Climate Change Stratosphere made up of gases that trap radiation (heat) from earth’s surface, causing it to be warmer than otherwise Acts like greenhouse, sunlight let in but not all radiation let out Natural effect that is vital to human life

Increasing greenhouse gases are related to an estimated warming of the earth of 0.3 degrees (celsius) per decade. This is much greater than estimate rate of change during previous periods of warming and cooling (0.05 degrees celsius)

Effects (Damage) of Climate Change Sea levels expected to rise due to melting ice in polar regions Coastal regions forced to adapt Island Nation Changes in agriculture; rising temperature may change location of crops Many poor countries largely dependent on agriculture Effects expected to be negative but actual changes are unknown Changes in ocean current

Scientists link increase in greenhouse gases to human activity Many human activities (such as exhaling) involve emission of greenhouse gases Increase in greenhouse gases linked to economic activity involving burning of fossil fuels

Carbon Dioxide is the most important greenhouse gas in stratosphere CO2 in the atmosphere has grown by 20% over the last 250 years In the last 30 years alone it has grown 8%

Urbanization and Greenhouse Gases A large part of the human contribution to CO2 emissions: A. Household consumption B. Household transportation Activities involving consumption of energy (fossil fuels)

Household Consumption Weather conditions responsible for substantial part of variation in household energy use A. Heating in winter B. Cooling in summer Household Transportation Differences across urban areas in commuting distance is a large determinant of variation in household transportation

The Greenness of Cities: Carbon Dioxide Emissions and Urban Development by Glaeser and Kahn - examines how the location and form of US cities affect CO2 emissions

Relationship between transportation and CO2 comes mainly in form of burning gasoline Using National Household Transportation Survey data, study finds gasoline consumption is: positively related to household income and size positively related to the household’s distance from the CBD inversely related to the population density of the census tract the household is located in inversely related to the density of the metropolitan area

Household Gasoline Consumption in Urban Areas Uses the average family with 2.62 members and income of $62,500 Predicts gasoline usage for the family in each urban area Prediction derived from placing average family in each census tract in urban area and simulating gasoline use Variation in predictions comes from differences in form of urban area Graph

Households and CO2 Emissions Household use of natural gas, electricity estimated by urban area Home heating, electricity influenced by climate Relationships generated by placing the average household in the various urban areas Graph

Ranking Urban Areas Table ranking urban areas Western urban areas more likely to consume electricity from nuclear, hydro, wind  Conversion of household energy use to CO2 takes source and region into account Gasoline consumption converted to 23.46 lb of CO2 per gallon consumed Table ranking urban areas