CGS NS 202 Final: NS Final pt 6
16 May 2018
School
Department
Course
Professor
▪ Ex: england growing season shortened by 1-2
• Atmospheric Conditions
o Greenhouse gases
▪ CO2
▪ Miocene Epoch: 25 mya
▪ CO 2 level as high as today
o Methane and water vapor
o Soot in the atmosphere
▪ Volcanic events
▪ Asteroid impacts
• Human Activity and Climate Change
• Anthropogenic climate change: alterations in longer-term atmospheric conditions caused by human activities
• History of thought
o 1869: Svante Arrhenius
▪ Introduces idea that fossil fuel burning might increase CO2 levels
▪ Suggests this enhanced greenhouse effect
o 1958: Charles Keeling
▪ Develops accurate method for measuring CO2 in the atmosphere
▪ Evidence CO2 increasing in atmosphere each year
• Human Additions of Greenhouse Gases
o Agricultural Revolution
▪ Cutting and burning forests
▪ Domestication of cows and sheep (CH4)
o Iron Age
▪ Cut forests and burn wood to make charcoal for Iron Age furnaces
o Industrial Revolution
▪ Burning of Fossil Fuels
• Addition of carbon to the Atmosphere
o Coal, Petroleum and Natural Gas
▪ High energy carbon fuels produced and stored in prehistory
▪ Each year *25 billion tons of CO2 are added to atmosphere by burning fossil fuels
o Deforestation/Human Land Use
o Forest fires and burning of wood for fuel
▪ Black carbon: absorbs light and warms the atmosphere
▪ Falls on glaciers and snow
o Synthetic greenhouse gases
▪ CFC compounds
▪ Refrigerants, cleaning solvents, plastic foam products
▪ Absorb light 10,000-20,000x more than CO2
• Estimating Global Temperature
o Patterns of temperature variation in many locations
o Benchmark
▪ Average annual temperature over specific time interval
o Temperature Anomaly
▪ Difference between years average temperature and benchmark
▪ Positive anomaly: year is warmer than benchmark
▪ Negative Anomaly: year is cooler than benchmark
• A warmer planet
o Water absorbs more heat energy
▪ Accelerates ice melting
o Increased energy to atmospheric circulation cells
▪ Greater precipitation in some areas
▪ Intense drying in other areas
▪ Ecosystems will alter
• Increase of productivity due to nutrient addition
o Phytoplankton, algae, seaweeds, grow quickly on surface
o Cause dead zone below them
▪ Prevent light from penetrating surface
▪ Prevent oxygen from being absorbed by organism living beneath them
▪ Decomposition on sea floor uses up oxygen
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