GC 170A1 1st Edition Lecture 17 Outline of Last Lecture I Group Activity Outline of Current Lecture I Climate Change Impacts a Arctic Sea Ice i Changes over the past years b Ice Sheets i Consequences ii Dynamics c Glaciers i Photography II Sustainable City Assignment Current Lecture The 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 temperature o No increasing trend in the natural temperature without the influence of humans Climate Change Impacts Arctic Sea Ice Ice Sheets Glaciers Three Main sources of ice on Earth Arctic Sea Ice o Frozen sea water on the ocean surface o Fluctuates seasonally o Changes in Arctic Sea Ice over the past 35 years Decreasing in area These 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 Effect o Poles are becoming warming relative to the equator o Less of a temperature gradient between poles and equator o 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 surface o What scientists are doing Snow accumulation being measured on the surface Surface melting is being monitored daily by satellites o 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 Glaciers o 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 ice o Greatest amount of melting in response to Global Warming o Sensitive to small changes in temperature o Repeat photography is a qualitative way of measuring the changes happening in glaciers Sea Level Rise o Mostly related to melting of mountain glaciers and ice sheets o A large portion is also related to thermal expansion of ocean water related to global warming Sustainable City Assignment o 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 emissions
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