How Urbanization Can Save(or Wreck) the Planet

(and the science we need)

Karen C. SetoAssociate Dean of Research

Professor of Geography and Urbanizationkaren.seto@yale.edu

Sustainable City SymposiumMay 19, 2015

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

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Urban areas generate 80% of global GDP.

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Urban areas use ~70% of global energy.

Where to “save” from urbanization?

habitats

agricultural landforests

renewable energy potential

Where to “save” urbanization?

sea level rise

extreme heat

sinking deltas

extreme precipitation

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Challenge 1: Single sector solutions

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Strong scientific understanding of individual components of cities

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

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 CO2 emissions due to concrete used in building construction.

82% increase35% decrease

(Guneralp and Seto. 2012)

More space to cool

(Guneralp and Seto. 2012)

Transition to sustainability cannot solely rely on technological improvements

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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 Houses1973-2013

(source: US Census )

19731975

19771979

19811983

19851987

19891991

19931995

19971999

20012003

20052007

20092011

20130

500

1,000

1,500

2,000

2,500

3,000

1525

2598

Squa

re F

eet

Liu et al. (2003)

Around the world, household size is declining

More households, bigger homes, global impacts

DrivesLocal and Global

Environmental Change

Climate change

Land use change

Loss of biodiversity

Water pollution

Air pollution

Inefficient resource use

Urbanization as Crisis for Sustainability

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

ImprovesPlanetary & 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

% P

op in

Ag

Income per Capita

Save land for nature

Total CO2 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 Thünen Burgess Alonso Mills Isard

Jacobs Mumford Fujita Friedmann Hall

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 theimpacts of cities and urbanization

http://www.yale.edu/yup/pdf/081979_front_1.pdf

Planetary urbanization requires rethinking urban impacts and sustainability

32(Elmqvist et al. 2013; Seto et al., 2012)

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“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, 1992

Thank you for your attention.

http://urban.yale.edu