RSS Feed
No RSS feeds have been linked to this section.

Science for Cities




NASA, 2010

Urban Sustainability Tools and Modeling

Humanity’s Ecological Footprint

Meredith Stechbart, Project Manager at Global Footprint Network, talked about humanity’s Ecological

Footprint in a severely resource-constrained future. Key questions include how much

regenerative capacity do we use?, how long can we overuse?, and what are the consequences of

overuse? She looked at the problem starting from the standpoint of the global system. She noted

that of the 51 billion hectares (1 hectare = 10,000 square meters) of surface area on the Earth, only

20% is biologically productive land. The remainder is 67% low productivity ocean, 4% biologically

productive ocean (continental shelf area), and 9% deserts, barren land, or icecaps.

To determine the Ecological Footprint, it is necessary to account for all components of the Foot

namely forest land, grazing land, cropland, built-up land, and fishing ground. It also requires


a look at the amount of forested land that would theoretically be needed to store the carbon dioxide

emissions created by humanity in that year. The process requires turning resource consumption

and waste creation into the associated land area to assimilate that activity. When you add up all the

components of the Footprint for all nations of the world, you get humanity’s Ecological Footprint.

Unfortunately, as shown in figure 6, our current Ecological Footprint is equivalent to about 1.3

Earths. The Ecological Footprint varies significantly across nations. The United Arab Emirates

and the United States have the largest Footprint (~9.5 global hectares per person, where a global

hectare represents world average land productivity). For comparison, the Ecological Footprint in

China is about 2 global hectares per person, compared with the biocapacity of Earth, which is 2.1

global hectares per person. This difference between the global Ecological Footprint (demand) and

global biocapacity (supply) is known as overshoot. We need to close this gap between demand and

supply if we are to have a sustainable future.


Stechbart discussed briefly an entrepreneurial charity based in the United Kingdom, Bioregional, that

is working through its “One Planet Living” program to build practical solutions to enable healthy

lives within our fair share of the Earth’s resources. The concept is based on high-density, energy

efficient housing that incorporates live-work opportunities to reduce the Footprint of people living

in the community. She ended by noting that further information on her organization, Global Footprint

Network, and its work to advance the science of sustainability can be found on the Internet at


System Dynamics of Urban Climate, Electricity, and Human

Health Issues

Dr. Jonathan Fink presented a contribution from Dr. Jay Golden, Professor in the School of Sustainability

at Arizona State University, concerning work of the National Center of Excellence on SMART

Innovations at Arizona State University (http://asusmart.com/). The goal of the Center is to provide

climate and energy solutions based on sound science and engineering to governments and industries

around the world. The Center provides local and regional governments a greater understanding of

neighborhoods with enhanced vulnerability to heat-island effects, such as heat-related health problems

and power interruptions.

The Center has used the Advanced Spaceborne Thermal Emission and Reflection Radiometer

(ASTER) on the Terra satellite to examine and track 911 calls (equivalent to heat health in Phoenix)

in relation to surface kinetics, vegetation, etc. to evaluate how the built environment influences health

vulnerability. The Center has carried out an analysis of power outages in Chicago to understand the

role that urban morphology (the study of the physical form of a city) has in driving power outages and

related health and crime vulnerabilities. NASA satellites are used in these studies, but are augmented

with remote sensing from helicopters when the thermal resolution from satellites is not adequate.

High-resolution images of land cover are needed to make substantive material and design recommendations

for urban areas. To reduce environmental and human health impacts and improve sustainability

requires detailed and vegetated material types of land cover in the models. A repository of

the thermal and radiative properties of urban materials is being created to improve the fidelity of the

models. Improved accuracy in the models will enable studies of urban climate change, storm water

quality, air quality, heat health, and electricity vulnerability, etc.

A new virtual organization called Heat-Waves.org that is working to quantify and reduce the impacts

of heat waves was discussed. Their web site (http://heat-waves.org) is designed to bring a national

community of researchers together to more effectively track the number of heat related morbidity

and mortality incidents, and to explore how regional energy, climate, physical morphology, socioeconomic

and governmental policies affect the occurrence of these incidents.

The presentation concluded by re-emphasizing several key points. First, there is a great need for a

“dedicated” urban satellite with higher resolution. Secondly, existing sustainability models need a

much better understanding of the engineered infrastructure and more fine-grained land cover. Finally,

there is a growing demand by regional governments to use existing sustainability models to plan

future development and to understand the tradeoffs of future scenarios.

Science for Cities click right