Constructed Climates: A Primer on Urban Environments Book

Preface
1 Cities and Nature Human population increased sixfold over the last century Water, warmth, and light make plants grow High evapotranspiration promotes biodiversity Humans exceed the natural population density for their body size The last century brought increased agricultural efficiency Fossil-fuel-based nitrogen production increased crop yields Urban land use grew as small farms disappeared Cities change ecological communities Agricultural and urban land use reduce streamwater quality Impervious surfaces in urbanized watersheds hurt organisms Durham rainfall exceeds regulated basin sizes Reservoirs reduce sediments while providing water
2 Shading and Cooling in City Climates Low vegetation correlates with high temperature in Durham Low vegetation correlates with high temperature in Indianapolis Low temperature correlates with high vegetation Urban heat islands spawn thunderstorms Cities change rainfall patterns Lightning strikes reflect urban weather changes Cities grow warmer Closed-in urban areas have higher heat islands The urban heat island may be weak while Earth warms Equal heat contained in air, a sprinkling of water, and an asphalt road Whiter surfaces are cooler Parking lot trees could provide shade Big trees could provide lots of shade Bigger and younger trees transpire more water Trees near asphalt stop transpiring early in the day Evapotranspiration is high from watersheds and lawns New developments can plan for shade Paving and grass can be combined
3 Energy Use and Carbon Budgets U.S. energy sources have changed States vary in their gasoline and electricity use Per capita energy use depends on a state’s population density Economic productivity correlates with energy use Photosynthesis links carbon, water, nitrogen, and sunlight Atmospheric CO2 increased with human emissions Global warming changes nature Species have different features in urban and rural environments Soils contribute to carbon budgets Vegetation stores and sequesters carbon Urban pruning can be very intensive Carbon costs of landscaping machines are high Durham citizens export their carbon sequestration Trees and white paint reduce energy consumption Trees help small houses keep cool and break even for heating Wood has low energy content Durham citizens use more energy than local forests can provide
4 Emissions and Urban Air Human sources of volatile organic compounds (VOCs) are high Fossil-fuel use produces many pollutants Trees produce VOCs VOCs produced by trees vary across the contiguous United States Trees produce more VOCs in bright light and high heat VOC sources vary in place and time VOCs, reactive nitrogen, and sunlight lead to ground-level ozone Large pollution inputs lead to high downwind ozone levels later Ozone production and levels have a complicated emissions dependence High ozone levels seenWednesday through Saturday, March through September Ozone in rural areas increases with temperature and nitrogen When it’s hot, urban ozone levels exceed regulatory allowances High ozone levels harm vegetation Air pollution varies greatly in space and time
5 Social Aspects of Urban Nature What’s the value of Chickpea?
S.A. Forbes (1880) estimates the value of birds Trees make satisfying neighborhoods People like neat trees, not messy forests Park features involving scenic beauty and perceived security Underbrush was bad as far back as 1285
About 10 out of 10 people prefer malls Varying tree cover in Chicago public housing Reduced vegetation correlates with higher crime Girls’ self-discipline develops better with nature Nature promotes emotional and physical health Trees promote bird and plant species richness
6 Human Health and Urban Inequities Heat waves lead to deaths a few days later Particulate matter is bad for older people High ozone and SO2 levels predict high asthma hospitalizations Asthma incidence and pollution aren’t tightly correlated through time Though cities differ, heat kills people in July and August Air conditioning reduces heat-related mortality Many people die in winter (accounting for age, race, and gender)
Lower income, fewer trees, and higher temperatures go together in Durham Wealth, homeownership, and trees connect in Milwaukee, Wisconsin Wealth, education, and vegetation correlate in Baltimore, Maryland Parks, trees, and plants come with wealth Minority populations have worse air, income, and asthma Healthier neighborhoods are usually wealthier neighborhoods Income helps education and increases life expectancy
7 Summary and Implications Appendix: Graphical Intuitions Three equivalent data representations Graphing visual correlations Importance versus significance Plotting transformed data Quantities covary Sample sizes and measures of variation

Notes References Index