation –Extremely slow process –Climate change would be very gradual over millions of years

© 2014 Pearson Education, Inc. Natural Causes of Climate Change Linked to Pleistocene Ice Age, Little Ice Age, Medieval Warm Period Recent change unprecedented –More likely result of human activity than natural causes

© 2014 Pearson Education, Inc. Documenting Human-Caused Climate Change Intergovernmental Panel on Climate Change (IPCC) –Global group of scientists –Predict global temperature changes of 1.4–5.8°C (2.5–10.4°F)

© 2014 Pearson Education, Inc. Human-Caused Climate Change Climate change models can mimic modern conditions only if human emissions are taken into account.

© 2014 Pearson Education, Inc. Public Service Announcement – Student Output Table Groups work together 30 seconds – will read aloud as a group Every person must have a part Must create an organization name responsible for PSA and state it in PSA Concept must be identified at least twice during PSA At least 5 vocabulary words used in PSA Everyone write it in your Science Notebook for a stamp Have minutes before presenting