How Urbanization Can Save (or Wreck) the Planet (and the science we need) Karen C. Seto Associate Dean of Research Professor of Geography and Urbanization Sustainable City Symposium May 19, 2015

From now until 2050, the global urban population will increase by 1.3 million every week. 2

Urban areas generate 80% of global GDP. 3

Urban areas use ~70% of global energy. 4

Where to “save” from urbanization? habitats agricultural land forests renewable energy potential

Where to “save” urbanization? sea level rise extreme heat sinking deltas extreme precipitation

Challenge 1: Single sector solutions 7

Strong scientific understanding of individual components of cities 8

Weak scientific knowledge of complexities, dynamics, and interdependencies among components 9

Example: Gains in energy efficiency overshadowed by scale of urban expansion A 25% decrease in energy required per tonne of concrete in China. A 300% increase in annual CO 2 emissions due to concrete used in building construction.

82% increase 35% decrease (Guneralp and Seto. 2012)

More space to cool (Guneralp and Seto. 2012) Transition to sustainability cannot solely rely on technological improvements

13 Challenge 2: Planetary limits, non-local impacts

Example: Demographic and cultural changes + urbanization lead to increased resource demand Decline in HH size Increase in # HHs

Average Size of New U.S. Single-Family Houses (source: US Census ) Square Feet

Liu et al. (2003) Around the world, household size is declining

More households, bigger homes, global impacts

Drives Local and Global Environmental Change Climate change Land use change Loss of biodiversity Water pollution Air pollution Inefficient resource use Urbanization as Crisis for Sustainability

Can cities and urbanization save the planet? (And if so, how?) 20

Improves Planetary & Human Well-Bring Lower per capita resource use Health services, clean water, & sanitation Efficient infrastructure use Innovation Engines of economic growth Urbanization as Opportunity for Sustainability % Pop in Ag Income per Capita Save land for nature

Total CO 2 emissions (per capita) needed to build up today’s infrastructure More infrastructure will be built over the next forty years than currently exists

Future CO2 emissions if world infrastructure increases to average developed country level

Aren’t cities more efficient than rural settlements?

The Need for Urban Systems Science Are we currently in a fundamentally different era of urbanization from the past? If yes, what do existing theories tell us?

von ThünenBurgessAlonso MillsIsard JacobsMumfordFujitaFriedmannHall

Beijing - Area: 16,800 km2 - Population: 21.5 million Shanghai - Area: 6,300 km2 - Population: 25 million

Australia - Area: 7.7 million km2 - Population: 23 million

Do our theories and models reflect and capture contemporary processes? The Need for Urban Systems Science

Plate Tectonic Theory: 1912, 1960s

Dominant perspective on the impacts of cities and urbanization

Planetary urbanization requires rethinking urban impacts and sustainability 32 (Elmqvist et al. 2013; Seto et al., 2012)

“The battle to ensure that our planet remains a hospitable and sustainable home for the human species will be won or lost in the major urban areas.” – Maurice Strong, Secretary General UN Conference on Environment and Development,

Thank you for your attention.