Ecology & Environmental Problems

Ron Chesser

Urban Ecology

Chapters 6, 27

Did You Know Your City is actually PLANNED?

• Neighborhood plans establish guidelines for the physical, environmental, and socioeconomic development of the community.

City Planning Foci

• Public SpacePhysical community space, including parks, plazas, open space, and gardens that reflect the community's social, cultural and historical characteristics.

City Planning Foci

• StreetsNeighborhood streets and sidewalks that are calmed by prioritizing pedestrians, bicycles, and public transportation.

City Planning Foci

• The Built FabricThe design of new and reused public and private buildings to serve neighborhood needs and establish a sense of place.

City Planning Foci

• Economic DevelopmentThe revitalization of neighborhood commercial districts through specific design recommendations, such as building fronts and sidewalks, and design and policy recommendations for increasing residential density to establish a local customer base.

City Planning Foci

• The Natural EnvironmentDesign incorporates an ecological sensibility. Design and policy recommendations that support natural systems, such as local food production, the use of renewable energy, and recycling.

Biodiversity in the Urban Environment

• Biodiversity refers to the number of different forms of life (plant and animal species) living in an area.

• By examining the level of biodiversity in a region, we can assess the health of the natural environment.

• Higher levels of biodiversity mean that ecosystems are better able to deal with disturbance.

• Past biodiversity research projects have ranged from inventorying biodiversity in parks to developing new methods for measuring biodiversity in large metropolitan areas.

Lubbock City Planning

• http://planning.ci.lubbock.tx.us/2002P&E/MainIndex3.htm

Energy Flow in Urban Environments

• Inputs– Air– Water– Food– Fuels– Raw Materials– People

• Outputs– Ideas– Waste heat– Finished goods– Wastewater– Solid wastes (landfills)– Air pollutants

Heat Island

Los Angeles

With increasing irrigation and orchards, Los Angeles cooled until major urban development began. (The pronounced temperature depression in the late 1880-90's is due to the a volcanic eruption.) Temperatures are ten-year averages, including the previous four years and the following five.

Heat Island in Los Angeles

– Air conditioning demand increased as temperatures increased.

– On warm afternoons, the demand for electric power rises nearly 2% for every degree Fahrenheit the daily maximum temperature rises. Also, peak power rises 3% for every 0.5°F rise in daily maximum temperature.

– In total, we estimate that about 1-1.5 gigawatts of power are used to compensate the impact of the heat island in a city like Los Angeles.

– This increased power costs the Los Angeles ratepayers about $100,000 per hour, about $100 million per year.

Urban Island-Temperature & Smog

• As power plants burned more fossil fuels, they increased both pollution levels as well as energy costs.

• The impact of these pollution levels is seen in smog. The formation of smog is highly sensitive to temperatures; the higher the temperature, the higher the formation and, hence, the concentration of smog.

• In Los Angeles at temperatures below 70°F, the concentration of smog (measured as ozone) is below the national standard. At temperatures of about 95°F all days are smoggy. Cooling the city by about 5°F would have a dramatic impact on smog concentration.

                                                             

About 40% of the area in the LA basin is covered by buildings and roads which could realistically be made 30% more reflective during their next resurfacing. If this were done, summer temperatures in LA at 3 p.m. on August 27 could become 5 to 9°F (or 3 to 5°C) lower. Then LA would consume 1/2 to 1 GW less in peak power, energy worth at least $100,000 per hour. Most areas would also have improved air quality, and the population-weighted average predicts an ozone reduction of 10 to 20% overall.

Pavement Albedo

"Albedo" or reflectivity is the ratio of the amount of light reflected from a material to the amount of light shone on the material. In the case of pavements, a lower albedo suggests that more sunlight in absorbed by the pavement. This sunlight is converted into thermal energy and the pavement gets hotter. Pavements with higher albedos albedo less energy and are thus cooler.

Urban Islands

• What Are Problems with the "Heat Island Effect?" – The higher temperatures in urban heat islands

increases air conditioning use and raises pollution levels.

Urban Islands

• What Causes an Urban Heat Island? – Causes of the "heat island effect" include dark

surfaces--that absorb more heat from the sun--and less vegetation that would provide shade and cool the air.

Are Food Webs in Cities Stable?

Exam on Thursday

• Chapters 6,19, 20, 23, 27• Chernobyl as an Environmental Disaster• Nuclear Power• Acid Rain• Water Resources• Air Pollution• Urban Environments• Ecosystems