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When worlds collide: urbanization,
climate change and disasters
Allen L. Clark, Ray Shirkhodai, and Joseph Bean, Pacific Disaster Center, USA
T
he world is constantly changing, but today this change
is more complex and uncertain than in the past. At least
four major processes – population growth, urbanization,
globalization and climate change – are converging to create much
more complex sets of challenges, particularly disaster risks.
To see the magnitude of these new challenges, consider this: while
population growth simply increases the exposure to hazards,
rapid urbanization (and especially development in marginal areas)
increases the vulnerability of those exposed. Worse yet, globali-
zation creates vulnerabilities in interdependent economies and
supply chains, while climate change drastically impacts ‘normal’
environmental conditions, amplifying the severity and frequency
of hydrometeorological hazards such as floods, drought, storms
and so on.
Managing the dramatically increasing scope and complexity of
disaster risks overall, and those associated with urban areas in
particular, presents two major challenges:
• How to approach present and future impacts of climate change
• How to simultaneously address the existing and future
challenges of evolving natural and human-induced disasters.
Drivers of urban risks
Population growth, urbanization, globalization and climate
change individually and collectively are major contributors to
increasing urban risk.
Population increased from 1 billion in 1804 to 3 billion in 1950,
continuing to increase at a rate of 1 billion every 15 years to reach
7 billion in 2012. Significant proportions of this increase have
been absorbed into rapidly expanding, often high-risk urban areas
in developing countries – areas that are growing five times as fast
as cities in developed countries.
In 2007, urbanization marked a turning point in history. Over
50 per cent of the world’s population lives in cities. That is
projected to increase to 60 per cent by 2030. Already, 1.5 billion
live in the 776 urban areas of more than 1 million inhabitants.
Within this urban population approximately 60 per cent, or 890
million people, live in areas of high risk and exposure to at least
one natural hazard.
Flooding is the most frequent and greatest hazard for the 633
largest cities and urban agglomerates.
1
Drought is the second most
frequent hazard, followed by cyclones and earthquakes. Among
the 63 most populated urban areas (>5 million inhabitants) 39
are in locations exposed to risk from at least one natural hazard,
with 72 per cent on or near a coastline. More than a quarter of
these cities are in Asia.
U
rban
I
ssues
Globalization, through its creation of linked econo-
mies, production and supply chains, transportation
and communication networks, and contributions to
greenhouse gas (GHG) emissions, extends disaster
impacts beyond the immediate localities where they
occur. Floods in Southeast Asia cause US auto produc-
tion to stall, and drought in the US puts food security
in Asia at risk.
Climate change, which has the potential to damage
every natural and human system on the planet, is argu-
ably the greatest challenge facing humanity. The scale
and scope of needed action is hugely varied. At present,
the main response to climate change worldwide is
focused on mitigation, especially the lowering of GHG
emissions across a variety of scales.
2
Unfortunately, to
date, effective and collective global action is lacking and
some climate change effects are now inevitable.
3
Their
impact will likely be felt to an increasing degree over
the coming decades and beyond, presenting enormous
challenges for the disaster management community.
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