GEOG 170A1 Lecture Notes - Lecture 13: Coastal Erosion, Ocean Current, Global Warming In Tuvalu
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14 Nov 2014
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GEOG 170- Earth’s Environment: Introduction to Physical Geography - Lecture 13:
Effects of Climate Change
Wednesday, 10/15/14
● El Nino (The Baby, or Christ child—so named because this happens in December in the
northern hemisphere) results when warm ocean water in the western pacific sloshes
against the Americas (north and South America) in the eastern Pacific.
○ Warmer ocean water piles up in the eastern Pacific, increasing evaporation and,
thus, winter precipitation. La Nina is the opposite.
● Global temperatures have risen 0.5 degrees Celsius over the last 100 years.
○ Ice-albedo Feedback Effect: The Arctic is warming fastest due to the increased
melting of sea ice.
○ This is a positive feedback cycle (i.e., the ice-albedo feedback effect): Increasing
sea surface temps melt increasing amounts of ice and land and water—
decreasing albedo and absorption of insolation, leading to further increases in
land and sea surface temperatures, and melting ice.
● Effects of the ‘melting’ Arctic will be felt at great distances—increasing sea levels and
changing ocean circulation.
○ Ocean circulation (i.e., thermohaline circulation) will change as fresh meltwater
dilutes the saltiness of seawater, changing seawater densities and circulation
patterns.
● Climate change is a general term for all climate changes. Global warming is a special
case of climate change, which refers to increasing surface temperatures due to the
trapping of heat by increased atmospheric greenhouse gasses.
○ Global temperatures have been increasing since the Industrial Revolution.
○ Public uncertainty persists about global warming.
● Tree rings and ice cores tell the ‘deep time’ story about climate change: Tree rings are
thick when precipitation is plentiful, and thin during droughts.
○ Ice cores record atmospheric carbon dioxide (i.e., CO2 bubbles).
○ Greenhouse Effect: Atmospheric CO2 traps and re-radiates outbound thermal
radiation, increasing surface temperatures.
○ China leads in anthropogenic CO2 emissions. Although per capita emissions for
China are low, China’s burgeoning population makes up for this!
● Coastal areas will see greatest impacts of sea level rise: coastal erosion; saltwater
intrusion, storm surges, and displaced populations. Unmitigated disaster!
○ Global warming will produce drought in some areas, floods in other areas.
Everything about Earth’s climate will intensify, as will effects (e.g., Formerly
tropical diseases will migrate north; wildfires will increase in frequency and
intensity).