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Archive for the ‘urban’ Category


Just add water…

Monday, November 1st, 2010

An amazing night-time photo from the International Space Station showing how human settlement along the Nile River and Delta stand out against the Sahara Desert (shot by Astronaut Doug Wheelock). Click here for a larger image.


Courtesy of EMP via Gizmodo via Astro_Wheels via defcon_5

Posted in energy, nature and culture, urban, water | No Comments »

New analysis of population trends and their impact on global greenhouse gas emissions

Tuesday, October 12th, 2010

In 40 years, there will be about 3 billion additional people living on the Earth (~9.5 billion total).   With all of these new folks, it’s easy to think about the added demands of energy, food, and water required to sustain their lifestyles.  And in terms of climate warming, it’s hard to escape the fact that significantly greater energy consumption will lead to rising rates of carbon emissions, unless there’s a shift to decarbonize the economy.

In this week’s early Edition of the Proceedings of the National Academy of Sciences (open access), Brian O’Neill and colleagues note that emissions are not just controlled by the sheer size of the human population but also by important demographic changes.

For example, how might an aging or more urban population affect emissions?  How about changes in household size?  Modelers of carbon emissions don’t usually ask these kinds of questions, so the conventionally projected emissions might be off if these additional demographic details matter.

The researchers developed a global economic model (Population-Environment-Technology, or PET) in which they specified relationships between demographic factors like houshold size, age, and urban/rural residency and economic factors like the demand for consumer goods, wealth, and the supply of labor.  Here’s a bit more on how this works:

In the PET model, households can affect emissions either directly through their consumption patterns or indirectly through their effects on economic growth in ways that up until now have not been explicitly accounted for in emissions models. The direct effect on emissions is represented by disaggregating household consumption for each household type into four categories of goods (energy, food, transport, and other) so that shifts in the composition of the population by household type produce shifts in the aggregate mix of goods demanded. Because different goods have different energy intensities of production, these shifts can lead to changes in emissions rates. To represent indirect effects on emissions through economic growth, the PET model
explicitly accounts for the effect of (i) population growth rates on economic growth rates, (ii) age structure changes on labor supply, (iii) urbanization on labor productivity, and (iv) anticipated demographic change (and its economic effects) on savings and consumption behavior.

Although there are some exceptions, households that are older, larger, or more rural tend to have lower per capita labor supply than those that are younger, smaller, or more urban. Lower-income households (e.g., rural households in developing countries) spend a larger share of income on food and a smaller share on transportation than higher-income households. Although labor supply and preferences can be influenced by a range of nondemographic factors, our scenarios focus on capturing the effects of shifts in population across types of households.

To project these demographic trends, we use the high, medium, and low scenarios of the United Nations (UN) 2003 Long-Range World Population Projections combined with the UN 2007 Urbanization Prospects extended by the International Institute for Applied Systems Analysis (IIASA) and derive population by age, sex, and rural/urban residence for the period of 2000–2100.

What did they find?


Posted in behavior, climate economics, energy, gender, population, sustainability, urban | No Comments »

City dwellers of the future: Urban heat island warming may be as large as doubling CO2

Monday, April 19th, 2010

I remember driving on a freeway in Phoenix after midnight in 1990.  The temperature was a cool 102 degrees F after breaking the all-time heat record of 126 F that day.  Deserts are good at cooling off at night.  But with all of the built environment in Phoenix storing heat from the day, the sidewalks, roads, and even swimming pools felt like they were being heated.

We all have probably experienced urban heat islands—the mass of dark asphalt and concrete absorbing solar radiation and radiating it back to space as heat.  The lack of water exacerbates the situation because there is little-to-no evaporative cooling.  Waste heat from cars, machines, air conditioners, and even human bodies also heat up the air.  And the warmer it gets, the stronger the tendency to crank up the air conditioners, generating even more waste heat.

The problem is potentially large in areas like the Middle East, India, parts of Africa, and the American Southwest, where rapid urbanization in warm, dry environments has the potential to make some urban areas much warmer at night than surrounding rural areas.

In a forthcoming article in Geophysical Research Letters1, Mark McCarthy and colleagues at the Met Office, Hadley Centre, UK used a climate model that examines what climate might look like in a doubled CO2 world and calculates the added warming caused by urbanization and wasted heat.

Their results were eye-opening:

  • Urban regions in places like the Arabian Peninsula, Iran, and India may experience night time warming by as much as 3-5 degrees C above and beyond that caused by doubled CO2 alone.
  • The number of hot nights per year (defined as temperatures in the 99th percentile of nonurban areas) increase in the following cities:
    • London: 1-2 hot nights now vs. up to 10 hot nights in 2050
    • Sydney: 1-2 hot nights now vs. up to 15 hot nights in 2050
    • Delhi: 5-10 hot nights now vs. up to 30 hot nights in 2050
    • Beijing: 3-6 hot nights now vs. up to 50 hot nights in 2050
    • Los Angeles: 8-12 hot nights now vs. up to 40 hot nights in 2050
    • Tehran: 20 hot nights now vs. up to 60 hot nights in 2050
    • Sao Paulo: <5 hot nights now vs. up to 80 hot nights in 2050
    • Lagos (Nigeria): <5 hot nights now vs. up to 150 hot nights in 2050

As mentioned in an earlier post, we only need to remember Chicago in 1995 to recall the deadly impact that heat waves can have on urban people.  And as we saw in that unfortunate example, the victims were disproportionately the elderly and African American.

Although we may not be able to mitigate this warming, basic adaptation steps should be set into motion, including re-thinking urban design, making cities more resilient to hot environments, developing better energy and technology solutions (including cooling), installing green roofs, and putting into place emergency disaster plans and social safety nets for vulnerable populations.

1Mark McCarthy, Martin Best, and Richard Betts (2010). Climate change in cities due to global warming and urban effects Geophysical Research Letters : 10.1029/2010GL042845

Photo Credit: / CC BY-NC-ND 2.0

Posted in climate adaptation, climate change science, energy, environmental justice, health, land use, population, race and class, sustainability, technology, urban | 3 Comments »

Land consumption and open space loss across U.S. cities

Tuesday, March 2nd, 2010

The issue of land use change is a complex, with many factors being important historically, such as

  • population growth (more land required for more people)
  • technology (e.g., automobiles made suburban expansion feasible)
  • economics (cheaper land and rents in suburbs compared to cities)
  • policy (things like 30-yr mortgages, mortgage insurance, and FHA loans had a large impact on urban sprawl because they often made it cheaper to own rather than rent)
  • cultural values (the romanticized notion of a detached home in a safe, pollution-free neighborhood with good schools)

In this week’s PLoS One, Robert McDonald and colleagues1 examined land use change for 274 metro areas (figure 1) in the U.S. to determine tends across cities.

Their results were interesting (excerpts):

  • 1.4 million ha of open space was lost, and the amount lost in a given city was correlated with population growth.
  • American cities vary by more than an order of magnitude in their MSA-wide per capita land consumption. Generally large cities have small per capita land consumption, with the five smallest in 2000 being New York (459 m2/person), Miami (476 m2/person), Philadelphia (519 m2/person), Los Angeles (535 m2/person), and Washington, DC (536 m2/person). Conversely, many small cities have large per capita land consumption, with the five biggest in 2000 being Grand Forks, ND (5394 m2/person), Bismark, ND (3913 m2/person), Flagstaff, AZ (3381 m2/person), Enid, OK (3249 m2/person), and Cheyenne, WY (3073 m2/person).
  • The per capita land consumption (m2/person) of most cities decreased on average over the decade from 1,564 to 1,454 m 2/person, but there was substantial regional variation and some cities even increased.
  • Cities with greater conservation funding or more reform-minded zoning tended to decrease in per capita land consumption (scroll to table 1) more than other cities.
  • The inequality of land consumption varied geographically, with less inequality on the East Coast compared to the West Coast (scroll to figure 4).

They provide a simplified snapshot of how development changes with history and geography (for a more-thorough yet readable treatment of land use in the U.S., check out Crabgrass Frontier by Kenneth Jackson):

The process of development plays out differently in cities with different socioeconomic histories. Moreover, cultural differences exist among and within many U.S. cities, leading to varying spatial patterns of development. However, a general historical pattern exists. In many U.S. cities, an urban core existed in the decades or centuries prior to the widespread use of the automobile, and these neighborhoods have high population density and small amounts of developed area per capita. The surrounding suburban and exurban areas, created predominately after WWII, contain residents living at lower population density and consume more land per capita. There are substantial economic links between these two zones, and in contemporary U.S. cities commuting occurs in both directions. Northeast U.S. cities that developed before the automobile typically follow this narrative. Many have a relatively dense urban core, but have adopted zoning policies that ensure contemporary suburban settlements occur at lower density. While they remain dense compared to other U.S. cities, they are getting less dense over time, as proportionally more of the population is in suburban areas. The declining manufacturing cities of the Rust Belt and the Southern Appalachians are an extreme example of this spreading out of population.

Southeastern U.S. cities, excluding Florida, are often newer and have less of a legacy of a dense urban core. They do not appear to be getting markedly denser, and the relatively fast population growth of these cities implies that their total impact on natural habitat in coming decades will be large. In contrast to the Southeast, Western cities appear to be getting denser, including those that do not have a historical legacy of a dense urban core such as Phoenix. These Western cities are often still growing quickly and consuming a great deal of land, but contemporary development is making these cities denser than they were previously. Many of these Western cities have a strong conservation culture, and the degree of conservation funding and reform-minded zoning correlates with how much denser they are getting. However, it should be noted that contemporary development in Western cities is still well below the densities found in the dense urban core of Northeastern U.S. cities, posing problems for designing effective public transit systems.

1McDonald, R., Forman, R., & Kareiva, P. (2010). Open Space Loss and Land Inequality in United States’ Cities, 1990–2000 PLoS ONE, 5 (3) DOI: 10.1371/journal.pone.0009509


Photo Credit: / CC BY-NC 2.0

Posted in behavior, land use, nature and culture, policy, population, sustainability, transportation, urban | 1 Comment »

Innovative ideas for financing home energy efficiency

Wednesday, December 9th, 2009

3189763520_b63667bc3dLet’s face it, how many people have a spare $10k lying around for a new furnace?  Not me, and I could use a new furnace.

Home weatherization and efficiency upgrades can make a big difference in U.S. carbon emissions.  As we saw in a previous post, American households (including personal transportation) are responsible for

  • 38% of the overall US carbon emissions
  • 8% of global emissions
  • more emissions of any single country except China

Unfortunately, there’s a big disconnect between things we can do to to save home energy and the ability for folks to pay for these improvements. New insulation, solar hot water, solar photovoltaics, high-efficiency furnaces: Take your pick….Each can cost $10k or more.

Fortunately, there are a lot of creative ideas coming to the rescue to help people defray these up-front costs:

  • Municipalities can issue bonds that homeowners can borrow from to pay the up-front costs of improvements.  The costs of these improvements are then payed back over an extended periods of time through raised property taxes.  Homeowners effectively get a zero-interest loan from their cities.
  • Banks can issue higher mortgages that include up-front costs for major energy efficiency improvements.  These added costs are then spread out over the life of the mortgage, resulting in manageable monthly payments for homeowners.
  • Or, the federal government can simply reimburse people for part of the costs of improvements.  The so-called “Cash for Caulkers” program reported today by CNN is an example.

These kinds of programs make a lot of sense and have the potential to be game changers, along with helping Americans transition to electric vehicles as soon as possible.

Related post:  Behavioral changes at home can have big impacts on U.S. emissions


Photo credit: / CC BY-NC 2.0

Posted in energy, policy, solutions, sustainability, urban | 1 Comment »

This week’s good ideas in campus sustainability: 11/9/09

Monday, November 9th, 2009


Let’s take a look at five innovative and exciting ideas from Stanford University, City College of New York,  Western Michigan University, UC-Davis, and the University of Arizona…


Posted in campus sustainability, environmental literacy, environmental science, higher education, sustainability, sustainable development, technology, transportation, urban | 1 Comment »

Chicago 1995: How social disparities lead to environmental disasters

Thursday, October 29th, 2009


As I mentioned in the last post, heat waves have the potential to harm or kill a lot of people.  Who are the people most likely to suffer first? The experiences from the Chicago 1995 heat wave offer some insights for urban America.  Eric Klinenberg’s 2002 book Heat Wave: A Social Autopsy of Disaster in Chicago is as relevant as ever to the current conversation about climate change.

Some excerpts from a U. Chicago Press interview with Klinenberg.

The heat made the city’s roads buckle. Train rails warped, causing long commuter and freight delays. City workers watered bridges to prevent them from locking when the plates expanded. Children riding in school buses became so dehydrated and nauseous that they had to be hosed down by the Fire Department. Hundreds of young people were hospitalized with heat-related illnesses. But the elderly, and especially the elderly who lived alone, were most vulnerable to the heat wave.

“It’s hot,” the mayor told the media. “But let’s not blow it out of proportion. . . . Every day people die of natural causes. You cannot claim that everybody who has died in the last eight or nine days dies of heat. Then everybody in the summer that dies will die of heat.” Many local journalists shared Daley’s skepticism, and before long the city was mired in a callous debate over whether the so-called heat deaths were—to use the term that recurred at the time—”really real.”

[T]he black/white mortality ratio was 1.5 to 1.

Another surprising fact that emerged is that Latinos, who represent about 25 percent of the city population and are disproportionately poor and sick, accounted for only 2 percent of the heat-related deaths…Chicago’s Latinos tend to live in neighborhoods with high population density, busy commercial life in the streets, and vibrant public spaces. Most of the African American neighborhoods with high heat wave death rates had been abandoned—by employers, stores, and residents—in recent decades. The social ecology of abandonment, dispersion, and decay makes systems of social support exceedingly difficult to sustain.

The heat wave was a particle accelerator for the city:  It sped up and made visible the hazardous social conditions that are always present but difficult to perceive. Yes, the weather was extreme. But the deep sources of the tragedy were the everyday disasters that the city tolerates, takes for granted, or has officially forgotten.

Related Post: Say so long to your furnace and hello to a new air conditioner

photo credit: / CC BY-ND 2.0

Posted in climate adaptation, environmental justice, race and class, social science, urban | 3 Comments »

Defining the good life in Baltimore

Tuesday, October 13th, 2009


Defining and describing what constitutes “the good life” for individuals and communities has been a vexing challenge for social scholars…

So begins a recent article1,2 in Environment and Behavior (subscription required)

…[T]he term “life satisfaction”, which comes from the psychological literature, refers to the cognitive evaluation of one’s happiness or subjective wellbeing and involves comparing the fulfillment of individual needs, goals, and aspirations to a meaningful standard.

One unique aspect of this study was that the team used surveys to assess people’s life satisfaction at two different scales: (1) their own lives and (2) their neighborhoods.

Bottom line:

  • Income and home ownership mattered more to individual satisfaction compared to satisfaction with neighborhoods.
  • In contrast, neighborhood satisfaction was more strongly correlated with social capital (shared knowledge, norms, rules, and networks that facilitate collective experience) and satisfaction with the natural environment in the neighborhood.
  • These results corroborate a large body of prior research indicating that wealth alone is not the only explanation for life satisfaction–our communities and environments matter as well.
  • Given that more people now live in urban environments than at any point in human history, this speaks to the need for (re)developing cities to promote green spaces and social networks.

1Vemuri, A., et al. (2009) A Tale of Two Scales: Evaluating the Relationship Among Life Satisfaction, Social Capital, Income, and the Natural Environment at Individual and Neighborhood Levels in Metropolitan Baltimore. Environment and Behavior, (Online First edition).

2Bowdoin people can link to the article here.

photo credit: / CC BY-NC-ND 2.0

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Posted in race and class, social science, urban | No Comments »

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