GC 170A1 1st Edition Lecture 17 Outline of Last Lecture I. Group ActivityOutline of Current Lecture I. Climate Change Impacts: a. Arctic Sea Icei. Changes over the past yearsb. Ice Sheetsi. Consequences ii. Dynamics c. Glaciersi. Photography II. Sustainable City AssignmentCurrent LectureThe increasing temperature trend depends on: - Volcanoes and sunspots (natural)- Fossil fuels, deforestation (human) - Global Climate Models can reproduce the increasing temperature trend of the 20th century. o Blue line = model output o Black line = observations of temperatureo No increasing trend in the natural temperature without the influence of humansClimate Change Impacts: - Arctic Sea Ice- Ice Sheets- GlaciersThree Main sources of ice on Earth- Arctic Sea Iceo Frozen sea water on the ocean surface o Fluctuates seasonallyo Changes in Arctic Sea Ice over the past 35 years: Decreasing in areaThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Decreasing in thickness Does not contribute to global sea-level rise New shipping routes will open in the arctic: good for the economy Reduced Albedo (more incoming radiation absorbed at surface) Change in storms and weather patterns in the arctic- Jet Stream Effecto Poles are becoming warming relative to the equator o Less of a temperature gradient between poles and equatoro Jet Stream becomes wavier and slower- Ice sheets (Greenland/Antarctica)o Snow accumulates over thousands of years o Compresses and becomes ice o Rests on a land surfaceo What scientists are doing Snow accumulation being measured on the surface Surface melting is being monitored daily by satelliteso Consequences of melting ice: Accelerates ice flow which leads to further melting Potential for sea-level rise Glaciers on the east and west sides of Antarctica are rapidly melting and retreating Ice shelf is becoming thinner and grounding line is rapidly retreating- Ice Sheet Dynamics: o Ice Sheets are very thick (3,000 – 4,000 meters) (1 – 2 miles thick) o Thickest in the center and thinner towards the edges o Ice flows outwards from the center- Mountain Glacierso Mass of ice on a mountain or in an alpine valley o Formed by constant accumulation of snow o Requires permanent, year-round snow to form iceo Greatest amount of melting in response to Global Warming o Sensitive to small changes in temperatureo Repeat photography is a qualitative way of measuring the changes happening in glaciers- Sea-Level Riseo Mostly related to melting of mountain glaciers and ice sheetso A large portion is also related to thermal expansion of ocean water related to global warming- Sustainable City Assignmento Read about the carbon emissions for another city in the US/World (we give suggestions) Compare with Tucson carbon emissions Learn about influences on Tucson emissions and then read a news article about efforts to reduce
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